Hyrostat drive

[tod stoner]

I have JD 757 ztrak. Right wheel not functioning, left seems fine. Right wheel will free turn, I've ensured free wheel nut is tight on pump.

 

[StarTech]

Sound like you got air in the system or you have a pump failure.

Now the 757 used two different pump setups. Later 757 (SN 030001- )(TC757MB010001- ) use the Tuff Torq dual pump. Eariler model used separate pumps.

 

[ILENGINE]

Sound like you got air in the system or you have a pump failure.

Now the 757 used two different pump setups. Later 757 (SN 030001- )(TC757MB010001- ) use the Tuff Torq dual pump. Eariler model used separate pumps.

And if the OP has the dual pump he better be sitting down and prevented from fainting when he sees the price of that pump.

 

[tod stoner]

Thanks for the replys, tried to attach a pic of the pump, but was too large. assume it's the dual as there is only one pump and both linkages attach on top of it, and there is a free wheel nut on each side. Yeah, around $2200. I found the air purge procedure I will try. Is there a way to determine if it is indeed the pump, before purchasing a new one? Can these be rebuilt?

 

[ILENGINE]

I have a customer on his third pump. Typical symptom is one wheel will start to slow down and not pull when hot. And then will reach a point that it doesn't pull at all. And it is always the right pump that fails. The pump and mating surface will both be scored. And repair parts are not really available from JD or even Tuff-Torq. And if you find the parts to repair the pumps it will cost you almost as much as a new pump.

 

[StarTech]

The problem is that Tuff Torq does manufacture the DUP-10S. It is made by Kanzaki Kokyukoki Mfg. Co., Ltd. Japan. Tuff Torq will not even give you an IPL with PNs for this unit.

Nor will they provide you a service manual even I got one with Kanzaki part numbers for DUP-10SA but I can not even find those part numbers on the web. So having a service manual is of no use.

It is one piece of equipment that John Deere US is trying to have exclusive rights to so they are the only supplier of the parts that I can find so far here in the USA.

 

[bertsmobile1]

They can be repaired if you can fu=ind a shop that repairs hydros by machining the kidney plate & valve chest then shimming them to the right spec .
Some old time tractor shops as in farm tractor shops do this because a lot of old heavy ( 100hp ) draught tractors had a hydro drive for going really really slowly
The Oliver we had here was 1 mph in first to 5 mph in top with a hydro to drop that even slower but more important have no mechanical connection between the engine & the wheels
And oddly enough a tractor the neighbour has uses a hydro for road gears , a whooping 10 mph, which id frighteningly fast on top of 48" wheels with 15 ton under you .

 

[Tiger Small Engine]

They can be repaired if you can fu=ind a shop that repairs hydros by machining the kidney plate & valve chest then shimming them to the right spec .
Some old time tractor shops as in farm tractor shops do this because a lot of old heavy ( 100hp ) draught tractors had a hydro drive for going really really slowly
The Oliver we had here was 1 mph in first to 5 mph in top with a hydro to drop that even slower but more important have no mechanical connection between the engine & the wheels
And oddly enough a tractor the neighbour has uses a hydro for road gears , a whooping 10 mph, which id frighteningly fast on top of 48" wheels with 15 ton under you .

Very few shops will work on hydraulic pumps, pump motor, and transaxles. I used to, but no longer offer this as a repair. It is not worth the time for the effort and money when lots of equipment is waiting to be worked on. It is normally a remove and replace nowadays and very expensive.