Fig. 7-12: Circuit Operation Above 40° - JLG Lull 1044C-54 II Series Service Manual

Boom Positioned Above 40°
31200079
BOOM ANGLE GREATER THAN 40 - OPEN
BOOM ANGLE LESS THAN 40 - CLOSED
S2
+12 VOLTS
FROM
FUSE PANEL
BOOM ANGLE GREATER THAN 20 - OPEN
BOOM ANGLE LESS THAN 20 - CLOSED
S1
Fig. 7-12: Circuit Operation Above 40°
(Ref. Fig. 7-12) The following describes the rear axle stabilizer circuit logic
when the boom is positioned above 40° elevation.
1. When the boom is above 40°, the proximity switch (S2) is not sensing
the boom. Therefore, the proximity switch (S1) opens and is also not
sensing the boom.
2. When the proximity switch (S2) is open, the Boom Over 40° relay is not
energized and power is directed to the coil of Relay K11 of the
transmission logic (see Transmission Section 8). When K11 is
energized, power is removed from all of the transmission solenoids,
which puts the transmission into Neutral and illuminates the
Transmission Disconnect Lamp in the instrument cluster.
3. Additionally, when the Boom Over 40° relay is not energized, Solenoid
Valves SV2 and SV3 are energized, which locks the rear stabilizer
cylinder. This prevents the frame from rotating on the rear axle and
illuminates the Rear Oscillation Lock lamp in the instrument cluster.
4. An additional effect of the Boom Over 40° relay not being energized is
theTransmission Disconnect Override Footswitch is enabled. Pressing
the Transmission Disconnect Override Footswitch, when the boom is
over 40°, reengages the transmission (first gear only) and allows very
slow, restricted oscillation of the frame on the rear axle. This allows
the machine to be moved. This is an extremely dangerous operation –
see the Operator's Manual.
5. The frame tilt is also restricted when the boom is over 40° because
Solenoid Valve (SV1) is energized.
86
30
BOOM
OVER 40°
NOT ENERGIZED
RELAY
85 87A 87
TO ENABLE FOOT
SWITCH AND TO
DISABLE
TRANSMISSION
86 30
BOOM
OVER 20°
NOT ENERGIZED
RELAY
85 87A
87
TO RESTRICT
TRANSMISSION
TO 1ST & 2ND
GEARS
Frame Tilt and Oscillation
3-WAY SOLENOID VALVE ON
REAR AXLE STABILIZER CONTROL
VALVE ON VALVE PLATE
(NOT ENERGIZED)
A
SV2
B
2-WAY SOLENOID VALVE ON
REAR AXLE STABILIZER VALVE
ON REAR STABILIZER CYLINDER
(NOT ENERGIZED)
A
SV3
B
SOLENOID VALVE ON
REAR AXLE STABILIZER
CONTROL VALVE
(NOT ENERGIZED)
A
SV1
B
MV0550
7-19