Ex Parte Knudson

Board of Patent Appeals and Interferences

Aug 8, 2012

11024181 (B.P.A.I. Aug. 8, 2012)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
11/024,181 12/28/2004 John C. Knudson 0B-046500US 3140
55714 7590 08/08/2012
ST. JUDE MEDICAL, ATRIAL FIBRILLATION DIVISION
Legal Department
One St. Jude Medical Drive
St. Paul, MN 55117-9913
EXAMINER
MEDWAY, SCOTT J
ART UNIT PAPER NUMBER
3763
MAIL DATE DELIVERY MODE
08/08/2012 PAPER
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
__________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________

Ex parte JOHN C. KNUDSON
__________

Appeal 2011-005633
Application 11/024,181
Technology Center 3700
__________

Before ERIC GRIMES, FRANCISCO C. PRATS, and
JACQUELINE WRIGHT BONILLA, Administrative Patent Judges.

BONILLA, Administrative Patent Judge.

DECISION ON APPEAL
This is an appeal under 35 U.S.C. § 134 involving claims directed to
an actuating assembly for a catheter. The Examiner has rejected the claims
as anticipated and obvious. We have jurisdiction under 35 U.S.C. § 6(b).
We reverse, but enter a new ground of rejection under 37 C.F.R. § 41.50(b).
App
App

incre
Spec

Figu
and a
[004
eal 2011-0
lication 11
The Spe
ases the le
ification a
re 1 presen
ctuator 30
2] – [0046
05633
/024,181
ST
cification
ngth of tra
re reprodu
ts a persp
movably
].) Figure
ATEMEN
describes a
vel of actu
ced below

ective view
mounted t
5 depicts
2
T OF TH
catheter h
ation wir
.

of cathet
o actuatio
a plan view
E CASE
aving an
es. Figure
er 10, flex
n handle 1
of an em
actuator th
s 1, 5 and
ible hollow
4. (Spec.
bodiment
at
7 in the

body 12
[0026],
of handle

,
Appeal 2011-005633
Application 11/024,181

3
14, and Figure 7 depicts an exploded perspective view of the actuation
mechanism of the handle. (Id. at [0032], [0034].) Figures 5 and 7 both
show actuator 30, gear rack 54, “one or more pulleys (i.e., a pulley
assembly) 48,” and pinion gear 50 mounted on axle 52. (Id. at [0054] –
[0056].)
Claims 10-17 and 26-29 are on appeal. Independent claims 10 and 26
are representative and read as follows:
10. A portable handheld device directly mechanically
manipulated by an operator of a cardiac catheter including first and
second actuation wires, the assembly comprising:
an actuator moveably coupled to a handle and adapted to be
directly mechanically manipulated by an operator;
a pulley assembly pivotally attached to the handle and including
a first channel for receiving the first actuation wire and a second
channel for receiving the second actuation wire; and
a rack secured to the actuator and engaged with an engagement
portion of the pulley assembly,
wherein when the actuator is manually displaced relative to the
handle, the engagement between the rack and the pulley assembly
causes the pulley assembly to pivot relative to the handle.
26. A portable handheld device directly mechanically
manipulated by an operator of a cardiac catheter including first and
second actuation wires, the assembly comprising:
an actuator pivotally coupled to a handle; and
means devoid of electrical circuitry for converting pivotal
motion of the actuator into linear displacement of the actuation wires.
Appeal 2011-005633
Application 11/024,181

4
Independent claim 27 recites an assembly comprising, inter alia, “a first rack
in engagement with the first engagement portion and adapted to displace
generally laterally relative to the handle.”
The claims stand rejected as follows:
• claims 10-12, 15, 17 and 26-29 under 35 U.S.C. § 102(b) as
anticipated by Takayama (U.S. Pat. No, 4,559,928, issued Dec. 24, 1985).
• claims 13 and 14 under 35 U.S.C. § 103(a) as obvious over
Takayama.
• claim 16 under 35 U.S.C. § 103(a) as obvious over Takayama in
view of Heinzelman et al. (U.S. Pat. No. 5,364,351, issued Nov. 15, 1994).
I.
Issues
Does the Examiner establish by a preponderance of the evidence that
Takayama anticipates claims 10-12, 15, 17 and 26-29? More specifically,
does the Examiner establish that Takayama expressly or inherently discloses
(i) a “rack” as recited in independent claims 10 and 27, or (ii) a “means
devoid of electrical circuitry for converting pivotal motion of the actuator
into linear displacement of the actuation wires” as recited in independent
claim 26?
Findings of Fact
1. Takayama describes an endoscope apparatus with a motor-driven
bending mechanism. (Takayama, col. 1, ll. 10-12.)
2. Figures 3 and 6 of Takayama are reproduced below.
App
App

Figu
show
Figu
part
3.
rotat
46-4
gear
34.)
that
contr
54-6
4.
“an a
30 is
5.
“gea
eal 2011-0
lication 11
re 3 in Tak
ing the m
re 6 depict
of an endo
As show
ing shaft o
7.) Wire d
36, which
An operat
it contacts
ols the rot
1; col. 6, l
The Exa
ctuator” a
a “rack” a
The Spe
r rack 54,”
05633
/024,181
ayama de
ain part of
s “a partia
scope app
n in Figur
f electric m
rum 32 in
meshes w
or moves
piezoelect
ational dir
l. 20-24.)
miner find
s recited in
s recited i
cification
also show
picts “a pa
an endosc
l perspecti
aratus” of
es 3 and 6
otor 28 (
cludes rot
ith worm g
deflection
ric rubber
ection and

s that defl
independ
n claims 1
does not d
n in Figur
5

rtial persp
ope appar
ve view sc
another em
above, wo
not shown
ating shaft
ear 30. (I
control lev
portion 66
speed of
ection con
ent claims
0 and 27.
efine the te
es 5, 7, an
ective view
atus.” (Id
hematical
bodiment
rm gear 3
in Figure
34 and is
d. at ll. 47
er 64 (sho
a, 66b, 68
the motor
trol lever 6
10, 26 an
(Ans. 3.)
rm “rack,
d 8 of the
schemat
. at col. 2,
ly showin
. (Id. at ll
0 is secure
3). (Id. at
coaxial wi
-51; col. 5
wn in Fig
a or 68b, w
28. (Id. at
4 in Taka
d 27, and
” but it de
Specificat

ically
ll. 49-52.)
g the main
. 60-62.)
d to a
col. 3, ll.
th spur
, ll. 31-
ure 3) so
hich
col. 5, ll.
yama is
worm gear
scribes a
ion.

Appeal 2011-005633
Application 11/024,181

6
6. A “rack” differs from a “worm gear.” See, e.g., Gear, Wikipedia
(Aug. 2, 2012) http://en.wikipedia.org/wiki/Gear (Attachment A, pages 5-6
of 22); see also http://www.sdp-si.com/estore/CoverPg/Gears.htm
(Attachment B, page 2 of 4). A rack is a toothed bar or rod, where the rod
“meshes with a gearwheel, pinion or other toothed machine part.” (Ans. 5.)
As the gearwheel, pinion or toothed machine part turns, a rack moves in a
straight line. (Attachment A, page 6.) By contrast, a worm gear resembles a
screw, as depicted in Takayama as worm gear 30 in Figures 3, 6 and 8.
(Attachment A, page 5.)
Principles of Law
The Examiner bears the initial burden, on review of the prior art or on
any other ground, of presenting a prima facie case of unpatentability. In re
Oetiker, 977 F.2d 1443, 1445 (Fed. Cir. 1992). If the Examiner meets that
initial burden, the burden of coming forward with evidence or argument
shifts to the applicant. In re Rijckaert, 9 F.3d 1531, 1532 (Fed. Cir. 1993).
After the applicant submits such evidence or argument, the PTO then
determines patentability “on the totality of the record, by a preponderance of
evidence with due consideration to persuasiveness of argument.” Oetiker,
977 F.2d at 1445. If the Examiner fails to establish a prima facie case of
unpatentability in the first instance, however, the rejection is improper and
must be reversed. Id.; Rijckaert, 9 F.3d at 1532.
Analysis
The Examiner relies on the disclosure of worm gear “30” in
Takayama for a teaching of a “rack” as recited in claims 1 and 27. (Ans. 3.)
Appeal 2011-005633
Application 11/024,181

7
The Examiner also defines a “rack” as a “ʻtoothed bar which meshes with a
gearwheel, pinion, or other toothed machine part.’” (Ans. 5.)
Appellant argues Takayama does not expressly or inherently disclose
a “rack” as recited in independent claims 10 and 27, and therefore Takayama
cannot anticipate claims 10-12, 15, 17, and 27-29. As stated by Appellant,
“Takayama teaches a worm gear 30,” and “[o]ne of ordinary skill in the art
would readily appreciate that Takayama’s worm gear, which is effectively a
screw, is not structurally identical to a rack.” (App. Br. 10.)
We agree that the term “worm gear” itself in Takayama indicates
something other than a “rack” (FF 6). Consistently, worm gear 30 in
Takayama resembles a screw, as depicted in Figures 3, 6 and 8 of the
reference (id.). In contrast with a worm gear, a rack is a toothed bar or rod,
where the rod “meshes with a gearwheel, pinion or other toothed machine
part,” as stated by the Examiner (Ans. 5). As a gearwheel or pinion turns, a
rack moves in a straight line (FF 6). This concept is consistent with
teachings in Takayama, which describe and depict slide buttons 90 and 92
that “serve as rack gears” and mesh with pinion gears 96, as shown in Figure
6 of Takayama (FF 2; Takayama, col. 7, ll. 6-25).1 Thus, the Examiner does

