Hammond Generator Start Motor

General Description

This is a shaded pole induction motor used for starting the generator. If your organ is having trouble starting you might suspect this motor. Be sure to eliminate other possibilities.


Make sure the threads are in place going to each bearing. From the generator oiling trough there are threads that go to each motor bearing. These threads provide the motor bearings with oil.
Hammond Organ Pinion Gear
Make sure the motor spins freely
To check the motor push the shaft that is exposed in and it should pop back out. If this movement is easy and free then the shaft bearings are oiled and OK. Also, a severely worn motor bearing here can cause problems with the motor spinning correctly. If the motor is stuck, apply oil directly to the bearings and turn it by hand until it becomes free. You can also help free it up by pushing the shaft in and out. The return spring is very light duty so the motor would be considered free if it springs back after pushing in the shaft.
Pinion Gear
Pinion Gear
The next thing to check is the pinion gear which the start motor engages with when starting the generator. This is the lower and larger gear shown above. This gear rotates with the generator and also slides from right to left on it’s shaft. Below you can see the pinion gear moved to the left exposing the smaller shaft that the pinion gear slides on. This sliding action is necessary to engage with the start motor. It is common for this pinion gear to get stuck either in or out causing the starting motor to be unable to engage properly. Simply slide it to the left, oil the shaft, and slide it back. After a couple of times it will move freely again.
Pinion Gear Moved
Pinion Gear Moved
Below are two shots of the pinion gear from the underside of the generator. The first view shows the pinion gear in the rested position. Notice the two springs on the pinion gear shaft. The larger spring right against the gear acts as a clutch for the pinion gear. The smaller spring to the left (in the tone wheel bin) is the return spring for the pinion gear.
Pinion Gear Bottom
Pinion Gear Bottom
The next shot shows the pinion gear moved to the left.
Pinion Gear Bottom 2
Pinion Gear Bottom 2
It’s a little hard to see but there is a flat spring pressing on the smaller motor gear. This is what returns the start motor to the “out” position when disengaged.


Most electrical problems with the start motor are really with the run start switches. Refer to Switchesfor more detail. If the field coil of the start motor is open or shorted, the motor will need to be replaced.




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