Does anyone know about hydraulic drive systems?

[oldnslo]

The inner tube or liner on suction hoses can collapse and the outer shell of the hose won't show any deformation at all. Does the pump sound change when the machine stops? Typically pump cavitation sounds like you are rock grinding Vs pumping oil and is very noticeable.

 

[strum456]

UPDATE:

The problem was the pressure relief valve. The valve is not even available from Deere, so we machined a bolt so it had a sealing surface like the pressure valve and threaded it in the hole, eliminating the valve. The mower has worked great ever since.

Thanks for all the ideas. I'm going to remember the possibility of a suction hose collapsing on the inside only - I never knew that was possible.

 

[oldnslo]

With no relief valve you are running on borrowed time the the pump is a dumb device it just wants to keep moving fluid until the weak link breaks which could be a hose, pump, motor, etc..

Was there any part numbers or brand names on the relief valve. I suspect it was made by a valve OEM and there is a replacement available, Deere just doesn't want to sell the valve, they want to sell a complete manifold.

Any pictures of the valve, thread size, etc.

 

[kuboman]

I concur about no relief. That is a very dangerous situation. I would not want to be anywhere around that machine when operation. If you encountered a situation where the relief would go and you don't have one you can explode a hydraulic motor or hose and have a lethal situation.

 

[beenthere]

UPDATE:

The problem was the pressure relief valve. The valve is not even available from Deere, so we machined a bolt so it had a sealing surface like the pressure valve and threaded it in the hole, eliminating the valve. The mower has worked great ever since.
.................

The relief (the older AE42656 or newer AE48929 depending on s/n) valve appears to be available through Deere. Price of the assembly is $300 for older to $400 for newer, but is available.