Stability systems, System safety, Rear oscillation lock system – Lull 1044C-54 Series II Operation Manual User Manual
Page 40: Drive lockout override, Theory of normal operation

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STABILITY SYSTEMS
SYSTEM SAFETY
REAR OSCILLATION LOCK SYSTEM
The Rear Oscillation Lock System prevents the frame 
from rotating on the rear axle.
System operation:
•
With the boom below 20° elevation, the rear axle 
oscillates freely.
•
With the boom between 20° and 40° elevation:
Transmission is limited to first or second gear.
Rear axle is in “restricted oscillation” mode.
Frame tilt function still operates, but at a reduced 
speed when the boom elevation is above 20°.
•
With the boom above 40° elevation:
Transmission is locked out and rear axle oscillation 
is locked to the frame.
Frame tilt function still operates, but at a reduced 
speed.
•
With the boom above 40° elevation and the drive 
lockout override switch (page 14) pressed down:
Transmission is limited to first gear.
Rear axle is in “very restricted oscillation” mode.
•
Fully pressing the brake pedal down locks the rear 
axle at any boom angle.
DRIVE LOCKOUT OVERRIDE
Important:
Read and understand the following 
instructions BEFORE using the Drive 
Lockout Override System!
Theory of Normal Operation
This vehicle is equipped with a stabilization system that 
does several things to increase lateral (side-to-side) 
stability. 
When the boom is raised above 20° elevation:
•
The transmission is limited to first and second 
gears.
•
The rear oscillation lock cylinder is limited to slow 
(orificed) movement.
•
The speed of the frame tilt function is limited.
When the boom is raised above 40° elevation:
•
The rear axle stabilization cylinder is locked, 
preventing the frame from rotating on the rear axle.
•
The transmission is disengaged, stopping drive 
capabilities.
Diagram 1: Stability Triangle (Front axle locked and 
frame free to rotate on rear axle)
Diagram 2: Stability Rectangle (Front and rear 
axles locked, preventing frame from rotating)
When the boom angle is below 20° the vehicle operates 
with a freely oscillating rear axle to negotiate rough 
terrain. (See Diagram 1)
Do not disconnect or 
bypass proximity 
switches.
Bypassing proximity 
switches may result in 
death or serious 
personal injury !
W1056
W1052
W1053
