SkyTrak 8042 Service Manual - Manual (Page 887)

Stabil-TRAK™ System and Boom Interlock System
10.46 Model 8042, 10042, 10054 Legacy Rev. 10/03
10.12.11 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).
10.12.12 Hydraulic Circuit Operation -
LOCKED MODE, Frame Sway Right
When the joystick control is placed in the frame sway
mode, cables activate the frame sway valve 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
Stabil-TRAK™ 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 Stabil-TRAK™ 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 (10), to the rod end of the
frame sway cylinder (11).
Oil from the base end of the frame sway cylinder flows
through a piloted-open check valve (12) 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). At this time
pilot pressure will cause the 100 psi relief valve (13) to
change position, allowing the excess oil to vent to the
reservoir.