3840 PTO comes on too hard

[binthere]

I have had my 3840 a couple of years 100 hours. The tractor is perfect for my needs, digging an occasional post hole, loading round bales, and brush cutting.
When the brushcutter is turned on the pin will shear 9 out of 10 times unless I use a technique I found on this board. By tilting the bucket all of the way up and causing the hydraulics to bypass turning the switch on and slowly releasing
they joystick I can bring the PTO power on slowly to keep from breaking pins.
It just seems to me that there should be an adjustment to keep this from happening in the first place. My dealer is clueless. If anybody has any ideas I would be grateful. The tractor is great! but this just bugs the crap out of me.

 

[atgreene]

So I assume you have an electric switch that turns on your pto? Not familiar with your tractor style, sorry.

Even at an idle the pto snaps on hard enough to shear bolts?! What are you using for bolts in the driveshaft? Does the tractor lug-down whne you engage?

I find it hard to believe at idle that a tractor pto can be engaged hard enough to break a shear bolt. I can dump my clutch at a moderate idle with pto engaged and not have any ill effects.

 

[Dallas_Lilly]

I have had my 3840 a couple of years 100 hours. The tractor is perfect for my needs, digging an occasional post hole, loading round bales, and brush cutting.
When the brushcutter is turned on the pin will shear 9 out of 10 times unless I use a technique I found on this board. By tilting the bucket all of the way up and causing the hydraulics to bypass turning the switch on and slowly releasing
they joystick I can bring the PTO power on slowly to keep from breaking pins.
It just seems to me that there should be an adjustment to keep this from happening in the first place. My dealer is clueless. If anybody has any ideas I would be grateful. The tractor is great! but this just bugs the crap out of me.

On this board people have said that their dealer adjusted the PTO solenoid and it has helped like here http://www.tractorbynet.com/forums/montana/95280-breaking-bush-hog-shear-bolts.html

But that sounds like it can cause damage also if it is adjusted to much it will slip and cause damage.

I can tell you that I now have 450 hours on my machine and over time the problem has been eliminated. It does not break shear bolts during engagement any more and I have done nothing.

 

[HogWild1]

Try a slip clutch on the cutter.

 

[BigKansas]

I have had the same problem with my shear pin breaking on my 5740. I have a pull behind mower and I had to replace the shear pin 6 times before I even started mowing. I have my tractor idle at around 700 RPM's and they still break. I started with grade 3 material and worked my way up to grade 8 and some the grade 8 still shear. I asked my dealer about the problem and he said the same thing about an adjustment but it could be hard on the internal clutch. I finally had to resort to putting my tractor in 1st gear, move the lever to forward, release the clutch, apply the brake until engine bogs down, and then turn on the PTO. As far as I am concern, should not have to do this much work to engage a PTO.

 

[Jerry/MT]

I have had the same problem with my shear pin breaking on my 5740. I have a pull behind mower and I had to replace the shear pin 6 times before I even started mowing. I have my tractor idle at around 700 RPM's and they still break. I started with grade 3 material and worked my way up to grade 8 and some the grade 8 still shear. I asked my dealer about the problem and he said the same thing about an adjustment but it could be hard on the internal clutch. I finally had to resort to putting my tractor in 1st gear, move the lever to forward, release the clutch, apply the brake until engine bogs down, and then turn on the PTO. As far as I am concern, should not have to do this much work to engage a PTO.

Using a grade 8 bolt as a shear pin is a recipe for a damaged drive line and PTO drive. It defeats the purpose of the shear pin. There must be some adjustment to limit the snap engagement of the pto that is causing you to damage a grade 2 shear bolt. The other option is to equip your cutter's drive line with a slip clutch and elimate the shear pin.