1 The Examiner’s Answer does not indicate (and we do not address)
whether slide button 90 or 92 in Takayama is “a rack secured to the actuator
and engaged with an engagement portion of the pulley assembly” as recited
in claim 10, or “a first rack in engagement with the first engagement portion
and adapted to displace generally laterally relative to the handle” as recited
in claim 27. In addition, the Examiner’s Answer does not indicate (and we
do not address) whether pending independent claims are obvious over
Takayama.
Appeal 2011-005633
Application 11/024,181

8
not establish that Takayama discloses a “rack” that is configured as recited
in claims 10 and 27.
Claim 26 recites a “means devoid of electrical circuitry for converting
pivotal motion of the actuator into linear displacement of the actuation
wires.” Appellant argues that Takayama “discloses extensive electrical
circuitry as part of the disclosed mechanism for linearly displacing
angulation wire,” and that “a central component of Takayama’s endoscope is
‘a reversible electric motor 28’” (App. Br. 11).
The Examiner states that component “32,” i.e., wire drum 32, in
Takayama “is capable of converting pivotal motion of the actuator into
linear displacement of the actuation wires and which is best understood by
Examiner to be devoid of electrical circuitry” (Ans. 3-4). The Examiner also
asserts that above-quoted phrase in claim 26 does not meet the requirements
of 35 U.S.C. § 112, paragraph 6, and therefore “any means that assists in
converting pivotal motion of the actuator into linear displacement of the
actuation wires may anticipate or render obvious the claimed invention” (id.
at 6). The Examiner also refers to “an axle 34 which couples to the handle
and wherein lateral displacement of the rack causes pivotal displacement of
the axel [sic] and wherein the handle, as best understood by Examiner, does
not have electrical circuitry coupled to the axle …” (id. at 6-7).
The phrase “means … for converting pivotal motion of the actuator
into linear displacement of the actuation wires” requires, at minimum, that
the “means” be capable of converting motion of an actuator into movement
of the actuation wires. Wire drum 32, i.e., a “pulley assembly” as described
by the Examiner (id. at 3), or rotating shaft 34, i.e., axle 34 according to the
Appeal 2011-005633
Application 11/024,181

9
Examiner (id. at 6), may be part of a means used to convert motion of an
actuator into movement of actuation wires in Takayama, but neither wire
drum 32 nor rotating shaft 34 can act as the “means” alone. The “means” in
Takayama necessarily involves other components, including electric motor
28. As stated in Takayama (col. 6, ll. 20-24), “when the deflection control
level 64 [actuator] is brought into tight contact with the piezoelectric rubber
portions . . ., the rotational direction and rotational speed of the motor 28 are
controlled.” Electric motor 28 (controlled by control lever 64) spins worm
gear 30, which leads to the rotation of wire drum 32, and ultimately the
movement of an actuation wire. (Id. at col. 3, ll. 44-57.) Thus, as suggested
by Appellant (App. Br. 11), the motor is necessarily part of the “means”
disclosed in Takayama, and that means is not “devoid of electrical circuitry”
as required by claim 26.
Conclusion of Law
We conclude that the Examiner does not establish by a preponderance
of the evidence that Takayama anticipates claims 10, 26 or 27, and therefore
the Examiner also fails to establish that Takayama anticipates claims 11-12,
15, 17 and 29, which depend on independent claims 10 and 27.
II.
Issue
Does the Examiner establish by a preponderance of the evidence that
claims 13 and 14 are obvious over Takayama?
Appeal 2011-005633
Application 11/024,181

10
Analysis
The Examiner asserts that although Takayama does not disclose a gear
rack as being an arcuate internal or external gear, as recited in claims 13 and
14, fashioning a gear rack in such a way was “an obvious design choice
having predictable results” (Ans. 4).
As discussed above, the Examiner does not establish that Takayama
discloses a “rack” that is configured as recited in independent claim 10, upon
which claims 13 and 14 depend. The Examiner likewise fails to establish a
prima facie case of obviousness by relying on “an obvious design choice” to
modify a component, i.e., a “rack,” that the Examiner has not established is
disclosed or suggested in Takayama.
Conclusion of Law
We conclude that the Examiner does not establish by a preponderance
of the evidence that claims 13 and 14 are obvious over Takayama.
III.
Issue
Does the Examiner establish by a preponderance of the evidence that
claim 16 is obvious over Takayama in view of Heinzelman?
Analysis
As discussed above, the Examiner does not establish that Takayama
discloses a “rack” as recited in independent claim 10, upon which claim 16
depends. The Examiner does not assert that Heinzelman discloses or
suggests a rack (Ans. 5). Rather, the Examiner states that Heinzelman
Appeal 2011-005633
Application 11/024,181

11
discloses first and second guides as recited in claim 16, and it would have
been obvious to use such guides in the assembly disclosed in Takayama
(id.). Because the Examiner does not establish that Heinzelman remedies
the deficiency in Takayama as to the rack element required in claim 10, the
Examiner fails to establish a prima facie case of obviousness of claim 16.
Conclusion of Law
We conclude that the Examiner does not establish by a preponderance
of the evidence that claim 16 is obvious over Takayama in view of
Heinzelman.
NEW GROUND OF REJECTION
We enter a new ground of rejection of claims 10-17 and 26-29 as
indefinite under 35 U.S.C. § 112, second paragraph, under the provisions of
37 C.F.R. §41.50 (b).
Independent claims 10, 26 and 27 each recite in the preamble: “A
portable handheld device directly mechanically manipulated by an operator
of a cardiac catheter including first and second actuation wires, the assembly
comprising …” (emphasis added). Each pending dependent claim recites:
“The assembly of claim [10, 12 or 27].” Thus, “the assembly” in the
preamble of all pending claims lacks antecedent basis.
Under a broad but reasonable interpretation, “the assembly” could
refer to the recited handheld device, cardiac catheter, or something else that
is part of the device or catheter. Thus, the “assembly” recited in the claims
is amenable to two or more plausible claim interpretations. While the
Specification describes an “actuating assembly” (see, e.g., Spec. [0006],
Appeal 2011-005633
Application 11/024,181

12
[0011]), it does not clarify which interpretation of “the assembly” in the
claims is correct. In re Skvorecz, 580 F.3d 1262, 1268-69 (Fed. Cir. 2009)
(indicating that a lack in explicit antecedent basis does not render a claim
indefinite if one of ordinary skill in the art would understand the claim when
viewed in the context of the specification).
“[I]f a claim is amenable to two or more plausible claim constructions,
the USPTO is justified in requiring the applicant to more precisely define the
metes and bounds of the claimed invention by holding the claim
unpatentable under 35 U.S.C. § 112, second paragraph, as indefinite.” Ex
parte Miyazaki, 89 USPQ2d 1207, 1211 (BPAI 2008) (“Precedential”).
SUMMARY
We reverse the rejection of claims 10-12, 15, 17 and 26-29 as
anticipated by Takayama. We also reverse the obviousness rejections of
claims 13 and 14 over Takayama, and claim 16 over Takayama in view of
Heinzelman. We enter a new ground of rejection of claims 10-17 and 26-29
as indefinite under 35 U.S.C. § 112, second paragraph.
TIME PERIOD FOR RESPONSE
This decision contains a new ground of rejection pursuant to 37
C.F.R. § 41.50(b). 37 C.F.R. § 41.50(b) provides that “[a] new ground of
rejection . . . shall not be considered final for judicial review.”
37 C.F.R. § 41.50(b) also provides that the Appellants, WITHIN
TWO MONTHS FROM THE DATE OF THE DECISION, must exercise
one of the following two options with respect to the new ground of rejection
to avoid termination of the appeal as to the rejected claims:
Appeal 2011-005633
Application 11/024,181

13
(1) Reopen prosecution. Submit an appropriate amendment of the
claims so rejected or new evidence relating to the claims so rejected, or both,
and have the matter reconsidered by the examiner, in which event the
proceeding will be remanded to the examiner. . . .
(2) Request rehearing. Request that the proceeding be reheard under
§ 41.52 by the Board upon the same record. . . .

No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a)(1)(iv).

REVERSED; 37 C.F.R. § 41.50(b)

cdc

Notice of References Cited

Application/Control No.

11/024,181
Applicant(s)/Patent Under
Reexamination
John C. Knudson
Examiner

Scott Medway
Art Unit

3700

Page 1 of 1

U.S. PATENT DOCUMENTS

* DOCUMENT NO. DATE NAME CLASS SUBCLASS
DOCUMENT
SOURCE **
APS OTHER

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FOREIGN PATENT DOCUMENTS

* DOCUMENT NO. DATE COUNTRY NAME CLASS SUBCLASS
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* DOCUMENT (Including Author, Title Date, Source, and Pertinent Pages)
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U

Gear, Wikipedia (Aug. 2, 2012) http://en.wikipedia.org/wiki/Gear

V

http://www.sdp-si.com/estore/CoverPg/Gears.htm

W

X

*A copy of this reference is not being furnished with this Office action. (See Manual of Patent Examining Procedure, Section 707.05(a).)
**APS encompasses any electronic search i.e. text, image, and Commercial Databases.
U.S. Patent and Trademark Office
PTO-892 (Rev. 03-98) Notice of References Cited Part of Paper No. 16

