SkyTrak 6036 Service Manual - Manual (Page 174)

Section 9 Hydraulic System
9-24 Model 6036/6036T S/N 9B0500 thru 14833
c. Testing
The frame tilt circuit should be tested whenever
repairs or adjustments are made to components of
the circuit.
1. Start the engine, park the forklift on level
ground and level the frame.
2. Check for signs of leakage of hydraulic oil
from circuit hoses and other components.
Correct any leakage problem before testing.
3. Operate the frame tilt control several times to
purge the system of air if necessary.
4. Starting with the frame tilted fully to the left, tilt
the frame fully to the right at full engine speed.
The time required for frame tilt right should be
8 to 12 seconds (no load).
5. Starting with the frame tilted fully to the right,
tilt the frame fully to the left at full engine
speed. The time required for frame tilt left
should be 7 to 11 seconds (no load).
6. Repeat steps 4 and 5 to check performance.
7. If the frame tilt test does not meet perform-
ance requirements (Refer to Troubleshooting,
paragraph 9.8) and correct before putting the
vehicle into service.
9.4.4 Brake Circuits
(S/N 9B0500 thru OE1179 –
Without Trans. De-Clutch)
a. Description
Hydraulic pressure is normally applied in the
service and park lock brake circuits by the 15 gpm
section (front half) of the tandem pump, which
draws its fluid through a suction strainer in the
reservoir, Fig. 9.14. A pressure of 610 - 660 psi
(42 - 45,5 bar) is maintained by the sequence
valve. This pressure is reduced to 525 ± 25
psi
(36,2 ± 1,7 bar) at the pressure reducing valve
prior to entering the solenoid-operated park lock
release valve and pedal-operated service brake
valve.
Service Brake Valve
When the brake pedal in the operator’s cab is not
depressed, the brake valve spool is spring-
positioned so that hydraulic flow is blocked at port
C, Fig. 9.14, no pressure is applied to the service
brakes. Return flow from the service brakes
passes through ports B to D to the reservoir.
When the brake pedal in the operator’s cab is
depressed, the brake valve spool is positioned so
that flow is directed through ports C to A, Fig.
9.14, to the service brake pistons. As pressure is
applied, the pistons press the brake discs together
slowing or stopping the wheel. The brake pedal
will return to the up position when released.
Park Lock Release Valve
When the park lock switch on the instrument panel
is placed in the engaged (up) position, the park
lock release valve solenoid is de-energized and
the valve spool is spring positioned so that hydrau-
lic flow from the park lock piston is directed
through ports B to C in the park lock release valve,
Fig. 9.14. With no pressure on the park lock
piston, the park lock springs force the discs
together, this engages the park lock. With the
park lock release valve solenoid in the de-ener-
gized position, pressurized hydraulic oil is blocked
at port D, Fig. 9.6. The park lock light on the dash
will illuminate whenever the park lock is engaged
and the ignition switch is in the RUN position.
When the park lock switch on the instrument panel
is placed in the disengaged (down) position, the
park lock release valve solenoid is energized and
the valve spool is positioned so that the hydraulic
flow is directed through ports D to A in the park
lock release valve, Fig. 9.14, to the park lock.
With hydraulic pressure being applied to the park
lock piston, the park lock springs are compressed.
Which disengages the park lock discs.
IMPORTANT: Never engage the park lock while
the machine is in motion. The park lock is not
designed to be used as a means to slow or stop
machine travel and could be damaged as a result.
b. Pressure Checks and Adjustments
The pressure checks and adjustments are the
same as the brake circuit with transmission de-
clutch, refer to paragraph 9.4.5.b.
c. Testing
The service brakes should be tested whenever
repairs or adjustments are made to components of
the circuit.
1. Start the engine, park the forklift on level
ground and level the frame.
2. Check for signs of leakage of hydraulic oil
from circuit hoses and other components.
Correct any leakage problem before testing.
3. Bleed the brake system as described in
paragraph 9.6.3.g if necessary.