Lull 944E-42 Service Manual - Manual (Page 238)

Stabil-TRAK™ System
10-26 944E-42
10.5.15 Hydraulic Circuit Operation - Locked Mode, Frame Sway Left
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 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, through the check valve with a
0.048" orifice (1), through the check valve (2) to the base
end of the frame sway cylinder (3).
Some of this oil is diverted to the pilot line of the check
valve (4) on the return side of the frame sway cylinder,
opening the valve.
Oil from the rod end of the frame sway cylinder flows,
through the check valve (4) opened by incoming pilot
pressure oil, through the check valve with a 0.041"
orifice (5), to the FTR port of the Stabil-TRAK™ manifold.
Oil entering at port FTR flows through solenoid valve 3 (6)
through check valve 2B (7), to the rod end of the stabilizer
cylinder (8). Some of this oil is diverted to the pilot line of
check valve 2A (9), opening the valve.
Oil from the base end of the stabilizer cylinder flows through
check valve 2A (9) and through a 0.030" orifice (10). This
orifice slows the movement of the frame sway. The oil
then flows through solenoid-operated valve 3 (6), through
port V, to the frame sway spool valve in the main control
valve. Oil flows through the 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 (11), 4B (12), 12A (13), and 12B (14).
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
DE
DE DE DE DE
200
PSI
MU4822
6
7
9
10
8
14
12
11
13
1
2
3
4
5