over-running pto clutch

Somebody please explain to me the concept, purpose, and need for an over-running clutch for the pto especially as it pertains to working a rotary mower with a tractor like my WD45. We never used "bush hogs" on our farm but did all the other pto work associated with running a 100+ cow dairy farm. The WD45 did its share running haybines and harvesters, none of which ever damaged the pto drive no matter how many times the clutch was pushed in thereby stopping the pto dead. I have heard stories of people running their mowers and then busting the pto drives out of WD/WD45 tractors only to find out that it probably wouldn't have happened if they would have made sure to use an over-running clutch on the pto. Why do rotary mowers appear to be so much harder on pto drives than other pto equipment? I can understand a little oversight with a new product at first explaining why the oldest rotary mowers may not have a built in over-running clutch. Do ALL new mowers have over-running clutches on the pto now or only certain brands? I have a friend offering to buy a "bush hog" if I would be willing to use my WD45 to help him keep a small field mowed down. I would like to make sure that everything is set up correctly so as not to damage my tractor whether that means getting a particular mower or having an over-running clutch installed on my tractor pto. Any and all information will be greatly appreciated. TIA

Lots of WD45s also ran balers, blowers, and choppers all which have a rotating mass that doesn't like to stop abruptly. I don't recall ever hearing about pto issues unless it involves a bush hog. The slip clutch doesn't allow for the necessary freewheeling of the rotating mass after the tractor pto has been stopped?

As long as you use the hand clutch you don't need one of these. A WD has "live pto" as long as you use the hand clutch to stop forward motion and leave the foot clutch alone.JP 

I can't  see how a brush hog driving  a WD/WD45 forward a little is going to damage anything on it as it takes very little force to drive the tractor forward.I've run those tractors all my life and never had an over riding clutch on one
and have never known anything to get damaged because of it.

With the ORC you don`t have to wait for the implement to spool down before shifting gears.

My main concern is being able to safely stop the pto when I want to such as when the job is done or when I may feel the need to (emergency) without breaking any shafts or shelling any gears in my WD45. So, it sounds to me like the consensus is to disengage the hand clutch first and then I would be able to use the foot clutch to stop the pto and disengage the pto drive safely without any fear of damaging something?? I have to admit, the ORC does sound more and more like extra insurance against OH $h!+ moments that we all know can happen when we are out there trying to get it done. Thanks guys. Learned something new today on top of why Dad insisted that us boys use the newer tractors when we started doing pto work in the fields. He used the WD45 on occasion but we only got to use the Oliver 1750 or 770s and sometimes even the 190XT. The only pto job we ever did with the WD45 was its main summer job of running the manure spreader after the daily barn cleaning. Usually never unhooked from the spreader except rare occasions when Dad needed it to run the haybine. 

You can also quickly drop the engine rpm and slide the pto out of gear.  The blades will freewheel till they stop.  Don't forget, if a WD/WD45 has a weak spot it is the PTO gearbox.  Panic stops using the brakes to nearly instantly shut down a very high inertia mower can (only can, not will) grenade the gearbox.  Simple fix is to buy an Allis spin mower.  They came with an orc in the driveline.

Oh, and a slip clutch is NOT the same as an over running clutch.  They are spring loaded devices designed to hold power under normal loads but will "slip" if a quick shock (like a stump or scalping the ground) occurs.
AaronSEIA

Gary Burnett wrote: I've stopped my 10ft Sidewinder cutter  with the brakes on my D19 when I pushed in the foot clutch.Actually its an advantage because then the cutter can be stopped quickly if it hits something or better before it hits something.I think some posters are working off theory on this one not actually experience.Or maybe they had an 8N Ford(LOL)

Edited by Orange Blood - 25 Sep 2016 at 7:53am

Orange Blood wrote: Gary Burnett wrote: I've stopped my 10ft Sidewinder cutter  with the brakes on my D19 when I pushed in the foot clutch.Actually its an advantage because then the cutter can be stopped quickly if it hits something or better before it hits something.I think some posters are working off theory on this one not actually experience.Or maybe they had an 8N Ford(LOL) All things being equal brakes on a D19 are far better than those on a WD, WD45 or even the D17. I have been in a situation, so I am not posting theory.  Yes you can stop a 5' rotary mower with WD brakes, even in moderate shape, but it still takes a foot or two, if you are standing on them.  I imagine the same is true of the 10' on the D19.  Bottom line that foot or two of ground travel in some cases can mean the difference between life or limb, on Nothing!!!!!  Now factor in most WDs have poor or weak brakes for whatever reason, and now the 6' brush cutter is pushing you 5-10' when you really want to stop now.......... BTW...The Allis pull type mowers I have seen all have overrunning and slip clutches built in.  They sit right in front of the gear box.

If you need to stop the tractor immediately then thats what the had clutch is for.

Gary Burnett wrote: Orange Blood wrote: Gary Burnett wrote: I've stopped my 10ft Sidewinder cutter  with the brakes on my D19 when I pushed in the foot clutch.Actually its an advantage because then the cutter can be stopped quickly if it hits something or better before it hits something.I think some posters are working off theory on this one not actually experience.Or maybe they had an 8N Ford(LOL) All things being equal brakes on a D19 are far better than those on a WD, WD45 or even the D17. I have been in a situation, so I am not posting theory.  Yes you can stop a 5' rotary mower with WD brakes, even in moderate shape, but it still takes a foot or two, if you are standing on them.  I imagine the same is true of the 10' on the D19.  Bottom line that foot or two of ground travel in some cases can mean the difference between life or limb, on Nothing!!!!!  Now factor in most WDs have poor or weak brakes for whatever reason, and now the 6' brush cutter is pushing you 5-10' when you really want to stop now.......... BTW...The Allis pull type mowers I have seen all have overrunning and slip clutches built in.  They sit right in front of the gear box. If you need to stop the tractor immediately then thats what the had clutch is for.

Edited by Orange Blood - 25 Sep 2016 at 9:03am

hi guys

Yes always check the free play in any pto setup when you hook up the first time. I remember there was a broken pto shaft for one of the tractors here when I was a kid. The shaft broke on the first turn because no one checked it on something we just bought. It was the tractor side that broke too pretty expensive and a pain to replace.

Install an orc. It helps prevent shock loads to tractor driveline and engine. You'll be glad you did. "Bush Hogging" is very hard on tractors...JMHO, Trev.

CrestonM wrote: I have an ORC on my 8N, and I really like it. Like was said earlier, you don't have to wait for the implement to wind down when shifting. Of course, I had to have an adapter of some sort because the 8N, as well as my B, have a 1 1/8" PTO shaft. So the ORC input is 1 1/8" and the output is 1 3/8". This way I can switch it easily between the 8N and the B, depending on which is doing PTO work.  A little off topic...I've never seen any PTO implements that require 1 1/8" shaft. Surely they made some though? All I've seen is the drive sheave for my sickle mower, which fits the 1 1/8" shaft.

So you got an 8N huh? Maybe you can settle a question for me fellow with an 8N swore it could
out pull my 3 legged Mule so I was gonna to bet him but he backed down when $$$
became involved.What'd you think?

About as often as I see a 8n pulling one... but then I never seen anyone actually use a 8n