Hydrostatic Transmission help

[fireman649]

Yea, I'm very confused to say the least. I'm pretty sure this tractor sat for a while without any use. After reading the manual last night, I think if come to somewhat of a conclusion. I really need to read the pressures, but don't have a gauge yet, so it may go to kubota for diagnostics. I think that there may be a check valve/relief valve stuck or broken, so I'm going to take them out today if it stops raining any time soon, and check them out. I'll post if I find anything more out. Also, both strainers have already been replaced with new ones. Thanks for everyones help. No gear noise while rolling the machine

 

[fireman649]

Alright, I don't know if this will help or not. I checked the relief/check valves, both look ok. I was reading the service manual, and saw thta there is 3 drain spots for the trans fluid. I only drained out of the bottom of the trans case. So I drained the fluid again, out of all 3 spots, fluid was milky color, I recleaned the screens again, and refilled. Let it sit for about 5 mins at medium speed, then tried it. I put it in high gear, and it took right off, worked good in forward and reverse. Climbed a hill(slope, I do live in Florida), no problem, tried in 4wd, no problem, crawled right up. So I went over to the side lot, and put the bucket down against the ground, and tried to juste barely scrape the top surface(grass, weeds), it was going good, then all the sudden it stopped again, now it doesn't work good in high gear again and is weak in low, I don't get it. It acts like when you put the bucket down against the ground and try to lift the tractor, and when it gets to it's max point, it stops(pops). Maybe this might help someone help me, I don't know.I'll be calling kubota tommorrow to get an appt.

 

[kubmech]

You can't always tell if you have a bad relief valve just by looking at it, however, while not impossible, it's usually very unlikely to have two relief valves go bad at the same time. One is for fwd and one is for reverse. If the problem is the same in both directions it's "usually" not a bad relief. If the problem only shows up in one direction. swap the reliefs, if the problem now appears in the other direction you have your answer. There also should be a relief for the charge pump. Some Kubotas used the hyd pump for charge oil but I'm pretty sure yours has the charge pump in the HST. From what I can tell from the posts, your problem is both in fwd and reverse. You mentioned you changed the fluid initially, was it milky then? There's usually two reasons for that color, water or air. If you let a sample sit for a while does it clear up to look like normal fluid? If it does then it's air and you have to find why your system is making excessive air. Your problem sounds like a suction or charge pump problem. You have new suction screens, is there any type of blockage or kink in the suction line going to the HST, if you could tap in and watch/check charge pressure this would give you a good idea of what's going on. Reach up and see if there is any excessive play in the driveshaft going in to the HST, this is where the charge pump is. Check for any suction leaks in both the hyd and hst system, this is usually what makes air in a hyd system. A cavitating hyd pump will also make air but "most" times you can hear that, or will notice jerky hyd funtions. If you have'nt seen any gold colored metal shavings it may mean the HST is still o.k. or that evidence was lost, being that you bought it with a problem, you don't know, but if the problem is in the HST itself, those shavings will show up again fast.

 

[MossRoad]

<font color="blue">I went out and check the clutch free play, which there was to much, so I adjusted it. Also today, I tried it again in high gear and this time it moved, but still not good, and in low gear, it was able to climb a hill better, but only a couple times then it stopped working again. I'm real confused. I did put a vise grip on driveshaft, started the machine and slowly let the clutch out, the motor stalled out, so I guessing my clutch is ok. </font>

If this is a hydrostatic transmission, why is there so much talk about a clutch??? /forums/images/graemlins/confused.gif Am I missing something??? /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif

 

[NIXON]

Mossroad . Generally speaking , Kubota's (HST ) have a clutch.
You aren't missing anything /forums/images/graemlins/smile.gif John

 

[fireman649]

Yes it has a clutch so you can disengage the live pto.
By the way, the tractor went to the shop yesterday, had to drive 50 miles to the shop because the one that's 15 miles away, sadi it would take 1 1/2 to 2 weeks just to look at it. The shop I brought it to said 2 days. I'll post what they find and the damage$$$$$

 

[fireman649]

Alright, got the tractor back the other day, I didn't know this little tractor had this much power. The hydro pump assmebly was shot, it wasn't putting out anywhere close to the pressure it should have. While they were there, they also changed the clutch, it was getting low, and mine as do it while it's split. $2,600 later, it works great. Thanks to everyone that posted some information.

Steve

 

[KiotiJohn]

</font><font color="blue" class="small">( Alright, got the tractor back the other day, I didn't know this little tractor had this much power. )</font>
Well, it did take a while to get it fixed.
You should be able to go for a long time now and really get to use it. Couldn't have bought another good tractor for the repair price either, but it sure was a shot.
Thanks for posting the results, and good tractoring to you. John