Lull 6K Service Manual User Manual
Page 192
Supply, Pressure, and Return Hydraulics
5-48
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K
Control Valve Operation
Fig. 5-31: Multi-Spool Control Valve Components
Each hydraulic circuit is controlled by a separate valve section (Fig. 5-31).
The valve sections are 4-way, 3-position with an open center. The 4-way,
3-position spool design allows for control of double-acting cylinders and
reversible motors, and is normally centered (closed or neutral position). An
open center permits flow through the section when the spool is centered.
The power-beyond sleeve (high pressure carryover) in the right cover
housing allows the flow from the open centers to be used by other
components downstream.
Each valve section is equipped with two load check assemblies, with the
exception of the carriage tilt section, which is equipped with two
combination relief and anti-cavitation check assemblies (CRA).
K
104
7
Power-Beyond
Sleeve
CRA Assembly
CRA Assembly
Valve Sections
Main Relief
Outlet
(Return to Tank)
Inlet
(From Pump #2)
Work Ports
Positioner Assembly
Bonnet Assembly
Load Check
Assembly