Over Running Couplers

rich_ncal · Jun 8, 2004

Any suggestions on over running clutches?

Agri-supply has two types. The over running clutch costs about twice as much as the over running coupler.

Any experience with these two? Do both last as long? Except for the time to remove and install do both perform the same?

http://www.agri-supply.com/pdfs/ASC238C20-25.pdf

Inspector507 · Jun 8, 2004

They perform the same, but I had the 31949.........quick release /forums/images/graemlins/grin.gif
Easy on, easy off

AlanB · Jun 8, 2004

I am not positive reading your post, but I believe you mean,

Slip Clutch and over running clutch.

There are also two types of mounts (there may actually be more) for the over running clutches that I am familiar with, one mounts with a roll pin and one mounts with a spring type quick release pin.

A slip clutch prevents damage to equipment and driveline, when the unstoppable force, (your bushhog) meets the immovable object, (Uhhh, lets say a 1" steel pin buried in the ground) it is the piece that gives. It acts in place of a shear bolt, but does not have to be replaced when it gets used.

The over running clutch prevents a bushhog or other heavy flywheel type device from back driving your tractor through the driveline if your tractor does not have this built in.

A note of caution that I never heard when buying the over running clutch is that they can only handle limited torque loads. They will not operate items that are high torque, such as a post hole digger, of course I found this out after mounting with a roll pin and had to change back!

So, my 2 cents is to buy the quick release one if you are looking at the over running clutch.

DavidJ · Jun 8, 2004

From the file you posted I saw the Slip Clutch and the over running coupler.

The slip clutch is as the name suggests. If you put too much torque on it, it slips. It's adjustable as to the amount of torque it takes to slip. It has no provisions for overrunning.

The overrunning coupler provides no provision for slip at high torque but prevents the implement from driving the PTO (as well as the tractor on single clutch non independent PTO's) when clutching the tractor.

The best of both worlds is an overrunning slip clutch. It takes care of both situations.

AlanB · Jun 8, 2004

The overrunning coupler provides no provision for slip at high torque but prevents the implement from driving the PTO (as well as the tractor on single clutch non independent PTO's) when clutching the tractor.

Hi David, I will kindly disagree, and this is the same information that I was told prior to my purchase of the overrunning clutch.

You will find that if you disassemble the common over running couplers available at TSC, Rural king, my local tractor place, and I bet the ones from Agri Supply shown, that there are ramps in both directions for the teeth on the over running coupler. It will not provide a positive, 100% lock in, in the forward direction. Those over running couplers will then "slip" if too much torque is applied to them.

Pull the outer snap ring and cover and you will see what I am referring too.

The signifigance of this, is that if you use a tractor as we do, that an over running coupler is reccomended on (New Holland 1925 HST) and you go between bush hogging and post hole digging often, you will need to remove the over running coupler to utilize the post hole digger.

If you chose to use the "pin on" type instead of the quick disconnect, you will then need to roll around under the tractor and drive out the roll pin to remove the coupler, and for me this was a task.

Soundguy · Jun 8, 2004

( You will find that if you disassemble the common over running couplers available )

Not disagreeing with you.. but My guess is that the different ORC's made by different manufacturers may not all function that way you describe.

I emailed a few of my buddies at ytmag where I hang out on the olf foord N board, and got this reply... certaintly didn't sound like any 'give' in his ORC if it twisted the spline off..

Soundguy

Here is my friends reply:

( I don't know about that BUT,I bought a new Speeco 1 3/8" for my IH424 about a month ago,hit a small (maybe 3") stump while hoggin,and it sure DIDN'T slip, it put about 1/2 a spline twist in the ORC before my grade 2 shear bolt broke..I was not impressed,dang near $60 )

Soundguy · Jun 8, 2004

I'm getting more replies with the same info.... no slippage.

I wonder. Could the units be machined to ratched either direction.. but be selected depending on how it was assembled? Like for a machine with a reverse pto?

Just wondering out loud...

Soundguy

Soundguy · Jun 8, 2004

Alan.. here's a question for you.. If these ORC's are built to slip in forward drive as you claim.. then how come we ORC users still shear bolts when we hit solid objects.. or blockages like sand mounds... doesn't seem to ring true here.

