slip clutch

[dclymer]

I was at my NH dealer today , I saw them installing a tiller. The power take off shaft looked like it had a clutch type system on the end of the shaft at the tiller end . Is this something new ? my tiller is just a shaft from tractor to tiller. Informe me.... D. Clymer

 

[Anonymous Poster]

<font color=blue>...my tiller is just a shaft from tractor to tiller...</font color=blue>

More than likely you are using a "Shear Bolt". Most small tillers are used on under 45 PTO hp tractors and will have a Grade 2 bolt. The shear bolt is always located at the implement end. {Check your owners manual to verify this}

If you are constantly shearing "pins or bolts" because of your type of ground conditions... then it would be advisable to "add" a "slip-clutch" to your tiller for convenience...

 

[RanchMan]

John-

Ok, really dumb question - How can you tell the difference between a Grade 0, 1, & 2 bolt?

My current understanding is that a Grade 8 has 6 "dashes" on it , on the outside corners pointed to the middle, Grade 5 same thing but 3 "dashes".

Someone told me that 0, 1, & 2 don't have any markings on them. Is this true? If so, back to my question, how do you tell the difference?

 

[centex]

John, I bought a slip clutch from Tractor Supply that is splined to fit the PTO shaft on the tractor. I planned to use with my 6' rotary mower which has a shear bolt at the implement end of the shaft. Is there any problem with doing this? I don't know if the clutch would slip at a lower torque than would shear the bolt but could not think of a reason why it would cause any kind of unsafe condition. I also thought about using it with my post hole digger but I doubt it would be of any real benfit because of the small size of the shear bolt on the digger drive shaft.

 

[Anonymous Poster]

Grade 2

Grade 5

Grade 8



<font color=blue>...2 don't have any markings on them. Is this true?...</font color=blue>

Yes, Grade 2 has no "hash marks"...

I've never seen or heard of a 0 or 1 grade? /w3tcompact/icons/crazy.gif

 

[DFB]

Ranchman,

I really don't think you can visually determine the difference. They're all classified as low-medium carbon steel (non tempered). The only difference being the tensile strength grading. Most of the low grade fasteners I've gotten lately such as the shear bolts for my plow and ripper have all been marked with the ASTM rating 307A.

Shear pin?

There's also a link in there to the Register of Fastener Insignia. Thru registered headmarks you can identify the manufacturer of the fastener.

DFB

 

[Anonymous Poster]

<font color=blue>...planned to use with my 6' rotary mower which has a shear bolt at the implement end of the shaft. Is there any problem with doing this? ...</font color=blue>

You always mount the slip clutch at the implement gearbox... never at the tractor...

On transmission driven PTO's, you may install an "overrunning clutch assembly" at the tractor side... {however many of the newer tractors have the "overrunning clutch" internally...}

All shear bolt type implements have a "smooth shaft", therefore you'll have to bring back your splined unit and trade for a smooth. In this case, I would still use a "shear bolt", but have the slip clutch adjusted accordingly... {Double insurance}

<font color=blue>I don't know if the clutch would slip at a lower torque than would shear the bolt but could not think of a reason why it would cause any kind of unsafe condition...</font color=blue>

Rule of Thumb -
2 Plate Slip Clutch - rated @ ~~ 57 PTO hp
4 Plate Slip Clutch - rated @ ~~ 92 PTO hp

These figures will vary somewhat depending on the manufacturer of the slip clutch. What this means, on day one when you buy that brand new slip clutch and retrofit your implement... without you doing anything... this is normally what they are adjusted for straight from the factory. So you will normally adjust them accordingly after purchase.

In a couple weeks, I'll start another thread and explain the in's and out's of adjustment...

 

[OverlyRun]

John,

Your proposed timing for your tutorial on slip clutch adjsutment is great. I a couple of weeks I will be back from a trip and need to get the rotary cutter into working order. Last Fall I installed a slip clutch and backed the slip clutch bolts off as the instructions suggest for winter...but the instructions are particularly unhelpful on how to actually re-set the tension springs ("loosen or tighten exactly two turns" is not so helpful when the two are separated by four months and several skinned knuckles). There are no guides for the preferred length of the compressed spring and absent better suggestions here, I suspect that some trial and error, along with care to insure equal compression around all eight bolts is what will be called for. While there is always the shear bolt that is still on the implement end of my slip clutch, I'd like the clutch to actually work, not just decorate the PTO shaft.

If I hung around the general store I suppose I could get lots of free advice on this, but I suspect the pool of expertise here on TBN is wider, if not also deeper.

Looking forward to the slip clutch adjustment thread....

Chas

 

[GaryK]

A slip clutch came with my Caroni tiller and I adjusted it to slip before my tractor stalled or did damage to PTO system. Its amazing how fast a stump or root will stop a tiller. I also put a clutch on my bush hog for the same reasons and adjusted it accordingly. My neighbor had a bush hog on his 35hp massy with a shear pin, it sounded like a gun shot when he sheared a pin which was often(he likes to run over things), he finally put on a clutch and no more broken shear pins which were 1/2" #2.

 

[kyoders]

GaryK,

I just got a Caroni tiller and it too came with a slip clutch. It looks to me like this thing has been sitting around outside for a while (faded paint,etc.) and I figure the slip clutch is most likely stuck/sticking. I was trying to get the shaft off the tiller and after finally getting the two bolts off, it seems to be frozen on by rust (yet more evidence of sitting outside). The place I got it from neglected to send me a manual, so for the next several days I don't even have that (and I'm not a patient man In an ideal world, there would be a table something like "for PTO HP of X, adjust to spring length Y", or maybe "torque to Y ftlbs.". There's probably too many variables for this to be totally reliable, but I have no clue how to even guesstimate the setting for the clutch.

In your post, you said you adjusted the clutch to slip before stalling your tractor. I have a small Kubota BX2200, and am very paranoid about causing any damage. Could you describe how you went about determining the proper setting for the clutch? I've been trying to figure out a "safe" procedure to test it out, but the only things I've come up with involve stupidity on my part to try (like getting the tiller up to full PTO speed, then jamming a 2x4 into the tines to stop them and see if the clutch slips).

Thanks for any input you might have.

Kevin