Did I Dodge a Bullet?

[JWR]

Was bush-hogging ... with the L2501 for a few hours and hit a rock. A big, solid piece of NH granite.... But it was 5-7 seconds of severe banging and horrible sounds /vibrations.

Now, this cutter has a slip clutch that I admittedly have not adjusted. I think its rusted solid. Before its used again, I will fix this or add a new one.

I left the PTO off for a minute, checked the blades (a little rounder than before, but no major harm), got back on and fired up the cutter. All is well. No strange noises. Finished the job, went home and cut my lawn with the finish mower. Turned the PTO on and off as needed, maybe 6 or more times since. No problems.

Yes, in a sense you dodged a bullet but you are very likely to dodge a LOT of them in the future if you cut much.

First, it is the hog at risk more so than your tractor. OK, confession time. It was 18 years ago when I first began to cut pasture brush on a brand new JD4700 with an MX6 hog on the back. A hilly WV farm with a moderate abundance of rocks. I had cut in prior years with smaller hogs and old tractors not up to the task. I've been trying to pick up those rocks and get them off the mowable areas since I was 8 or 9 with my grandfather and I am 75 now. It was after not more than 4 or 5 hrs of use that I hit a head-sized sandstone rock and shattered it to pieces with the remains clunking around under the hog for several seconds as I hurriedly raised the hog. Scared the beehaysus out of me ! During the last 18 years I have switched to a MF2660 pulling a Bush Hog brand model 297 7ft hog. Every cutting season I will hit 4 or 5 big rocks that I somehow did not see, though I try hard to avoid them. I do NOT abuse my machines but rock hazzards are often impossible to avoid. The more you cut a piece of land the more you get rid of the worst.

I have been just amazed at how hard the steel is in hog blades! Secondly, both the MX6 and the BH 297 stood up beyond what I thought was possible over the years. Both had slip clutches which are good but don't depend on them for a whole lot. Your slip clutch is adjusted about right if you get some squeal when you engage the pto but do not detect slippage while cutting even in heavy brush. The suggestion to loosen and re-tighten about once a year is a good one. While a slip clutch may look "rusted solid" that is very unlikely at the actual friction surfaces. Many suggest measuring the adjustment bolt /spring length between the contact surfaces and maintaining that tightness over time. Cut and try to get it right to start with. The springs will lose tension but it takes years.

So my bottom line advice is: Do not be overly alarmed by some nerve jarring awful sounding clashes back there so long as they are fairly rare. Obviously avoid all those clashes that you can. Maintain your stuff well and inspect for nicked blades and other issues frequently.

 

[crashz]

Thanks guys! Both relieved and motivated to adjust the slip clutch. The clutch is one that I haven't seen before as it doesn't have springs, but one huge center nut that I think gets tightened to adjust pressure.

 

[ovrszd]

Yep, there will be a "cupped" spring washer between the nut and the clutch plates. Tighten the nut and apply even and constant pressure against the disc pack. Very common and durable setup.

 

[SDT]

You need to loosen & clean a slip clutch annually at a minimum.

When I did the maintnance on my tiller last year it was an eye opener. I loosened up all the bolts so they were flopping around loose & it wasn't loose at all. I jammed a 2x4 into the tiller tines & fired it up at an idle. There was a nice loud bang. The tiller cut over half way through the 2x4 before the clutch let loose.

Nothing but rust & junk glued it together enough to cut well over half way through a 2x4. Add that to the properly tightened bolts & it wouldnt ever slip. Make sure you loosen it up & run it a bit while slipping to polish off any rust & pitting.

Bingo.

Few people even adjust a slip clutch appropriately for the HP of the tractor, and almost no one loosens a slip clutch annually to prevent corrosion lock.

This is why a shear bolt is better protection for most folks than is a slip clutch.

SDT

 

[JWR]

Bingo.

Few people even adjust a slip clutch appropriately for the HP of the tractor, and almost no one loosens a slip clutch annually to prevent corrosion lock.

This is why a shear bolt is better protection for most folks than is a slip clutch.

SDT

True, people do not adjust or pay attention to slip clutches very often. That is a good reason to have them, not a reason to avoid them. That is not a good reason to go without one and use the mechanically crude, yet cheap, solution of a shear bolt/pin. Slip clutches rarely ever cause lost time or problems. Shear bolts are simply a pain in the tusch. Most drivelines are using so much plastic to protect us from ourselves that getting to the shear pin to drive the broken part out and replace it becomes a lost-time issue and waste of time. Shear pins and related holes are sensitive to near perfect fit and chronic breakage issues including out of round holes,selection of material in the shear pin, and other wonderful wastes of time. A slip clutch is an excellent investment if your time is worth anything and you want to protect your equipment without a lot of nuisance.

Of course there are other opinions but that is mine.

 

[ovrszd]

Both good discussion.

The precise wording of SDT's is the most logical.

A slip clutch requires at a minimum annual investment of time. My 6ft shear bolt cutter has required no maintenance in 7 years of use with no broken bolt.

With that said, I prefer clutches on my larger cutter.

 

[Fallon]

Both good discussion.

The precise wording of SDT's is the most logical.

A slip clutch requires at a minimum annual investment of time. My 6ft shear bolt cutter has required no maintenance in 7 years of use with no broken bolt.

With that said, I prefer clutches on my larger cutter.

I was pissed when I found no clutch on my rotary cutter that was suppose to have one when I dug around under the guards to do the annual maintnance. 0 maintnance on it other than greasing when I sold it 3 years later. So really it ended up being better with a pin I never sheered.

 

[JWR]

It varies so much with the individual's situation and what/where he mows.

SDT, Overszd and Fallon are right and have good logic depending on which of the many situations you are in. I use a 4ft clunker JD hog in one location pulled by a B2150. I use a 5ft near-new Bush Hog brand using a different B2150 in another location with drastically different topography, humps, bumps and obstacles. All this monthly. Both those are shear-pin hogs. I've had to replace pins on the 4ft JD 3 times over 5 years and the 5ft unit 3 times in 2 years. A problem is that it is so easy to accidentally run over a hump or pile of something in a few seconds of "not paying close enough attention" and can't hit the shutoff fast enough. With these smaller shear pin hogs, that means downtime and frustration fooling with shear pin replacements. As overszd says, I would never put up with shear pins on my larger hog (7ft Bush Hog 297) also used monthly. The slip clutch on it has been very effective and totally trouble-free. Never 1 minute downtime for that.