Lull 6K Service Manual - Manual (Page 211)

Supply, Pressure, and Return Hydraulics
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K 5-67
Control Valve Functions
The following is a description of the seven control valves in the control
manifold assembly and their function.
Compensator Valve
The Compensator (CS) valve is a load sensing bypass type with priority
relief. It allows hydraulic fluid to flow to steering on demand. It limits
pressure in the steering circuit to 2200 psi. Pressure can be checked at the
Steering Pressure Gauge (PSG) port. A pressure reading can be taken
from the steering diagnostic port (see Fig. 5-58 on page 5-90). When not
steering, all flow goes out the Excess Flow (EF) port.
The CS valve will distribute priority flow to the steer orbitrol using a signal
sent from the load sense port on the steer orbitrol. There is a built-in
adjustment relief to keep steer pressure at approximately 2250 psi. Flow
that is not used for steering is available downstream for boom functions.
Check Valve
When charging of accumulator or pressurization of Excess Flow (EF) port,
the Check Valve (CV) allows flow to charge accumulator. The CV flows in
one direction only — towards Accumulator (AC) port.
Valve Specifications
Description Load sensing bypass type with priority relief
Priority Relief Setting 2250 ± 50 psi @ 1 gpm
Maximum Operating Pressure 3000 psi
Nominal Flow Capacity 40 gpm (Inlet)
Maximum Control Flow 20 gpm
Bias Pressure 150 psi
Load Sense Signal Static
Service Seal Kit P33199
Valve Specifications
Description Poppet type check valve
Crack Pressure 5 ± 1 psi
Maximum Operating Pressure 3500 psi
Nominal Flow Capacity 6 gpm
Maximum Internal Leakage 20 gpm
Bias Pressure 5 Drops/Minute
Service Seal Kit P33195