SkyTrak 6036 Service Manual - Manual (Page 125)

Section 9. Hydraulic System
Model 6036 S/N 9B0499 and Before 9-12
2. Operate the hydraulic controls after the engine
has stopped to relieve any trapped pressure.
3. Remove the transmission cover from the
frame.
4. Install a tee and pressure gauge capable of
measuring 0-4000 psi (275,6 bar) at the 30
gpm section outlet of the tandem pump, Fig.
9.5.
5. Start the engine. Operate the frame tilt control
several times to purge the system of air.
6. Allow engine to run at idle. Place the fork and
frame control lever in the “left” position and
hold until the frame tilt cylinder bottoms out.
Continue holding the lever in the “left” position
until the pressure readings are taken.
7. Check the pressure gauge reading. It should
read 1200 ± 50 psi (82,7 ± 3,4 bar). If not,
adjust the frame tilt “left” relief valve, Fig. 9.2,
turning the adjustment screw clockwise to
increase pressure or counterclockwise to
decrease pressure. Torque nuts on relief
valve to 10 ± 1.5 lb-ft (13,5 ± 2 N m) after
adjustment.
8. Stop the engine. Operate the hydraulic
controls after the engine has stopped to
relieve any trapped pressure.
9. Remove the pressure gauge and tee from the
tandem pump and reconnect the hydraulic
line.
10. Start the engine. Operate the frame tilt control
fully several times to purge the system of air.
11. Install the transmission cover after adjustment.
Frame Tilt Right Relief Valve
1. Engage the park lock, place the travel select
lever in neutral, and stop the engine.
Left Position
When the grille and frame tilt control lever is
placed in the “left” position”, the directional control
valve spool is positioned so that pump supply
pressure is directed through ports E to A, Fig. 9.5,
to the base (extend) end of the frame tilt cylinder
piston. If supply pressure reaches 1200 psi (82,7
bar), the frame tilt “left” relief valve, Fig. 9.2, will
open allowing hydraulic oil to return to the return
filter and reservoir, Fig. 9.5.
Return oil from the rod end of the frame tilt cylin-
der piston is directed back to the directional
control valve though ports B to D, Fig. 9.5, to the
return filter and reservoir. If the return filter
becomes clogged, hydraulic oil will bypass the
filter when the pressure reaches 10 to 15 psi
(0,7
to 1,0 bar).
Right Position
When the grille and frame tilt control lever is
placed in the “right” position, the directional control
valve spool is positioned so that pump applied
pressure is directed through ports E to B, Fig. 9.5,
to the base (retract) end of the frame tilt cylinder
piston. If supply pressure reaches 1200 psi
(82,7
bar), the frame tilt “right” relief valve, Fig. 9.2,
will open allowing hydraulic oil to return to the
return filter and reservoir, Fig. 9.5.
Return oil from the base end of the frame tilt
cylinder piston is directed back to the directional
control valve though ports A to D, Fig 9.5, to the
return filter and reservoir. If the return filter
becomes clogged, hydraulic oil will bypass the
filter when the pressure reaches 10 to 15 psi (0,7
to 1,03 bar).
Pilot-operated check valves, Fig. 9.5, in the
frame tilt cylinder permit free flow on both ends of
the cylinder piston when supply pressure is
applied to open either pilot-operated check valve.
When the grille and frame tilt control lever is not
activated, no supply pressure is applied. The two
check valves prevent any back flow of hydraulic oil
and the frame tilt cylinder is locked in position.
b. Pressure Checks and Adjustments
Frame Tilt Left Relief Valve
1. Engage the park lock, place the travel select
lever in neutral, and stop the engine.
Warning !
Wait for the hydraulic fluid to cool before servic-
ing any hydraulic component. Hot hydraulic fluid
can cause severe burns.
Warning !
Before starting the engine be sure all hydraulic
connections are tight and all tools are removed
from the forklift.
Warning !
Relieve hydraulic pressure before servicing any
hydraulic component. Escaping hydraulic fluid
under pressure can penetrate the skin causing
serious injury.