Lull 944E-42 Service Manual - Manual (Page 798)

Stabil-TRAK™ System
10.40 Model 644E-42/944E-42 Rev. 6/04
10.8.11 Hydraulic Circuit Operation - Locked
Mode
a. Conditions:
• Boom angle is above 40°
• Park brake ON, or service brake ENGAGED, or travel
select lever in (N) NEUTRAL
b. Operation:
When the conditions are met, solenoids 4A, 4B, 12A and
12B are de-energized and solenoid 3 is energized. In the
LOCKED MODE, oil is prevented from flowing through
the Stabil-TRAK™ manifold due to check valves in
solenoid-operated valves 4A (1), 4B (2), 12A (3), and
12B (4).
10.8.12 Hydraulic Circuit Operation -
Locked Mode, Frame Sway Right
When the joystick control is placed in the frame sway
mode, pilot pressure activates the frame sway section in
the main control valve assembly. As the joystick is moved
to the right, the frame sway spool valve is shifted, allowing
oil to flow through the valve, to the Stabil-TRAK™
manifold, port V.
Oil entering the Stabil-TRAK™ manifold at port V flows
through solenoid cartridge valve 3 (5), through a .030"
orifice (6) and check valve 2A (7), to the base end of the
stabilizer cylinder (8). The orifice slows the movement of
the frame sway.
Some of this oil is diverted to the pilot line of check
valve 2B (9), opening the valve.
Rod end oil from the stabilizer cylinder flows through
check valve 2B (9), opened by pilot pressure in the
Stabil-TRAK™ manifold. The oil then flows through
cartridge valve 3 (5), out of the Stabil-TRAK™ manifold at
port FTR, through a check valve fitting with a .041"
orifice (11), through a check valve (12), to the rod end of
the frame sway cylinder (13).
Oil from the base end of the frame sway cylinder flows
through a piloted-open check valve (14), through the
check valve fitting with a .048" orifice (15) and back
through the frame sway spool valve in the frame sway
section of the main control valve, dumping the returned
oil to the reservoir.
Pressurized oil entering the Stabil-TRAK™ manifold at
port P is stopped at the four closed solenoid-operated
valves 4A (1), 4B (2), 12A (3) and 12B (4).
Suction
Return
Load Sense
Pressure
Pilot Pressure
HYDRAULIC
RESERVOIR
ACCUMULATOR
CHARGE/SECONDARY
FUNCTION VALVE
LS
DRAIN P1
LSG ACR
SW P
ACF EF CF PIL PB
PBG
PPG
SW
HYDRAULIC OIL
COOLER
FRAME SWAY
JOYSTICK
CHECK
VALVE
FITTING
CHECK
VALVE
FITTING
SOLENOID COIL
STATE
ENERGIZED
DE-ENERGIZED
E
DE
Ø .041
P
T
2 1
ATTACH
TILT
FRAME EXT/RET LFT/LWR
AU
X
TRANS
MAIN CONTROL
VALVE
INLET
OUTLET
PUMP
Ø .048
FRAME
SWAY
CYLINDER
FTR
FTB
STABILIZER
CYLINDER
.060 DIA.
FTR
P
T
V G3 G2
G1
4A 4B 12B
3
2B
2A
12A
.060 DIA.
.030 DIA.
100 PSI
STABIL-TRAK TM
MANIFOLD
E
DE DE DE DE
200
PSI
MU4811
1
3
8
2
7
9
5
4
11
12
13
14
15
6