Sec. 11. DISABILITY RESULTING FROM PERFORMANCE OF DUTY. If any member shall become totally or permanently disabled as a direct and proximate result of the performance of duties in the police department, said member shall be retired on a pension of Seventy-five Dollars ($75) per month.

By total and permanent disability is meant such disability as permanently incapacitates a member from performing the usual and customary duties of a police officer.

Before any retirement on disability pension is made, the pension board shall require such medical examination and such other evidence as it may see fit to establish such total and permanent disability, as above provided.

When any member has been retired for total and permanent disability, he shall be subject at all times to re-examination by the pension board and shall submit himself to such further examination as the pension board may require. If any member shall refuse to submit himself to any such examination, the pension board may within its discretion, order said payment stopped. If a member who has been retired under the provision of this Section, should thereafter recover so that in the opinion of the pension board, he is able to perform the usual and customary duties of a police officer, and such member is reinstated or tendered reinstatement in the police department, then the pension board shall order such payments stopped.

Said pension board may, at its discretion, retire on said permanent and total disability pension, those members of said police department who have heretofore become totally and permanently disabled, as that term is above defined.