Service Manual User guide
Table Of Contents
- 10709790_B_644B,6K,844C,8K,1044C,10K_Lull_Service_Mnl
- Quick Reference
- Revision Record
- Table Of Contents
- List Of Figures
- List Of Tables
- Section 1 Safety
- Section 2 Identification & Specifications
- Section 3 General Maintenance
- Section 4 Reference Diagrams
- Section 5 Supply, Pressure & Return Hydraulics
- Section 6 Boom & Transfer
- Section 7 Frame Tilt & Oscillation
- Section 8 Transmission
- Section 9 Brakes
- Section 10 Outriggers
Supply, Pressure, and Return Hydraulics
5-68
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K
Logic Valve
The Logic (LC) valve opens and closes dependent upon a pilot signal from
the Pilot Unloading (PU) valve.
Pilot Directional Valve
The Pilot Directional (PD) valve allows oil downstream to the pressure
reducing valve once the engine has started and back pressure meets or
exceeds 50 psi. When the engine is running, it allows flow to joysticks.
When engine shuts down, back pressure is lost and the PD assumes a
closed position.
Valve Specifications
Description Poppet type logic valve, vent to open, side
orifice
Maximum Operating Pressure 3500 psi
Maximum Leakage 5 Drops/minute
Pilot Flow @ 1000 psi 60 Cubic Inches/Minute
Bias Pressure 50 psi
Pilot Ratio 2:1
Service Seal Kit P33197
Valve Specifications
Description Three-way, two-position, directional valve;
external pilot to shift
Minimum Shift Pressure 50 psi @ 1 Pilot Port
Maximum Operating Pressure 3500 psi
Nominal Flow Capacity 2 gpm
Maximum Internal Leakage 5 Cubic Inches/Minute
Service Seal Kit P33196