Question on overrunning clutch coupler use on a rotary tiller

[Tractor Gal]

Got a JD 647 tiller (sorry it's green but the price was right). There is no slip clutch. I have used it once this Fall and it operated well but I have concerns with the shear pin concept. There are not a lot of huge rocks in the garden to till but you never know. I could get a slip clutch, I suppose, but would an overrunning clutch might be better if there is additonal use with a bush hog. Either one of these will require shortening the PTO shaft which I have already done to fit the tiller and that was hard but not hard, if you know what I mean. Or perhaps having the shear pin alone would be fine since there are no plans to till open ground, only ground that has been used for a garden for a number of years. Any opinions are welcomed. I know there are a lot of scenarios with this question but I like to learn other ways to think. (I'm getting ready for Spring...in my thoughts!)

Tractor Gal

 

[old and tired]

The shear pin is most likely a bolt, do you know what grade the bolt is? Since it's used, most likely not, just take a photo of the bolt head and post it or Google "grade bolt markings" and look at images.

I would try and get away with Grade 2... if it breaks too much, move to a grade 5... Grade 8 is too strong!!!

 

[GreensvilleJay]

I have shear pin on my 5' tiller, break 3-4 a season as softball sized rocks 'magically' appear in 2 gardens....
Always have extras and wrenches on tiller.
OR clutch not needed for tiller but usually a 'must' with a bushhog.
My PTO shaft stays with the tiller.....

 

[old and tired]

Just to add... I have a slip clutch on mine mower, never adjusted it since it seized... I break about one bolt a year and keep several on hand. When I had a tiller, I don't think I ever broke a pin. The tiller would jump over rocks if it hits one.

 

[Russell King]

An over running clutch does not protect the tractor in the same manner as the slip clutch and shear pin do.

I also believe that your tractor has an over run clutch built into it already (unless it is a really old tractor or it is failed somehow).

You can also run a shear pin and the slip clutch both if you wanted to.

You can also weaken the shear pin by adding grooves into it at the correct locations along the length of the bolt if you want to.

 

[SDT]

Got a JD 647 tiller (sorry it's green but the price was right). There is no slip clutch. I have used it once this Fall and it operated well but I have concerns with the shear pin concept. There are not a lot of huge rocks in the garden to till but you never know. I could get a slip clutch, I suppose, but would an overrunning clutch might be better if there is additonal use with a bush hog. Either one of these will require shortening the PTO shaft which I have already done to fit the tiller and that was hard but not hard, if you know what I mean. Or perhaps having the shear pin alone would be fine since there are no plans to till open ground, only ground that has been used for a garden for a number of years. Any opinions are welcomed. I know there are a lot of scenarios with this question but I like to learn other ways to think. (I'm getting ready for Spring...in my thoughts!)

Tractor Gal

An ORC will not protect tractor or tiller from damage due to obstructions and is not needed with a tiller.

Nothing wrong with shear pin protection if proper shear pin is used.

 

[Tractor Gal]

The shear pin is most likely a bolt, do you know what grade the bolt is? Since it's used, most likely not, just take a photo of the bolt head and post it or Google "grade bolt markings" and look at images.

I would try and get away with Grade 2... if it breaks too much, move to a grade 5... Grade 8 is too strong!!!

Good thoughts, old and tired. I do know how to "interpret" the grade of the bolt but hadn't really looked at that.

TG

 

[Tractor Gal]

I have shear pin on my 5' tiller, break 3-4 a season as softball sized rocks 'magically' appear in 2 gardens....
Always have extras and wrenches on tiller.
OR clutch not needed for tiller but usually a 'must' with a bushhog.
My PTO shaft stays with the tiller.....

Yes, I know about "magically appearing rocks." In fact, it seems I grow more rocks than vegetables! I have an over running clutch on the 2N but I haven't ever hit anything that caused a problem. That's a miracle! Anyway, good to know. But, breaking 3-4 a season? Oh my. But, then again, that's what the shear pin is for...break it, not the equipment. Thanks for the thoughts.