Attachment A
Gear 1
Gear
Two meshing gears transmitting rotational
motion. Note that the smaller gear is rotating
faster. Although the larger gear is rotating less
quickly, its torque is proportionally greater. One
subtlety of this particular arrangement is that the
linear speed at the rim is the same on both gears.
A gear is a rotating machine part having cut teeth, or cogs, which mesh
with another toothed part in order to transmit torque. Two or more
gears working in tandem are called a transmission and can produce a
mechanical advantage through a gear ratio and thus may be considered
a simple machine. Geared devices can change the speed, torque, and
direction of a power source. The most common situation is for a gear
to mesh with another gear, however a gear can also mesh a
non-rotating toothed part, called a rack, thereby producing translation
instead of rotation.
The gears in a transmission are analogous to the wheels in a pulley. An
advantage of gears is that the teeth of a gear prevent slipping.
When two gears of unequal number of teeth are combined a
mechanical advantage is produced, with both the rotational speeds and
the torques of the two gears differing in a simple relationship.
In transmissions which offer multiple gear ratios, such as bicycles and cars, the term gear, as in first gear, refers to a
gear ratio rather than an actual physical gear. The term is used to describe similar devices even when gear ratio is
continuous rather than discrete, or when the device does not actually contain any gears, as in a continuously variable
transmission.[1]
The earliest known reference to gears was circa A.D. 50 by Hero of Alexandria,[2] but they can be traced back to the
Greek mechanics of the Alexandrian school in the 3rd century B.C. and were greatly developed by the Greek
polymath Archimedes (287–212 B.C.).[3] The Antikythera mechanism is an example of a very early and intricate
geared device, designed to calculate astronomical positions. Its time of construction is now estimated between 150
and 100 BC.[4]
Definition of gear terminology.
Comparison with drive
mechanisms
The definite velocity ratio which
results from having teeth gives gears
an advantage over other drives (such as
traction drives and V-belts) in
precision machines such as watches
that depend upon an exact velocity
ratio. In cases where driver and
follower are in close proximity gears
also have an advantage over other
drives in the reduced number of parts
required; the downside is that gears are
more expensive to manufacture and
their lubrication requirements may
impose a higher operating cost.
Gear 2
Types
External vs internal gears
Internal gear
An external gear is one with the teeth formed on the outer surface of a
cylinder or cone. Conversely, an internal gear is one with the teeth
formed on the inner surface of a cylinder or cone. For bevel gears, an
internal gear is one with the pitch angle exceeding 90 degrees. Internal
gears do not cause direction reversal.[5]
Spur
Spur gear
Spur gears or straight-cut gears are the simplest type of gear. They
consist of a cylinder or disk with the teeth projecting radially, and
although they are not straight-sided in form, the edge of each tooth is
straight and aligned parallel to the axis of rotation. These gears can be
meshed together correctly only if they are fitted to parallel shafts.
Helical
Helical gears
Top: parallel configuration
Bottom: crossed configuration
Helical or "dry fixed" gears offer a refinement over spur gears. The
leading edges of the teeth are not parallel to the axis of rotation, but are
set at an angle. Since the gear is curved, this angling causes the tooth
shape to be a segment of a helix. Helical gears can be meshed in
parallel or crossed orientations. The former refers to when the shafts
are parallel to each other; this is the most common orientation. In the
latter, the shafts are non-parallel, and in this configuration are
sometimes known as "skew gears".
The angled teeth engage more gradually than do spur gear teeth
causing them to run more smoothly and quietly.[6] With parallel helical
gears, each pair of teeth first make contact at a single point at one side
of the gear wheel; a moving curve of contact then grows gradually
Gear 3
across the tooth face to a maximum then recedes until the teeth break contact at a single point on the opposite side. In
spur gears teeth suddenly meet at a line contact across their entire width causing stress and noise. Spur gears make a
characteristic whine at high speeds. Whereas spur gears are used for low speed applications and those situations
where noise control is not a problem, the use of helical gears is indicated when the application involves high speeds,
large power transmission, or where noise abatement is important.[7] The speed is considered to be high when the
pitch line velocity exceeds 25 m/s.[8]
A disadvantage of helical gears is a resultant thrust along the axis of the gear, which needs to be accommodated by
appropriate thrust bearings, and a greater degree of sliding friction between the meshing teeth, often addressed with
additives in the lubricant.
Skew gears
For a 'crossed' or 'skew' configuration the gears must have the same pressure angle and normal pitch, however the
helix angle and handedness can be different. The relationship between the two shafts is actually defined by the helix
angle(s) of the two shafts and the handedness, as defined:[9]
for gears of the same handedness
for gears of opposite handedness
Where is the helix angle for the gear. The crossed configuration is less mechanically sound because there is only
a point contact between the gears, whereas in the parallel configuration there is a line contact.[9]
Quite commonly helical gears are used with the helix angle of one having the negative of the helix angle of the other;
such a pair might also be referred to as having a right-handed helix and a left-handed helix of equal angles. The two
equal but opposite angles add to zero: the angle between shafts is zero – that is, the shafts are parallel. Where the
sum or the difference (as described in the equations above) is not zero the shafts are crossed. For shafts crossed at
right angles the helix angles are of the same hand because they must add to 90 degrees.
• 3D Animation of helical gears (parallel axis) [10]
• 3D Animation of helical gears (crossed axis) [11]
Double helical
Double helical gears
Double helical gears, or herringbone gears, overcome the problem of
axial thrust presented by "single" helical gears, by having two sets of
teeth that are set in a V shape. A double helical gear can be thought of
as two mirrored helical gears joined together. This arrangement cancels
out the net axial thrust, since each half of the gear thrusts in the
opposite direction. However, double helical gears are more difficult to
manufacture due to their more complicated shape.
For both possible rotational directions, there exist two possible
arrangements for the oppositely-oriented helical gears or gear faces.
One arrangement is stable, and the other is unstable. In a stable
orientation, the helical gear faces are oriented so that each axial force is
directed toward the center of the gear. In an unstable orientation, both
axial forces are directed away from the center of the gear. In both
arrangements, the total (or net) axial force on each gear is zero when
the gears are aligned correctly. If the gears become misaligned in the axial direction, the unstable arrangement will
generate a net force that may lead to disassembly of the gear train, while the stable arrangement generates a net
corrective force. If the direction of rotation is reversed, the direction of the axial thrusts is also reversed, so a stable
configuration becomes unstable, and vice versa.
Gear 4
Stable double helical gears can be directly interchanged with spur gears without any need for different bearings.
Bevel
A bevel gear is shaped like a right circular cone with most of its tip cut off. When two bevel gears mesh, their
imaginary vertices must occupy the same point. Their shaft axes also intersect at this point, forming an arbitrary
non-straight angle between the shafts. The angle between the shafts can be anything except zero or 180 degrees.
Bevel gears with equal numbers of teeth and shaft axes at 90 degrees are called miter gears.
• 3D Animation of two bevel gears [12]
Spiral bevels
Spiral bevel gears
The teeth of a bevel gear may be straight-cut as with spur gears, or they
may be cut in a variety of other shapes. Spiral bevel gear teeth are
curved along the tooth's length and set at an angle, analogously to the
way helical gear teeth are set at an angle compared to spur gear teeth.
Zerol bevel gears have teeth which are curved along their length, but
not angled. Spiral bevel gears have the same advantages and
disadvantages relative to their straight-cut cousins as helical gears do
to spur gears. Straight bevel gears are generally used only at speeds
below 5 m/s (1000 ft/min), or, for small gears, 1000 r.p.m.[13]
Hypoid
Hypoid gear
Hypoid gears resemble spiral bevel gears except the shaft axes do not
intersect. The pitch surfaces appear conical but, to compensate for the
offset shaft, are in fact hyperboloids of revolution.[14][15] Hypoid gears
are almost always designed to operate with shafts at 90 degrees.
Depending on which side the shaft is offset to, relative to the angling
of the teeth, contact between hypoid gear teeth may be even smoother
and more gradual than with spiral bevel gear teeth. Also, the pinion can
be designed with fewer teeth than a spiral bevel pinion, with the result
that gear ratios of 60:1 and higher are feasible using a single set of
hypoid gears.[16] This style of gear is most commonly found driving
mechanical differentials; which are normally straight cut bevel gears;
in motor vehicle axles.
Gear 5
Crown
Crown gear
Crown gears or contrate gears are a particular form of bevel gear
whose teeth project at right angles to the plane of the wheel; in their
orientation the teeth resemble the points on a crown. A crown gear can
only mesh accurately with another bevel gear, although crown gears
are sometimes seen meshing with spur gears. A crown gear is also
sometimes meshed with an escapement such as found in mechanical
clocks.
Worm
Worm gear
4-start worm and wheel
Worm gears resemble screws. A worm gear is usually meshed with a
spur gear or a helical gear, which is called the gear, wheel, or worm
wheel.
Worm-and-gear sets are a simple and compact way to achieve a high
torque, low speed gear ratio. For example, helical gears are normally
limited to gear ratios of less than 10:1 while worm-and-gear sets vary
from 10:1 to 500:1.[17] A disadvantage is the potential for considerable
sliding action, leading to low efficiency.[18]
Worm gears can be considered a species of helical gear, but its helix
angle is usually somewhat large (close to 90 degrees) and its body is
usually fairly long in the axial direction; and it is these attributes which
give it screw like qualities. The distinction between a worm and a
helical gear is made when at least one tooth persists for a full rotation
around the helix. If this occurs, it is a 'worm'; if not, it is a 'helical
gear'. A worm may have as few as one tooth. If that tooth persists for
several turns around the helix, the worm will appear, superficially, to
have more than one tooth, but what one in fact sees is the same tooth
reappearing at intervals along the length of the worm. The usual screw
