| Tweet |
Custom Search
|
|
|
||
 TM 55-1905-242-14
0006 00
Pilothouse Gauge
A single gauge, mounted in the pilothouse console, monitors pressure in the bow ramp circuit. The pressure in the bilge
pump and crane circuits is unmonitored.
Ramp Control Valve
A three-position, four-way valve controls the bow ramp circuit. The valve is actuated by the bow ramp handle in the
pilothouse. When the valve is in the NEUTRAL position, oil from the hydraulic pump is routed directly back to the reservoir.
When the valve is in the RAMP UP position, oil from the hydraulic pump is directed to the hydraulically powered winch,
rotating it in the inhaul direction. When the valve is in the RAMP DOWN position, oil from the hydraulic pump is directed
to the hydraulically powered winch, to the winch brake, and to the ramp latch cylinders. In this configuration, the hydraulic
pressure extends (unlatches) the ramp latch cylinders, releases the winch brake, and rotates the winch in the outhaul
direction.
The ramp control valve has an internal relief valve to protect the circuit from damage caused by overpressurization. The
relief valve is set at 2100 lb/in (144.8 bar).
Counterbalance Valve
A counterbalance valve, located inline between the ramp control valve and the hydraulically powered winch, prevents the
winch from overspeeding or "freespooling" during ramp lowering operation.
Hand Pump
A hand pump is installed in the circuit to permit emergency lowering of the ramp. The hand pump provides hydraulic
pressure to release the ramp latch cylinders and the winch brake when both hydraulic pumps are inoperative or in use for
bilge pumping.
Hydraulically Powered Winch
A hydraulically powered winch handles the cable that raises and lowers the bow ramp. The hydraulically powered winch is
rotated in the inhaul and outhaul directions by a hydraulic motor. The hydraulically powered winch also contains a spring
applied, hydraulically released brake assembly that prevents the winch from freewheeling.
Ramp Latch Cylinders
Two ramp latch cylinders, one on each side of the bow ramp, latch the ramp in the closed position. The cylinders are opened
with hydraulic pressure and closed by internal spring pressure. Hydraulic pressure, required to move the cylinders to the
unlatched position, is supplied from the ramp control valve when it is moved into the RAMP DOWN position.
Hand Pump Valve
A hand pump valve, installed in the piping between the hand pump and the brake release line, isolates the hand pump from
the rest of the hydraulic circuit. The valve is closed during normal operation and open only when the hand pump is used to
lower the bow ramp.
Winch Brake Valve
The winch brake valve, installed in the winch brake release line, isolates the winch brake line from the rest of the hydraulic
circuit. The valve prevents hand pump pressure from backfeeding into the rest of the bow ramp circuit when the hand pump
is used to lower the bow ramp. The winch brake valve is open during normal operation and closed only when the hand pump
is used to lower the bow ramp.
0006 00-9
|
||
|
||
