Should any member of a fire or police department become or be found to be permanently and totally disabled for the discharge of his duties as a member of said fire department or police department, mentally or physically, by reason of sickness or injury, and who has had not less than five years’ service with such department, there shall be paid to said fireman or policeman from the firemen’s and policemen’s disability and relief fund, provided the municipality has such a fund, for each year’s active service, not to exceed a period of twenty years, one-fortieth of the monthly salary of such policeman or fireman at the time such disability is incurred, to be paid throughout such permanent and total disability. In passing upon the question of disability said board shall require an examination of the applicant by the city physician or other physician or physicians as it may deem proper, and may require like examinations from time to time throughout the period of disability claimed by said fireman or policeman. If said city pays a salary to its firemen or policemen while disabled in an amount equal to the disability relief allowed under this section, said firemen or policemen shall not be entitled to any disability relief under this section.