SkyTrak 6036 Service Manual - Manual (Page 155)

Section 9 Hydraulic System
Model 6036/6036T S/N 9B0500 thru 14833 9-5
D E F D E F D E F
A
LOWER RAISE
CENTER
RAISE
LOWER
TO BOOM EXTEND/
RETRACT CYLINDER
RIGHT BOOM RAISE
CYLINDER
LEFT BOOM RAISE
CYLINDER
COUNTERBALANCE
VALVES
TANDEM
PUMP
RETURN FILTER
RESERVOIR
MAIN RELIEF VALVE
2700 -100/+150 PSI
DIRECTIONAL CONTROL
VALVE POSITIONS
MAIN CONTROL
VALVE
30
GPM
15
GPM
STRAINER
Fig. 9.4 Cable Control Boom Raise/Lower Circuit
MA3000
BOOM RAISE PORT
RELIEF VALVE
2850 ± 50 PSI
0-4000 PSI
PRESSURE
GAUGE
B C A B C A B C
Lower Position
When the joystick is placed in the lower position,
the directional control valve spool is shifted so that
supply pressure is directed through ports E to B,
Fig. 9.4, to the rod (top) end of both left and right
boom hoist cylinder pistons. This supply pressure
also pilots open the counterbalance valve, Fig.
9.4. The open counterbalance valve allows return
oil from the base end of the cylinder to return
through ports A to D, Fig. 9.4, of the directional
control valve to the return filter and reservoir. If
supply pressure reaches 2700 -100/+150 psi
(186 -6,9/+10,3 bar), the main relief valve, Fig.
9.4, will open, allowing hydraulic oil to return to the
reservoir. If the return filter becomes clogged,
hydraulic oil will bypass the filter when the pres-
sure reaches 10 to 15 psi
(0,69 to 1,03 bar).
Raise Position
When the joystick is placed in the raise position,
the directional control valve spool is shifted so that
supply pressure is directed through ports E to A,
Fig. 9.4, to the base end of both left and right
boom hoist cylinder pistons. If supply pressure
reaches 2850 psi (196,4 bar), the boom raise
port relief valve, Fig. 9.4, will open allowing
hydraulic oil to return to the reservoir.
Return oil from the top end of the boom raise
cylinder piston is directed back to the directional
control valve through ports B to D, Fig. 9.4, to the
return filter and reservoir. If the filter becomes
clogged, hydraulic oil will bypass the filter when
the pressure reaches 10 to 15 psi
(0,69 to 1,03
bar)