TM 5-3810-306-10
Section III - TECHNICAL PRINCIPLES OF OPERATION
INTRODUCTION
This section contains functional descriptions of the
operation of the crane’s major subsystems. Emphasis is
on how the operator’s controls interface with the rest of
the equipment.
HYDRAULIC SYSTEM
The hydraulic system provides adequate pressure and
volume for simultaneous operation of various crane
functions. It consists of two pumps, a reservoir, an oil
cooler and control valves.
The 165-gallon (624 liter) hydraulic reservoir is located
on the right side of the frame. A full flow return type 25-
micron filter and a sight gauge are installed in the
reservoir.
Pumps. The crane utilizes one three-section pump and
one two-section pump. Two pump drive assemblies
transmit power from the torque converter to the hydraulic
pumps. The three-section pump can be disengaged
from the engine for cold weather starting. This is
accomplished by a PUMP DISCONNECT lever located
on the pump. Pump engagement must be performed
with the engine shut down.
Directional Control Valves. The directional control valves
are four-way, three-position with either an open or closed
spool. The valves are grouped into valve banks
permitting simultaneous, independent control of crane
functions. The closed spool type valve contains an
integral load check valve to prevent back sliding of
components which support heavy loads. Each bank
contains a main relief valve. Certain crane functions are
additionally protected by a circuit relief valve.
Outriggers. The outriggers, part of the carrier frame, are
controlled and operated from the cab. They are full
hydraulic, double box type. When positioned they
provide a rigid four-point platform (fully extended and
set) capable of supporting the machine and its maximum
load capacity. Integral holding valves and floats are
provided. A sight level bubble indicator is located in the
vicinity of the outrigger control panel to assist the
operator in leveling the crane.
Turntable Assembly and Swing Mechanism. An anti-
friction roller bearing supports the superstructure on the
carrier frame, allowing 360 degrees of continuous
rotation
(swing)
in
either
direction.
Swing
is
accomplished by a hydraulically-driven motor driving a
gearbox which in turn drives the roller bearing. A
hydraulically actuated brake is used to stop swing and
hold the superstructure in the desired position. To
further secure the superstructure in a desired position, a
positive swing lock is also provided.
Boom Assembly. The boom assembly is a two-section,
trapezoidal design and extends from 34.4 to 60.4 feet
(10.52 to 18.46 meters). The boom is elevated by two
hydraulic cylinders with integral holding valves. Boom
elevation is from -4 degrees to +80 degrees.
Main Hoist. The main hoist provides power for all load
raising and lowering operations. Two hydraulic motors
drive the hoist drum by means of a planetary gear
reduction system. A metallic disc brake is also an
integral part of the hoist assembly, and operates
automatically when the control lever is in neutral.
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