Hi everyone. I've got so much information from this group that i just want to start by saying thank you. So my issue is that i have a large stump grinder Rayco T275 (35K lbs). It has a cat undercarriage and the final drives are Tenzieke??? Or Komatsu sorry I don't have that yet. The system is electronic over hydraulic. When i'm tracking in low speed my left track seems to bind and shutter but as soon as i shift into high everything clears up. I'm not sure if my swash plate is sticking or maybe it's electronic. Does anyone have a good starting point? I checked that charge pressure of the pump and it seems to be good st idle (400) but drops to 200 when operating.
Teijin Seki? I don't know anything about the Rayco but it sounds like: A) from the charge pressure reading, you have an internal bypass issue in either the motor or pump. and: B) since the swash plate angle becomes less when in high speed, the pistons stay further in the rotating cylinder bores which may be why it gets smoother in high speed. Just a guess. One thing you might try is measuring the motor case drain flow from that side, and lacking any specs from Rayco or a service manual, compare it with the other side? The low charge pressure, especially if motor case pressure is up, can actually cause the piston feet to lift off the swash plate.
Thanks lantraxco, I couldn't get back on to the web site!!! No wonder I'm having trouble with my final drive Ok so the manual says the charge pressure should be around 350 so I think the charge pressure is good. Is it bad if the charge pressure drops when I operate the track? Since it is electronic over hydraulic i thought i'd start on the joy stick. There are some lights that say whether the machine is sending a signal to the rheostat. Also is seems like it might be a brake issue over there but since all goes away when i switch to the high speed its got me a little stumped.
Speaking generically there should be a small drop in charge pressure when you operate the track, most of these systems have a "flushing valve" or "Hot oil shuttle valve" on the motor to release hot oil out through the motor case and allow cool oil from the charge pump into the loop. Usually only about 30 psi drop though. I don't know but at 200 psi you may be right on the edge of what's needed to keep the brake released.
It really seems like the brake comes on. The track doesn't start off stuck it becomes stuck after shuttering. So I'd go with the brake theory (assuming the pump was having trouble) if i could explain the high speed making the problem go away.
Which begs the question, did you check the charge pressure in high speed? Just a guess but it's really sounding to me like an issue with the rotating group in that travel motor, but that's really a shot in the dark. You can lose charge pressure anywhere in the loop.... Does this have Sauer-Danfoss series 90 pumps for the track drive circuits? Oh, and is the problem the same in forward and reverse?
That charge pressure is to low. Check vacuum gauges at top of right console should read under 5 if it's above check suction strains in hydraulic tank. Don't run machine with low charge pressure.
OK so after a week of other business I finally got back to this issue. I had a bad o-ring in the the hydraulic split for the track drive motors. (Only on the rt track side) The leak was culminating in the debris in the belly pan. (machine had not been cleaned yet) Repaired the leak which restored the pressure. I think this has taken care of the problem although I have not thoroughly tested it yet. Thanks for everyone thinking about it!