PTO Clutch

[jnelson]

I own a Cub Cadet 6284 CUT. I use both a 6' finish mower and a 4' bush hog with it. The other day I was having a conversation with another 6284 who told me that he had been told to never use a 3 pt mower with the 6284 without a (slip clutch or overrun clutch - he was unclear about this) or it would destroy the PTO on the tractor.

I assume that whoever told him this was referring to a slip clutch since an overrun clutch doesn't make any sense to me considering that this tractor has a hydrostatic transmission which (if I am correct) will eliminate the overrun issue. On the other hand I can see that a slip clutch would protect the tractor PTO from shock in the drive train caused by grounding the blades, hitting rocks or stumps, etc.

My question is how necessary is a slip clutch if the areas that I am mowing don't represent a threat of large rocks, stumps, etc? If the clutch is necessary does anyone have recommendations on make/model/source of one?

Thanks in advance.

JN

 

[kenstrac]

It is not necessary to have a slip clutch as long as there is a shear bolt.
Shear Bolts are the best protection for damage.
If the proper bolt is used!

 

[jnelson]

Ken,

Thanks for the reply. Both decks do have shear bolts - fashioned from grade five bolts as recommended in the manual for the bush hog.

JN

 

[Soundguy]

eww. I dislike gr5 for shear.. but.. as long as the manufacturer is will to stand behind it.. etc..

only thing a orc is good for on a live pto/independent pto machine is to save the pto brake, if one exists.

soundguy

 

[greg_g]

An over-running clutch (ORC) is the wrong tool for the job. If that Cub's got an electric PTO clutch - and you're accustomed to engaging it at speed - you'd best either lay in a large supply of shear bolts, or invest in a slip clutch

//greg//

 

[jnelson]

I dislike gr5 for shear.

That is what was recommended in the manual that came with my bush hog. The finish mower was used when I got it and had a grade 5 bolt in it - no manual.

The 6284 is an electric engaged PTO so there is some shock to the system when it is engaged. Having never used 3 pt PTO driven equipment before I sheared a bolt (shear pin) the first time I tried to use the bush hog. The manual made no reference to reducing the engine speed as low as possible before engaging - I learned that lesson quick!

Now when I engage the PTO the idle speed is so low that the engine stalls. I have to raise the engine RPM slightly to around 1200 RPM to successfully engage the mower deck.

I can understand how a slip clutch might cushion some of the shock when engaging the PTO if it is set to slip easy enough. But if it is too easy to slip I can also see that it might slip (and possibly burn up) when run at normal loads. Are these clutches adjustable? How easy are they to install and use? I assume that all of the PTO shafts will have to be shortened accordingly to accommodate a slip clutch.

I read on another thread that it is difficult to find a good quality slip clutch any more. Any suggestions for a make and a source for one?

Thanks!

JN

 

[greg_g]

Are these clutches adjustable? How easy are they to install and use? I assume that all of the PTO shafts will have to be shortened accordingly to accommodate a slip clutch.

I read on another thread that it is difficult to find a good quality slip clutch any more. Any suggestions for a make and a source for one?

• Yes,
• simple,
• yes,
• for a small tractor like yours, you don't have much a choice in quality.
• See EUROCARDAN CLUTCHES - Agri Supply

//greg//

 

[Soundguy]

That is what was recommended in the manual that came with my bush hog.
JN

I don't doubt you.

I just hope they engineered the yoke with that semi-hard bolt in mind. I've seen some cast yokes that start to egg out when hard bolts are used.. once it eggs, then you get snappy action and can shear bolts faster

soundguy

 

[jnelson]

It looks like the splined slip clutch makes the most sense since the same clutch can be used with any of my PTO driven implements. Can the slip clutch install on either end (tractor or implement) end of the PTO shaft? It appears from dimensions that I have seen that I will need to shorten my PTO drive shafts by 7 to 8" - no big deal.

The only downside I can see to running a slip clutch is that it will increase the angle that the u-joints run at when the implement is lower or higher than in direct line with the tractor PTO output. This is probably not an issue since the shaft angle shouldn't be much when the implement is in the operating position if it is hung correctly.

I looks like I will be getting a slip clutch soon.

JN

 

[kenstrac]

Depending on the shafts on your equipment you might have to buy 1 for each piece of equipment .
If you get 1 for the tractor yes it will change the angle of the PTO shaft u-joints and if its lifted and it binds you have more of a chance of trashing the tractor shaft.
Putting on a slip clutch is not just put it on and forget it, you have to periodically loosen it up and make it slip and reset it.
I have run all types of attachment with clutch and shear bolt and if I did not break 2-3 shear bolt a year it was not wort putting a slip clutch on.

 

[jnelson]

if I did not break 2-3 shear bolt a year it was not wort putting a slip clutch on

That's interesting. I am not bush hogging or mowing rough areas. The only shear bolts I have broken were when I first tried to use a 3 pt mower deck before I learned to idle down as far as possible. It makes me wonder if the slip clutch will cushion the start-up of the mower deck at all since it has to be set firm enough to not slip under load. This is probably one of those things that can be debated forever.

I suppose there is no downside to running the slip clutch other than cost and the work involved in installing it. On the other hand why add complexity if it is not needed. Looks like I am going to have to really think on this one.

JN

 

[Soundguy]

I wouldn't be relying on a slip clutch to lessen the felt load on the tractor or the implement for a shock-start for a non slip electric engagement style pto.

soundguy

 

[greg_g]

Can the slip clutch install on either end (tractor or implement) end of the PTO shaft?

Safety demands they be installed on the implement end only. All those spinning bolts and springs directly behind the operator seat are just an accident waiting to happen. Besides, I'd be surprised if it fits under the shield that covers your Cub's PTO output shaft.

These aren't quick-change devices. I'm pretty sure you'll get a unanimous opinion from those of us who've used slip clutches for a while. That is, forget the one-clutch-fits-all idea. But just because an implement is PTO driven, doesn't mean it automatically needs a slip clutch. Finish mowers for example; a slip clutch is a waste of money. PTO driven log splitters - same thing. And the list goes on. Most common applicatios - rotary cutters and rotary cultivators (tillers).

//greg//