Lull 6K Service Manual - Manual (Page 534)

Frame Tilt and Oscillation
7-32 Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K
The functions of these components depend upon the mode of the
oscillation lock system: LOCKED or UNLOCKED.
During LOCKED mode:
1. No electrical power is supplied to solenoid valve V1. Pilot pressure
from port PIL does not reach the pilot pistons at check valves 3.1 and
3.2.
2. Check valves 3.1 and 3.2 keep hydraulic fluid trapped in the cylinder,
locking the cylinder and preventing the frame from rotating on the rear
axle.
3. System pressure from port SYS is reduced to 150 psi at the pressure
reducing valve. This fluid flows through an orifice and is then routed
back to tank through port T.
During UNLOCKED mode:
1. Electrical power is supplied to solenoid valve V1. and pressure from
port PIL is directed to each pilot piston. The pistons force open check
valves 3.1 and 3.2. Fluid may then enter and escape the rear
oscillation lock cylinder, permitting the frame to rotate on the rear axle.
2. System pressure from port SYS is reduced to 150 psi at the pressure
reducing valve. This fluid is available to the cylinder. Fluid from the
cylinder, as well as excess from port SYS, is routed through an orifice
and back to tank through port T.