I'm in shear pin purgatory! Please help

[Laminarman]

I think I got her unstuck. I loosened all bolts the same amount, marked the plates and engaged her. They all seemed to move. Then I did it again, and no matter what I do I can only seem to get one moving, two seem not to move. But I tightened, mowed and all seems fine so far. Thanks for your help.

 

[greg_g]

There should be two friction plates sandwiched between three pressure plates. Simply loosening/retightening the nuts isn't going to fix your problem. You need to disassemble the thing, and most likely sand some oxidation off the pressure plates. Over-tightening the nuts will also inhibit the desired slippage.

Not sure what slip clutch you have, but mine's adjustable to to match the rated PTO output of the tractor. It's a matter of tightening the nuts to the extent that spring length match that specified on the adjusting chart (which came with mine).

//greg//

 

[MikeD74T]

Has anyone got manufacturers' documentation that a slip clutch & shear pins should not be used togeather ? I use a slip clutch on my bush hog because the fender mounted electric pto clutch switch on the DK45S is easily bumped & if disengaged then reengaged at operating speed it's a guaranteed broken shear pin. I went thru 5 the first time I used the BH on the Kioti before I realized what was happening. My old Ford without live pto would engage slowly as the clutch was released. Put on the slip clutch - problem solved. I still use the shear pins because if the clutch fails to slip, the shear pins will protect the mower / tractor.
Not having any adjustment chart, I tighten the slip clutch springs until there's no evidence of slippage, i.e. it doesn't heat up. Occasionally I'll lower into heavy hardhack & engage at an idle to ensure some slippage occurs. I'm not sure I want it tight enough to be at 100% pto rating all the time, I want enough power more than max power. MikeD74T

 

[Laminarman]

I look and look and I have three plates in there between the end plates. Like I said first time all three were moved off the marks, second time, bolts not tightened, only one seemed to move (ie two were "stuck"). Now, the first time I did it I heard a loud BANG while ramping up PTO's and I think that was the plate releasing and becoming unstuck. If I need to disassemble to free them all up, is that a huge job? I am still struggling with the darn PTO shaft plastic cover and working around that beast.

 

[greg_g]

Simple job, just a little time-consuming when it comes to adjusting tension on 8 springs. See http://www.tractorbynet.com/forums/attachments/attachments/75110d1177265787-slip-clutch-slip-clutch-settings.jpg

//greg//

 

[john_bud]

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!

Not at all. However, if your dealer told you to engage at full 540 pto speed, I think he may be....

Try loosening the slip clutch bolts up more and "slipping it on purpose". I do that by raising the rpms to about 2000 (2600 = 540 pto speed) and flipping on the pto. The shock load causes it to slip (and smoke!). It's a flip on / flip off deal with maybe a repeat cycle in there.

I also totally agree with Lonecowboy - you need to do it if the equipment has sat for a couple weeks. Slip clutches freeze up all the time and that is a great way to damage the tractor as froze SC = no slip so all the shock goes into the PTO housing and can break expensive stuff.

 

[gemini5362]

OK i dont see slip clutches and shear pins being an either or. I tend to look at them as defense in depth. For normal useage and hitting something that might stop the tines the clutches slip and protect the unit and the tractor. In case the clutches freeze up and dont work the shear pin gives another depth of protection. This makes sense to me that you would have a backup for the clutches.

 

[jinjimbob]

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

Yep, been reading the manual today. All 4 of those bolts are almost all the way out, there is gap between the bolt and the plate, and yet it doesn't slip.

The plates looks rusty, maybe its been on the dealers lot for a year or so?

 

[Rara Avis]

Has anyone got manufacturers' documentation that a slip clutch & shear pins should not be used togeather ? I use a slip clutch on my bush hog because the fender mounted electric pto clutch switch on the DK45S is easily bumped & if disengaged then reengaged at operating speed it's a guaranteed broken shear pin. I went thru 5 the first time I used the BH on the Kioti before I realized what was happening. My old Ford without live pto would engage slowly as the clutch was released. Put on the slip clutch - problem solved. I still use the shear pins because if the clutch fails to slip, the shear pins will protect the mower / tractor.
Not having any adjustment chart, I tighten the slip clutch springs until there's no evidence of slippage, i.e. it doesn't heat up. Occasionally I'll lower into heavy hardhack & engage at an idle to ensure some slippage occurs. I'm not sure I want it tight enough to be at 100% pto rating all the time, I want enough power more than max power. MikeD74T

Driveline Protection
! CAUTION
Engage parking brake, disengage PTO, shut off tractor, and
remove key before making any of the following adjustments.
Cutter drive components are protected from shock loads
by either a two plate friction clutch or a shear bolt. Avoid
shear bolt failure by engaging the PTO slowly at low
engine rpm. See your Land Pride Dealer when replacing
shear bolts.

The above is right out of the LANDPRIDE ROTARY CUTTER OPERATOR MANUAL...
Land Pride Single Deck Rotary Cutters

 

[IslandTractor]

Driveline Protection
! CAUTION
Engage parking brake, disengage PTO, shut off tractor, and
remove key before making any of the following adjustments.
Cutter drive components are protected from shock loads
by either a two plate friction clutch or a shear bolt. Avoid
shear bolt failure by engaging the PTO slowly at low
engine rpm. See your Land Pride Dealer when replacing
shear bolts.

The above is right out of the LANDPRIDE ROTARY CUTTER OPERATOR MANUAL...
Land Pride Single Deck Rotary Cutters

I don't see that statement as indicating you should not use both shear pin and slip clutch but rather as a manufacturer's instructions intended to cover models that have one or the other. Some models are identical except for slip clutch vs lower priced shear pin. Clearly you need either one or the other but what is the downside of having (in theory) a primary slip clutch, well adjusted and maintained of course, and a backup shear pin for when the slip clutch rusts or is badly adusted? How could the two protection devices interfer with each other?