In the event that the board of supervisors of any county having established any of the improvements or facilities authorized by this act determines that any city, village, township or township improvement district is in need of extensions, improvements or repairs to such improvements and facilities of and within such units of government, such board of supervisors by a two-thirds majority vote of its members elect is authorized to appropriate, advance and loan to and by agreement with such unit of government from the general funds of the county, such sums as are necessary to provide such extensions, improvements or repairs. The board of supervisors may, by resolution adopted by a two-thirds majority vote of its members elect, make such advance and loan on condition that the legislative body of the unit of government borrowing and receiving said sum shall enter into an agreement therefor and approve such advance and loan by a two-thirds vote of its members elect. Any sum to be borrowed for the benefit of a township improvement district shall be authorized by action of the township board in the township where said district is situated. No such loan shall be made by the board of supervisors without there first being irrevocably pledged to the payment thereof current or delinquent taxes evidenced by promissory notes paying interest at not to exceed 5 per cent per annum and maturing within a period of 10 years: Provided, The total sum advanced and loaned to any such unit of government for 1 or more of the improvements or facilities authorized herein shall not, in total amount, exceed 10 per cent of its current taxes and 80 per cent of all its delinquent taxes, and current and/or delinquent taxes pledged shall not exceed said amount. Such advances and loans are authorized irrespective of the amount of tax delinquency of the unit of government borrowing money for the purpose herein provided, and shall not require the approval of the state loan board, the public debt commission or any other state authority.