TM 9-2320-272-10
1-21.
HYDRAULIC SYSTEM OPERATION (Contd)
(3) Major components for extending and retracting the boom for the CROWD action are:
G
ROLLERS - Guides inner boom assembly and permits smooth extension and retraction of boom.
H
INNER BOOM ASSEMBLY - Extends when crowd control lever is pushed forward and retracts when control lever
is pulled back.
I
CROWD CYLINDER - A hydraulically-driven piston that extends outward when crowd control lever is pushed
forward to EXTEND position. Piston is hydraulically driven back into the cylinder when crowd control lever is
pulled back to RETRACT position. This cylinder is contained in the inner boom assembly.
J
CROWD CONTROL LEVER - Manual control attached to the control valve that determines oil flow for extending
and retracting the crane boom. Lever is pushed forward to extend the boom and pulled back to retract the boom.
K
CROWD CONTROL VALVE - Two-way hydraulic valve located directly below crowd control lever. Valve directs
hydraulic oil from the hydraulic pump to the crowd cylinder to extend and retract inner boom assembly.
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