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- เผยแพร่เมื่อ 16 ก.ย. 2024
- Does anyone have any suggestions as to where the hydraulic fluid could be bypassing and causing the squeal sound and loss of power? The sound comes from inside the hydrostatic motor.
The pressure should build to ~4000psi (beyond this gauge) before bypassing through a relief valve.
Mine is doing the same thing, did you figure it out? can you please let me know I am in the dark here please help!
Hello,
I haven't fixed the problem yet, however, I believe that I know what it is. A couple years ago I had separated the tractor, taken out the hydrostatic drive and opened it up. It looked fine to me, but a very nice guy (Bill) was reading my posts and commented that it did not look fine to him. He pointed out wear in the rotation group and said it was likely bypassing and causing the power loss and squealing. He suggested replacing and/or lapping the plates, pistons and piston faces. I'm not sure if I can post a link. If it works, the specific post is below. The forum is at tractorbynet and the thread is called "Tractor squeals under load after getting warm". A lot of people wrote a lot of information in the thread which was very kind.
www.tractorbynet.com/forums/hydraulics/173127-tractor-squeals-under-load-after-post3160751.html#post3160751
I am still only using the tractor in low gear, and it has some power before it starts squealing, but not a lot. If I'm on the road and accelerate slowly I can put it in medium, but other than that I have to keep it in low gear and work with a light foot to keep it from squealing and bypassing.
well I did the deed and dropped it off at the newholland dealer ship and they are going to split it and look it over and test the pump the hydrostat and the pressure relief valve and they said it would be one of them 3 if not 2 or all 3 so I will let you know what I find out. they said it could cost as little as 3-4 hundred it its just the pressure relief valve and as much as 4-5 thousand if needs a new hydro stat and pump so I guess here we go hope its the valve! thanks for your input. And I will let you know what I find out, Lee
Messicks.com has parts and breakdown diagrams for the tractor. If you do take the tractor apart and find where the wear is, you can see what new parts cost.
www.messicks.com/NH/61815.aspx
Looking at the HST Assembly, it looks like you could purchase a complete new rotating group for around $1500. It doesn't appear that you can purchase the pistons separately, but you can buy the valve pump plate for $250.
There are two hydrostatic drive's which have identical rotating groups. One is the pump and the second is the motor. You would have to determine which, if not both, is bypassing. The only difference is the valve pump plate.
On mine I actually drilled out the case so I could adjust the pressure relief valve without separating the tractor. You probably don't want to drill out the case as it can weaken the bell housing and the tractor could split when you're using it. Adjusting the pressure relief valve didn't do anything on mine.
They are a pretty good dealer if it will only cost a few hundred dollars for a new relief valve! According to the messicks breakdown, the relief valve (SBA322840510) costs $338.35, so with labor and parts, they're giving you a pretty good deal!
Hopefully they don't determine that the HST drive needs to be replaced. It looks like it costs $7595 (SBA322800033)!
I'm excited to hear what they find wrong! Hopefully they give you a detailed description of the problem and what they do to fix it! Thanks for taking one for the "team" and taking it in!