36 volt motor no power

[ralph1478]

I'm not a mechanic so bear with me. Can the brushes wear down so far that the motor loses power and runs erratically? It's an old 1978 5 solenoid system. I can hear the solenoids click but no speed change. It will suddenly speed up or slow down with no pedal change.

[sthreatt]

In very old motors with a LOT of use I have seen them wear down so short that the brush springs hit the brush retainers and lose pressure on the brushes to the commutator. That can make for erratic running. Speeding up and slowing down without pedal change sounds more like solenoid ( or solenoids ) dropping out or in during ride. Could be bad or weak solenoids or intermittent connection in wiring to those solenoids. More or less voltage being sent to the motor depending on how many resistor coils you're engaging/disengaging.

[CustomCurt]

it sounds more like the slide that actuates the micro switches is worn, but you can test the solinoids easy enough, there is a copper bar that hooks the five solinoids together, remove it and then you can test each one idividually which will also pinpoint which of the micro switches have gone bad or that the actuator is not actuating

[Fairtax4me]

Yes, brushes wear out eventually. And yes, they will cause low power or jerky operation/changes in speed with no change in throttle.
On a motor that old, I would be pulling it apart to check the brushes and the commutator.