40 ILCS 5/6-152
Any fireman who is not eligible for minimum annuity, who becomes disabled after the effective date as the result of any cause other than the performance of an act or acts of duty, shall have a right to receive ordinary disability benefit during any period or periods of such disability, after the first 30 days of disability. Payment of such benefits shall not exceed, in the aggregate, throughout the entire service of the fireman, a period equal to 1/2 of the total service rendered by him prior to the time he became disabled, but not to exceed 5 years. In computing such period of service, the time that the fireman received ordinary disability benefit shall not be included.
The first payment of the benefit shall be made not later than one month after the benefit is granted and each subsequent payment shall be made not later than one month after the time when the latest payment was made.
When a disabled fireman becomes eligible for minimum annuity, the disability benefit shall cease and he shall thereafter receive such annuity or annuities as are provided for him in accordance with other provisions of this Article.
Ordinary disability benefit shall be 50% of the fireman's salary at the time the disability occurs. Before any payment is made, a sum ordinarily deducted from the fireman's salary for annuity purposes during a period of time equal to that for which such payment of ordinary disability benefit is to be made shall be deducted from such payment and credited to him as a deduction from his salary for such period. The sums so credited shall be regarded, for annuity and refund purposes, as sums contributed by the fireman.
40 ILCS 5/6-152