Slip clutch won't slip.

[BufordBoone]

Started a new thread to carry this on.

Old news: Slip clutch on Bush Hog I inherited probably has not been "slipped" in many, many years.

I tried loosening the nuts a couple of turns, still wouldn't slip. I asked about what to do here and got a number of replies similar to: "Rev it up and drop it on an old stump"

I had fear that it was really bound up and I didn't want to risk damaging my tractor PTO. Turns out I was right.

I took it apart today. All 4 fiber discs were corroded and stuck to other parts. I had to use a screw driver to get them separated. I cleaned the metal parts with a chisel, followed by a wire cup brush on an angle grinder.

All 8 bolts were rusted and would not turn with a wrench. The DeWalt impact wrench freed four of them then broke one in half. For the last three, I screwed a nut on and tapped with a hammer while using the impact wrench. I drilled the broken one.

I'll probably replace all 8 bolts. I suspect (hope) the 8 springs are still good. I'll get four new fiber discs (local dealer has them and they are not expensive) and reassemble.

I enjoyed an afternoon of figuring out how things work.

I post this for anyone else that might be in a similar situation. I doubt my clutch would have ever slipped.

Edited for clarity.

 

[countrybumpkin]

Sounds as if you did the correct thing, and will have it in proper working order.

 

[mddorange]

I had a similar problem last year and replaced my discs and four bolts and all nuts.

 

[Tx Jim]

Slip clutch maintenance is very easy to ignore until something happens so one needs it to operate correctly. Last yr I twisted off the input shaft on gearbox on my JD rd baler because slip clutch was seized when a drive chain broke then locked down my baler

 

[oldballs]

Thanks for posting Buford. I seldom, if ever, check my two clutches.....guess I'd better get to it. It's almost making shear pins look good.
Cheers,
Mike

 

[CobyRupert]

I use to loosen the bolts then "pop" the pto into gear to bump-shock the slip clutch into slipping, marking the disks to verify that they do in fact slip.

However it's easier to verify its slipping by turning the pto on, with the tractor OFF, thus locking the pto in place, then reach in and turn the blades by hand while verifying that the pto shaft isn't turning.

Edit: I suppose with an overrun clutch you have to turn the blades their opposite direction

 

[ericm979]

However it's easier to verify its slipping by turning the pto on, with the tractor OFF, thus locking the pto in place, then reach in and turn the blades by hand while verifying that the pto shaft isn't turning.

Neat idea.
That'd save having to remove the safety cover on the mower (and remove and install the PTO shaft again to re-install the cover) so you can see if the clutch slipped.

My mower's slip clutch came set too tight from the factory. I didn't check it last year when I got it on the assumption that it had been set correctly.

 

[CobyRupert]

Neat idea.
That'd save having to remove the safety cover on the mower (and remove and install the PTO shaft again to re-install the cover) so you can see if the clutch slipped.

My mower's slip clutch came set too tight from the factory. I didn't check it last year when I got it on the assumption that it had been set correctly.

I don't know if you can get it to slip without loosening the slip clutch bolts. (I'm not sure if that's what you're suggesting?). I should try, that would save more time.

 

[ericm979]

On mine the adjustment bolts are easy to get to, without removing anything. So I can back them off to get the clutch to slip. But to see if the clutch has slipped you have to remove the PTO shaft, unbolt the big plastic guard that the clutch fits in, then put the PTO shaft back on to run the mower. Then reverse the process to put the guard back on. With your method I can leave all that stuff on, loosen the adjustment and if the mower turns by hand the clutch is slipping. It wouldn't "burn in" the plates but it would verify that they're not stuck. Then I can tighten the adustment bolts back to spec. Thanks!

 

[JRobyn]

Mine got really worn like that except the friction discs were simply GONE! The pressure plate was so rust pitted that I took it to a machine shop and had them grind 0.20"-0.30" off each side to smooth it up some.