6-14 4181383 First Edition
HYDRAULICS
6
Lower Circuit Schematic and Theory
of Operation
See Figure 6-9.
System Conditions:
• Engine running
• Traction control switch in the OFF position
• Raise/lower joystick in the LOWER position
NOTES
• See “Raise/Lower Circuit—Theory of Operation” on
page 4-30 for the electrical operation of this circuit.
• All cylinders operate the same way; left rear cylinder
shown.
Operating-pressure oil is supplied to port "P" of the lift
valve assembly by the steering circuit. (See “Steering
Circuit Schematic and Theory of Operation” on
page 6-10.) With the raise solenoid valve de-energized,
the operating-pressure oil flows through the valve, back
to the return filter and oil cooler, and then back to the
hydraulic oil tank.
Gravity pulls the cutting units down, pulling against the lift
cylinders. Oil from the rod end of the lift cylinders flows
through the 0.040 inch (1.016 mm) orifices in each
cylinder, and back into the lift valve through ports “C1”
through “C5” in parallel. The oil is applied against the
check valve, closing the valve. Oil then flows through the
energized lowering/proportional solenoid valve and back
to the return filter, oil cooler, and hydraulic tank.
NOTE
The lower proportional solenoid valve will remain
energized until the raise/lower joystick is moved to the
raised position.
A small amount of oil is also supplied to the piston end of
the cylinder to compensate for the change in volume as
the piston moves back.
To Next Page
Loading...
Need help?
General
