Service Manual User Manual

Hydraulic System
9-51
c. DOWN Position
With the right button depressed and held on the joystick,
and the joystick moved to the right, the attachment tilt
spool valve (Fig. 9– 39) in the directional control valve is
shifted so system pressure is directed to ports A-D,
through ports E-B to the rod end of the attachment tilt cyl-
inder and the slave cylinders. The extension of the slave
cylinders is fixed by the position of the boom so that only
the attachment tilt cylinder is retracted to tilt the attach-
ment downward. This system pressure also pilots open
the counterbalance valve. The open counterbalance
valve allows return oil from the base of the attachment tilt
cylinder to flow to ports C-F of the attachment tilt section
of the main control valve, to the return filter and ultimately
to the reservoir. If system pressure reaches 3500 ± 50
psi (241,5 ± 3,5 bar) the main relief will open and allow
hydraulic oil to return to the return filter and to the reser-
voir. In any case, if the return filter becomes restricted,
hydraulic oil will bypass the filter when the pressure
reaches 25 psi (1,7 bar).
Model 3606 • Origin 10/99