Lull 6K Service Manual - Manual (Page 213)

Supply, Pressure, and Return Hydraulics
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K 5-69
Pilot Unloading Valve (PU)
The Pilot Unloading (PU) valve is one of three valves used to recharge the
accumulator. When pressure is below 1200 psi, the valve energizes,
closing off the logic valve, and fills the accumulator to 1600 psi. At 1600
psi, the PU valve opens the Logic (LC) valve allowing the 3 gpm to go to
the Excess Flow (EF) port.
Pressure Reducing Valve
The Pressure Reducing (PR) valve limits pressure to the Filter (F) port to
450 psi for the joystick controllers and park brake cylinder. The Pilot Gauge
(PG) port gives a reading in the joystick circuit. A reading can be taken
from the pilot diagnostic port (see Fig. 5-58 on page 5-90).
Priority Flow Control Valve
The Priority Flow (PF) control valve is a three-port flow regulator allowing
3 gpm for charging the accumulator circuit.
Valve Specifications
Description Internally adjustable pilot unloading valve
Unload Pressure Setting 1600 ± 50 psi
Maximum Operating Pressure 75% of Unload Setting
Reload Ratio 40 gpm (Inlet)
Maximum Operating Pressure 3000 psi
Nominal Flow Capacity 2 gpm
Service Seal Kit P33196
Valve Specifications
Description Pressure reducing/reviving valve, direct
acting, internally adjustable
Reduced Pressure Setting 450 ± 25 psi
Maximum Inlet Pressure 3000 psi
Nominal Flow Capacity 6 gpm
Service Seal Kit P33196
Valve Specifications
Description Fixed priority flow control
Control Flow 3 gpm ± 15%
Maximum Inlet Flow 30 gpm
Maximum Operating Pressure 3000 psi
Service Seal Kit P33198