TM 9-2320-272-24-1
1-24. HYDRAULIC SYSTEM OPERATION (Contd)
(3) Major components for extending and retracting the boom for the CROWD action are:
Key Item and Function
7 ROLLERS - Guide inner boom assembly and permit smooth extension and retraction of boom.
8 INNER BOOM ASSEMBLY - Extends when crowd control lever is pushed forward and retracts
when control lever is pulled back.
9 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.
10 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.
11 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.
1-77
