RK55 HST slipping probelm

[5030]

Actuation takes pressure, maybe I should reword that to actuation pressure instead.

 

[oldnslo]

That's what I'm assuming as well. I've babied this thing since I bought it brand new.
Also, I've heard of starting on a hill in low range but not keeping it in low range for any incline. The engine doesn't bog when going up the hills when it's not slipping.
I spoke with the mechanic at RK and he feels there's a problem in the hydrostatic pump. I assumed a seal bypassing, picking up air since I have checked the fluid and it would have more air bubbles than it should have after an episode of jerking.

Air in oil is another clue. Again I do NOT know how RK built this HST but it would be of interest to see a parts break down. Most HST tractors the pump and motor are contained in common housing similar to a transaxle so there really are no seals to leak allowing air into the system. It is possible there is a leak some place acting like a venturi drawing air into the circuit from fluid passing across the leak point. Most common source of air is the pump inlet lines leaking or possibly something floating around in the tranny housing partially restricting a pump inlet. Bu again you should see this flow loss on other functions besides the HST unless this model has a stand alone charge pump. Then if that pump is drawing air or starving you would experience the problems described. Checkin charge pump pressure should show low pressure if this is the cause.

 

[oldnslo]

Actuation takes pressure, maybe I should reword that to actuation pressure instead.

If this model is not direct operated swash plate you are correct that low pilot pressure - typically charge pressure would cause the pump to not come on stroke producing oil.

 

[5030]

If this model is not direct operated swash plate you are correct that low pilot pressure - typically charge pressure would cause the pump to not come on stroke producing oil.

Last hydrostat I owned was 30 years ago, Kubota 5030 HSTC. I'm all hydraulic shuttle now. Much more efficient for what I do. Less complex too.

Like I said, something is fishy but I don't see a Rural King outlet store to be competent in fixing it.