2015 RTV1100 New HST, no pressure from Main pump

[b.e.thesolution]

Hello all,

I've been searching, studying and reading every post I can find that has to do with RTVs not moving, and I think I've ran out of possible new information, so I'm just going to throw this out there.

I'm a service manager for a repair shop, and the owner has had this RTV sitting in the shop since I started last year. It stopped moving one day, and a previous employee did the disassemble and diag, and determined a new HST was needed. This was ordered, that employee abruptly left, and it had sat ever since until last week, due to the volume of external work the shop had. Now that I've got some time to put a guy on our own equipment, he's been piecing everything back together. He got it all reassembled and fired up. It just won't do anything in gear. We have a WSM, and he has gone through and made sure all of the linkages are adjusted correctly, fluid levels are good, etc. He has checked the operating pressures for the charge pump and the main pump. The charge pump is about 113psi IIRC, but there was zero movement on the needle for the main pump, not even able to bump off 0psi. As far as we can tell, everything is aligned and set right. Just don't know why the charge pump is where it needs to be, and the main pump has nothing. We're at the point where we're worried we're overlooking something obvious, and both pulling our hair out.

Brand new assembly.
Brand new Kubota brand filters
New Kubota hydraulic oil
No visible leaks

We did pull the pump housing back off to check everything inside. We have checked the high pressure relief poppet valve. It is not stuck in the 'relief' position.
I'm wondering if the servo adjustment screw is correct. Because it almost seems to me like even though the hst/accelerator linkage is set right, it's not opening up to allow pressure to the main pump, in turn, not driving the gearbox. All the gearbox gears move and with the axles up, spinning the axles in gear spins the main input shaft on the gearbox, which the main pump shaft drives.



I'll gladly give any more info/pics to anyone who can be of any help!

 

[aurthuritis]

well you have charge pressure that is good. are you sure you removed all of the little plastic plugs that keep dirt out of everything before you re assembled? the servo piston is actuated by charge pressure but the oil that does this has to go through the servo regulator assembly. but if the high pressure releif valve isn't working properly you should get flow but no high pressure. do you get flow through the high pressure test port? but no pressure?

 

[b.e.thesolution]

We are awaiting a new gasket/orings to arrive tomorrow so that he can reassemble the back end. I will make sure he checks on plug caps, and then we will get it filled up and running and check pressures again. If the high pressure port has zero pressure, we will open it up and see if we have flow.

Thank you.