963G hydraulic chatter

[pconnelly]

If anyone can make suggestions, I am eager to hear them We have a Bobcat 963G with 1640 hours. Moving a lot of snow this winter, but when I lower - not raise - the arms of the loader at a regular working rate, not fast, not slow, I get a really bone-shaking chatter. I have to let go of the joysticks and just stop whatever I'm doing. I have changed two hydraulic filters plus the big belt driving the big hydraulic pump plus the breather cap on the hydraulic tank. Suggestions so far include checking the joysticks, more grease on the arms, check to see if the arms are aligned properly. I'll take any ideas you have, thanks.

 

[Tazza]

That sounds like a charge pressure issue, but i would have thought lowering the arms would have increaded the pressure. When the steering levers shake violently its usually when you have low charge pressure and you are trying to move the machine. The pistons that run on the swash plates lift off and smash into it, giving the shaking feeling. The swash plates are connected to the steering levers, that's why you can feel it through the sticks.
I have had this on my 743, when i would dump dirt and lower the arms rapidly the charge pressure light would flicker and if i tried to move while doing this, you could feel the pump bite at the sticks.
I assume it does not do this if you are stationary and let the arms fall?