HYDRAULIC MOTOR
The hydraulic motor (see fig. 4-43) is rotated by
pressurized fluid from the main hydraulic accumulator.
Various directional valves located on the retraction
engine manifold control speed and direction of rotation.
The hydraulic motor is coupled directly to the drum
assembly, causing the drum to rotate in the same
direction and speed as the motor.
DRUM ASSEMBLY
The drum is a grooved, cylindrical shaped as-
sembly which winds and unwinds the drive system
cables to either advance or retract the grab, based on
directional rotation of the hydraulic motor. The drum is
directly coupled to the hydraulic motor and is geared to
the screw and traverse carriage installation.
SCREW AND TRAVERSE CARRIAGE
INSTALLATION
The screw and traverse carriage installation (fig.
4-44) is mounted on the retraction engine frame above
the drum and is driven by a gear arrangement connected
to the drum. Rotation of the drum causes the traverse
carriage to slide along tracks mounted on the engine
frame. A sheave and adapter assembly, bolted to the
carriage body, acts as a guide for the advance and
retract cables as they wind and unwind on and off the
drum preventing the cables from becoming tangled. As
the carriage assembly moves along the length of the
retraction engine, cams mounted on top of the carriage
body come in contact with valves and switches
mounted within the retraction engine frame. The cams
actuate the advance and retract dump valves, advance
and retract cutoff limit switches, grab fully aft limit
4-36
TRACK
SHEAVE AND ADAPTER
ASSEMBLY
CAMS
SCREW
SHEAVE AND ADAPTER
ASSEMBLY
DRUM
GEARING
ABEf0445
Figure 4-44.—Screw and traverse carriage.