TG

 

[Tractor Gal]

An ORC will not protect tractor or tiller from damage due to obstructions and is not needed with a tiller.

Nothing wrong with shear pin protection if proper shear pin is used.

thanks, SDT. I'm getting the idea: Bush hogs can "run into issues;" Tillers mostly have issues with rocks. I have looked into a rock rake but haven't found one that warranted the cost. Rather, I take strolls through the garden and toss the rocks. Cheaper and good exercise.

 

[Tractor Gal]

An over running clutch does not protect the tractor in the same manner as the slip clutch and shear pin do.

I also believe that your tractor has an over run clutch built into it already (unless it is a really old tractor or it is failed somehow).

You can also run a shear pin and the slip clutch both if you wanted to.

You can also weaken the shear pin by adding grooves into it at the correct locations along the length of the bolt if you want to.

I wouldn't have thought that this tractor has an overrunning clutch built in. They SHOULD have one but, again, I didn't know they did. I used the tiller once this Fall on a small plot because I could hardly wait to try it! There were no issues. When I till the larger plot this Spring, I'll do subsequent passes with deeper till each time. As I use this thing a bit more, I'll probably get the hang how best to protect it. thanks for the thoughts.

TG

 

[North Idaho Wolfman]

I wouldn't have thought that this tractor has an overrunning clutch built in. They SHOULD have one but, again, I didn't know they did. I used the tiller once this Fall on a small plot because I could hardly wait to try it! There were no issues. When I till the larger plot this Spring, I'll do subsequent passes with deeper till each time. As I use this thing a bit more, I'll probably get the hang how best to protect it. thanks for the thoughts.

TG

Your BX23D does not have an overrunning clutch.
And it's not needed, or required, or beneficial for you to have one.
The PTO is not directly coupled to the drive, so an Implement can't push the tractor.
And an implement pushing the tractor is exactly what an overrunning clutch is for.
Like others have said an over running clutch does not protect the tractor from jams or shock loads.

 

[Russell King]

Your BX23D does not have an overrunning clutch.
And it's not needed, or required, or beneficial for you to have one.
The PTO is not directly coupled to the drive, so an Implement can't push the tractor.
And an implement pushing the tractor is exactly what an overrunning clutch is for.
Like others have said an over running clutch does not protect the tractor from jams or shock loads.

Since I was the one causing the confusion about the ”over run clutch” built into the tractor…

How does the independent PTO get powered on these newer tractors?

As I understand the engine has an output shaft into the hydrostatic transmission, that may also drive other hydraulic pumps but I haven’t seen any discussion about driving the PTO shaft. And there may be the mid PTO and rear PTO to consider. I am just curious about how it gets done at a generally high level of explanation.

(And because I didn’t want to (couldn’t) get too technical about it I was being sloppy in the use of over running clutch to describe any system that separates the pto from the tractor drive system)

 

[Smokeydog]

I prefer a slip clutch. If breaking more than one shear bolt a season I would use a slip clutch. If adjusted right very kind to your tractor’s internal clutch. Have never wore out a slip clutch.

Use an override clutch on the bigger M59 for two reasons. Its pto is braked. So heat and wear from rotary cutters. Heavy Brown tree cutter takes 2 minutes to spin down. Second, needed longer length for other pto implements after installation of Pat’s quick hitch.

 

[Tractor Gal]

Your BX23D does not have an overrunning clutch.
And it's not needed, or required, or beneficial for you to have one.
The PTO is not directly coupled to the drive, so an Implement can't push the tractor.
And an implement pushing the tractor is exactly what an overrunning clutch is for.
Like others have said an over running clutch does not protect the tractor from jams or shock loads.

Good info, NIW. So, the protection for this tractor when using a tiller would be either a shear pin or slip clutch?

TG

 

[North Idaho Wolfman]

Good info, NIW. So, the protection for this tractor when using a tiller would be either a shear pin or slip clutch?

