SkyTrak 6036 Service Manual - Manual (Page 270)

Hydraulic System
8.54 Model 6036 Legacy
8.8.23 Attachment Tilt and Slave Circuit
Description
System pressure is applied in the attachment tilt and
slave cylinder circuit (Fig. 8-11 and Fig. 8-12) from the
attachment tilt section of the main control valve.
Fluid flow is directed to either side of the attachment tilt
and slave cylinder pistons by shifting of the spool valve in
the attachment tilt section of the main control valve
assembly. The spool valve is shifted by the operator
joystick and its associated control cable.
Moving the joystick BACKWARD controls attachment tilt
UP. Moving the joystick FORWARD controls attachment
tilt DOWN.
a. DOWN Position (Fig. 8-11)
With the joystick moved FORWARD, the
attachment tilts DOWN. The spool valve in the
main control valve is shifted so system pressure
is directed to the rod end of the attachment tilt
cylinder 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 attachment downward. The
pilot pressure opens the counterbalance valve. The open
counterbalance valve allows return oil from the base of
the attachment tilt cylinder to flow to ports of the
attachment tilt section of the main control valve, to the
unloader valve, to the oil cooler, to the return filter and
then to the reservoir.
If system pressure reaches 3250 ±100 psi (224 ±7 bar)
the main relief will open and allow hydraulic oil to return
to the return filter and to the reservoir. In any case, if the
return filter becomes restricted, hydraulic oil will bypass
the filter when the pressure reaches 25 psi (1,7 bar).
b. UP Position (Fig. 8-12)
With the joystick moved BACKWARD, the
attachment tilts UP. The spool valve in the main
control valve is shifted so system pressure is
directed to the base end of the attachment tilt
cylinder and the slave cylinders.
If system pressure reaches 3250 ±100 psi (224 ±7 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 the spool valve, to the unloader valve, to
the oil cooler, to the return filter and then to the reservoir.
If the return filter becomes restricted, hydraulic oil will
bypass the filter when the pressure reaches 25 psi
(1,7 bar).
8.8.24 Pump, Unloader Valve and Cooling
Circuit Description
In the pump, unloader valve and cooling circuit
(Fig. 8-13), the pump draws fluid from the hydraulic
reservoir and sends pressurized fluid to the unloader
valve.
The unloader valve regulates maximum system operating
pressure for various vehicle functions. It sends fluid to the
main control valve and to the secondary function manifold.
When fluid from the unloader valve is returned to the
reservoir, it is sent through the hydraulic oil cooler first.
8.8.25 Auxiliary Hydraulics Circuit Description
The auxiliary hydraulics circuit (Fig. 8 -14 and
Fig. 8-15) functions can be achieved by
moving the auxiliary attachment control lever.
Moving the control lever to the left controls
auxiliary function in one direction, usually
forward, if the auxiliary device is so designed. Moving the
control lever to the right controls auxiliary functions in
reverse, or the opposite direction.
a. Male Coupler Pressurized (Fig. 8 -14)
With the auxiliary attachment control lever moved
to the right, pressure will shift the auxiliary spool
valve, allowing system pressure to flow from the
auxiliary spool valve to the male connection of the
auxiliary hydraulics coupler. From the coupler, fluid flows
to the attachment, back to the female auxiliary coupler, to
the auxiliary spool valve, to the unloader valve, to the oil
cooler, to the return filter and then to the reservoir.
b. Female Coupler Pressurized (Fig. 8-15)
With the auxiliary attachment control lever
moved to the left, pressure will shift the auxiliary
spool valve, allowing oil to flow from the auxiliary
spool valve to the female connection of the
auxiliary hydraulics coupler. From the coupler, fluid flows
to the attachment, back to the male auxiliary coupler, to
the auxiliary spool valve, to the unloader valve, to the oil
cooler, to the return filter and then to the reservoir.
MT3780
MT3790
MA7250
MA7260
MA7270