HST problem in reverse?

[JKeane]

Hello all,
I own a MF1758 HST tractor that has begun to act strangely when I back up. Seems just fine in forward.
I feel a surging like motion, like I'm backing up over cobbles. Sort of like I feel resistance and then no resistance, if that makes sense. The engine rpm does not fluctuate.

Only about 300 hours on this unit (still a pup), HST fluid is full, running the original R4 rear tires - loaded and inflated to 15 psi. This happens in all three HST ranges.

Any thoughts on this would be appreciated.

Thanks.
John

 

[jeff9366]

Are you sure the parking brake is released?

 

[Thomas]

Under foot plate for build debris build up.

 

[JKeane]

Are you sure the parking brake is released?

Thanks. Yes, the parking brake is released. However you got me thinking in that direction. I checked and lubed the brake linkage. Didn't see any binding but a little oil can't hurt. I haven't put any time on the tractor since. Plenty of field work coming up soon; I'll let you know if it worked.
Thank you.

 

[JKeane]

Under foot plate for build debris build up.

Thanks for your response. I crawled under and check for debris. Couldn't see anything. I lubed the brake linkage (as per previous post).
Thank you

 

[BeezFun]

What kind of tires do you have? I can imagine an aggressive ag tread feeling different going backward.

 

[Hoss710]

sounds like something is binding in reverse.

 

[oldnslo]

I have no idea on what type of control is on that HST but possible there is something in the reverse logic causing the surging. Does it do this full speed reverse vs just trying to move slow like inching back to hook something up?

Any unusual sounds or does engine seem to load up a little then unload during the surging?

 

[JKeane]

What kind of tires do you have? I can imagine an aggressive ag tread feeling different going backward.

Tractor has R4 loaded rear tires. Original and in good condition.

 

[JKeane]

I have no idea on what type of control is on that HST but possible there is something in the reverse logic causing the surging. Does it do this full speed reverse vs just trying to move slow like inching back to hook something up?

Any unusual sounds or does engine seem to load up a little then unload during the surging?

I imagine that its possible that something in the reverse logic is causing this issue. Hoping for something more simple. It will surge in reverse at any speed and all ranges. The engine sound and rpm never changes.
Thanks for the input.