JLG 800S Service Manual - Manual (Page 241)

SECTION 4 - BOOM & PLATFORM
3121139 – JLG Lift – 4-25
4.6 ELECTRONIC PLATFORM LEVELING
Description
Electronic platform leveling replaces the conventional
hydraulic method of platform leveling. The term "platform
leveling" does not refer to the system maintaining the plat-
form at level (or 0°) with respect to gravity, but instead
refers to the controls automatically maintaining the plat-
form within several degrees of a preset angle.
To control electronic platform leveling the platform is
equipped with a pair of tilt sensors, one primary and one
secondary, mounted to the non-rotating portion of the
platform rotator, level up and level down valves that are
used to provide proportional hydraulic flow for each direc-
tional function, and a control module that interprets the
sensor readings and actuates the leveling valves.
PRIMARY AND SECONDARY TILT SENSOR INTERAC-
TION
Two tilt sensors, mounted on each side of the platform
support, are used to measure the incline of the platform
with respect to gravity and control the automatic platform
angle control function. The right one (as viewed from
standing in the platform) is used as the primary sensor
and the left one as a secondary back up sensor.
If a fault occurs with the primary sensor, control will revert
to the secondary sensor. (This is discussed in more detail
in the error response section.)
Because of the mounting orientation of the tilt sensors, the
primary tilt sensor will output ascending voltage values
with increases in positive platform tilt angle. The backup
or secondary tilt sensor will output descending voltage
values with increases in positive platform angle.