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
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K
5-77
Pump Unloader Valve
General
644B-37 (S/N 101–590, 592–666)
644B-42 (S/N 101–207)
6K -37 (S/N 101–317)
6K-42 (S/N 101–119)
With Naturally Aspirated Engines
Fig. 5-46: Pump Unloader Valve Location
(Ref. Fig. 5-46) The pump unloader valve is located on the valve plate near
the center of the machine. It is used on 644B and 6K models with naturally
aspirated engines and control manifold hydraulics.
0
80
60
40
20
-20
K1111