farm Pro 2420

RonMar · May 3, 2012

bigearl42 said:
the shaft slowes down and stops turning so i need to loosen the bolts a lttle then?

With the PTO engaged and the tractor in gear, as you lift the clutch pedal from the fully depressed position, at what point in the clutch pedal travel does the PTO/mower start rotating? At what point in the pedal travel does the tractor start moving? In a proper setup, the PTO should start to turn just after the pedal comes off the fully depressed position. The tractor should start to move when the pedal reaches about the 1/2 way point in it's travel. This way you can shift gears or stop the tractor by depressing the pedal 1/2 way without disengaging the PTO clutch.

When you step on the pedal, the levers lift the main plate, the main plate inturn lifts the pto plate. The main drive clutch engagement and the clutch pedal freeplay are controlled by a combination of the outside linkage adjustment and the bolts at the ends of the 3 lever arms on the clutch(#24 in the drawing?). The relationship between the main clutch and the PTO clutch is controlled by the three #6 bolts in Gregs diagram. Since the plates being down/forward is where the discs are being gripped, It sounds like the three #6 bolts are too tight and are not allowing the PTO plate to fully grip the PTO disc, even with the main plate in the full forward/engaged position...

greg_g · May 4, 2012

Go back to that diagram I uploaded on April 17th. I hope you're not adjusting the bolts (24) that move the fingers (19). Sounds more like the PTO friction disc (2) is slipping between the flywheel (1) and the PTO pressure plate (4). This can be because of wear, or because of incorrect adjustment(s). The degree to which the disc is squeezed between the plates is regulated by the amount of pre-load tension on the PTO Belleville spring (5). That pre-load tension is regulated by three adjusting nuts (6).

Too much pre-load, the plates won't release the disc. Not enough, the disc slips between the plates. It's important that all 3 adjusting nuts exert equal tension on the Belleville. If even one out out of spec, the disc can slip. It's also important to lock down the adjusting nuts with their respective jam nut (7). If that's not done, vibration can loosen one or more of the adjusting nuts, and the disc will slip under load.

As far as how much to adjust those three nuts, I'm afraid it's plain old trial an error on a used tractor. On a new clutchpack, the gap between #6 and #22 should be adjusted to about 1.2 millimeters. That's sufficient to reveal a coil or two of the compression spring on bolt #3. But PTO clutch material wears away with use (or abuse), so #6 must be adjusted periodically to compensate for the wear. This means the gap between #6 and #22 will necessarily get smaller following each adjustment. So as you adjust the PTO clutch over the years, you'll eventually lose sight of that little compression spring. But regardless of age, all three nuts must be adjusted adjusted to a degree that ensures pre-load tension is distributed equally around the Belleville spring.

//greg//