TM5-3810-305-10
General Theory of Operation
The LRT 110 Crane is a self-contained vehicle
featuring 7 1/2 ton maximum lifting capacity,
optional four-wheel drive, outriggers for added
stability during lifting operations and three
different steering modes: front wheel steering
for normal driving, crab steering for diagonal
moves and four-wheel steering for minimum-
radius turns.
Power originates from an in-line, four-cylinder,
diesel engine mounted at the rear of the vehicle.
The transmission is mounted directly on the
engine and is used to turn drive shafts and to
power the tandem hydraulic pump. One-half of
the tandem hydraulic pump supplies hydraulic
pressure to the winch, and the other half supplies
hydraulic pressure to actuate the boom telescope
cylinder, boom hoist cylinder, boom swing
motor, outrigger cylinders, axle lockout cylinders
and steering controls, and to provide hydraulic
assistance for the brake system.
The boom is a two-section telescope-type with a
rotating boom support. Two large-diameter,
double-acting hydraulic cylinders telescope and
hoist the boom assembly. The hydraulic swing
motor and worm gear rotate the upperstructure.
The cable and hook block assembly are operated
by the hydraulic winch. The hydraulic and
electrical systems on the upperstructure are con-
nected to the rest of the vehicle by the hydraulic
rotary manifold and electrical collector ring.
Transmission Theory of Operation
The transmission is capable of four-speed shift-
ing in both forward and reverse. Direction and
speed are selected through hydraulically actuated
multiple-disc clutches. The clutches are power
absorbing, allowing shifts under full engine
power in both forward and reverse. The clutches
are hydraulically controlled and spring released.
Hydraulic control makes the clutches self-
adjusting. Each clutch is made of friction plates
and polished-steel reaction plates.
The transmission receives power from the engine
through the torque converter. The torque con-
verter is fluid driven, creating a smooth and
shock-free drive. Fluid drive also eliminates
engine stalling and lugging when vehicle has a
heavy load. With light loads, the torque con-
verter is able to transmit engine power directly to
the transmission at most engine speeds with no
torque multiplication. This provides variable and
automatic speed ratios, reducing need for shifting
gears.
Axle Theory of Operation
The front and rear axles have remote breathers to
allow operation in up to 30 in. (762 mm) of
water. The rear axle has lockout cylinders to
provide increased stability during hoisting.
Steering for each axle is enhanced by dual-acting
hydraulic cylinders which are tied together by a
single tie rod which provides smooth, sharp,
synchronized turning with minimum alignment
and adjustment requirements. The service brakes
are shoe-type hydraulic units, and are part of the
axle. The front axle has a disc brake that can be
used either as a parking brake or as an emer-
gency brake. Each axle has its own differential.
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