40 ILCS 5/8-164
An employee whose disability continues after he has received ordinary disability benefit for the maximum period of time prescribed by this Article, and who withdraws before age 60 while still so disabled, is entitled to receive annuity of such amount as can be provided from the accumulation to his credit from employee contributions and city contributions to be computed as of his age on the date of withdrawal.
The annuity to which his wife shall be entitled upon his death, shall be fixed on the date of his withdrawal. It shall be provided from the amount to his credit for widow's annuity on the date of such withdrawal.
Upon the death of any such employee while on annuity, if his service was at least 4 years after the date of his original entry, and at least 2 years after the date of his latest re-entry, his child or children under age 18 shall be entitled to annuity as specified in this Article for children of an employee who retires after age 55, subject to prescribed limitations on total payments to a family of an employee.
40 ILCS 5/8-164