2014 RTV 900 EU complete loss of drive

[amel741]

I have read through all 22 pages of the all thread “kubota-rtv-900 transmission problems” which has been very informative.

The machine came to me not moving at all and the driver had said it had got stuck in gear and they had removed the selector and corrected this. I am not sure if this mistaken.

I am fairly sure the problem lies in the HST as the input shaft it connected to the engine, as the auxiliary hydraulics still work. On the output side I can see the shafts in the gearbox turn when the wheel is turned when looking into the selector.

The linkage is all working and the shaft on the servo control rotates as it should. To me it seems as if the piston is not moving the swash plate and I guess the first think to check is the charge pressure. The fault is absolutely complete, no attempt to rotate the wheel even when jacked up.

I have pressure gauges and was attempting to check the charge pressure but I have rounded the allen socket on the ¼ BSPP plug which I think is the correct one, the middle of 3 on the RHS of the Port Block cover.

I have referred to a WSM addendum for a new transmission issued in 2006 and although very good on the operation and looks as if the transmission has not changed much, it has no guidance on dismantling the HST.

-So can anyone point me in the direction of a better manual available in UK?
- Dvaepat4 referred to a local trader who could supply parts in Scotland, I am in Cumbria so would be good to know the trader, that might be the source of the correct WSM.

- Any ideas of what might have happened?

- Is there more than one place the charge pressure can be measured and was I on the only correct plug that I cannot get out now, unless I dismantle?

Look forward to hearing form anyone who may be able to point me in the right direction.

 

[bczoom]

Welcome to the forum. Wish it was under better circumstances.
I am NOT a tranny guy. The gurus should pop into this thread soon.
Again, I'm not any good with transmissions but your condition sounds like something I've seen on the forum in the past. Could it be related to the shift forks?

Here's a thread. There may be others. Search for shift forks or just forks.

Stuck in reverse

We had a guest driving our RTV900 today and he got the thing stuck in gear. Not only that but it was crosswise ( he was doing a back and fill U-turn) in a country lane that was lined with trees and thick brush so we couldn't just back it around. On top of that we were waiting for an out of state...

www.nettractortalk.com

 

[amel741]

Welcome to the forum. Wish it was under better circumstances.
I am NOT a tranny guy. The gurus should pop into this thread soon.
Again, I'm not any good with transmissions but your condition sounds like something I've seen on the forum in the past. Could it be related to the shift forks?

Here's a thread. There may be others. Search for shift forks or just forks.

Stuck in reverse

We had a guest driving our RTV900 today and he got the thing stuck in gear. Not only that but it was crosswise ( he was doing a back and fill U-turn) in a country lane that was lined with trees and thick brush so we couldn't just back it around. On top of that we were waiting for an out of state...

www.nettractortalk.com

Thanks for your quick response. Before I looked at it the Lads had taken the cover off and correctly inserted the selector rod in correctly. I subsequently check this and eventually ran the machine with the cover off and a wheel off the ground. When the pedal is pressed and it is in a gear, no shaft turns. When the wheel is turned in neutral one shaft turns and when in gear both shafts you can see turn and there is increased resistance. So to me it seems the gearbox side is OK, certainly operation of the selector slides are working. However it would seem strange to have unrelated faults at the same time. Could it be the piston/servo has been sticking causing difficult gear change which did cause the selector fork to be forced out, and now it has stuck or failed in the no flow position?

 

[bordercollie]

Is the HLM shifter snug or is it floppy ? Just trying to eliminate areas. I once had to take all the areas loose under the "hood" bonnet because they had become very stiff from having no grease , just crud .Sanded with a piece of sand paper and then greased, and then it shifted much easier. I know that's not your problem but thought I'd add that information while you were doing the once over on it. I was hoping your problem would be solved by doing the adjustment video in Zoom's link above , but sounds like it was already done. Best of luck to you. If I think of anything else, I check back in. My brain is tired out today as we've been building fence and just came in from giving a new calf a dose of colostrum ( 9: 30 pm ) and then moving them away from a pond. If all else fails take a look at that video in the link just in case something is out of order. Usually the fork pops out , when someone forces it by a hard shift.

