SkyTrak 8042 Service Manual - Manual (Page 889)

Stabil-TRAK™ System and Boom Interlock System
10.48 Model 8042, 10042, 10054 Legacy Rev. 10/03
10.12.14 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,
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, through the check valve (1) to the base
end of the frame sway cylinder (2).
Some of this oil is diverted to the pilot line of the check
valve (3) 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 (3) opened by incoming pilot
pressure oil, to the FTR port of the Stabil-TRAK™
manifold.
Oil entering at port FTR flows through solenoid valve 3 (4)
through check valve 2B (5), to the rod end of the Stabil-
TRAK™ cylinder (6). Some of this oil is diverted to the
pilot line of check valve 2A (7), opening the valve.
Oil from the base end of the Stabil-TRAK™ cylinder flows
through check valve 2A (7) and through a .030" orifice (8).
This orifice slows the movement of the frame sway. The
oil then flows through solenoid-operated valve 3 (4),
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 (9), 4B (10), 12A (11), and 12B (12). 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.