Hydrostatic with torque generator power steering

mytc30 · Nov 30, 2020

I have a Simplicity Prestige garden tractor with a Tuff Torq K71 hydrostatic transmission and an Eaton series 17 torque generator used for power steering. This summer the power steering failed. Since I did not have any other issues, tractor goes forward and reverse and deck lift works, I then purchased a new in the box Eaton torque generator, and carefully and correctly installed the unit. This did not solve my problem. I then dumped the 5W 30 transmission oil and replaced it with 5W 50. This is objective but I think there was an ever so small improvement in the power steering. This leads me to believe that possibly my hydrostatic pump is worn enough that is can supply the tractor movement but lacks the ability to create enough flow or build enough pressure to activate the torque generator completely.

So what do you think? Is my hydrostatic pump the problem, or did I miss the obvious, hey you bought a new part and it's bad?

Either way, I could use some help as to what my next step could be. Thanks.

Richard001 · Dec 1, 2020

Welcome to TBN
:welcome:

Could you give us the model of your tractor and it's age or number of hours on it.

Richard

oldnslo · Dec 1, 2020

mytc30,
Not sure if Simplicity has service manual but can you check the charge pressure to see if it is to spec. I have no clue what it should be but hat could provide an indication of where to look next.

mytc30 · Dec 2, 2020

Thanks for replying, the tractor is a Simplicity Prestige package # 2690123 with a Tuff Torq k71Transmission # 71E-0014183. I believe it is a 2002, I bought it used in 2004. It has just over 1000 hours. I do have the Simplicity service and repair manual. It shows how to remove and replace transmission but does not go into troubleshooting or pressure specs. Looks to me, since there is no external pressure test port, it would require making a new line with a gauge in-line to check pressure, , but then I don't have any idea what the pressure should be and under what conditions it should change.

oldnslo · Dec 2, 2020

Mytc30
Silly question but is it possible the steering cylinder has failed? If you jack the front tires off the ground does it turn?

Can you manually push on the tires and turn?

Again not familiar with Simplicity but other brands do have cylinder failures.

mytc30 · Dec 4, 2020

oldnslo

I finally received a response from a tech at Tuff Torq. He explained that the charge pump in the transmission was responsible for the flow and pressure to operate the steering torque generator and the cylinder that lifts the deck. He suggested that I replace the pump and that would solve my down stream problems. I'm going to give that a try.