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Service and Repair Manual
Boom Components
1-1
Boom Proximity Switch
The boom angle switch is a proximity switch. This
switch functions by sensing a change in the
electromagnetic field of the switch, due to the
introduction of metal into the field. A proximity
switch is, simply, a metal detector.
The switch generates an electromagnetic field at
the face of the switch. This field senses when steel
has been moved close to the switch as well as
when the steel has been moved away, which is
how the switch contacts open and close.
These switches are of a fail-safe design. Should
the switch or the switch wire circuit be faulty, the
machine will not function outside its designed
range of use.
The boom proximity switch is a component of the
drive circuit and the chassis sway circuit. Both the
drive and the chassis sway functions are disabled
when the boom is raised to 60° or higher.
18
How to Test a Proximity Switch
How to T est a Pr oximity Switc h
1
Remove the switch from the machine. Do not
disconnect the switch wire harness from the
machine.
2
Start the engine.
3
Move the switch away from any ferrous or
metallic object
Result: The light of the limit switch assembly
is not illuminated.
4
Move the switch close to any ferrous or
metallic object
Result: The light of the proximity switch
assembly turns on. The switch is functioning
correctly.
1 boom angle proximity switch (located on
engine side)
GTH
-844
™
September 2021
Part No. 1288232GT
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