Whenever it considers such purchase or lease advisable, to purchase or lease highway construction and maintenance equipment under contracts providing for payment in installments over a period of time of not more than 10 years with interest on the unpaid balance owing not to exceed the amount permitted pursuant to "An Act to authorize public corporations to issue bonds, other evidences of indebtedness and tax anticipation warrants subject to interest rate limitations set forth therein", approved May 26, 1970, as amended.
605 ILCS 5/5-101.11