Road implements purchased by a township must be paid out of the highway taxes of the township and may be paid in not to exceed five annual installments. A copy of the note or contract issued upon the purchase must be filed in the office of the township clerk, and such township clerk shall present a statement of the sum due thereon to the board of township supervisors at each regular meeting held thereafter for the audit of the township claims and charges, and the board shall audit the same. Not more than one-half of the highway taxes of the township may be applied to the payment thereof in any one year.