Drive System; Drive Orientation System - JLG H340AJ Service And Maintenance Manual

SECTION 3 - CHASSIS & TURNTABLE

3.5 DRIVE SYSTEM

The Drive system consists of 4 independently controlled asyn-
chronous AC motors, each connected to an electric brake and
drive hub. Each motor is equipped with a speed sensor that
relays RPM information to its own drive motor controller. The
operator can provide a Drive speed and direction command to
the control system via displacement of the Drive joystick. The
Universal Ground Module (UGM) interprets this joystick dis-
placement as a commanded system speed and computes the
allowed travel speed based on Drive Personalities and operat-
ing conditions (e.g., Elevation, Tilt, etc.). The UGM communi-
cates the speed command via the CAN Bus to the wheel motor
drive controllers that compute and coordinate the individual
wheel speeds.
The rear drive assemblies are mechanically mounted directly
inside a fixed axle. The front drive assemblies are mechanically
mounted to a spindle which is pinned to the axle and tie rods.
On the right hand side, a steering angle sensor sits atop the tie
rod and detects the position of the wheels. It sends the infor-
mation to the right front drive motor controller, which relays
the information to the UGM. The UGM then responds with
commands to each drive motor controller, which produces
smooth drive motion with good traction when the machine is
being turned.
There are two drive modes which are controlled by the posi-
tion of the boom. The chart below describes how the system
works in each drive mode.
3-8
Table 3-2. Drive System Mode Chart
Speed Select Mode
Boom Position
(Toggle switch on the Platform Console)
Max Speed
In Transport
Max Torque
Max Speed
Out of Transport
Max Torque

3.6 DRIVE ORIENTATION SYSTEM

The Drive Orientation System (DOS) is intended to indicate to
the operator conditions that could make the direction of
movement of the chassis different than the direction of move-
ment of the drive/steer control handle. The system indicates to
the operator the need to match the black and white direc-
tional arrows on the platform control panel to the arrows on
the chassis. The system uses a limit switch mounted on the
underside of the turntable, an indicator light and an override
switch on the platform display panel. The limit switch trips
when the turntable is swung +/- 42 degrees off center of the
normal driving position. This occurs roughly when the boom is
swung past a rear tire. When the turntable is in the normal
drive position with the boom between the rear tires, no indica-
tions or interlocks are made. When the machine is actively
driving when the turntable is swung past the switch point, the
system is ignored until drive/steer is released. When drive is
initiated with the boom swung past the switch point, the DOS
indicator will flash and the drive/steer functions will be dis-
abled. The operator must engage the DOS override switch to
enable drive/steer (High Speed drive will remain disabled).
When the DOS is enabled, the DOS indicator will be illumi-
nated continuously and a 3-second enable timer will be
started and will continue for 3 seconds after the end the last
drive/steer command. If the timer expires, the DOS override
switch must be re-engaged to enable drive/steer.
Approx.
Max Speed
MPH (kph)
3.1 (5)
1.5 (2.4)
0.6 (0.97)
0.6 (0.97)
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