Electric clutch troubles

[WITom]

Ever since I bought my Deutz Allis 1914 Sunstar, there has been a slight delay when engaging the electric pto - never more than about 1 second from the time I throw the switch until the deck engages. Today, while mowing grass, I shut the deck down to move a swingset, and I couldn't get it to start again. The light comes on which leads me to think the switch is good - seat light is on too. I drove it to the shop and wiggled the wires going to the clutch to no avail. I pulled the connecter apart and stuck a piece of wire into it and touched the other end to the pos. batt. post - nothing. I got back on the tractor, flipped the switch and nothing happened UNTIL I threw the throttle open - then the clutch engaged. I finished mowing with no problems, but had no reason to shut it down until I was done. Before putting it away, I tried reengaging the clutch and couldn't get it to work again, even with throttle wide open. I would also add that the battery is in good condition, it charges correctly, and I have never had the clutch disengage on me for no reason. Any ideas as to what my problem might be? Thank you! WI Tom

[Al]

Hi, Some of the earlier interlock modules sensed the engine rpm, the later replacements don't. I suspect your problem is the clutch needs adjusting. There 3 nuts against the brake plate. The brake plate controls the clearance between the rotor and the clutch plate. When the clutch is engaged and the coil induces a magnetic field in the rotor that causes the rotor to pull the clutch plate against it and away from the brake plate. As the clutch wears, the clearance increases and as the gap increases, the magnetic field can't pull the plate in. If you have ever held 2 magnets together, you will have noticed that when they get very close, you can no longer hold them. This what happens in the clutch as the gap increases. When the field coil gets hot from running, the resistance of the wire increases. When this happens, the current goes down. This results in less power to pull in the clutch. So it works cold and won't pull in hot. This is a very common problem. To address it, take a .010" feeler guage and a 9/16 wrench and insert the feeler guage in the little rectangular holes in the side of the brake plate just offside and behind the nuts. Tighten the nuts up until you can just feel a little drag on the feeler guage. Then go to the next one etc. Go around the 3 nuts at lease 2 times, because if you need to change them very much, they affect each other a little. Getting the 010 clearance fixes most of them. If you have a Magnum engine, use a .012 guage, as they typically have a little more crankshaft end play. Good luck, Al Eden

[WITom]

Thanks for the advice, Al. I checked the air gap today and I'm guessing I had close to 1/16th of an inch before I adjusted it. After adjusting it to .012 (for the Magnum), the clutch now engages immediately upon flipping the switch. I haven't had a chance to try it yet after it gets hot, but I'm quite confident that your advice corrected the problem. Actually, after thinking some more about the situation, it makes sense the too large of an air gap would lead to the clutch engagine after the engine it revved up. By watching the volt meter, my tractor runs at about 12.5 volts at idle, and about 13.8 at full throttle. By revving the engine up, it feeds more voltage to the clutch allowing it to overcome the air gap. Thank you once again, Sir!! WI Tom