JLG 1100S Service Manual - Manual (Page 207)

SECTION 4 - BOOM & PLATFORM
3121256 – JLG Lift – 4-59
PLATFORM VALVES
The platform specific valves are located in a manifold at
the platform.
There are individual proportional control valves that con-
trol each of the four platform functions; Platform Level,
Platform Rotate, Jib Lift, and Jib Swing (1100SJP Only).
There is also a Platform Dump Valve, located in the plat-
form valve manifold, which is used to hydraulically isolate
the control valves and to improve hydraulic response.
The Ground Module controls this valve to provide manual
platform leveling in the event that the Platform Module is
inoperable.
In ground mode, the platform dump valve is turned on
whenever any platform or jib valve output is turned on.
Whenever all platform and jib valves are turned off, the
platform dump valve is turned off.
In platform mode, the platform dump valve is turned on
whenever the footswitch is depressed.
Normal Operation
LEVELING
Two tilt sensors, mounted on either side of the platform
support, are used to measure the incline of the platform
with respect to gravity and control the automatic leveling
function, one is used as the primary sensor and one as a
secondary back up sensor.
The level system shall assume a new fixed set point
(fixed incline of the platform with respect to gravity) each
time the control system is powered up (cycling of the
EMS).
Automatic platform leveling only functions while operating
drive, telescope, lift or swing. It does not operate while
operating any other function (e.g. rotate, jib, or steer).
The proportional control for these valves varies. This is
dependant on the tilt variance from target as well as on the
impact coil temperature is having on the current to the
valves.
If a command from the Platform Level Up and Down tog-
gle switch on either the platform or the ground is received,
automatic platform leveling will cease and the appropriate
output will be commanded to turn on.
When the toggle switch is released, after ¼ second, the
current filtered value of tilt angle will be taken as the new
set point.
In order to obtain acceptable performance while perform-
ing all hydraulic functions, five sets of parameters are
used. These “zones” allow compensation for differences
in how the basket level changes when doing different
functions. These zones are as follows:
1. Lift up
2. Lift down
3. Other boom functions
4. Drive
5. Auxiliary
The other boom functions zone includes Swing, Tele-
scope, Jib swing (It is not necessary to level with jib lift,
since the mechanical linkage keeps the basket level).
These zones are prioritized when multiple functions are
active. The priorities are as follows.
1. Auxiliary power and any other function, zone = aux-
iliary power
2. Drive and any other function, zone = Drive
3. Lift up and any other function, zone = Lift up
4. Lift down and any other function, zone = Lift down
5. Other boom functions, zone = Other boom func-
tions
During the power-up procedure, function enable, in both
Platform and Ground Mode, is delayed during the 1.5 sec-
ond startup lamp test. During this 1.5 second startup
period, the basket level up valve will be energized at 100%
duty cycle for 0.5 second, and then the basket level down
valve energized at 100% duty cycle for 0.5 second. This
will help to keep the valves from sticking.
PLATFORM LEVEL MANUAL OVERRIDE
In addition to automatic leveling the operator is able to
manually adjust the platform level position by means of
the level override switches located at the platform and
ground control positions (similar to a Master/Slave
hydraulic system).
The level system assumes a new set point after a level
override switch is operated. In other words the operator
can chose a platform level incline other than level with
gravity and the system will maintain this set point during
automatic leveling.