Section II. EQUIPMENT DESCRIPTION AND DATA

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FIGURE 1-1. Bow Ramp Assembly

TM-55-1905-223-24-10 Bow Ramp Assembly for Landing Craft Utility (LCU) NSN 1905-01-154- 1191 Manual

Table 1-1. Bow Ramp Winch Equipment Data

TM 55-1905-223-24-10

Section II. EQUIPMENT DESCRIPTION AND DATA

1-6. General Description . The LCU 2000 Class Watercraft bow ramp assembly consists of a winch assembly and a

hydraulic power pack assembly. The hydraulic power pack assembly has an electric motor, a drive coupling, a hydraulic

pump and reservoir tank, and associated pipes, valves, and gauges. This assembly provides hydraulic motive power to

the winch assembly via pipes and valves. The major components of the winch assembly are the emergency handcrank,

hydraulic motor, hydraulic brake, brake release pump, gear reducer, and drum. Reference FIGURE 1-1 for major

components of the bow ramp assembly.

1-7. Characteristics, Capabilities, and Features . A very broad view of the bow ramp assembly is as follows:

Characteristics

(1) Controls the raising or lowering of bow ramp.

(2) Controlled from pilot house, forecastle deck and at th e winch.

Capabilities and Features

(1) Can operate at any one of three locations.

(2) When operating from the pilot house control station, all other stations are inoperative.

1-8. Location and Description of Major Components . Both assemblies of the bow ramp assembly are separately

located on the forward starboard side of the main deck. The winch control valve manifold assembly is mounted on the

starboard bulkhead separately from the hydraulic power pack assembly.

a. Hydraulic Winch Assembly. When the RAISE or LOWER switch is activated, the hydraulic motor energizes the

gear reducer which rotates the winch drum. To lower the ramp, the drum unwinds two wire ropes that are connected to

one port and one starboard chain. The two chains are secured to the top, outer sides of the ramp. To raise the ramp, the

drum winds up the two wire ropes. Deactivating the RAISE and LOWER switch stops the winch. The hydraulic brake

and chain stoppers on the two ramp chains, maintain the position of the ramp. During winch operation, loss of electric

power or hydraulic fluid or pressure, activates the hydraulic brake to maintain the position of the ramp. An emergency

hand crank is used to raise or lower the ramp to the desired position. However, prior to using the emergency hand crank,

the hydraulic brake must be released. For this purpose, a brake release pump is part of the winch assembly. One of the

winch crew inserts a portable handle into a mounting hole on the brake release pump. The crew member rotates the

handle clockwise. This action restores hydraulic pressure and overrides the hydraulic brake. The emergency handcrank

is a ratchet type which prevents the load from overrunning the operating during manual operation. It will take

approximately 1,450 revolutions of the emergency handcrank to pay out or haul in 25 feet of the two lengths of active

wire rope.

b. Hydraulic Power Pack Assembly . Pressing the POWER ON push-button indicator switch starts the electric

motor. The electric motor is connected to the

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