I'm in shear pin purgatory! Please help

[Laminarman]

I keep breaking shear pins on my heavy duty 6' Land Pride rotary cutter. I do have the model with the slip clutch, but not sure what the heck good that's doing me right now. I broke NO pins in four years, now at least a DOZEN since last fall. Could it be a slip clutch problem?

Oddly the shear bolts directly from Land Pride (at $4 each, no thank you) break every time on start up with PTO anywhere from 2,000 RPM's up. My grade 5's from the hardware store ($.99 each, thank you) last longer but still break with little effort after even a little bit of bottoming out. I have lubricated the gear box as instructed. Blades do need to be sharpened, but at a loss here for what might be going on. Figured I'd check here first to hopefully avoid the every escalating service call my dealer charges (due to gas prices they say). Can't afford a service call, too busy buying shear bolts. Thanks folks.

Lam

 

[Rara Avis]

This is right out of the LandPride Rotary Cutter Manuals...
Land Pride Single Deck Rotary Cutters
Driveline clutch slipping or
Shear bolt breaking
Problem...............................Solution
Scalping the ground...............Raise cutting height
Cutting too fast....................Reduce travel speed
PTO being engaged too..........Slowly engage PTO at low engine rpm
fast at high engine rpm
Cutting over solid objects.......Avoid solid objects



2000 RPM is NOT a LOW engine rpm...

 

[GaryCrowell]

I'd venture a guess that your slip clutch isn't slipping properly, you probably need to loosen the bolts and slip it a bit to get it unstuck. That needs to be done at least once a year to keep the slip clutch working.

However, you main problem is throwing the PTO on at 2000 rpms, bad, bad, bad. The PTO needs to be engaged while the engine is at idle, then increase the engine speed with the PTO engaged. When you throw the PTO on with the engine at operating speed you're shock loading the system and the shear pin is doing what it's designed to do, shear before something more expensive breaks.

 

[jinjimbob]

I also have a Landpride tiller, had it for a few weeks, the slip clutch is not working. I have to take it apart and check it.

It never slips, just stalls the engine. Not good for brand new.

 

[MarkV]

I also have a Landpride tiller, had it for a few weeks, the slip clutch is not working. I have to take it apart and check it.

It never slips, just stalls the engine. Not good for brand new.

Not need to take it a part. Just loosen each bolt an equal amount until the clutch slips and then retighten each bolt the same amount. The clutch plates will often stick together when the unit has not been used recently, even new ones, and need to be freed up. This is pretty standard maintenance for a slip clutch.

MarkV

 

[LoneCowboy]

yep
engage PTO at low speed (idle preferably)
and you have to break apart teh slip clutch. Pretty much anytime it's been sitting for 7-10 days. You just loosen all the bolts up, then start it up and turn the PTO on and watch that the shaft is turning, but not the mower (takes two people)

then tighten it back up again. It's probably frozen together and when you shock it turning the PTO on at high RPM it's not slipping and bam, that's the shear pin.

BTW, you should never use BETTER bolts in place of a shear pin, defeats the whole point of a shear pin. Just use those cheap junk made in china bolts, they shear right away. (shock!)

 

[greg_g]

The Cowboy is correct, shear pins and slip clutches are an either/or proposition. You want one or the other - not both.

• Disassemble/clean/reassemble/adjust the slip clutch
• use a fastener bolt where you're now using a shear bolt
• engage the PTO just above idle
• THEN throttle up to the 540 mark on your tach

Check also to make sure breaking all these bolts didn't start to egg out the bolt holes. If you see the hole(s) getting egg-shapped, they'll only get worse. The usual remedy is to overbore to a larger bolt size.

//greg//

 

[Rara Avis]

yep
engage PTO at low speed (idle preferably)
and you have to break apart teh slip clutch. Pretty much anytime it's been sitting for 7-10 days. You just loosen all the bolts up, then start it up and turn the PTO on and watch that the shaft is turning, but not the mower (takes two people)

then tighten it back up again. It's probably frozen together and when you shock it turning the PTO on at high RPM it's not slipping and bam, that's the shear pin.

BTW, you should never use BETTER bolts in place of a shear pin, defeats the whole point of a shear pin. Just use those cheap junk made in china bolts, they shear right away. (shock!)

LC...nice catch...

DUH!!!
I didn't even realize he was using BOTH...was working off his Title Line...

 

[Laminarman]

Goodness you all think I'm an idiot. I usually do engage the PTO at idle, even though my dealer told me to engage at FULL 540 to avoid the blades getting tangled up. I tried the higher engage speed to see if it might break there, and yup, it did. I did it once more to see if the other bolt would break, nope it didn't. I'll do the maintenance on the slip clutch. Thanks folks!

 

[AchingBack]

Goodness you all think I'm an idiot. I usually do engage the PTO at idle, even though my dealer told me to engage at FULL 540 to avoid the blades getting tangled up. I tried the higher engage speed to see if it might break there, and yup, it did. I did it once more to see if the other bolt would break, nope it didn't. I'll do the maintenance on the slip clutch. Thanks folks!

You're not an idiot, and thanks to your question, many of us have learnt a good lesson.