nomenclature applies: a one-toothed worm is called single thread or
single start; a worm with more than one tooth is called multiple thread
or multiple start. The helix angle of a worm is not usually specified.
Instead, the lead angle, which is equal to 90 degrees minus the helix
angle, is given.
In a worm-and-gear set, the worm can always drive the gear. However,
if the gear attempts to drive the worm, it may or may not succeed. Particularly if the lead angle is small, the gear's
teeth may simply lock against the worm's teeth, because the force component circumferential to the worm is not
sufficient to overcome friction. Worm-and-gear sets that do lock are called self locking, which can be used to
advantage, as for instance when it is desired to set the position of a mechanism by turning the worm and then have
the mechanism hold that position. An example is the machine head found on some types of stringed instruments.
Gear 6
If the gear in a worm-and-gear set is an ordinary helical gear only a single point of contact will be achieved.[19] If
medium to high power transmission is desired, the tooth shape of the gear is modified to achieve more intimate
contact by making both gears partially envelop each other. This is done by making both concave and joining them at
a saddle point; this is called a cone-drive.[20] or "Double enveloping"
Worm gears can be right or left-handed following the long established practice for screw threads.[5]
• 3D Animation of a worm-gear set [21]
Non-circular
Non-circular gears
Non-circular gears are designed for special purposes. While a regular
gear is optimized to transmit torque to another engaged member with
minimum noise and wear and maximum efficiency, a non-circular
gear's main objective might be ratio variations, axle displacement
oscillations and more. Common applications include textile machines,
potentiometers and continuously variable transmissions.
Rack and pinion
Rack and pinion gearing
A rack is a toothed bar or rod that can be thought of as a sector gear with
an infinitely large radius of curvature. Torque can be converted to linear
force by meshing a rack with a pinion: the pinion turns; the rack moves
in a straight line. Such a mechanism is used in automobiles to convert
the rotation of the steering wheel into the left-to-right motion of the tie
rod(s). Racks also feature in the theory of gear geometry, where, for
instance, the tooth shape of an interchangeable set of gears may be
specified for the rack (infinite radius), and the tooth shapes for gears of
particular actual radii then derived from that. The rack and pinion gear
type is employed in a rack railway.
Gear 7
Epicyclic
Epicyclic gearing
In epicyclic gearing one or more of the gear axes moves. Examples are
sun and planet gearing (see below) and mechanical differentials.
Sun and planet
Sun (yellow) and planet (red) gearing
Sun and planet gearing was a method of converting reciprocating
motion into rotary motion in steam engines. It was famously used by
James Watt on his early steam engines in order to get around the patent
on the crank.
In the illustration, the sun is yellow, the planet red, the reciprocating
arm is blue, the flywheel is green and the driveshaft is grey.
Harmonic drive
Harmonic drive gearing
A harmonic drive is a specialized gearing mechanism often used in
industrial motion control, robotics and aerospace for its advantages
over traditional gearing systems, including lack of backlash,
compactness and high gear ratios.
Gear 8
Cage gear
Cage gear in Pantigo Windmill, Long Island
A cage gear, also called a lantern gear or lantern pinion has
cylindrical rods for teeth, parallel to the axle and arranged in a circle
around it, much as the bars on a round bird cage or lantern. The
assembly is held together by disks at either end into which the tooth
rods and axle are set. Lantern gears are more efficient than solid
pinions, and dirt can fall through the rods rather than becoming trapped
and increasing wear.
Sometimes used in clocks, the lantern pinion should always be driven
by a gearwheel, not used as the driver. The lantern pinion was not
initially favoured by conservative clock makers. It became popular in turret clocks where dirty working conditions
were most commonplace. Domestic American clock movements often used them.
Magnetic gear
All cogs of each gear component of such gear are performed as a constant magnet with periodic alternation of
opposite magnetic poles on mating surfaces and nearest poles of cogs of different gear components are similar. And
gear components are mounted with a backlash with capability of mechanical gearing.
At not too big load such gear works without touch of motive details and has a raised reliability without noise.
(Literature: Kravchenko A.I., Bovda A.M. Gear with magnetic couple. Pat. of Ukraine N. 56700 – Bul. N. 2, 2011 –
F16H 49/00.)
Nomenclature
General nomenclature
Gear 9
Rotational frequency, n
Measured in rotation over time, such as RPM.
Angular frequency, ω
Measured in radians per second. rad/second
Number of teeth, N
How many teeth a gear has, an integer. In the case of worms, it is the number of thread starts that the worm
has.
Gear, wheel
The larger of two interacting gears or a gear on its own.
Pinion
The smaller of two interacting gears.
Path of contact
Path followed by the point of contact between two meshing gear teeth.
Line of action, pressure line
Line along which the force between two meshing gear teeth is directed. It has the same direction as the force
vector. In general, the line of action changes from moment to moment during the period of engagement of a
pair of teeth. For involute gears, however, the tooth-to-tooth force is always directed along the same line—that
is, the line of action is constant. This implies that for involute gears the path of contact is also a straight line,
coincident with the line of action—as is indeed the case.
Axis
Axis of revolution of the gear; center line of the shaft.
Pitch point, p
Point where the line of action crosses a line joining the two gear axes.
Pitch circle, pitch line
Circle centered on and perpendicular to the axis, and passing through the pitch point. A predefined diametral
position on the gear where the circular tooth thickness, pressure angle and helix angles are defined.
Pitch diameter, d
A predefined diametral position on the gear where the circular tooth thickness, pressure angle and helix angles
are defined. The standard pitch diameter is a basic dimension and cannot be measured, but is a location where
other measurements are made. Its value is based on the number of teeth, the normal module (or normal
diametral pitch), and the helix angle. It is calculated as:
in metric units or in imperial units.[22]
Module, m
A scaling factor used in metric gears with units in millimeters whose effect is to enlarge the gear tooth size as
the module increases and reduce the size as the module decreases. Module can be defined in the normal (mn),
the transverse (mt), or the axial planes (ma) depending on the design approach employed and the type of gear
being designed.[22] Module is typically an input value into the gear design and is seldom calculated.
Operating pitch diameters
Diameters determined from the number of teeth and the center distance at which gears operate.[5] Example for
pinion:
Gear 10
Pitch surface
In cylindrical gears, cylinder formed by projecting a pitch circle in the axial direction. More generally, the
surface formed by the sum of all the pitch circles as one moves along the axis. For bevel gears it is a cone.
Angle of action
Angle with vertex at the gear center, one leg on the point where mating teeth first make contact, the other leg
on the point where they disengage.
Arc of action
Segment of a pitch circle subtended by the angle of action.
Pressure angle,
The complement of the angle between the direction that the teeth exert force on each other, and the line joining
the centers of the two gears. For involute gears, the teeth always exert force along the line of action, which, for
involute gears, is a straight line; and thus, for involute gears, the pressure angle is constant.
Outside diameter,
Diameter of the gear, measured from the tops of the teeth.
Root diameter
Diameter of the gear, measured at the base of the tooth.
Addendum, a
Radial distance from the pitch surface to the outermost point of the tooth.
Dedendum, b
Radial distance from the depth of the tooth trough to the pitch surface.
Whole depth,
The distance from the top of the tooth to the root; it is equal to addendum plus dedendum or to working depth
plus clearance.
Clearance
Distance between the root circle of a gear and the addendum circle of its mate.
Working depth
Depth of engagement of two gears, that is, the sum of their operating addendums.
Circular pitch, p
Distance from one face of a tooth to the corresponding face of an adjacent tooth on the same gear, measured
along the pitch circle.
Diametral pitch,
Ratio of the number of teeth to the pitch diameter. Could be measured in teeth per inch or teeth per centimeter.
Base circle
In involute gears, where the tooth profile is the involute of the base circle. The radius of the base circle is
somewhat smaller than that of the pitch circle.
Base pitch, normal pitch,
In involute gears, distance from one face of a tooth to the corresponding face of an adjacent tooth on the same
gear, measured along the base circle.
Interference
Gear 11
Contact between teeth other than at the intended parts of their surfaces.
Interchangeable set
A set of gears, any of which will mate properly with any other.
Helical gear nomenclature
Helix angle,
Angle between a tangent to the helix and the gear axis. It is zero in the limiting case of a spur gear, albeit it can
considered as the hypotenuse angle as well.
Normal circular pitch,
Circular pitch in the plane normal to the teeth.
Transverse circular pitch, p
Circular pitch in the plane of rotation of the gear. Sometimes just called "circular pitch".
Several other helix parameters can be viewed either in the normal or transverse planes. The subscript n usually
indicates the normal.
Worm gear nomenclature
Lead
Distance from any point on a thread to the corresponding point on the next turn of the same thread, measured
parallel to the axis.
Linear pitch, p
Distance from any point on a thread to the corresponding point on the adjacent thread, measured parallel to the
axis. For a single-thread worm, lead and linear pitch are the same.
Lead angle,
Angle between a tangent to the helix and a plane perpendicular to the axis. Note that it is the complement of
the helix angle which is usually given for helical gears.
Pitch diameter,
Same as described earlier in this list. Note that for a worm it is still measured in a plane perpendicular to the
gear axis, not a tilted plane.
Subscript w denotes the worm, subscript g denotes the gear.
Tooth contact nomenclature
Line of contact Path of action Line of action Plane of action
Gear 12
Lines of contact (helical gear) Arc of action Length of action Limit diameter
Face advance Zone of action
Point of contact
Any point at which two tooth profiles touch each other.
Line of contact
A line or curve along which two tooth surfaces are tangent to each other.
Path of action
The locus of successive contact points between a pair of gear teeth, during the phase of engagement. For
conjugate gear teeth, the path of action passes through the pitch point. It is the trace of the surface of action in
the plane of rotation.
Line of action
