Lull 6K Service Manual - Manual (Page 545)

Frame Tilt and Oscillation
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K 7-43
Boom Elevation Proximity Switch
Description
Fig. 7-26: Boom Elevation Proximity Switch
(Ref. Fig. 7-26) The boom elevation proximity switch is located on the left
side of the transfer carriage/boom cradle. This normally open switch
closes when the boom is below 40° elevation. The switch is a component
of the rear oscillation lock system. See “Rear Oscillation Lock System” on
page 7-18.
Fig. 7-27: Boom Elevation Proximity Switch Operation
(Ref. Fig. 7-27) The switch operates by sending out a constant, high
frequency magnetic field a short distance from the oscillator end of the
switch. Eddy currents are produced in metal when the magnetic flux lines
pass through it. These eddy currents oppose the oscillations of the
magnetic flux lines and the oscillations stop. A sensor in the switch detects
if the oscillator is on or off and this gives the switch its on/off function.
Transfer Carriage/Boom Cradle
Proximity Switch
Boom
J
1109
Proximity Switch
Transfer Carriage/Boom Cradle Boom
J
1
108
Magnetic Flux
Lines
Oscillator