The Stovebolt Site Forums The Parking Lot Big Bolts 62 1,5 ton alternator.

The two coils with the points spring loaded in the closed position are the current and voltage regulators. The one in the middle with the heavy windings controls maximum current, which is usually set at 25-35 amps, depending on the capacity of the generator. Some commercial vehicles like yours might have been equipped with a 45 amp unit because of multiple short trips and repeated engine starts. A 45 amp generator will have ball bearings on both ends instead of a bushing in the rear end frame. The far right coil regulates voltage, and has much smaller windings. The one on the left with the "normally open" points is the cutout relay. It disconnects the battery from the generator when the engine stops. On startup, when the generator voltage gets higher than the battery voltage, the cutout snaps shut and stays there until the voltage drops on shutdown. If it sticks, the battery discharges itself through the regulator and generator, and usually fries both of them in the process. Never, ever, push the cutout points closed when the engine isn't running! They will stick closed and overheat and burn the contacts in a matter of seconds. Opening either the voltage or current regulator points manually will shut off the generator output and cause the cutout to snap open- - - -that's how I check for normal operation while adjusting a regulator. It's OK to run the engine with the regulator cover removed- - - -just be careful not to short anything out as you reinstall the cover.

Regulators are pretty primitive units, but millions of them worked well for several decades. Now, there's a lot more regulators out there than us old geezers who remember how to work on them!
Jerry