Rotary Cutter Rotary Cutter Shear Pin Set-up?

[jinman]

</font><font color="blue" class="small">( It gets bent due to the random orientation and the periodic shear force, so eventually it stops to slide. )</font>

Britt, I think you inadvertently hit on the reason a loose bolt shears less often. The point of shear can change up and down the shank of the bolt if it is loose. I always use 4" bolts, run the nut down to the end of the threads, and then crush the threads sticking out of the nut with vise-grips or channel locks so it won't back off.

 

[DiskDoctr]

Britt,

Just a few more possible issues, if you think it is shearing more than it should.

1. Is your driveshaft bent (wobbles)?

2. Do you make a lot of turns?
a. If so, does your shaft slide in and out freely to adjust its length for a turn?
b. Don't turn too tightly or stop the PTO first.

3. Are you just abusing it by hitting stumps, multiflora rose, etc /forums/images/graemlins/grin.gif Been there, done that- makes a good stump grinder /forums/images/graemlins/tongue.gif

4. Check your slip clutch. They have a tendency to seize up.

5. You aren't running it with your PTO at 1000RPM instead of 540RPM, are you ? /forums/images/graemlins/blush.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/crazy.gif

6. Make sure to keep your universal greased.

Not trying to imply you're doing any of the above, but if you are, you can decide if the shear pins are worth it.

BTW- Keep a set of bolt cutters on hand to replace bent shear pins. Just cut off one end and pull it out from the other side.

Let us know how you make out.

-JC

 

[BB_TX]

Talking about loose shear pins has me curious. I use a nylon lock nut on mine (that's what came on it). I tighten it until it just comes into contact with the collar on the PTO shaft. The pin is not tightened down, but it is not loose either. The nylon lock nut will not come off even though the pin is not tightened down. How does everyone else do it?

 

[Soundguy]

Since KK provides bolts+nuts+lockwashers in their shear pin kit for the 5' mowers.. that's what I use.

Soundguy

 

[Britt]

Update on the shear pin set-up...
I definitely feel that the loose shear pin is a good way to reduce breakage - seems to work well for me after several breaks with experimentation, and I'm on some rough terrain. I tried the lock nuts but as TSC they are 0.40 each, so I like to smash the threads with my pliers to hold the nut as a much cheaper option. I'm not changing the pin material because I know the risk. I'm not using a slip clutch because I am not confident in the system. How to assure the setting is very important, and the shear pin seems a better direct way to manage safety for the drive line over time.
Thanks to all for the feedback to my post. Happy cutting!

 

[Soundguy]

Yep.. I would think buying the shear pin parts seperately might be a tad expensive.. I simply buy the 5? pack that hangs in the KK parts area at TSC.. you get something like 5 bolts, 5 nuts, and 5 washers and lock washers... price is 4.50? or so?

Soundguy

 

[Gary_in_Indiana]

<font color="blue"> Yep.. I would think buying the shear pin parts separately might be a tad expensive.. I simply buy the 5? pack that hangs in the KK parts area at TSC.. you get something like 5 bolts, 5 nuts, and 5 washers and lock washers... price is 4.50? or so?"</font>

That's STILL too expensive for me. I go down the aisle where they sell the same grade bolts, nuts and washers by the pound and get mine there. I'm pretty sure that $4.50 worth there would rip through the bag! /forums/images/graemlins/shocked.gif

The only differences are that a) I don't get the fancy packaging with the 'shear bolt' label, and b) I have to decide between 3" and 4" bolts (either of which will work) as the bulk bolts there do not come in the 3 1/2" length. /forums/images/graemlins/smirk.gif

To me, it's no contest. I'll buy by the pound. /forums/images/graemlins/grin.gif /forums/images/graemlins/cool.gif

 

[BB_TX]

<font color="blue"> by the pound </font>
That's the way to buy. I sheared one a few weeks ago and didn't have any extras. I drove to a small locally owned farm store in a nearby town. Never been there before but it was the closest. Their bolts in the bulk bins were priced individually and a little high. Pickup up two 3 1/2" bolts and an additional lock nut. By the marked price, it would have been near $3. Took them to the counter, lady dropped them on the scale (including the nut), said 68 cents please. /forums/images/graemlins/laugh.gif I should have went back for more.
Haven't lost a lock nut yet. Have always found it either still inside the plastic PTO collar or laying on the deck. /forums/images/graemlins/smile.gif

 

[MicroPilot]

Hmm. I use 8" long lag bolts and pound the end over with a hammer!!!

/forums/images/graemlins/crazy.gif