The path of action for involute gears. It is the straight line passing through the pitch point and tangent to both
base circles.
Surface of action
The imaginary surface in which contact occurs between two engaging tooth surfaces. It is the summation of
the paths of action in all sections of the engaging teeth.
Plane of action
The surface of action for involute, parallel axis gears with either spur or helical teeth. It is tangent to the base
cylinders.
Zone of action (contact zone)
For involute, parallel-axis gears with either spur or helical teeth, is the rectangular area in the plane of action
bounded by the length of action and the effective face width.
Path of contact
The curve on either tooth surface along which theoretical single point contact occurs during the engagement of
gears with crowned tooth surfaces or gears that normally engage with only single point contact.
Length of action
The distance on the line of action through which the point of contact moves during the action of the tooth
profile.
Gear 13
Arc of action, Qt
The arc of the pitch circle through which a tooth profile moves from the beginning to the end of contact with a
mating profile.
Arc of approach, Qa
The arc of the pitch circle through which a tooth profile moves from its beginning of contact until the point of
contact arrives at the pitch point.
Arc of recess, Qr
The arc of the pitch circle through which a tooth profile moves from contact at the pitch point until contact
ends.
Contact ratio, mc, ε
The number of angular pitches through which a tooth surface rotates from the beginning to the end of
contact.In a simple way, it can be defined as a measure of the average number of teeth in contact during the
period in which a tooth comes and goes out of contact with the mating gear.
Transverse contact ratio, mp, εα
The contact ratio in a transverse plane. It is the ratio of the angle of action to the angular pitch. For involute
gears it is most directly obtained as the ratio of the length of action to the base pitch.
Face contact ratio, mF, εβ
The contact ratio in an axial plane, or the ratio of the face width to the axial pitch. For bevel and hypoid gears
it is the ratio of face advance to circular pitch.
Total contact ratio, mt, εγ
The sum of the transverse contact ratio and the face contact ratio.
Modified contact ratio, mo
For bevel gears, the square root of the sum of the squares of the transverse and face contact ratios.
Limit diameter
Diameter on a gear at which the line of action intersects the maximum (or minimum for internal pinion)
addendum circle of the mating gear. This is also referred to as the start of active profile, the start of contact,
the end of contact, or the end of active profile.
Start of active profile (SAP)
Intersection of the limit diameter and the involute profile.
Face advance
Distance on a pitch circle through which a helical or spiral tooth moves from the position at which contact
begins at one end of the tooth trace on the pitch surface to the position where contact ceases at the other end.
Gear 14
Tooth thickness nomeclature
Tooth thickness Thickness
relationships
Chordal thickness Tooth
thickness
measurement
over pins
Span measurement Long and short
addendum teeth
Circular thickness
Length of arc between the two sides of a gear tooth, on the specified datum circle.
Transverse circular thickness
Circular thickness in the transverse plane.
Normal circular thickness
Circular thickness in the normal plane. In a helical gear it may be considered as the length of arc along a
normal helix.
Axial thickness
In helical gears and worms, tooth thickness in an axial cross section at the standard pitch diameter.
Base circular thickness
In involute teeth, length of arc on the base circle between the two involute curves forming the profile of a
tooth.
Normal chordal thickness
Length of the chord that subtends a circular thickness arc in the plane normal to the pitch helix. Any
convenient measuring diameter may be selected, not necessarily the standard pitch diameter.
Chordal addendum (chordal height)
Height from the top of the tooth to the chord subtending the circular thickness arc. Any convenient measuring
diameter may be selected, not necessarily the standard pitch diameter.
Profile shift
Displacement of the basic rack datum line from the reference cylinder, made non-dimensional by dividing by
the normal module. It is used to specify the tooth thickness, often for zero backlash.
Rack shift
Displacement of the tool datum line from the reference cylinder, made non-dimensional by dividing by the
normal module. It is used to specify the tooth thickness.
Gear 15
Measurement over pins
Measurement of the distance taken over a pin positioned in a tooth space and a reference surface. The
reference surface may be the reference axis of the gear, a datum surface or either one or two pins positioned in
the tooth space or spaces opposite the first. This measurement is used to determine tooth thickness.
Span measurement
Measurement of the distance across several teeth in a normal plane. As long as the measuring device has
parallel measuring surfaces that contact on an unmodified portion of the involute, the measurement will be
along a line tangent to the base cylinder. It is used to determine tooth thickness.
Modified addendum teeth
Teeth of engaging gears, one or both of which have non-standard addendum.
Full-depth teeth
Teeth in which the working depth equals 2.000 divided by the normal diametral pitch.
Stub teeth
Teeth in which the working depth is less than 2.000 divided by the normal diametral pitch.
Equal addendum teeth
Teeth in which two engaging gears have equal addendums.
Long and short-addendum teeth
Teeth in which the addendums of two engaging gears are unequal.
Pitch nomenclature
Pitch is the distance between a point on one tooth and the corresponding point on an adjacent tooth.[5] It is a
dimension measured along a line or curve in the transverse, normal, or axial directions. The use of the single word
pitch without qualification may be ambiguous, and for this reason it is preferable to use specific designations such as
transverse circular pitch, normal base pitch, axial pitch.
Pitch Tooth pitch Base pitch relationships Principal pitches
Circular pitch, p
Arc distance along a specified pitch circle or pitch line between corresponding profiles of adjacent teeth.
Transverse circular pitch, pt
Circular pitch in the transverse plane.
Normal circular pitch, pn, pe
Circular pitch in the normal plane, and also the length of the arc along the normal pitch helix between helical
teeth or threads.
Axial pitch, px
Linear pitch in an axial plane and in a pitch surface. In helical gears and worms, axial pitch has the same value
at all diameters. In gearing of other types, axial pitch may be confined to the pitch surface and may be a
Gear 16
circular measurement. The term axial pitch is preferred to the term linear pitch. The axial pitch of a helical
worm and the circular pitch of its worm gear are the same.
Normal base pitch, pN, pbn
An involute helical gear is the base pitch in the normal plane. It is the normal distance between parallel helical
involute surfaces on the plane of action in the normal plane, or is the length of arc on the normal base helix. It
is a constant distance in any helical involute gear.
Transverse base pitch, pb, pbt
In an involute gear, the pitch on the base circle or along the line of action. Corresponding sides of involute
gear teeth are parallel curves, and the base pitch is the constant and fundamental distance between them along
a common normal in a transverse plane.
Diametral pitch (transverse), Pd
Ratio of the number of teeth to the standard pitch diameter in inches.
Normal diametral pitch, Pnd
Value of diametral pitch in a normal plane of a helical gear or worm.
Angular pitch, θN, τ
Angle subtended by the circular pitch, usually expressed in radians.
degrees or radians
Backlash
Backlash is the error in motion that occurs when gears change direction. It exists because there is always some gap
between the trailing face of the driving tooth and the leading face of the tooth behind it on the driven gear, and that
gap must be closed before force can be transferred in the new direction. The term "backlash" can also be used to
refer to the size of the gap, not just the phenomenon it causes; thus, one could speak of a pair of gears as having, for
example, "0.1 mm of backlash." A pair of gears could be designed to have zero backlash, but this would presuppose
perfection in manufacturing, uniform thermal expansion characteristics throughout the system, and no lubricant.
Therefore, gear pairs are designed to have some backlash. It is usually provided by reducing the tooth thickness of
each gear by half the desired gap distance. In the case of a large gear and a small pinion, however, the backlash is
usually taken entirely off the gear and the pinion is given full sized teeth. Backlash can also be provided by moving
the gears further apart. The backlash of a gear train equals the sum of the backlash of each pair of gears, so in long
trains backlash can become a problem.
For situations in which precision is important, such as instrumentation and control, backlash can be minimised
through one of several techniques. For instance, the gear can be split along a plane perpendicular to the axis, one half
fixed to the shaft in the usual manner, the other half placed alongside it, free to rotate about the shaft, but with
springs between the two halves providing relative torque between them, so that one achieves, in effect, a single gear
with expanding teeth. Another method involves tapering the teeth in the axial direction and providing for the gear to
be slid in the axial direction to take up slack.
Gear 17
Shifting of gears
In some machines (e.g., automobiles) it is necessary to alter the gear ratio to suit the task, a process known as gear
shifting or changing gear. There are several ways of shifting gears, for example:
• Manual transmission
• Automatic transmission
• Derailleur gears which are actually sprockets in combination with a roller chain
• Hub gears (also called epicyclic gearing or sun-and-planet gears)
There are several outcomes of gear shifting in motor vehicles. In the case of vehicle noise emissions, there are higher
sound levels emitted when the vehicle is engaged in lower gears. The design life of the lower ratio gears is shorter,
so cheaper gears may be used (i.e. spur for 1st and reverse) which tends to generate more noise due to smaller
overlap ratio and a lower mesh stiffness etc. than the helical gears used for the high ratios. This fact has been utilized
in analyzing vehicle generated sound since the late 1960s, and has been incorporated into the simulation of urban
roadway noise and corresponding design of urban noise barriers along roadways.[23]
Tooth profile
Profile of a spur gear Undercut
A profile is one side of a tooth in a cross section between the outside circle and the root circle. Usually a profile is
the curve of intersection of a tooth surface and a plane or surface normal to the pitch surface, such as the transverse,
normal, or axial plane.
The fillet curve (root fillet) is the concave portion of the tooth profile where it joins the bottom of the tooth space.2
As mentioned near the beginning of the article, the attainment of a non fluctuating velocity ratio is dependent on the
profile of the teeth. Friction and wear between two gears is also dependent on the tooth profile. There are a great
many tooth profiles that will give a constant velocity ratio, and in many cases, given an arbitrary tooth shape, it is
