massey baler clutch p.t.o. problem

We are expericieng slipping where the yoke of the PTO meets the cluch assembly.

Taking it apart there is a a brass busshing on the yoke which fits on a shaft in the assembling.

We do not understand why there is no key on this shaft. We cleaned the bushing once and put it back together only to have it slip again.

Does this have to be pressed together?

Do the shaft and the bushing have a slight taper?

On the outside of the yoke we have something that looks like a roller bearing, but really is not a roller bearing. It would only slide on this when the clutch slips.

Do we have to press this assembly together?

Thanks for your help.

Rod C. MacNeil
Getting by on Borrowed balers in Cape Breteon. NS

The dealer will print out a blow up of the parts for you if you need to view the parts and how they work.

If you pull the yoke off you'll see the bushing inside. There are also pawls that are spring loaded that pop open if they are working right when you pull the yoke out.

The bushing is so when the machine over runs the pto shaft can stay still and the balers spins. This isn't needed so much now as most tractors have a built in over runing clutch.

The pawls engage a clutch disc on the flywheel with notches in it. The flywheel also rides on bushings so when the shear pin breaks it can spin on the shaft.

On our baler, the flywheel bushings went and the pawls came partly disengaged from the clutch disc. This chewed the pawls up and the disc so the next time it overran the pawls wouldn't drop out of the yoke assembly to catch the disc.

When you engage the tractor PTO, the clutch grabs, and drives the baler.

If you slow down the throttle, or stop the tractor, (or step on the clutch, if your tractor does not have "live PTO"), the clutch on the baler "overruns" to prevent the kinetic energy stored in the baler flywheel from "feeding back" and powering the tractor. While it is "overrunning", the PTO yoke is spinning on the bushing you mention.

You are near to figuring this out, when you mention the "roller bearing that is not a roller bearing", as this is the part that gives the clutch it's "one-way" action.

Study this out a but more until you figure out how this clutch locks up when the tractor is powering the baler, but releases when the baler is no longer being powered by the tractor.