Hogging and stalling the tractor

Gamemaster · May 31, 2006

I have stalled my tractor w/ a KK 4' hog a couple of times over past 1.5 yrs since starting tractoring. Does this or will this damage the tractor. I have never broke a shear pin yet. Hit mostly stumps/big rock, but only stalled it. Is this normal or should the shear pin break before stalling?

Gamemaster · May 31, 2006

I have stalled my tractor w/ a KK 4' hog a couple of times over past 1.5 yrs since starting tractoring. Does this or will this damage the tractor. I have never broke a shear pin yet. Hit mostly stumps/big rock, but only stalled it. Is this normal or should the shear pin break before stalling?

joerocker · May 31, 2006

It's never GOOD to stall an engine especially like that.

I'd suggest a weaker shear bolt that will break before stalling.

joerocker · May 31, 2006

It's never GOOD to stall an engine especially like that.

I'd suggest a weaker shear bolt that will break before stalling.

Bird · May 31, 2006

You probably didn't hurt the tractor; how many tractors, or even cars and pickups with manual transmissions, are there that someone hasn't stalled the engine on a time or two, or more. /forums/images/graemlins/wink.gif However, as Joe said, it really doesn't do one any good either. You'd expect the shear pin to break; however, I stalled my B7100 HST a couple of times without breaking the shear pin on my 4' brush hog. I didn't hit anything solid enough to stop everything really suddenly, but hit big fire ant mounds that stalled it. I learned to approach them more slowly. /forums/images/graemlins/tongue.gif

Bird · May 31, 2006

You probably didn't hurt the tractor; how many tractors, or even cars and pickups with manual transmissions, are there that someone hasn't stalled the engine on a time or two, or more. /forums/images/graemlins/wink.gif However, as Joe said, it really doesn't do one any good either. You'd expect the shear pin to break; however, I stalled my B7100 HST a couple of times without breaking the shear pin on my 4' brush hog. I didn't hit anything solid enough to stop everything really suddenly, but hit big fire ant mounds that stalled it. I learned to approach them more slowly. /forums/images/graemlins/tongue.gif

greg_g · May 31, 2006

Check your shear bolt head against this diagram;

If you don't currently have a Grade 2 bolt in there, that's what I recommend.

//greg//

greg_g · May 31, 2006

Check your shear bolt head against this diagram;

If you don't currently have a Grade 2 bolt in there, that's what I recommend.

//greg//

Highbeam · May 31, 2006

A shear bolt protects the drivetrain from shock damage. A brushhog can be gently put into situations where it takes more power to spin it than what your PTO shaft has to offer and your engine will stall. No impact, no shear bolt break. I see it as normal operation to occasionaly lose some RPMs in the rough stuff. When this happens you need to change your method a bit to keep the rpms up. Sometimes the rpms drop too quickly and before you can adjust your operation the engine stalls. When it happens, start the engine back up right away and get back to work. I wouldn't feel right letting a diesel engine stall and then sit since as it was stalling the fuel was being poured in to keep it running and that fresh fuel is still in there.

Highbeam · May 31, 2006

A shear bolt protects the drivetrain from shock damage. A brushhog can be gently put into situations where it takes more power to spin it than what your PTO shaft has to offer and your engine will stall. No impact, no shear bolt break. I see it as normal operation to occasionaly lose some RPMs in the rough stuff. When this happens you need to change your method a bit to keep the rpms up. Sometimes the rpms drop too quickly and before you can adjust your operation the engine stalls. When it happens, start the engine back up right away and get back to work. I wouldn't feel right letting a diesel engine stall and then sit since as it was stalling the fuel was being poured in to keep it running and that fresh fuel is still in there.

cp1969 · May 31, 2006

When you talk about stumps, big rocks, etc., that isn't a gradual slowing down of the engine til it stops. That is an abrupt stop and yes, the shear pin should have prevented that.

cp1969 · May 31, 2006

When you talk about stumps, big rocks, etc., that isn't a gradual slowing down of the engine til it stops. That is an abrupt stop and yes, the shear pin should have prevented that.

Highbeam · May 31, 2006

Oh yes, I missed that point. As the mower is unsuccessfully trying to eat a rock and making the bang bang bang sound as it is slowing the engine the shear pin should have popped. If it is just being slowed down while happily munching thick stuff the shear pin may not pop.

Highbeam · May 31, 2006

Oh yes, I missed that point. As the mower is unsuccessfully trying to eat a rock and making the bang bang bang sound as it is slowing the engine the shear pin should have popped. If it is just being slowed down while happily munching thick stuff the shear pin may not pop.

Hooked_on_HP · May 31, 2006

Does it have a shear pin or does it have a slip clutch thas not working. When you hit something that stops the motor dead it puts extreme torsional stress on every thing from the crankshaft to the gearbox on the mower. Then after the engine stops everything unwinds. This is verry hard on gears .

Hooked_on_HP · May 31, 2006

Does it have a shear pin or does it have a slip clutch thas not working. When you hit something that stops the motor dead it puts extreme torsional stress on every thing from the crankshaft to the gearbox on the mower. Then after the engine stops everything unwinds. This is verry hard on gears .

Alan L. · May 31, 2006

Well now I'm a little worried. I have sheared one pin in 7 years. That was about 4 or 5 years ago. I have hit stumps, rocks, logs, fire ant mounds, etc. and stalled the tractor on occasion, but no sheared pin.

The one I put in there came from the Kubota dealer and is supposed to be the proper shear pin. It does not have any marks on the head but has "SJ" on it.

Alan L. · May 31, 2006

Well now I'm a little worried. I have sheared one pin in 7 years. That was about 4 or 5 years ago. I have hit stumps, rocks, logs, fire ant mounds, etc. and stalled the tractor on occasion, but no sheared pin.

The one I put in there came from the Kubota dealer and is supposed to be the proper shear pin. It does not have any marks on the head but has "SJ" on it.

flusher · May 31, 2006

Same thing happened to me when mowing with a 4-ft KK brush hog and my B7510HST a month ago. Hit an old almond stump and killed the engine without cutting the shear bolt. Scary. Thought I creamed the PTO transmission, but everything works OK.

Was using the bolt that KK supplied. It has an "L" on the head and a dab of yellow paint on the L. Anybody know if this is Grade 2?

Bought some spare shear bolts at TSC. They have "307A CYI" on the head. According the info from Nucor Fasteners, this bolt is interchangeable with Grade 2 and is actually a little weaker than Grade 2. See

302 shear bolt

flusher · May 31, 2006

Same thing happened to me when mowing with a 4-ft KK brush hog and my B7510HST a month ago. Hit an old almond stump and killed the engine without cutting the shear bolt. Scary. Thought I creamed the PTO transmission, but everything works OK.

Was using the bolt that KK supplied. It has an "L" on the head and a dab of yellow paint on the L. Anybody know if this is Grade 2?

Bought some spare shear bolts at TSC. They have "307A CYI" on the head. According the info from Nucor Fasteners, this bolt is interchangeable with Grade 2 and is actually a little weaker than Grade 2. See

302 shear bolt