shear pin vs. slip clutch on a brush hog

[OkieG]

Gary,
My cutter of 4 years has a shear pin. I thought about a slip clutch, but for no certain reason decided to go with the shear pin.
Don't know much about electronically engaged PTOs, but I engage mine at slow idle...and seems to engage pretty smooth. Even (unintentionally) trimming rocks and saplings too big for the cutter, so far, the tractor engine will die before a pin shears. Have never broken a shear pin, but with pivoting cutter blades, have never had the blades stopped cold, either.
I bought a shear pin model, even though I was a bit reluctant to go that route. But now, am not nearly as concerned that I gave up much by not getting a slip clutch.

OkieG

 

[rockyridgefarm]

Yup, the 855 doesn't have the electric pto engagement, does it?. On the 000's it really kicks in hard!

 

[R_squared]

Rockyridgefarm brought up a good point. Our DK45 has an electric engaging PTO. Last year I borrowed my neighbor's 6 foot rotary cutter because we didn't have a mower yet. While engaging the electric PTO, we must have snapped 6 or 7 sheer pins. The engine was kept idling. The extra time removing the pins and driving to find new ones was a pain. Some pins came out easy and some didn't. I purchased several grade 2 and ten grade 8 for worst case. The grade 2 snapped like dry spaghetti. The grade 8's lasted to the end. We didn't sheer a pin while mowing. We returned the rotary cutter with several spare sheer pins and my neighbor said that the original one had lasted him 6 years. The Mrs. mowed and I changed the sheer pins. The one good thing about the situation was that she agreed to get a mower sooner than later. A final thought, you could always add a slip clutch later.

 

[Soundguy]

</font><font color="blue" class="small">( The grade 2 snapped like dry spaghetti. The grade 8's lasted to the end )</font>

Yikes.. I wouldn't use anything other than a grade 2 as a shear pin... If you used a grade 8.. sounds like somehting in the tranny might be weaker.. /forums/images/graemlins/ooo.gif

Soundguy

 

[Soundguy]

</font><font color="blue" class="small">( The elecrically engaged ptos sure can snap a shear pin! )</font>

Even if you reduce rpm you are still getting cut pins?

Soundguy

 

[rockyridgefarm]

Dunno! I have a slip clutch!! I heeded the warnings from my fine tbn buddies!

 

[rockyridgefarm]

On my old mower i broke a few shear pins, then the mower twisted up like a shinny can...

 

[R_squared]

Soundguy,

Yeah, they would sheer within a few seconds after engaging. The First Choice RFM behaves differently. The startup force seems to be taken up by the belts. Sometimes they will squeak for a second until they grab. The tiller has a slip clutch and engages smoothly - I can't detect any slip.

 

[Soundguy]

I just can't imagine a pto that is designed to engage like that.. seems backwards. That's why I like 2 stage clutch setup instead of independent pto... I can use my foot to engage the pto slowly if I want to... Seems like every time somethingmoves ahead in the favor of progress.. they are also taking a step back as well.

Soundguy

 

[timb]

It's not the independent PTO per se - it's the head-in-the-sand engineering behind the user interface. The 5000-series ag JD's (and I'm sure most other larger tractors) have fully independent PTO's but they have a by-gosh mechanical (gads!) lever i.e. hand-clutch that let's you ease in the load just fine. The only two possible advantages of the electric-switch units I can see is 1) they are easier to incorporate into an overall 'operator presence' system (read lawyers doing the engineering) and 2) I suppose they do make it easy to slap the PTO off in a move-quick situation. Otherwise IMO they bite.

Tim