JLG 1850SJ Service Manual - Manual (Page 46)

SECTION 3 - CHASSIS & TURNTABLE
3-4 – JLG Lift – 3121619
will be driven based on the information available from the
other sensors. This axle will not track perfectly and will
become farther out of position over time. When the wheel
becomes prohibitively out of position, the wheels can be
resynchronized by fully steering against the mechanical stops.
3.5 DRIVE/STEERING SPEED CONTROL
The Drive/Steering Speed Control system uses the steering
sensors from the steering control system to increase operator
control and comfort by reducing the effect of turning the
chassis on the resulting lateral platform speed. The system
proportionally varies the drive speed based on the predicted
turning radius of the chassis for both coordinated and conven-
tional two wheel steer modes. The tighter the turn the slower
the allowable drive speed. As crab steer does not steer on a
radius, full drive speed is maintained regardless of steer angle.
3.6 TRACTION CONTROL SYSTEM
The traction control system uses the steering sensors from the
steering control system to optimize the performance of the
drive system. This is especially important due to the disparity
of wheel speeds generated between the inside and outside
wheels of the extended axle chassis with large steering angle
capability. The steering sensors are used to predict the rolling
path and therefore the required wheel speed of each wheel as
the steering angles change and steering modes change. The
control system can then command the ideal flow from each of
the two drive pumps, one for the right side of the machine and
one for he left side. Two flow dividers, one for the right side,
front to back and one for the left side, front to back absorb the
variation in wheel speed, front to back.