TM 9-2350-256-34
0003 00
Figure 13. Hydraulic Subplate Assembly--Right-Front View.
Main and Hoist Control Valves
The main winch control valve (Figure 13) and hoist winch control valve (Figure 12) are manually operated, three-position,
open-center, directional control valves and are spring-loaded to the HOLD or centered position. When the valve is in the
spring-centered HOLD position, pilot pressure is directed through the valve to the tank return. Also, pressure is bled from the
winch combination control valve to the same tank return. Manually placing the valve in the PAYOUT, or LOWER position
directs the pilot pressure to the winch combination control valve and the brake cylinder and closes the port opening to the tank
return. Moving the valve to the INHAUL, or RAISE position blocks the pilot pressure to the control valve and bleeds the pilot
pressure from the winch combination control valve and brake cylinder, through the control valve, to the tank return.
Boom Combination Control Valve
The boom combination control valve (Figure 12) is a manually operated, three-position, closed-center, directional control valves
and are spring-loaded to the HOLD or centered position. This control valve also contains one-way check valves and maximum
pressure relief valves. When this control valve is in the spring-centered HOLD position, main pump pressure is blocked and
pilot pressure is directed to the tank return. Manually placing the valve in the FORWARD position cuts off pressure and directs
main pump pressure through a one-way check valve and a flow restriction to the boom-actuating cylinders. Pressure from the
opposite side of the cylinders is directed by the valve to the tank return. If maximum pressure is exceeded, the relief valve opens
and bleeds off pressure to the tank return. Placing the valve in the RETRACT/STOW position cuts off pilot pressure and directs
main pump pressure through a one-way check valve and a flow restriction to the boom-actuating cylinders and the stayline
cylinders. Pressure from the opposite end of the cylinders is ported through the valve to the tank return. The maximum pressure
relief valve opens if preset pressure is exceeded.
0003 00-14