possible to develop a tooth profile for the mating gear that will give a constant velocity ratio. However, two constant
velocity tooth profiles have been by far the most commonly used in modern times. They are the cycloid and the
involute. The cycloid was more common until the late 1800s; since then the involute has largely superseded it,
particularly in drive train applications. The cycloid is in some ways the more interesting and flexible shape; however
the involute has two advantages: it is easier to manufacture, and it permits the center to center spacing of the gears to
vary over some range without ruining the constancy of the velocity ratio. Cycloidal gears only work properly if the
center spacing is exactly right. Cycloidal gears are still used in mechanical clocks.
An undercut is a condition in generated gear teeth when any part of the fillet curve lies inside of a line drawn tangent
to the working profile at its point of juncture with the fillet. Undercut may be deliberately introduced to facilitate
finishing operations. With undercut the fillet curve intersects the working profile. Without undercut the fillet curve
Gear 18
and the working profile have a common tangent.
Gear materials
Wooden gears of a historic windmill
Numerous nonferrous alloys, cast irons, powder-metallurgy and
plastics are used in the manufacture of gears. However, steels are
most commonly used because of their high strength-to-weight
ratio and low cost. Plastic is commonly used where cost or weight
is a concern. A properly designed plastic gear can replace steel in
many cases because it has many desirable properties, including
dirt tolerance, low speed meshing, the ability to "skip" quite well
[24] and the ability to be made with materials not needing
additional lubrication. Manufacturers have employed plastic gears
to reduce costs in consumer items including copy machines,
optical storage devices, VCRs, cheap dynamos, consumer audio
equipment, servo motors, and printers.
The module system
Countries which have adopted the metric system generally use the
module system. As a result, the term module is usually understood
to mean the pitch diameter in millimeters divided by the number of
teeth. When the module is based upon inch measurements, it is
known as the English module to avoid confusion with the metric
module. Module is a direct dimension, whereas diametral pitch is
an inverse dimension (like "threads per inch"). Thus, if the pitch diameter of a gear is 40 mm and the number of teeth
20, the module is 2, which means that there are 2 mm of pitch diameter for each tooth.[25]
Manufacture
Gear Cutting simulation (length 1m35s) faster,
high bitrate version.
Gears are most commonly produced via hobbing, but they are also
shaped, broached, and cast. Plastic gears can also be injection molded;
for prototypes, 3D printing in a suitable material can be used. For
metal gears the teeth are usually heat treated to make them hard and
more wear resistant while leaving the core soft and tough. For large
gears that are prone to warp, a quench press is used.
Inspection
Gear geometry can be inspected and verified using various methods
such as industrial CT scanning, coordinate-measuring machines, white
light scanner or laser scanning. Particularly useful for plastic gears,
industrial CT scanning can inspect internal geometry and imperfections
such as porosity.
Gear 19
Gear model in modern physics
Modern physics adopted the gear model in different ways. In the nineteenth century, James Clerk Maxwell
developed a model of electromagnetism in which magnetic field lines were rotating tubes of incompressible fluid.
Maxwell used a gear wheel and called it an "idle wheel" to explain the electrical current as a rotation of particles in
opposite directions to that of the rotating field lines.[26]
More recently, quantum physics uses "quantum gears" in their model. A group of gears can serve as a model for
several different systems, such as an artificially constructed nanomechanical device or a group of ring molecules.[27]
The Three Wave Hypothesis compares the wave–particle duality to a bevel gear.[28]
References
[1] Howstuffworks "Transmission Basics" (http:/ / auto. howstuffworks. com/ cvt1. htm)
[2] Norton 2004, p. 462
[3] Lewis, M. J. T. (1993). "Gearing in the Ancient World". Endeavour 17 (3): 110–115 [p. 110]. doi:10.1016/0160-9327(93)90099-O.
[4] " The Antikythera Mechanism Research Project: Why is it so important? (http:/ / www. antikythera-mechanism. gr/ faq/ general-questions/
why-is-it-so-important)", Retrieved 2011-01-10 Quote: "The Mechanism is thought to date from between 150 and 100 BC"
[5] ANSI/AGMA 1012-G05, "Gear Nomenclature, Definition of Terms with Symbols".
[6] Khurmi, R.S, Theory of Machines, S.CHAND
[7] Schunck, Richard, "Minimizing gearbox noise inside and outside the box." (http:/ / motionsystemdesign. com/ mechanical-pt/
gear-drives-loud-0800/ index. html), Motion System Design, .
[8] Doughtie and Vallance give the following information on helical gear speeds: "Pitch-line speeds of 4,000 to 7,000 fpm [20 to 36 m/s] are
common with automobile and turbine gears, and speeds of 12,000 fpm [61 m/s] have been successfully used." – p.281.
[9] Helical gears (http:/ / www. roymech. co. uk/ Useful_Tables/ Drive/ Hellical_Gears. html), , retrieved 15 June 2009.
[10] http:/ / www. youtube. com/ watch?v=Qcgjsor1Q-Y
[11] http:/ / www. youtube. com/ watch?v=ZpJuyK842RQ
[12] http:/ / www. youtube. com/ watch?v=o-Kdj_f6WCQ
[13] McGraw Hill Encyclopedia of Science and Technology, "Gear", p. 742.
[14] Canfield, Stephen (1997), "Gear Types" (http:/ / gemini. tntech. edu/ ~slc3675/ me361/ lecture/ grnts4. html), Dynamics of Machinery,
Tennessee Tech University, Department of Mechanical Engineering, ME 362 lecture notes, .
[15] Hilbert, David; Cohn-Vossen, Stephan (1952), Geometry and the Imagination (2nd ed.), New York: Chelsea, pp. 287,
ISBN 978-0-8284-1087-8.
[16] McGraw Hill Encyclopedia of Science and Technology, "Gear, p. 743.
[17] Vallance Doughtie, p. 287.
[18] Vallance Doughtie, pp. 280, 296.
[19] Doughtie and Vallance, p. 290; McGraw Hill Encyclopedia of Science and Technology, "Gear", p. 743.
[20] McGraw Hill Encyclopedia of Science and Technology, "Gear", p. 744.
[21] http:/ / www. youtube. com/ watch?v=mNI0TwHKNi4
[22] ISO/DIS 21771:2007 : "Gears – Cylindrical Involute Gears and Gear Pairs – Concepts and Geometry", International Organization for
Standardization, (2007)
[23] Hogan, C Michael; Latshaw, Gary L [http://www.worldcatlibraries.org/wcpa/top3mset/2930880 The Relationship Between Highway
Planning and Urban Noise , Proceedings of the ASCE, Urban Transportation Division Specialty Conference by the American Society of Civil
Engineers, Urban Transportation Division, 21 to 23 May 1973, Chicago, Illinois
[24] Smith, Zan (2000), "Plastic gears are more reliable when engineers account for material properties and manufacturing processes during
design." (http:/ / motionsystemdesign. com/ mechanical-pt/ plastic-gears-more-reliable-0798/ index. html), Motion System Design, .
[25] Oberg, E; Jones, F.D.; Horton, H.L.; Ryffell, H.H. (2000), Machinery's Handbook (26th ed.), Industrial Press, pp. 2649,
ISBN 978-0-8311-2666-7.
[26] Siegel, Daniel M. (1991). Innovation in Maxwell's Electromagnetic Theory: Molecular Vortices, Displacement Current, and Light.
University of Chicago Press. ISBN 0521353653.
[27] MacKinnon, Angus (2002). "Quantum Gears: A Simple Mechanical System in the Quantum Regime". Nanotechnology 13 (5): 678.
doi:10.1088/0957-4484/13/5/328. arXiv:cond-mat/0205647.
[28] Sanduk, M. I. (2007). "Does the Three Wave Hypothesis Imply Hidden Structure?". Apeiron 14 (2): 113–125.
Gear 20
Bibliography
• American Gear Manufacturers Association; American National Standards Institute (2005), Gear Nomenclature,
Definitions of Terms with Symbols (ANSI/AGMA 1012-F90 ed.), American Gear Manufacturers Association,
ISBN 978-1-55589-846-5.
• McGraw-Hill (2007), McGraw-Hill Encyclopedia of Science and Technology (10th ed.), McGraw-Hill
Professional, ISBN 978-0-07-144143-8.
• Norton, Robert L. (2004), Design of Machinery (http:/ / books. google. com/ ?id=iepqRRbTxrgC) (3rd ed.),
McGraw-Hill Professional, ISBN 978-0-07-121496-4.
• Vallance, Alex; Doughtie, Venton Levy (1964), Design of machine members (4th ed.), McGraw-Hill.
Further reading
• Buckingham, Earle (1949), Analytical Mechanics of Gears, McGraw-Hill Book Co..
• Coy, John J.; Townsend, Dennis P.; Zaretsky, Erwin V. (1985), Gearing (http:/ / ntrs. nasa. gov/ archive/ nasa/
casi. ntrs. nasa. gov/ 20020070912_2002115489. pdf), NASA Scientific and Technical Information Branch,
NASA-RP-1152; AVSCOM Technical Report 84-C-15.
• Kravchenko A.I., Bovda A.M. Gear with magnetic couple. Pat. of Ukraine N. 56700 – Bul. N. 2, 2011 – F16H
49/00.
External links
• Geararium. Museum of gears and toothed wheels (http:/ / geararium. org) Antique, vintage, contemporary gears,
sprockets, gear-related objects and interesting connections.
• Kinematic Models for Design Digital Library (KMODDL) (http:/ / kmoddl. library. cornell. edu/ index. php)
Movies and photos of hundreds of working models at Cornell University
• Mathematical Tutorial for Gearing (Relating to Robotics) (http:/ / www. societyofrobots. com/ mechanics_gears.
shtml)
• Animation of an Involute Rack and Pinion (http:/ / www. brockeng. com/ mechanism/ RackNPinion. htm)
• Explanation Of Various Gears & Their Applications (http:/ / www. geardesign. co. uk)
• Booklet of all gear types in full-color illustrations (http:/ / motionsystemdesign. com/ Gears. pdf) PDF of gear
types and geometries
• "Gearology" – A short introductory course on gears and related components (http:/ / www. bostongear. com/
training/ gearology. asp)
• American Gear Manufacturers Association website (http:/ / www. agma. org)
• Gear Solutions Magazine, Your Resource for Machines Services and Tooling for the Gear Industry (http:/ / www.
gearsolutions. com)
• The Four Basic Styles of Gears (http:/ / www. groschopp. com/ the-4-basic-styles-of-gears/ )
• Gear Technology, the Journal of Gear Manufacturing (http:/ / www. geartechnology. com)
• "Wheels That Can't Slip." (http:/ / books. google. com/ books?id=AyEDAAAAMBAJ& pg=PA120&
dq=popular+ science+ 1930& hl=en& ei=4dTRTu6lLsvUgAed8uifDQ& sa=X& oi=book_result& ct=result&
resnum=5& ved=0CEIQ6AEwBDhG#v=onepage& q& f=true) Popular Science, February 1945, pp. 120–125.
Article Sources and Contributors 21
Article Sources and Contributors
Gear  Source: http://en.wikipedia.org/w/index.php?oldid=504918357  Contributors: 16@r, 2301700056mark, 28421u2232nfenfcenc, 360creep, 7severn7, 84user, A DudeManGuy, A3RO,
A8UDI, AbhiSuryawanshi, Abhinav.sharma88, Achalmeena, Adam850, Adjwilley, AeonicOmega, Af648, Agamemnon2, AjeetKhurana, Alai, Alansohn, Aldie, Alex.muller, Alexknight12,
Alfonso Márquez, Alonades, AndrewH, Andy Dingley, Angr, Another Stickler, Antandrus, Apparition11, Arbitrarily0, Archivist, Arreazaman, Arthur Clarke, Ashokaengineering, Atlant, Aua,
Aulis Eskola, Avi Ravner, Avé, BD2412, BTLizard, Badgernet, Barthulley, Bavgang123, BenFrantzDale, Bender235, Bento00, Betterusername, Bgold4, Bhwhiz, Bigbadshow123456, Biscuittin,
Bjankuloski06en, Bkell, Bkusmono, Blehfu, Bobbo, Bobo192, Boism, Boleyn, Bongwarrior, Boxhead81, Brian0918, BrianSfinasSSI, Brianhe, Bryan.burgers, Bsadowski1, Buster2058, Butter
Bandit, CLEChick, Caggy27, Callan 01, Can't sleep, clown will eat me, Cannissolis, CardinalDan, Catgut, Catsquisher, Cek, Chetvorno, Chick0514, ChrisCork, Christopher Thomas, Chzz,
