Said board shall hear and decide all applications for such relief or pensions under sections 86.510 to 86.577, and its decisions on such applications shall be final and conclusive and not subject to a review and reversal except by the board, and a record shall be kept by its secretary of all meetings and proceedings of the board which may convene at any time, by order of the president of the board or a majority of the members of said board. Said board of trustees shall serve without pay.