And if they do 'slip'.. like you claim.. then they are useless.. as they 'slip' at a point heavier than a shear pin... Therefore.. if the mower is designed to be protected by that force where that shear pin breaks.. then relying on the ORC to protect the mower is letting a higher than planned fore get thru to the gearbox ( and your tractor pto! ).

We need to get some manufacturers specs here... something doesn't sound correct. Come to think of it.. I've seen ORC's on round hay bailers... now if that isn't a load.. nothing is..

Soundguy

rich_ncal · Jun 8, 2004

Great information in the responses on overrunning couplers.

I was interested in the benefit of the pin install type or the quickly release type. Everyone favors the quick release type?

Would the pin through the PTO shaft in the pin install type coupler act as a shear pin?

I use a Howse 400 48" rotary cutter, with two blades spin freely on bolts connected to large spinning disk in the center. If I hit a rock or stump don't the blades just bounce back and spin around on the pivot points?

Any other responses to how well the units from Agri-supply hold up over time?

Soundguy · Jun 8, 2004

( Would the pin through the PTO shaft in the pin install type coupler act as a shear pin?
)

No.. a 'roll pin or dowell' is what pins the OR-coupler to the tractors pto shaft. A shear pin there would be useless as the splines are present.. all the splines would have to shear off.. and the shear pin too... wouldn't work too well.
Quick release is nice as you can slid it on and off with thumb pressure on the release button.. no need to remove grease zerks and plugs.. then use a drift and mallet to drive the roll pin out.

( I use a Howse 400 48" rotary cutter, with two blades spin freely on bolts connected to large spinning disk in the center. If I hit a rock or stump don't the blades just bounce back and spin around on the pivot points? )

Well.. yes.. the blades do pivot on the stump jumper.. that just helps 'clear' a obstruction.. the shock load when the blades hit is still present even if the blades can pivot...And you still need either shear or slip protection in the driveline though.

Soundguy

Soundguy · Jun 8, 2004

Here's a pic someone else posted on the other site I frequent.. it shows a internal diagram of the orc he uses.

Sure doesnt look like it slips in any but one direction.. except that you could remove the whole inner ( 2) pieces and reinstall backwards.. and change the directioon in which it drives and slips.. etc. but deffinately it would not slip both directions..

Soundguy

AlanB · Jun 8, 2004

Well, buy the pin type as it is cheaper, and it semi permanently installs and is the same mechanism as the quick release, if you go with the theory that it can hold high torque loads.

If you think you are going to have to remove it. Which I can tell you, I HAVE TO DO, on my NH 1925 driving my TSC post hole digger, otherwise it slips, than I stongly suggest you spend the extra couple of bucks and get the quick release one.

The "Pin" on the pin type locks the mechanism to the shaft like the latch pin, to keep your driveline connected, it does not interfere with the rotation of the device, for it to work for over running, it must spin free. The pin, when you look at it, is actually only through the center of the coupler.

Soundguy,

I agree with you certainly that different manufacturers can be doing it differently. I went to the tractor place and disassembeled two different color ones, Rural King and took apart one of theirs and TSC (Which I believe is Speeco) and took apart one of theirs and they were all the same.

I also initially thought I had a "Left hand" one and not a "Right hand" one, or however you care to describe it, but have not found any reference to that, nor found any implements that run "backwards"

Back to Rich,

Yes, you absolutely need a shear pin or slip clutch in your driveline to protect your equipment and you. I doubt that they sell a bushog without it, you will probably find that your drive shaft is held on with a grade 2 bolt on a smooth polished and hopefully greased shaft.

Best way I can think of describing why.

Take a bucket of water in your hand and start spinning around, the bucket will go out straight, now, as you are still spinning walk so that the bucket hits a corner of a wall.

The bucket is going to pivot back sure, but I bet your arm will hurt like heck and take some abuse where if that bucket disconnected when it hit the wall, you would just keep spinning.