TG

Yes a shear pin coupling or a slip clutch are both options that will get the job done.

 

[mcmxi]

How does the independent PTO get powered on these newer tractors?

As I understand the engine has an output shaft into the hydrostatic transmission, that may also drive other hydraulic pumps but I haven’t seen any discussion about driving the PTO shaft. And there may be the mid PTO and rear PTO to consider. I am just curious about how it gets done at a generally high level of explanation.

(And because I didn’t want to (couldn’t) get too technical about it I was being sloppy in the use of over running clutch to describe any system that separates the pto from the tractor drive system)

I'm down this rabbit hole at the moment with a Land Pride folding cutter.

The PTO clutch pack consists of clutch disks, drive plates, a bellville washer and one pressure plate. Hydraulic pressure through the PTO clutch valve moves a clutch piston which drives the clutch disks and drive plates together and towards the pressure plate. The bellville washer is there to reduce shock when engaging the PTO. This design has been used for decades and seems to be reliable.

What's cool about the clutch disks and drive plates is that the clutch disks are splined and fit on the PTO clutch input shaft. The drive plates have notches around the outer circumference that fit into notches in the outer cup of the output shaft. If you look at the second screen shot from the WSM you'll see the clutch disk (top) and drive plate (bottom).

So with today's modern tractors, it seems that an overrunning clutch isn't required. The live independent shaft to the PTO clutch pack is driven directly off the engine, and once hydraulic pressure drops enough after the PTO is disengaged, the PTO clutch disks and drive plates can no longer transmit torque out to the PTO shaft that drives the implement.

 

[North Idaho Wolfman]

I'm down this rabbit hole at the moment with a Land Pride folding cutter.

The PTO clutch pack consists of clutch disks, drive plates, a bellville washer and one pressure plate. Hydraulic pressure through the PTO clutch valve moves a clutch piston which drives the clutch disks and drive plates together and towards the pressure plate. The bellville washer is there to reduce shock when engaging the PTO. This design has been used for decades and seems to be reliable.

What's cool about the clutch disks and drive plates is that the clutch disks are splined and fit on the PTO clutch input shaft. The drive plates have notches around the outer circumference that fit into notches in the outer cup of the output shaft. If you look at the second screen shot from the WSM you'll see the clutch disk (top) and drive plate (bottom).

So with today's modern tractors, it seems that an overrunning clutch isn't required. The live independent shaft to the PTO clutch pack is driven directly off the engine, and once hydraulic pressure drops enough after the PTO is disengaged, the PTO clutch disks and drive plates can no longer transmit torque out to the PTO shaft that drives the implement.

View attachment 124190

View attachment 124191

Actually the reason you do not need a One way clutch on your tractor has nothing to do with the type of PTO drive or drive clutch, it has to do with the movement portion of the tractor.
Your main shaft is driven via a flex plate no manual clutch, and as it goes back it transfers to 2 seperate drives, one for motion, one for PTO drive.
So you can stop the drive or the pto completely independent of each other.
this makes it where the PTO is not direct coupled to the drive ever.

One caveat to this kind of system, If you cause the implement or any part of the PTO system to get jammed, it transmits directly to the engine, and can do some serious damage in a quick hurry!
This is why it's so important to have a good Slip clutch or shear bolt setup.

 

[mcmxi]

Actually the reason you do not need a One way clutch on your tractor has nothing to do with the type of PTO drive or drive clutch, it has to do with the movement portion of the tractor.
Your main shaft is driven via a flex plate no manual clutch, and as it goes back it transfers to 2 seperate drives, one for motion, one for PTO drive.
So you can stop the drive or the pto completely independent of each other.
this makes it where the PTO is not direct coupled to the drive ever.

One caveat to this kind of system, If you cause the implement or any part of the PTO system to get jammed, it transmits directly to the engine, and can do some serious damage in a quick hurry!
This is why it's so important to have a good Slip clutch or shear bolt setup.

