19 boom positioned above 40 – Lull 1044C-54 Series II Service Manual User Manual

Page 301

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Frame Tilt and Oscillation

31200079

7-19

Boom Positioned Above 40°

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.

ON REAR STABILIZER CYLINDER

REAR AXLE STABILIZER VALVE

2-WAY SOLENOID VALVE ON

(NOT ENERGIZED)

VALVE ON VALVE PLATE

REAR AXLE STABILIZER CONTROL

3-WAY SOLENOID VALVE ON

(NOT ENERGIZED)

SOLENOID VALVE ON

REAR AXLE STABILIZER

CONTROL VALVE

(NOT ENERGIZED)

MV0550

S2

BOOM ANGLE GREATER THAN 40 - OPEN

BOOM ANGLE LESS THAN 40 - CLOSED

BOOM ANGLE LESS THAN 20 - CLOSED

BOOM ANGLE GREATER THAN 20 - OPEN

S1

OVER 40°

BOOM

86

30

87

87A

85

B

A

SV1

OVER 20°

BOOM

86

30

87

87A

85

RELAY

RELAY

FROM

FUSE PANEL

+12 VOLTS

B

A

SV3

B

A

SV2

NOT ENERGIZED

NOT ENERGIZED

TO RESTRICT

TRANSMISSION

TO 1ST & 2ND

GEARS

TO ENABLE FOOT

SWITCH AND TO

DISABLE

TRANSMISSION

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