Main Boom Lift End Of Stroke Dampening; Jib Lift End Of Stroke Dampening; Machine Safety Override (Msso) (Ce Only); Transport Position Sensing System - JLG 400S Service And Maintenance Manual

SECTION 4 - BOOM & PLATFORM

Main Boom Lift End of Stroke Dampening

When the lift cylinder is activated to lower or raise the main
boom, the UGM monitors the main boom angle through an
angle sensor. When the boom is approaching maximum angle
and is within 5° of end of stroke, the UGM will slow down the
travelling speed of the cylinder to provide end of stroke damp-
ening by controlling hydraulic valve flow rate of the lift cylin-
der. The damping rate can be adjusted by personal settings
through JLG hand analyzer.

Jib Lift End of Stroke Dampening

The Jib Lift cylinder is constructed in a way that causes the Jib
Lift cylinder oil flow to be restricted by an orifice while lower-
ing the jib near the end of stroke at minimum elevation. This
restriction reduces the speed of the function just before bot-
toming out the cylinder.

Machine Safety Override (MSSO) (CE Only)

The Machine Safety System Override allows the boom and jib
to be lowered in the event that a machine safety system is pre-
venting machine operation. This system uses an additional
button found on the Ground Panel to allow all boom functions
to function from the Ground Station with the engine running.
When MSSO is used, an event will be logged in the JLG Control
System and will require service access to clear.
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Transport Position Sensing System

The transport position sensing system is consisted of a boom
angle sensor (this sensor has built-in redundancy to meet
safety related regulations) mounted in the pivot end of the lift
cylinder, and two boom length proxy switches mounted near
the pivot end of the base boom. The system uses these three
sensor/switches combination to sense if the boom is in the
position associated with high speed travel. The control circuit
reads two redundant angular sensor signals from the boom
angle sensor.
Above transport angle is recognized when one angular sensor
signal from the boom angle sensor reads more than 5° greater
than horizontal (with respect to the turntable), and resets to
within transport position when both angular sensor signals
read less than 3° greater than horizontal (with respect to the
turntable).
Transport length is recognized when any one of the two
length switches reads more than 12 in. (30.5 cm) extension of
fly boom. During failures of either of the two length switches,
the system will sense a disagreement. Then it will assume the
boom is extended out past the limit. The position of the articu-
lated jib is not considered.
This system is used to control the following systems:
• Above Elevation (Above Horizontal) - Drive Speed Cutback
System
• Drive/Steer – Boom Function Interlock System – CE Only
• Oscillating Axle lock up System
• Lift cylinder end of stroke electrical damping stop
The transport position sensing system uses the following com-
ponents:
• Boom angle sensor
• Boom length sensors
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