Service Manual User Manual

Section 9
9-50
Figure 9– 39. Attachment tilt spool valve circuit.
a. Center Position
When the joystick is in the center or neutral position, the
attachment tilt spool valve (Fig. 9– 39) in the directional
control valve is positioned to prevent flow to any of the
working ports.
b. UP Position
With the right button depressed and held on the joystick,
and the joystick moved to the left, 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 B-F to the base end of the attachment tilt
cylinder and slave cylinders. The extension of the slave
cylinders is fixed by the position of the boom so that only
the attachment tilt cylinder is extended to tilt the attach-
ment upward.
If system pressure reaches 3500 ± 50 psi (241,5 ± 3,5
bar) the main relief will open, allowing hydraulic oil to flow
to the return filter and to the reservoir. If the return filter
becomes restricted, hydraulic oil will bypass the filter
when the pressure reaches 25 psi (1,7 bar).
Return oil from the rod side of the attachment tilt cylinder
is directed back to the attachment tilt section of the main
control valve through ports E-C of the spool valve, to the
return filter and to the reservoir. If the return filter
becomes restricted, hydraulic oil will bypass the filter
when the pressure reaches 25 psi (1,7 bar).
SHUTTLE IN
PILOT SELECT
MANIFOLD
PORT 7
LOAD SENSE
OUT
INLET
PILOT SELECT
MANIFOLD PORT 8
ROD END OF
CYLINDERS
BASE OF
CYLINDERS
RESERVOIR
15 GPM
MAX
C
B
A
F
E
D
C
B
A
F
E
D
C
B
A
F
E
D
MS1970
Model 3606 • Origin 10/99