[AT] Adventures with shear pins

[Dean Vinson]

Hi Dean.   No, this rotary cutter doesn't have a slip clutch--just the shear
bolt, which according to the operator's manual has to be grade 2 (since
there's no slip clutch, I presume).   The assembly instructions at the back
of the manual show both the shear bolt driveline (i.e., standard square-tube
telescoping driveline with U joints, all encased in a free-rotating plastic
safety shield, with a shear bolt connection at the input shaft to the
gearbox on the mower deck) or the slip clutch driveline (slip clutch at the
final U joint, just in front of the input shaft to the gearbox).   I assume
the original owner bought it that way.  It's a pretty lightweight mower, and
yes, the 620 is a little too much tractor for it.    I'd like a heavier and
somewhat wider mower (this one is only a six foot cut, not quite enough to
cleanly pick up the wheel tracks), so that's on the shopping list for
someday.   For now, it works well enough and the only times I've broken the
shear pin were when I hit something I wouldn't have wanted to hit if I'd
known it was there.

Dean Vinson
Saint Paris, Ohio


-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Dean VP
Sent: Thursday, July 24, 2014 11:06 PM
To: 'Antique tractor email discussion group'
Subject: Re: [AT] Adventures with shear pins

Dean,

But I'm not powering the brush cutter with a JD 620 with nearly 50HP either.
My little JD 750 at best puts out 20HP to the PTO.  The JD 620 might be a
little more tractor than what the brush cutter was designed to handle. 

Dean VP
Snohomish, WA

They say necessity is the mother of invention. 
Don't know who the father is, probably remorse.
Red Green

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Dean VP
Sent: Thursday, July 24, 2014 7:43 PM
To: 'Antique tractor email discussion group'
Subject: Re: [AT] Adventures with shear pins

Dean,

Doesn't the brush hog have a slip clutch?  If it does it isn't doing its
job. May be frozen due to age and the elements.  A shear pin isn't
necessarily just a grade 5 bolt.  May require something harder.
Check the Owner's Manual of the Brush Hog for the right pin. You probably
have already done that.
Don't want the wrong pin in there and then not do the job it is supposed to.
I've owned a Brush cutter for over 10 years and have never sheared a pin and
I've gotten into some really nasty stuff
with it.   But I won't mention the name of manufacturer of it!  :-) 

Dean VP
Snohomish, WA

They say necessity is the mother of invention. 
Don't know who the father is, probably remorse.
Red Green

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Dean Vinson
Sent: Thursday, July 24, 2014 7:20 PM
To: 'Antique tractor email discussion group'
Subject: [AT] Adventures with shear pins

I've given up brush hogging the scruffier areas of my new place until the
summer growth dies down and I can do more effective walk-throughs.   Lots of
hard old osage orange branches laying low in the grass, along with
occasional bits of nasty junk like cinder blocks and old rusty tangles of
woven-wire fence sections.   I've replaced the shear bolt on the mower quite
a few times, and had to have somebody out to fix a flat rear tire on the 620
after a heavy piece of wire--possibly from that mass of old fence
wire--punctured it.   Time to stop beating up the equipment and wait until I
can really clear all the obstructions out.

But the weather was spectacularly nice this evening, so after finishing up
another chore I hooked the 620 back up to the mower and went out to the
meadow by the orchard.   It had all been mowed last fall when I first
visited this place and I walked around it several times back then, all very
nice and trimmed, almost yard-like, so I was confident I wouldn't hit
anything.    Spun up the brush hog, eased the clutch forward, and off I
went...and then not two minutes later heard the mower suddenly hit
something, followed by the "pop" of the shear bolt breaking and the sound of
the mower coasting down, no longer being driven by the PTO.   #*^@! it, what
the heck was down there?    

Turned out to be about 150 feet of very nice rubber garden hose, loosely
coiled up in big easy ovals and spread over an area about four feet wide and
eight feet long.   Still had water in it, or at least it did before that
mower chopped it into about 20 pieces.   I hope the previous owner doesn't
want it back...

Dean Vinson
Saint Paris, Ohio

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