SkyTrak 6036 Service Manual - Manual (Page 114)

Section 9. Hydraulic System
9-1 Model 6036 S/N 9B0499 and Before
Warning !
CONTENTS
• If anyone is injured by or if any hydraulic fluid
is injected into the skin, obtain medical
attention immediately or gangrene may result.
• Wear appropriate eye protection. Hydraulic
fluid can cause permanent eye injury. Do not
wear loose fitting clothing when servicing the
forklift.
SECTION 9
HYDRAULIC SYSTEM
9.1 CIRCUITS 9-1
9.1.1 Boom Raise/Lower 9-1
9.1.2 Boom Extend/Retract 9-5
9.1.3 Grille Tilt and Slave Circuit 9-8
9.1.4 Frame Tilt Circuit 9-11
9.1.5 Brake Circuits 9-14
9.1.6 Power Steering Circuit 9-17
9.1.7 Optional Auxiliary Circuit 9-20
9.2 CYLINDERS 9-23
9.2.1 Boom Hoist Cylinder 9-23
9.2.2 Extend Cylinder 9-27
9.2.3 Slave Cylinder 9-30
9.2.4 Grille Tilt Cylinder 9-33
9.2.5 Frame Tilt Cylinder 9-36
9.2.6 Steering Cylinder 9-39
9.2.7 Side Tilt Carriage Cylinder
(Optional) 9-42
9.3 VALVES 9-45
9.3.1 Main Control Valve Assembly 9-45
9.3.2 Brake Valve 9-50
9.3.3 Park Lock Release Valve 9-54
9.3.4 Steer Select Valve 9-56
9.3.5 Sequence Valve 9-57
9.3.6 Steer Relief Valve 9-57
9.3.7 Pressure Reducing Valve 9-58
9.3.8 Counterbalance Valve 9-59
9.4 PUMPS 9-60
9.4.1 Main Tandem Pump 9-60
9.4.2 Steering and Emergency
Brake Pump (S/N 7P0013 & Before) 9-67
9.4.3 Steering and Emergency
Brake Pump (S/N 7P0014 & After) 9-68
9.5 TROUBLESHOOTING 9-71
9.6 SPECIFICATIONS 9-78
9.1 CIRCUITS
NOTE: Refer to the 6036 Hydraulic Schematic in
the Troubleshooting Section 9.5 for an overall
diagram
9.1.1 Boom Raise/Lower
a. Description
Hydraulic pressure is applied in the boom raise/
lower circuit by the 30 gpm section (rear half) of
the tandem pump, which draws its fluid through a
suction strainer in the reservoir, Fig. 9.1. Supply
pressure is directed to either side of the right and
left boom hoist cylinder pistons, by the shifting of a
spool in a directional control valve found in the
main control valve assembly. The spool is shifted
by the operator joystick and its associated
control cable. The joystick positions for raising
and lowering the boom are as follows:
Center Position
When the joystick is placed in the center or neutral
position, the directional control valve spool is
positioned so that supply pressure is directed
through ports F to C, Fig. 9.1, to the return filter
and reservoir, Fig. 9.1. If the filter becomes
clogged, hydraulic oil will bypass the filter when
the pressure reaches 10 to 15 psi
(0,7 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. 9.1, to the base end of both left and right
boom hoist cylinder pistons. If supply pressure
reaches 2650 psi (182,6 bar), the boom hoist
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