bx1830 vibration loss of power

[Volfandt]

re. flow priority valve. It splits/prioritizes hydraulic flow between the implement control (FEL, 3ph etc.) circuits and the power steering circuit, it has nothing to do w/the HST other than shareing the same common hydraulic sump.
There are two hydraulic pumps on a BX. The HST's pump is integral to the HST and is only for operating the HST. The external hydraulic pump is what provides the hydraulic power to the implement & P/S circuits and it also provides precharge hydraulic power for the HST pump.

There was a poster that posted similar prblems with his BX1500 (or could have been 1800) HST awhile back. It whined louder, had reduced power on flat surfaces and would hardly climb a hill.
Ends up the problem was internal to the HST. IIRC the bearings on the swash plate were bad which allowed too much hydraulic pressure to bypass the plate/hydraulic motor.
I believe the dealer was able to narrow it down via pressure tests of the HST.
He had the HST rebuilt.
Not saying this could be your problem but you may want to get the HST pressure tested if all the easy checks/fixes have been done.
Good luck
Dave

 

[MattJ]

SPYDERLK, were you able to rebuild the HST? Mine does sound similar except I didn't have any power steering issues or lift issues. Both were very strong and the FEL only failed to lift when I buried it and the relief valve kicked in as expected.

For the flow priority I thought the flow does go to the power steering but also provides low pressure flow to the HST pump per my amatuer reading of the manual.

As for pressure testing I still need to find the fitting to check charge pressure per the troubleshooting flow diagram but I did have the fitting to check the High pressure relief circuit per the manual on the forward direction circuit. Up on jacks and with the peddle depressed it was a few hundred PSI. With the brake engaged, forward peddle depressed, and the tranny straining and chattering it was just barely 1000 psi. The relief is supposed to dump north of 1900 psi. Anybody know what the typical psi should be under load?? The manual only lists the relief pressure (not sure how you'ld test where it would trip) and 1000 psi and chattering seems low and starved.

Thanks again

 

[Volfandt]

SPYDERLK, how ironic, I didn't read your link and it ends up that you're HST repair was what I was refering too.

Matt, sounds like you have a WSM, if so it should indicate where the test points are and what you should be reading.
Good luck

 

[SPYDERLK]

SPYDERLK, were you able to rebuild the HST? Mine does sound similar except I didn't have any power steering issues or lift issues. Both were very strong and the FEL only failed to lift when I buried it and the relief valve kicked in as expected.

New HST. I kept the old one and may get a round tuit one day. My malady seemed to affect- and be affected by other hyd functions in the latter stages. It went from barely noticeable to barely movable in about 20 hrs of use. The chatter/kickback thru the pedal you mention is what makes me think yours has a similar problem. Hope its not.
larry

 

[MattJ]

One more question if you guys don't mind. I am trying to understand this system a bit more as an engineer (not hydraulic related if you didn't notice), and the question I have is looking at the circuit it comes out of the charge pump at high pressure for the implements etc, some of the stream gets split by the priority valve to help feed the HST pump, and by the time it gets to the HST and the charge relief valve its at low pressure again before its boosted by the HST pump. So what is reducing the pressure before it gets to the charge relief valve.

Sorry, I always have to tear things apart and figure them out. I hate operating something I don't understand.

 

[MattJ]

As an fyi it seems that the flow priority valve was the main problem. I am still going to watch the tractor carefully for a while but it seems in better shape. The details are on this link below.


http://www.tractorbynet.com/forums/kubota-owning-operating/207216-hyraulics-question.html

 

[MattJ]

I got down to the root cause and posted an update with pictures here

http://www.tractorbynet.com/forums/...16-hyraulics-question-2.html?highlight=bx1830

 

[MattJ]

As an fyi I brought this to closure with a new HST I installed plus I added a gauge to watch the HST charge pressure for future peace of mind.

new hst install - TractorByNet.com