Any person retired for disability under this chapter may be summoned before the board herein provided for, at any time thereafter, and shall submit himself or herself thereto for examination as to his or her fitness for duty, and shall abide the decision and order of said board with reference thereto; and all members of such police force who may be retired under the provisions of this chapter, shall report to the chief of police of such city where so retired on the first Mondays of April, July, October, and January of each year; and in cases of emergency, may be assigned to and shall perform such duty as said chief of police may direct, and such persons shall have no claim against such city for payment for such duty so performed.