TM 9-2350-256-34
0003 00
Figure 10. Hoisting Boom Assembly--Installed View.
Raising The Boom
With the power control valve ON, the boom combination control valve in the FORWARD position and the boom safety valve
held in the STOW position, hydraulic pressure is directed to the back of the boom cylinder; thus causing the piston rod to extend,
raising the boom. Since no pressure is directed to the stayline cylinders, the crank arms are mechanically moved to their vertical
position by the stayline cables, actuating the boom limit valves. Once the boom is raised, release of the boom safety valve allows
the valve to return to its normal live position; thus restricting the boom to four feet of movement.
Lowering The Boom
With the power control valve ON, the boom combination control valve in the RETRACT/STOW position and the boom safety
valve held in the STOW position, hydraulic pressure is directed to the rod end of the boom cylinders and bled off the back; thus
causing the piston rod to retract and lower the boom. Pressure is also directed to the back end of the stayline cylinders causing
the crank arm to retract.
0003 00-11