You're talking about something else entirely. I'm well aware of the benefits of a slip clutch that's on my RCR1884 for example as well as the new folding cutter that I ordered. I'm also familiar with the concept of shear pins and their value in preventing expensive damage. The slip clutch (or shear pin) is there to prevent a huge and "instant" resistive load on the PTO output shaft which would be transferred all the way to the engine. I get that. However, this situation is encountered while the PTO is engaged and when the operator isn't expecting it.

The point about overrunning clutches is that they deal with the engaging and disengaging of the PTO output where nothing is coming to dead stop in the blink of an eye, as is the case if the cutter blades or some part of the spindle hit something immovable. In that situation, the rotating mass of the implement can feed back to the tractor and cause the tractor to move if you don't have an independent, live PTO. With these tractors the PTO shaft is powered off the transmission and not the engine, so if you depress the clutch, the PTO stops rotating.

Part of my process of understanding something is putting it into words and mistakes will be made, but the idea is to eventually get a better and more accurate understanding of the system.

 

[North Idaho Wolfman]

The point about overrunning clutches is that they deal with the engaging and disengaging of the PTO output where nothing is coming to dead stop in the blink of an eye, as is the case if the cutter blades or some part of the spindle hit something immovable.

Sorry but no, that's not right.
The purpose of an overrunning clutch or a one way clutch is so when the input shaft (motor side) is running slower than the output shaft (implement side), that shaft just over runs till it slows to a point where they catch back up, and can get back into sync.
Old tractors needed that because they the drive was broken at the flywheel (clutch), only one input shaft was available for the drive and PTO.
So in the event that you had a mower running, and you pushed in the clutch with the tractor in gear, that tractor would now be pushed by the mower.
Yours can't do that because the drive and the PTO are broken (clutched) separately, even though they use the same drive.
Now theoretically a mower (spinning mass) can still push the tractor is both are clutches are engaged and the drive becomes disconnected from the motor (like a broken flex plate).
It's rear but it can happen, but in most cases the drive also powers the HYdraulics so at that moment of failure bot clutches disengage from the lack of pressure so you would never know it.

 

[mcmxi]

Sorry but no, that's not right.
The purpose of an overrunning clutch or a one way clutch is so when the input shaft (motor side) is running slower than the output shaft (implement side), that shaft just over runs till it slows to a point where they catch back up, and can get back into sync.
Old tractors needed that because they the drive was broken at the flywheel (clutch), only one input shaft was available for the drive and PTO.
So in the event that you had a mower running, and you pushed in the clutch with the tractor in gear, that tractor would now be pushed by the mower.
Yours can't do that because the drive and the PTO are broken (clutched) separately, even though they use the same drive.
Now theoretically a mower (spinning mass) can still push the tractor is both are clutches are engaged and the drive becomes disconnected from the motor (like a broken flex plate).
It's rear but it can happen, but in most cases the drive also powers the HYdraulics so at that moment of failure bot clutches disengage from the lack of pressure so you would never know it.

This what I stated.

" The point about overrunning clutches is that they deal with the engaging and disengaging of the PTO output where nothing is coming to dead stop in the blink of an eye"

I don't see how any of that is wrong.

For example, an operator depresses or feathers the clutch while making a slow turn with a cutter, so that's the "disengaging of the PTO" stated above. The cutter continues to spin at a certain rpm, and now the operator completes the turn and lets the clutch out so that's the "engaging" of the PTO. But the output rotational speed of the PTO (slower) doesn't match the rotational speed of the input shaft to the cutter gearbox (faster), so without an ORC, a ratcheting kind for example, the cutter would deliver a shock to the PTO output shaft, due to the mismatch in rotational velocity.

Nothing I stated is wrong. I used "deal with" because an ORC "deals with" the discrepancy in angular velocity between the two rotating shafts.

All of this has come about because a member keeps going on and on about his ORC on his Land Pride cutter and yet he lists his tractor as an M7060. So why the heck is he lauding the ORC when his tractor doesn't need it?

Isn't this fun?!