Avant 200 series

[SamUK]

Hey guys, recently bought this little avant and having a bit of an issue, I'll try and explain the best I can..

The drive is full hydraulic, 4 motors at each corner. Forwards and reverse are via 2 pedals, if I press a pedal it IS supposed to stop when I loose a pedal but it doesn't. The pedals attach to some kind of valve block which I've just had reconditioned by my local hydraulics specialist but the problem still persists.

The above wouldn't matter if I was using this around the yard but, it's for grabbing muck out of stables so not being able to stop in a confined area could get a little damaging to the buildings!

My questions are, why is it creeping forwards or backwards when I loose a pedal? Is there something else that controls the flow to the motors that I've missed?

Any help and advice is greatly appreciated guys, thanks in advance

 

[oldnslo]

There should be some spring loaded centering device in the control linkage somewhere. There could also be some centering adjustments on the control linkage.

Have you checked to see if there are any grease fittings on the pivot points of the pedals? Do these move easily?

I am not familiar with the Avant system so I cannot tell you exactly what you have.

 

[SamUK]

There should be some spring loaded centering device in the control linkage somewhere. There could also be some centering adjustments on the control linkage.

Have you checked to see if there are any grease fittings on the pivot points of the pedals? Do these move easily?

I am not familiar with the Avant system so I cannot tell you exactly what you have.

I didn't look for adjustment on the valve linkage, I just assumed it would have been pressure tested and set whilst it was in for repair. I'll check that out today.

It's totally confused me as there is nothing else's between the 4 way 2 direction valve and the motors, so to me that suggests it should stop as soon as you loose the pedal. Does that sound about right?
If there's no adjustment all I can think is that the valve hasn't been pressure tested and is still not working as it should.

 

[CincyFlyer]

I didn't look for adjustment on the valve linkage, I just assumed it would have been pressure tested and set whilst it was in for repair. I'll check that out today.

It's totally confused me as there is nothing else's between the 4 way 2 direction valve and the motors, so to me that suggests it should stop as soon as you loose the pedal. Does that sound about right?
If there's no adjustment all I can think is that the valve hasn't been pressure tested and is still not working as it should.

Yes, if the valves block the work ports in neutral, it will abruptly stop the motors (they do make motor valves that dump the work ports to tank in the neutral position, but you'd then need to use the brakes every time.) But as oldnslo notes, the valve then must be centered in neutral for this "braking" to occur.
Does it steer by turning wheels, or by differential wheel speed? If by wheels:
Either the valve itself is spring centered or the pedal linkage does the centering; in either case it appears that the valve is not centered properly. If you disconnect the pedal linkage and the wheels lock then you likely have a linkage adjustment issue. At that point you can directly check the valve centering, perhaps a little push will make the difference, in which case the valve may need some work.
Note that this assumes that the motors aren't simply worn out, and the valve is not scored in any way.