What exactly is a slip clutch and how does it work?

[tony123]

Thanks Greg. But I suppose I'm a little slow. I realize the pin is a fastener only. However, I feel like the PTO is tied directly to the transmission. Why then does it not allow me to change gears until the blades stop spinning? Is that just typical operation for everyone?

I was thinking this pin I made was too long and holding both parts of the clutch together. That maybe the pin should be shorter to allow the clutch to spin?

Again, I'm sure you've given a great explanation, I'm just trying to wrap my brain around it.

[flathead]

Tony,

That should be a hardened roll pin, not some type of shear pin. Shear pins go where you want two shafts to come apart. In this case the shaft splines keep the two components from spinning apart and the roll pin acts as a retainer. If your bolt is too long it can prevent the ORC from spinning when it is supposed to. Even if it's not too long it will probably slip to one side or the other unless it's a press fit.

You should be able to find the right roll pin as TSC etc. Hardware stores also carry them but may need to be cut down a bit (abrasive wheel - not hacksaw)

flathead

[schmism]

Originally Posted by greg_g

Putting the gearshift into neutral means nothing to the ORC, since the PTO drive shaft turns independent of the transmission drive shaft. All it does is buffer the extra RPMs when the spinning blades happen to make the PTO shaft turn faster than the tractors output shaft (like the downhill example).
//greg//

I thought the more common case was when you hit the clutch to "stop" the tractors forward movement, but because the heavy rotional momentum behind you (could be brushhog, or bailer with flywheel etc) that would continue to spin the PTO and drive the transmission pushing you forward/backward based on what gear you were still in.

[tony123]

Originally Posted by schmism

I thought the more common case was when you hit the clutch to "stop" the tractors forward movement, but because the heavy rotional momentum behind you (could be brushhog, or bailer with flywheel etc) that would continue to spin the PTO and drive the transmission pushing you forward/backward based on what gear you were still in.

That's what's happening to me right now, even with the clutch on.

Flathead, I think you hit it spot on. I'm going to TSC today.

[waytech]

With tractor off and PTO engaged, can you turn your PTO shaft on the ORQ?

It should allow you to turn it one way only. If you can not turn it, then the bolt you put in is too long and is locking the two clutch halves together.

[greg_g]

Originally Posted by schmism

I thought the more common case was when you hit the clutch to "stop" the tractors forward movement, but because the heavy rotional momentum behind you (could be brushhog, or bailer with flywheel etc) that would continue to spin the PTO and drive the transmission pushing you forward/backward based on what gear you were still in.

If your driveline clutch is disengaged (or the transmission is in neutral) explain to me how a still-rotating implement PTO shaft can drive the tractor wheels. Now if you said "hit the brakes to stop the tractors forward movement"......

It is as I said; a typical ORC permits the implement PTO shaft to turn faster than the tractor PTO output shaft. Period.

I do however, heartily agree with the hardened roll pin sugggestion.

//greg//

[JerryG]

Originally Posted by schmism

I thought the more common case was when you hit the clutch to "stop" the tractors forward movement, but because the heavy rotional momentum behind you (could be brushhog, or bailer with flywheel etc) that would continue to spin the PTO and drive the transmission pushing you forward/backward based on what gear you were still in.

When the PTO on the tractor end is disengaged and power is no longer being transmitted, the Over Riding ratchet part of ORC is over ridden which allows the tractor part to stop. The implement part which is no longer powered will be allowed to spin at a faster rate than the now slowed or stopped tractor part of the PTO. For tractors with transmission driven PTOs (and without dual clutches or independent PTO) the tractor can now stop without the implement pushing it forward.
In other words you are right.

[JerryG]

Originally Posted by greg_g

If your driveline clutch is disengaged (or the transmission is in neutral) explain to me how a still-rotating implement PTO shaft canl drive the tractor wheels. Now if you said "hit the brakes to stop the tractors forward movement"......

If the tractors PTO is transmission driven, then the implement can push the tractor forward even if the clutch is disengaged unless it has a ORC installed.

Originally Posted by greg_g

It is as I said; a typical ORC permits the implement PTO shaft to turn faster than the tractor PTO output shaft. Period.

That's right.

[xlr82v2]

Originally Posted by greg_g

If your driveline clutch is disengaged (or the transmission is in neutral) explain to me how a still-rotating implement PTO shaft canl drive the tractor wheels. Now if you said "hit the brakes to stop the tractors forward movement"......

It is as I said; a typical ORC permits the implement PTO shaft to turn faster than the tractor PTO output shaft. Period.

I do however, heartily agree with the hardened roll pin sugggestion.

//greg//

Greg,

If you ever get a chance to drive an old Ford 8N with a bushhog attached that is not equipped with an ORC, it will quickly become very clear! The ORC prevents the momentum of your PTO powered implement from backfeeding power back into the transmission when you disengage the clutch on your tractor, such as when you're trying to stop to change gears/direction.

If your tractor has Live or Live Independent PTO, then you don't need an ORC, since the PTO power path in the transmission is not connected to the wheel drive power path. However, in a "Transmission Driven" PTO, this isnt' the case... The power path through one of these tractors for the PTO and the wheels is one and the same. Explained another way... If you jack up the rear wheels, then engage the PTO and then go back and turn the PTO shaft by hand, then you will also see that the rear wheels will turn as well (obviously, assuming that you have the transmission in gear and the clutch depressed so that you're not trying to turn over the engine as well). The ORC is simply a "one-way" clutch that prevents the implement from backfeeding power back into the transmission.

Although it's technically correct, when you say:

Originally Posted by greg_g

a typical ORC permits the implement PTO shaft to turn faster than the tractor PTO output shaft. Period."

...I don't think it clearly conveys or describes the real job that the ORC is there to do... when you describe it in terms of "power transfer" I believe it better paints the mental picture of what the ORC does.

[greg_g]

No problem guys - I think we're all pretty much saying the same thing, just using different words to do it. I did have an ORC at one time by the way, on an old Yanmar. First time the rotary cutter pushed me downhill, I drove straight over to the farm store and bought one.

//greg//