Theory Of Operation And Circuit Logic - JLG Lull 1044C-54 II Series Service Manual

Frame Tilt and Oscillation

Theory of Operation and Circuit Logic

7-18
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. 7-11: Circuit Operation Below 40°
(Reference Fig. 7-11) Major components of the rear oscillation lock system
are:
1. Boom Over 20° Elevation Proximity Switch (S1)-senses when boom
position is above 20°.
2. Boom Over 40° Elevation Proximity Switch (S2)-senses when boom
position is above 40°.
3. Boom Over 20° Relay-receives signal from the Boom Over 20°
Elevation Proximity Switch (S1).
4. Boom Over 40° Relay-receives signal from the Boom Over 40°
Elevation Proximity Switch (S2).
5. Solenoid Valve (SV1)-controls frame tilt functions.
6. Solenoid Valve (SV2)-controls rear stabilizer cylinder along with
Solenoid Valve (SV3).
7. Solenoid Valve (SV3)-controls rear stabilizer cylinder along with
Solenoid Valve (SV2).
8. Service Brake Valve (not shown)-locks the rear stabilizer cylinder when
applied regardless of the status of SV2 and SV3.
3-WAY SOLENOID VALVE ON
REAR AXLE STABILIZER CONTROL
VALVE ON VALVE PLATE
86
30
BOOM
OVER 40°
2-WAY SOLENOID VALVE ON
RELAY
REAR AXLE STABILIZER VALVE
85 87A
87
ON REAR STABILIZER CYLINDER
TO ENABLE FOOT
SWITCH AND TO
DISABLE
TRANSMISSION
SOLENOID VALVE ON
REAR AXLE STABILIZER
CONTROL VALVE
86
30
BOOM
OVER 20°
RELAY
85 87A 87
TO RESTRICT
TRANSMISSION
TO 1ST & 2ND
GEARS
A
SV2
B
A
SV3
B
A
SV1
B
MV0540
31200079