School me on shear bolts vs slip clutch

Bob in SD

Member
I have an IH-80 snowblower that needs a new PTO shaft. It's supposed to have 1 grade 5 shear bolt in it, and I'm looking at having a new one built or just grabbing whatever they have on the shelf at Runnings or TSC. Does a slip clutch serve the same purpose as the shear bolts, or is one better than the other (for a snowblower in particular)?

Thanks,
 
Both server the same purpose, by protecting the equipment should the load (due to snow in this case) causes a sudden stop. A "slip clutch" does not need to be "reset" after the equipment is cleared, where the bolt will require replacement after is "shears". As long as the torque required to "shear" the bolt can be matched or under estimated by the slip clutch they could be interchanged.

The maximum torque on a shear bolt would be approximately = N(number of shear planes; in this case 2)*Fs(shear factor; between .45 and .56)*A (area of the bolt)*Fu(Ultimate stress of bolt based on grade) * R (radius of the shaft to the shearing plane of the bolt).

You also could use a lower grade bolt that would shear more often and have more on hand if parts are getting hard to find and you want extra protection.
 
Forget the extra cost of a slip clutch for a snow blower. The obstacles that you will encounter will need a quick disconnect from the tractor PTO power which a shear bolt offers.
A slip clutch is needed where you have loads that may be sudden impact, or slugging which could overload other components of the driveline, but quickly clear the equipment and not get lodged or wedged in it.-------Loren
 
I don't trust slip clutches on anything. Shear bolt shears as long as the interface isn't rusted together. On shearing, a high grade bolt will snap whereas a low grade bolt will take a few whacks before it shears and it smears, not shears so that you can find the remnants easier to drive out with a punch.....my preference even though my JD 375 round baler specs a ⅛" Grade 8.....well for what it's worth, I've had it 15+ years and never got it jammed up so I never tested the logic of Mother Deere on that pin.
 
Slip clutches rust solid and offer no protection, only 10% of people ever remember to service them.

Shear bolts are annoying that they shear and get replaced with grade 8 bolts or drilled out bigger and again offer no protection.

But we can point and say the protection is there, and feel good about it.

Paul
 
Ive been looking into getting a slip clutch b/c the old bush hog that I have is all splined, no place to put a shear bolt.

Is there a certain brand/clutch that is preferred? Its the standard 1 3/8 6 spline ford 3000 pto.
 
This one must be better.




FD1 PTO Slip Clutch, 1-3/8" 6-Spline Male and Female End
#31951
Be the first to review this product
$129.99 EA

This FD1 slip clutch can be used with up to a Series 6 PTO shaft to help protect your gears and smooth out your torque
levels. It has a 1-3/8 inch 6-spline male and female end. This clutch can handle up to 7970 inch-pound torque.


cvphoto24063.jpg
 
(quoted from post at 18:48:37 05/23/19) This one must be better.

FD1 PTO Slip Clutch, 1-3/8" 6-Spline Male and Female End
#31951

Think Ill go with that one when the time comes. May go ahead and buy extra friction discs just to have. Took me while to find the part number for the discs; for whatever reason agri supply doesnt list the replacement discs with the FD1 clutch like they do the other clutches.

http://www.djonesa.com/AGMATE/europto.pdf

https://www.agrisupply.com/friction-disc-140mm/p/31953/
 
If I accidentally purchase equipment with one that's what I do and let it spin good to shine up the rusted steel plates. Good way to do that is leave it loose and run (like on a brush hog) fast through high grass forcing it to slip.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top