trying to diagnose a "well loved" machine we got. when stationary, with no input the controls the machine turns to the left and also the bucket lowers. both of these can be compensated on the controls. the bucket cylinder does have some nicks on the chrome, but dosent apear to be leaking. im fairly new to machines, we are basically buying some to do a project. im wondering where the control valves are located, do the sticks directly actuate them or are they remote / electronically actuated?
The most likely reason is that the hydraulic oil is contaminated or deteriorated, causing the valve core under the bullet head to get stuck and cause the automatic rotation failure.
See screenshot below of the main control valve with the “dig“ functions identified. The main control valve is pilot controlled by the left and right control sticks and the 2 foot pedals. I agree with @Universal Parts that you are likely fighting a hydraulic oil contamination issue. Pull the hydraulic return filter out of the hydraulic tank and see what you find.
thanks
thanks again dave, i will check the filter. its definitely got signs of neglect and sitting for a while, i intend to do a full service soon. do the joystick controls operate hydraulically too, and do they just actuate the main valve? not very familiar with hoe these work.
The joysticks control pilot oil pressure which strokes the individual function spools in the main control valve. I assume there a “forestry“ control valve mounted near the base of the boom. The forestry control valve is generally solenoid operated and is controlled by the electric button switches on the joystick handles.
yes that's how the shear operates with joystick switches. thanks for the info. where would you recommend getting filters? should i buy john deere?