Lull 6K Service Manual User Manual
Page 280
Boom and Transfer
6-30
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K
(Ref. Fig. 6-18) The following procedures describes disassembly for the
boom hydraulic control valve.
1. Follow preparation procedures as outlined in Section 3.
2. Install a 0–600 psi gauge into the brake diagnostic test port marked
“BRAKES” located behind the cab step.
3. While watching test gauge, press brake pedal numerous times until
pressure gauge reads 0 psi. Remove test gauge and cap diagnostic
port.
4. For models 644B, 844C, and 1044C, remove roll-back hose tray.
5. Thoroughly clean boom hydraulic control valve (Item 9).
6. Tag and
slowly loosen the two upper hydraulic hose swivel elbows
(Item 1) from the long connectors. Bleed any remaining oil into a
suitable container.
7. Tag and
slowly loosen the two lower hydraulic hose swivel elbows
(Item 2) from the short connectors. Bleed any remaining oil into a
suitable container.
8. Loosen the hose clamp (Item 7) securing the hydraulic return hose
(Item 6) to the elbow on the boom control valve. Disconnect the
hydraulic return hose.
9. Tag and
slowly loosen both ends of the hydraulic tube (Item 10) Bleed
any remaining oil into a suitable container. Disconnect the tube from
both connectors — the one that is attached to the boom control valve
and the one on the hydraulic control manifold block (Item 11). Remove
the hydraulic tube.
10. Tag and
slowly loosen the four (4) hydraulic hoses (Item 8) connected
to the elbows on each end of the boom control valve. Disconnect
hoses and bleed any remaining oil into a suitable container. Cap all
hoses and fittings.
Note: Models 644B and 6K with naturally aspirated engines have a pump
unloader assembly that uses one (1) elbow and three (3) tees instead of
four elbows. For these models, it will be necessary to disconnect seven (7)
hydraulic hoses.
11. Remove the four (4) each capscrews (Item 3) and lockwashers(Item 4)
securing the boom control valve to the valve plate (Item 12).
12. Remove the boom hydraulic control valve to a suitable area for further
disassembly and overhauling.