Hence one of the reasons I wouldn't do it with a wheelchair motor.rkcarguy wrote: ↑Wed Oct 21, 2020 1:05 pmOh, and one more FYI. Right angle drives can contain worm gears which DO NOT spin down when the power is cut to the electric motors driving them. As a result, if they are used in a large scale train application and the throttle is chopped, all that rolling momentum in the train gets turned into lateral forces on the worm gear drive which blows the gearbox apart (or the wheels lock up and the train slides).
BTW, worm gear drives can be made to be reversible. An example of this fact with which you may be familiar is the recirculating ball steering gear that was widely used in automobiles before rack-and-pinion became popular.
Reduction in a worm drive is defined as N ÷ S, where N is the number of teeth on the worm gear (the one driving the output shaft) and S is the number of starts on the worm pinion. In most production gearing, N will be 1, 2 or 4. A worm drive with a four-start worm is generally reversible and would work as gearing in a model locomotive. Using a 30 tooth worm gear and a four-start worm, a reduction of 7.5:1 would be produced and the gear train would be reversible.
Another right-angle solution is helical gearing with a 45 degree helix. Two gears of the same helix direction can be mounted on perpendicular, non-intersecting shafts to produce a reversible, right-angle drive. This is the gearing used in Tolo-Matic's shaft-mounted gearboxes. However, a reduction greater than about 3:1 is generally impractical due to the significant sliding action between the teeth.