4-204. COUNTERBALANCE VALVES
This task covers:
a. Replacement of Valve Cartridge
d. Follow-on Maintenance
b. Removal of Valve Block
c. Installation of Valve Block
Tool Kit, General Mechanics, Automotive
Ladder Fully Retracted and Elevated (see para 2-14 .)
(Appendix B, Section III, Item 1)
Main Engine Shutdown (see para 2-12 .)
APU Shutdown (see para 2-16 .)
Emergency hydraulic system deactivated
Grease, Automotive (Item 1, Appendix E
(see para 2-15 .)
Tags (Item 32, Appendix E)
Batteries Disconnected (see para 4-114 .)
Hydraulic Oil (Item 28, Appendix E)
Caps, Shipping and Sealing (Item 39, Appendix E)
O-ring (Figure 188, Appendix F)
a. Replacement of Valve Cartridge.
(1) With engine off, actuate three ladder control
levers in each direction to relieve pressure in
Do not loosen or tighten hex fitting on end of valve
cartridge. Do not attempt to adjust or change the
setting of the valve cartridge.
(2) Remove valve cartridge (1) by unscrewing large
hex nut (2) closest to valve block.
(3) Install new valve cartridge (1) and tighten large hex
nut (2) closest to valve block only.
b. Removal of Valve Block.
(1) Tag and disconnect two hydraulic hoses (3) and
two tubes (4). Cap hose and tube ends to prevent
entry of dirt.
(2) Remove two capscrews (5) and remove valve
block (6) from end of cylinder. Remove and discard
two O-rings (7) between valve block and cylinder.