 

[amel741]

Is the HLM shifter snug or is it floppy ? Just trying to eliminate areas. I once had to take all the areas loose under the "hood" bonnet because they had become very stiff from having no grease , just crud .Sanded with a piece of sand paper and then greased, and then it shifted much easier. I know that's not your problem but thought I'd add that information while you were doing the once over on it. I was hoping your problem would be solved by doing the adjustment video in Zoom's link above , but sounds like it was already done. Best of luck to you. If I think of anything else, I check back in. My brain is tired out today as we've been building fence and just came in from giving a new calf a dose of colostrum ( 9: 30 pm ) and then moving them away from a pond. If all else fails take a look at that video in the link just in case something is out of order. Usually the fork pops out , when someone forces it by a hard shift.

Thanks for the suggestion but unfortunately it is not a gear selection issue. I managed to get the middle plug on the RHS out (glued a 1/4 allen key in with thread locker) and checked the charge pressure and it is only 1.6 bar 25 PSI with the oil cold. The part manual I have says 75 to 104 PSI at 40 - 60 deg C. I doubt the cold oil accounts for the pressue being that low. I am going to look at the suction filter, it is ALCO SP929 so hoping it could be wrong but on the other hand there is no sign of the hose flattening. Do the charge relief valves ever cause a low pressure?

 

[amel741]

I took the suction filter off and could see bits of black plastic that had not made it through the holes into the filter. I then cut the filter open using a pipe cutter wheel and a lathe. See picture. The was a fair amount of swarf in the filter (not sure how concerning this is?)
The plastic looks as if it could have been a plastic disc with holes in it. Any suggestions what it could be?
I think I will strip it down now and see what I find.

 

[bczoom]

Are you using OEM filters?

 

[amel741]

This is the first time I have worked on this machine. It clearly had the wrong filter as when I look it up it is an oil filter used on many cars. The swash bearing has failed and then the whole cylinder block of the pump has smashed up. The bit of plastic I found in the filter were the support cage on the bearing.

I suspect the bearing failure is a result of cavitation and starvation of oil due to a limited oil supply from the charge pump due to excessive drop across an incorrect filter, but on second thoughts the oil should be returning from the motors.
Any thoughts on the failure mechanism?
So if any of you can advise on if it is possible to rebuild it in situ? I guess the input shaft need to come out and I have read about gaining access through the brake assembly hole.
Any help from anyone who has done this would be appreciated.

 

[Doc]

Man. Sorry.
We have some guys in the know in this stuff but sometimes answers do not come quick.

 

[amel741]

I thought I would update as I find a full story is useful to future readers like myself earlier this week. I removed the rear axle and the RHS brake assembly, then pulled the input shaft out through the back. I made a clamp out of a bit of poly propylene 12 mm sheet so I could attach a slide hammer to pull the shaft. (See picture) It was quite tight. I was then able to get at the charge pump and inspect. It does show signs of wear. However the rear wearing face of the pump is actually the transmission housing so not much can be done about that.

I think what has happened to this machine is that non OEM filters were fitted and they were mixed up suction for delivery. I am thinking that the consequent low pressure on the suction side of the charge pump may have scavenged oil from behind the main hydro pump leading to a lack of lubrication of the thrust bearing that failed. It has actually worn all the way through the race into the support cradle.

Has anyone ever seen this before? The motor components look OK so am just going to replace the pump assembly and fit the valve plate kit so parts about £400. I am expecting the charge pressure to be poor, but hoping it will be OK.

 

[aurthuritis]

the bits of black plastic are from the thrust bearing on the swash plate or the one behind the valve assy or. it isn't an uncommon failure.

 

[amel741]

Just to conclude this story the parts were more like £550 .+ VAT before oil and new filters. Thats just the pump cradle, bearing and pump assembly and cover set. All back together and running. I was unsure if the motor shaft could be pulled out in the same way as the pump shaft so did not fully inspect the fixed angle thrust bearing but it felt smooth enough. Hope this does not turn out to be big mistake! Charge pressure at 5 bar so bottom end of acceptable. I drove it for first time and was alarmed by the braking when you lift off the pedal. They have 4 of these and tell me they are all the same.
Another thing I had a problem with is when putting the brake assembly (RHS) back in I had the diff lock lever held in lock(to keep it out of the way) and it went tight and the drive also went tight as I tightened the assembly. I slacked off and did again with the lever back and all was OK.