And one other tidbit, if you do not keep the shafts that slip on each other, or the internal mechanism of over running coupler greased and such, none of it works. (slip clutches that I have seen are not greased)

From what I have seen in the field, maintenance is not high on the list of many tractor owners / operators list.

Soundguy · Jun 8, 2004

Upon very close inspection.. I can see how it would appear that there is a back ramp.. where the locking dog contacts the outter sleave and rides.. I really don't get the feeling that it is intended to slip there though.. but instead that angle matches the angle of the dog so it can engage squarely.. as it is held up at one end with a sping. I guess if the dogs became rounded enough from wear that it certaintly could slip in the drive direction. I would considder this a abherent behavior... nor normal operation though.

Comments?

Soundguy

AlanB · Jun 8, 2004

I guess we are typing at the same time!

Look at your attatchment close, see the "short" side of the ramp, when you pull one apart instead of it being 85 degrees like it looks in that picture, you will find it about 75 degrees. Given enough load, it will slip.

Does not sound like I can convince you, and I guess at some point, it does not matter. I am not going to go hook it up and make a movie to prove the point.

Either way, his question was is it worth the extra money for the quick connect. My answer is a resounding yes, and my rationale is explained in my previous posts with regards to my equipment. I would be willing to bet that others that try the same will have the same results.

Also, I was not suggesting to use this as a slip device, I said it would slip under heavy loads, that is why it is important that it be easy to remove, hence my choice of a quick disconnect.

My 5' bush hog, has a well greased, checked, shear bolt in place.

AlanB · Jun 8, 2004

The over running clutches (2) that I tried in operation on my machine (thought the first one was bad) were both brand new.

Soundguy · Jun 8, 2004

( Look at your attatchment close, see the "short" side of the ramp, when you pull one apart instead of it being 85 degrees like it looks in that picture, you will find it about 75 degrees. Given enough load, it will slip.
)

Well.. I see we are running around wording. I'm talking about '-designed-' purpose.. not '-actual use-'. I believe that the ORC is NOT designed to slip.. however I will concede that looking at it.. the dogs are the weak link and could under great force pop back down.. under '-Actual use-' conditions.

( Does not sound like I can convince you, and I guess at some point, it does not matter. I am not going to go hook it up and make a movie to prove the point.
)

Unless you can produce manufacturere info that it is
'-designed-' to slip in the drive direction.. probably not.

Given that you could make it slip with great force.. I would think is moot.. as that great force is probably what the shear pin is in the system to prevent.. I.E. the shear pin pops before the ORC functions incorrectlyand bypasses during a gross load exceding its designed capabilities...

I would also agree that a quick release one is the way to go.

Soundguy

Soundguy · Jun 8, 2004

( also initially thought I had a "Left hand" one and not a "Right hand" one, or however you care to describe it, but have not found any reference to that, nor found any implements that run "backwards"
)

Though rare.. there are a few reverse implements.. older cub comes to mind.. as well as kubota and certian other grey machines.

But no.. I havn't seen a reverse orc for sale either.

But after reading the last message.. I think wqe are on the same page.. and agree with each other /forums/images/graemlins/laugh.gif

And in the end.. the most important thing occoured... the original poster got some good info.

Soundguy

Inspector507 · Jun 8, 2004

If you look CLOSELY at the Agri-Supply ad, they call the same basic thing by 2 different names. Over Running Clutch and Over Running Coupler. Yes different manufacturers. They work the same way, just the mounting is different, one is quick connect and one is held on by a roll pin (SpeeCo). They also show a slip clutch, which I don't think that is what he was looking at.
I used the quick connect for years and never had it "slip". I screwed up and bought the roll pin type at first, then figured out I needed to remove it to run the tiller. I bought the quick connect and let it go with the Yanmar.

AlanB · Jun 8, 2004

I cannot stand it so I will bite, why did you have to remove it to run the tiller???

Oh, also side note, you need to reverify your drive shaft lengths when you install any coupler etc, as it effectively lengthens your driveshaft by a couple of inches.

Al B

rich_ncal · Jun 8, 2004

Thanks for the education.

I will get the one with the quick release, check the grease on the PTO shear pin, and check the length of the PTO shaft after installation.