Hydraulic Circuit Operation - Locked Mode, Frame Sway Left - JLG sky trak mmv Service Manual

Stabil-TRAK™ System
11.4.18 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
Note: Refer to Section 11.4.21, Electrical Schematic -
Locked Mode, for the electrical schematic for this circuit.
When the joystick control is placed in the frame sway
mode, the frame sway solenoid-operated valve in the pilot
select manifold is energized. As the joystick is moved to
the left, oil flows through the solenoid-operated valve in
the pilot select manifold, and then flows to the frame sway
spool valve in the frame sway section of the main control
valve.
This pilot pressure causes the spool valve to shift posi-
tion, allowing oil to flow through the valve to a spool valve,
allowing oil to flow through a check valve (1) to the base
end of the frame sway cylinder (2).
11.22
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 stabilizer
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 stabilizer 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 re-
turned 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.
Model MMV Rev. 12/04