Cleveland Saxon, Closedmouth, Control.valve, Corvus cornix, Cpkondas, Craig Pemberton, Cst17, CyberSkull, Cybercobra, Cyberstrike2000x, CyclePat, Cyrus Andiron, DARTH SIDIOUS 2,
DMacks, Da Joe, Daa89563, Dancing-jenny, Danhash, DaughterofSun, David D., Dbfirs, Deli nk, Delldot, Deor, DerHexer, Dhritiman Talukdar, Dickandharry, Diligent Terrier, Doctor It,
Doh5678, Dolphin51, DoriSmith, Dougofborg, Dr. Gear, Dtgriscom, Duk, Dvd101x, ERcheck, EdJogg, EleanorRugby, Elgrozni, Elkman, Enter The Crypt, Epbr123, Eric-Wester, Ettrig, Evand,
Evil Eccentric, FF2010, Favonian, Feef, Finn-Zoltan, Floddinn, Formula uno, Fredrik, Frencheigh, Fæ, G-Man, GRAHAMUK, Gadfium, Gantiganti, Gavin77, GearHeads, Geneb1955, Giftlite,
Gilliam, Glenn, Graibeard, Greenpowered, Gregorydavid, Gregzore, Gun Powder Ma, Gzuckier, Hahifuheho, Ham Pastrami, Heathhunnicutt, Heron, Home Row Keysplurge, Honaroog,
Hooperbloob, IceFire, Ignaciomella, Igor Zarebski, Ilmari Karonen, Imjustmatthew, Incompetence, Infrogmation, Ixfd64, J.delanoy, J36miles, JAKoulouris, JForget, Jackehammond, Jagged 85,
JamesBWatson, Jamesontai, Jawadreventon, Jeffwishart, Jleedev, Jmajeremy, JoJan, Johntex, Jose77, Jsallen1, Julesd, Jusdafax, Justsail, KGV, Kaboldy, Katalaveno, Keilana, KeithB, Kerotan,
Khalid hassani, Kielenova, Kjrreid, Knotnic, Kosebamse, Kostmo, Kri, Krótki, Kudpung, L.K, Lahiru k, Lankiveil, Leebo, LegitimateAndEvenCompelling, Leonard G., Lfhc96tetra, Lhc67,
Lkesteloot, Lolman223, Lord Eru, Luna Santin, Lupo, MER-C, MLRoach, Mac, Macauleyd4, Magnus Manske, Maheshsm19, Manda.L.Isch, Mandarax, Marek69, Martin451, Massestephanie,
Mathewignash, Mathonius, Mboverload, Mean as custard, Meggar, Mentifisto, Mike1975, Mild Bill Hiccup, Miniminimo, Minna Sora no Shita, Mintleaf, Miranda, Mo0, MoCellMan,
MortimerCat, Mukkakukaku, Mushlack, NAGARAJU.GUMMADI, Nagle, Naikprem, Nakon, Nathan Laing, Nathan.f77, Naturrien, NawlinWiki, Neparis, Nereth, Next-Genn-Gamer,
Nomad1234, Nskillen, Nuttycoconut, Ocaasi, Ohconfucius, Omicronpersei8, Optichan, Optimist on the run, Orange Suede Sofa, Ospalh, PULSER47, Pagw, Patrick, Pb30, Pbroks13, Peedarp007,
Peripitus, Perkinma, Peter Horn, Philip Trueman, Phmoreno, Piano non troppo, Pinethicket, Pol098, Polyparadigm, Prashanthns, Pretzelpaws, Prof McCarthy, Pwhited39, QTCaptain, Qef,
Qp10wo29ei38, Quest for Truth, Qwerqwerqwer, R'n'B, RadioFan, RainbowOfLight, Ranveig, Raz.you.up, Razr95, Redjar, Redtricycle, Remag Kee, Rich257, Rjwilmsi, Robert.Baruch,
Roguelazer, Romakuzhlev, Rossami, RottweilerCS, Rror, Ryan Reich, SBKT, SCEhardt, SGBailey, Sakuraghi, Sam Korn, Samgunner, Scetoaux, ScienceUpdates, Seth Ilys, Several Pending,
Shadowjams, Shanes, Sherlockspock, Silivrenion, Silly rabbit, SimonP, Singularity, Sintaku, Skarebo, Some jerk on the Internet, Sonett72, SpaceFlight89, Sparkignitor, Stca, StefanBurke, Stepa,
StephenBuxton, Stevertigo, Storkk, SummerPhD, Supercaptianawesomejesus, Surendra mohnot, THEN WHO WAS PHONE?, TWCarlson, Tamber-Krain, Tempodivalse, The Thing That Should
Not Be, TheFeds, TheRedPenOfDoom, Thehelpfulone, Thorney¿?, Three-quarter-ten, Tim1357, Timwi, Tnxman307, Toddst1, Tommy2010, Toolmasters, Tornvmax, Travelbird, TreasuryTag,
Treisijs, Tropylium, Trunks ishida, Twirlip, Tyler69, Ukexpat, Ummit, Uncle G, Uni student101, Urbane User, Vald, Van helsing, VanBurenen, Versus22, Vivers, Vovchyck, Waggers,
Wapcaplet, Werdan7, Westonmr, Why Not A Duck, WikHead, Wiki13, Wikinaut, Wikiwkr, Wimt, Wizard191, Wmberg, Wolfkeeper, Woohookitty, Wragge, Wysprgr2005, XJamRastafire,
Xiaphias, Yar Kramer, Zack, Zad68, 898 anonymous edits
Image Sources, Licenses and Contributors
File:Gears animation.gif  Source: http://en.wikipedia.org/w/index.php?title=File:Gears_animation.gif  License: Public Domain  Contributors: BD2412, Guam, Jahobr, Mdd, Túrelio,
WikipediaMaster
File:Gear words.png  Source: http://en.wikipedia.org/w/index.php?title=File:Gear_words.png  License: Creative Commons Attribution-ShareAlike 3.0 Unported  Contributors: See source.
File:Inside gear.png  Source: http://en.wikipedia.org/w/index.php?title=File:Inside_gear.png  License: Creative Commons Attribution-ShareAlike 3.0 Unported  Contributors: honaroog
File:Spur Gear 12mm, 18t.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Spur_Gear_12mm,_18t.svg  License: Public Domain  Contributors: Inductiveload
File:Helical Gears.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Helical_Gears.jpg  License: Public Domain  Contributors: Original uploader was Arthur Clarke at en.wikipedia
File:Herringbone gears (Bentley, Sketches of Engine and Machine Details).jpg  Source:
http://en.wikipedia.org/w/index.php?title=File:Herringbone_gears_(Bentley,_Sketches_of_Engine_and_Machine_Details).jpg  License: unknown  Contributors: Andy Dingley, Hohum,
WikipediaMaster
File:Gear-kegelzahnrad.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Gear-kegelzahnrad.svg  License: Public Domain  Contributors: Myriam Thyes
File:Sprocket35b.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Sprocket35b.jpg  License: Public Domain  Contributors: Hapesoft
File:Crown gear.png  Source: http://en.wikipedia.org/w/index.php?title=File:Crown_gear.png  License: GNU Free Documentation License  Contributors: Arbitrarily0, Panther,
WikipediaMaster, 1 anonymous edits
File:Worm Gear and Pinion.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Worm_Gear_and_Pinion.jpg  License: Public Domain  Contributors: Original uploader was Arthur
Clarke at en.wikipedia
File:Worm Gear.gif  Source: http://en.wikipedia.org/w/index.php?title=File:Worm_Gear.gif  License: Public Domain  Contributors: Frank C. Müller, Jahobr, 1 anonymous edits
File:Non-circular gear.PNG  Source: http://en.wikipedia.org/w/index.php?title=File:Non-circular_gear.PNG  License: Creative Commons Attribution-Sharealike 3.0  Contributors: Igor Zarebski
File:Rack and pinion animation.gif  Source: http://en.wikipedia.org/w/index.php?title=File:Rack_and_pinion_animation.gif  License: Public Domain  Contributors: Andy Dingley, BD2412,
Friviere, Guam, Jahobr, Mdd, Premkudva, Túrelio, Vonvon, Wikieditoroftoday, WikipediaMaster, Ö, 3 anonymous edits
File:Epicyclic gear ratios.png  Source: http://en.wikipedia.org/w/index.php?title=File:Epicyclic_gear_ratios.png  License: GNU Free Documentation License  Contributors: Abdullah Köroğlu,
DuLithgow, Fabartus, Julia W, Kozuch, Ma-Lik, Mats Halldin, WikipediaMaster
File:Sun and planet gears.gif  Source: http://en.wikipedia.org/w/index.php?title=File:Sun_and_planet_gears.gif  License: Creative Commons Attribution-ShareAlike 3.0 Unported  Contributors:
User:Emoscopes
File:Harmonic drive animation.gif  Source: http://en.wikipedia.org/w/index.php?title=File:Harmonic_drive_animation.gif  License: Creative Commons Attribution-Sharealike 3.0,2.5,2.0,1.0
 Contributors: LaurensvanLieshout
File:Cage Gear.png  Source: http://en.wikipedia.org/w/index.php?title=File:Cage_Gear.png  License: Public Domain  Contributors:
Interior_view_Pantigo_Windmill_East_Hampton_Suffolk_County_New_York.jpg: Historic American Buildings Survey, National Park Service derivative work: Twirlip (talk)
File:Contact line.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Contact_line.jpg  License: GNU Free Documentation License  Contributors: User:SreeBot
File:Action path.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Action_path.jpg  License: GNU Free Documentation License  Contributors: Original uploader was GearHeads at
en.wikipedia
File:Action line.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Action_line.jpg  License: GNU Free Documentation License  Contributors: Original uploader was GearHeads at
en.wikipedia
File:Action plane.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Action_plane.jpg  License: GNU Free Documentation License  Contributors: Original uploader was GearHeads at
en.wikipedia
File:Contact lines.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Contact_lines.jpg  License: GNU Free Documentation License  Contributors: Original uploader was GearHeads at
en.wikipedia
File:Action arc.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Action_arc.jpg  License: GNU Free Documentation License  Contributors: Original uploader was GearHeads at
en.wikipedia
File:Action length.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Action_length.jpg  License: GNU Free Documentation License  Contributors: Original uploader was GearHeads at
en.wikipedia
File:Limit diameter.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Limit_diameter.jpg  License: GNU Free Documentation License  Contributors: User:SreeBot
File:Face advance.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Face_advance.svg  License: GNU Free Documentation License  Contributors: GearHeads, Vectorised by Qef
File:Action zone.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Action_zone.jpg  License: GNU Free Documentation License  Contributors: Original uploader was GearHeads at
en.wikipedia
File:Tooth thickness.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Tooth_thickness.jpg  License: GNU Free Documentation License  Contributors: User:SreeBot
Image Sources, Licenses and Contributors 22
File:Thickness relationships.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Thickness_relationships.jpg  License: GNU Free Documentation License  Contributors: User:SreeBot
File:Chordial thickness.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Chordial_thickness.svg  License: GNU Free Documentation License  Contributors: Pbroks13
File:Pin measurement.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Pin_measurement.jpg  License: GNU Free Documentation License  Contributors: User:SreeBot
File:Span measurement.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Span_measurement.jpg  License: GNU Free Documentation License  Contributors: GearHeads at
en.wikipedia
File:Addendum teeth.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Addendum_teeth.jpg  License: GNU Free Documentation License  Contributors: Original uploader was
GearHeads at en.wikipedia
File:Pitches.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Pitches.jpg  License: GNU Free Documentation License  Contributors: User:SreeBot
File:Tooth pitches.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Tooth_pitches.jpg  License: GNU Free Documentation License  Contributors: User:SreeBot
File:Base pitch.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Base_pitch.jpg  License: GNU Free Documentation License  Contributors: Original uploader was GearHeads at
en.wikipedia
File:Principal pitches.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Principal_pitches.jpg  License: GNU Free Documentation License  Contributors: User:SreeBot
File:Tooth surface.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Tooth_surface.jpg  License: GNU Free Documentation License  Contributors: User:SreeBot
File:Undercuts.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Undercuts.svg  License: GNU Free Documentation License  Contributors: User:GearHeads, Vectorised by User:Qef
File:Cogwheel in Malbork.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Cogwheel_in_Malbork.jpg  License: Creative Commons Attribution-Sharealike 3.0,2.5,2.0,1.0
 Contributors: DerHexer
File:Skupaj ogv q10ifps2fr6.ogv  Source: http://en.wikipedia.org/w/index.php?title=File:Skupaj_ogv_q10ifps2fr6.ogv  License: Public Domain  Contributors: 84user, Andy Dingley, Aushulz,
Queeg
License
Creative Commons Attribution-Share Alike 3.0 Unported
//creativecommons.org/licenses/by-sa/3.0/

