drift on hydraulic motor circuit

quietrangr · Oct 18, 2015

I put new valves on my Barko 40 log loader, but I still have serious drift on the swing. The loader has two swing motors, and I noticed on one of them is a rectangular piece about 5 X 7 X 1 inch thick where the two hoses come in. It has plugs at two corners and another one about midway on the top. It says Eaton, and 2000, and some other numbers that are probably model and serial numbers, but they're hard to read. I'm not sure what that thing is, but could there be a problem in there with internal leakage, causing drift? Is that thing maybe some kind of cushion valve? Or might the I have a problem with the motors causing the drift?

oldnslo · Oct 19, 2015

Eaton 2000 is a low speed high torque motor series. Yes these can leak or drift and there could also be some form of cushion valve installed in your system. Without knowing your circuit or system I am only guessing at what the problem could be.

CJONE · Oct 19, 2015

Or it could be a brake. Hydraulic motors will drift especially if they have wear. I built a hydraulic system for a unload arm on a freighter. The customer did not want to spend the 2k on a brake. Well of course the arm would drift, so it cost them 5k to install it after the fact. So I would guess on a log loader it could possibly be a brake. Take a picture and post it. CJ

quietrangr · Oct 20, 2015

OK, thanks guys. I'll try to get a picture of it today.

quietrangr · Oct 21, 2015

OK, here are the pictures, I hope. Also, as to symptoms, the loader drifts "downhill," and when I go back "uphill," it struggles. I can increase the engine speed to get it uphill, but it still struggles. Any ideas?

CJONE · Oct 21, 2015

Well, I don't see a brake. 2 wonderful pictures of the backside of the motors. A pic of the block and the bottom of the motor where the line goes in. The block on the ports of the motor could be a lock valve or a cushion valve like oldnslo stated. You need to get a pressure gauge and see if you are getting full pressure to the motors. The cushion valve [if there] could be bypassing or your motors could be worn out. A relief could be washed out, spring broke, something in it. It can be a bunch of different things. This is when you find out if your hydraulics guy is worth a darn. Anybody can throw parts at it but a good tech can find out what is bad and fix it. CJ

quietrangr · Oct 23, 2015

Thanks, Cjone, I'll try a pressure gauge when I get some time. Those motors are probably about 40 years old, so I fear the worst. About 900 each to replace.

CJONE · Oct 26, 2015

Sounds about right for the motors. BUT I would stick ball valves in different parts of the circuit to isolate the problem before doing anything. The motors can also have the geroller section changed for a decent price if that is all that is wrong with them. CJ