Does anybody know what the nema type of motor a standard geriatric wheelchair uses? I have the ones that have the big square 90 degree gear head on them. Lots of power wheelchairs use this exact motor and gear head. The gear head has a keyed 5/8" output shaft. I am looking for a clean way to mount some US digital encoders to the other end after removing the brakes. If I can find out what nema type it is I may be able to find a direct fit part.