Attachment B
Home > Product Listing > Gears > Image Index | GEARS Site Map

IMAGE INDEX

SDP/SI ON-LINE eStore offers: Spur Gears, Helical Gears, Miter Gears, Worm Gears, Worms, Anti-
backlash Gears, Anti-backlash Worms, Bevel Gears, Gear Clamps, Cluster Gears, Differential End Gears,
Composite Spur Gears, Flexiracks, Gear Hubs, Dial Hubs, Racks, Pinion Wire and Pinion Shafts.
Click on [Inch] or [Metric] to go directly to our eStore and shop online.

42
1
Spur Gears
Metal Spur Gears
Inch • Metric
Press Release 1
Press Release 2
Press Release 3
Spur Gears
Plastic Spur Gears
Inch • Metric
Press Release 1
Press Release 2
Anti-backlash Gears
Spur Gears
Inch • Metric • Press Release
Composite Spur Gears
Inch
Differential End Gears
Spur Gears
Inch
Spur Gears
Spur Gear Stock
Inch • Metric
Spur Gears
Spur Gear - Pinion Shafts
Inch • Metric
Pinion Wire
Inch • Metric
Pinion Shafts
Undersize Diameters
Inch• Metric
Miter Gears
Straight Toothed
Inch • Metric
Miter Gears
35° Spiral Angle - Precision
Metric
Miter Gears
35° Spiral Angle - Commercial
Metric
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8/6/2012http://www.sdp-si.com/estore/CoverPg/Gears.htm
Bevel Gears
Straight Tooth - Precision
Inch
Bevel Gears
Straight Tooth - Commercial
Inch • Metric
Bevel Gears
35° Spiral Angle Tooth- ISO 4
Metric
Worm Gears
Right-Hand Lead
Inch • Metric
Worm Gears
Left-Hand Lead
Metric
Worms
Commercial & Precision
Inch • Metric
Anti-backlash Gears
Worm Gears
Inch
Mating Worms for Anti-backlash Gears
Inch
Internal Gears
Precision & Commercial
Inch • Metric • Press Release
Helical Gears
Precision & Commercial
Inch • Metric • Press Release
Differential End Gears
Clamp Type
Inch
Gear Blanks
Plastic & Metal
Inch • Metric
Cluster Gears
Style A
Inch
Cluster Gears
Style B
Inch
Cluster Gears
Style C
Inch
Racks
Rectangular
Inch • Metric • Press Release
Racks
Round Racks
Inch • Metric
Racks
Rectangular Mounting Hole Racks
Inch
Page 2 of 4Spur Gears, Helical Gears, Miter Gears, Worm Gears, Worms, Anti-backlash Gears, Anti-...
8/6/2012http://www.sdp-si.com/estore/CoverPg/Gears.htm
Racks
Joining Gauge
Metric
Flexiracks
Metric
Flexiracks
Flexirack Pinions
Metric
Flexiracks
Clamps
Metric
Flexiracks
Guide Rails
Metric
Gear & Dial Hubs
Precision - Fairloc® Hub
Inch
Gear & Dial Hubs
Commercial - Pin Type
Inch
Gear & Dial Hubs
Precision - Pin Type
Inch
Gear & Dial Hubs
Precision
Metric
Gear & Dial Hubs
Precision - Clamp Type
Inch
Gear & Dial Hubs
Precision - Cluster Gear Hub
Inch
Gear & Dial Hubs
Precision Removable Type Pin
Inch
Gear & Dial Hubs
Precision Removable Clamp Type
Inch
Gear Clamps
Commercial & Precision
Balanced-Type Gear Clamps
Inch • Press Release
Gear Clamps
Commercial & Precision
Split-Hub Gear Clamps
Inch
Gear Clamps
Commercial & Precision
Split-Hub Gear Clamps
Inch
Gear Clamps
Commercial & Precision
Split-Hub Gear Clamps
Inch
Gear Clamps
Commercial & Precision
Split-Hub Gear Clamps
Inch
Page 3 of 4Spur Gears, Helical Gears, Miter Gears, Worm Gears, Worms, Anti-backlash Gears, Anti-...
8/6/2012http://www.sdp-si.com/estore/CoverPg/Gears.htm
Gear Clamps
Commercial & Precision
Reduced Clearance Gear Clamps
Inch • Press Release
Gear Clamps
Commercial & Precision
Two-Piece Balanced Gear Clamps
Inch
Gear Clamps
Commercial & Precision
Two-Piece Balanced Gear Clamps
Inch • Press Release
Gear Clamps
Commercial & Precision
Two-Piece Balanced Gear Clamps
Inch
Gear Clamps
Commercial & Precision
Screw-Type Gear Clamps
Inch
Note: Prices and specifications are subject to change without notice. Every effort has been made to provide accurate technical
and product information. The company disclaims responsibility for any error or omission in the accuracy of the technical and
product information published.

Page 4 of 4Spur Gears, Helical Gears, Miter Gears, Worm Gears, Worms, Anti-backlash Gears, Anti-...
8/6/2012http://www.sdp-si.com/estore/CoverPg/Gears.htm