Harsh PTO engagement on new XG 3140H

[CobyRupert]

Regarding the shear bolts, I find shear bolts to be very random.

I have a PTO shaft with a M8 shear bolt on my brush mower. I usually mow really high and dense stuff. Sometimes I go really hard on the brush just to see what the tractor can hold or if the shear bolt will break and it will hold just fine. Other times I go slower and it just breaks really easily without any apparent reason.

I think you're experiencing the difference between horsepower and torque.

 

[air8]

This is the one thing on the whole tractor that is a negative. I absolutely love the XG3140 otherwise. It's fantastic.

I'll look into getting slip clutches installed.

 

[ptsg]

I'm a bit surprised that some of you break shear bolts by just turning the PTO on with your mower.

Over here, our brush mowers have big high strength chains instead of blades, which have a lot more mass and will eat a lot of HP. I've never broke a shear bolt while starting the PTO up, even in the times I forget to reduce the engine RPMs to idle.

Maybe the grade of the bolt isn't properly sized for the tractor since they usually sell these PTO shafts to fit a range of HP.

Here is a small clip I removed from some footage I have. Hard to see the harsh engagement on a video but it kinda shakes everything around. Including the chains that hit the top of the mower making that big "bang" sound.

 

[Halftrack]

Had a friend with a later model IH 100 hp tractor he used on a batwing mower. Engagement was so severe, he would shear the internal drive shaft of the PTO, on every third use. ($$$) This was happening at absolute idle. Dealer loved the shop time, but finally suggested to let the machine warmup and engage above idle 200 or 300 rpm. Theory was the hydraulic system was not up to normal pressure to allow the hydro clutch to work properly. No problems since. Consult your dealer of service rep for their suggestion.

 

[ptsg]

After reading your post, I started using my brain a little bit and that might actually make sense.

The PTO valve on this system usually have pressure and flow control valves to make sure the clutch pack gets the right amount and pressure of oil. With the engine idling, there might not be enough flow for these valves to work right which can cause the harsh engagement.

Next time I have the mower or tiller attached to the tractor, I will play with the RPMs to see if I get different results. Although this will probably vary according to different brands.