HammondWiki - Start Motor

From '53 Hammond tech sheet

A shaded pole induction motor is used for starting the ToneGenerator, and is located at the right-hand end of the ToneGenerator as viewed from the back. The rotor of this motor slides endwise when current is supplied and engages a pinion on its shaft with a gear on the driveshaft of the ToneGenerator, bringing the ToneGenerator up to slightly greater than SynchronousSpeed.

This motor has a resistor added in series at the application of the RunSwitch. The loss of power causes the system to fall to SynchronousSpeed with the SynchronousMotor carrying the load.

It should be clear that the induction start motor is geared to turn faster than the synchronous speed of 1200RPM. When the run switch is turned on, the resistor drops the start motor speed closer to synchronous speed.

This can be used as a special effect to off-speed the tone generator and "bend" the note. One of the most famous uses of this technique is at the very end of Santana's Everything's Coming Our Way. You can easily hear ?GreggRolie off-speed the organ at 3:04. The pitch drops as Gregg turns on the ?StartSwitch to the start motor. This extra load drops the tone generator's speed and drops the pitch. At 3:05 he releases the start switch and the synchronous motor surges back and goes slightly over speed and then drops back into synch right as the song ends.