Section II. EQUIPMENT DESCRIPTION AND DATA

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FIGURE 1-1. WAV-850 Gearbox.

TM-55-1905-223-24-2 Main Reduction Gear for Landing Craft Utility (LCU) NSN 1905-01-154-1191 Manual

Table 1-1. Gearbox Equipment Data

TM 55-1905-223-24-2

Section II. EQUIPMENT DESCRIPTION AND DATA

1-6. Description and Characteristics. The WAV-850 Model Marine Reverse Reduction Gearbox transmits torque

from the engine to the propeller shaft. The unit is capable of providing either forward or reverse rotation to the shaft.

Speed reduction is the same in both directions, 4.941:1. The LCU 2000 Class watercraft is equipped with two gearboxes,

one per engine, turning the propeller shafts in opposite (counter rotating) directions. Direction of rotation is shown on the

equipment nameplate and cannot be changed except by factory modification. Therefore, units cannot be replaced

without first making sure that the rotation of the new unit is the same as that of the unit to be removed.

1-7. Characteristics, Capabilities and Features. A very broad view of the reduction gear is as follows:

Characteristics

(1)

Three-piece housing design provides for ease of maintenance in the craft.

(2)

Self-lubricated by means of a shaft powered pump.

(3)

Operation delay tanks soften shifting action to reduce shock to propulsion system components.

Capabilities and Features

(1)

Uses the same lubricating oil as the engine.

(2)

Rugged construction assures minimum breakdown.

(3)

Lubricating oil drained by a sump pump common with the engine. Valve positioning permits draining

either the engine or gearbox.

1-8. Location and Description of Major Components. FIGURE 1-1 shows the location of the lubricating oil pump

(1), control valve (2), heat exchanger (3), input shaft (4), output shaft (5), and lubricating oil filter (6). Table 1-1 gives the

specification data for the gearbox.

a. Controls. The gearbox is controlled from the bridge by a single lever which also controls engine speed.

Center position is NEUTRAL or STOP with the engine at idle speed. Movement of the control lever forward from the

center or STOP position shifts the gearbox to the FORWARD or AHEAD mode. Engine speed increases proportionally

to the degree of movement away from the center position. To reverse the gearbox to ASTERN, the lever is moved

rearward until the desired speed is attained.

(1) The air-operated bridge controller moves a hydraulic actuator at the gearbox control valve, directing

operating oil pressure to effect the proper operating mode, i.e. STOP, AHEAD, or ASTERN.

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