SkyTrak 6036 Service Manual - Manual (Page 157)

8-5 6036, 6042, 8042, 10042, 10054
Hydraulic System
1. Park the machine on a firm, level surface. Engage
the park brake, place the travel select lever in (N)
NEUTRAL, level the boom and turn the engine OFF.
2. Test port is located at top right corner of main control
valve. Install a pressure gauge capable of measuring
at least 10% more pressure than that which circuit
being checked operates under.
3. Start the engine. Operate machine functions several
times to allow hydraulic oil to reach operating
temperature. The hydraulic oil temperature should
be between 100-120°F (38-49° C). If a temperature
gauge or thermometer is unavailable, the hydraulic oil
reservoir should be warm to the touch.
4. Refer to Section 8.4.1, “Hydraulic Pressures,” for
testing procedures.
5. Fully depress accelerator pedal if required. Place
and hold joystick in position needed to operate the
particular machine function being checked. Continue
holding the joystick in position until pressure
readings are taken.
6. Check pressure gauge reading. It should read
as specified in Pressure Readings column of the
charts found in Section 8.4.1, “Hydraulic Pressures.”
If the reading is not as specified, turn the engine
OFF and check other components in the system.
Verify that all related hydraulic components and
electrical switches, sensors, solenoids, etc. are
operating correctly.
7. Adjust relief valve by turning adjustment screw.
Turning clockwise will increase pressure; turning
screw counterclockwise will decrease pressure.
8. Start engine and check pressure again. Turn engine
OFF. If there is pressure reading in gauge, bleed it
off then disconnect or remove pressure gauge from
the machine.
8.4 HYDRAULIC CIRCUITS
This section covers the hydraulic circuits and includes
listings for all hydraulic function pressures, where and
how to check those pressures and a hydraulic schematic.
Electrical and hydraulic functions are often related. Verify
that electrical components of the circuit are functioning
properly whenever troubleshooting the hydraulic circuit.
Always check the following before beginning to
troubleshoot a circuit that is not functioning correctly.
1. Check hydraulic oil level in reservoir. Level should be
in middle of sight glass with all cylinders retracted.
2. Check hoses, tubes, fittings and other hydraulic
components for leaks, bends, kinks, interference, etc.
3. Check for air in the hydraulic system. Erratic machine
performance and/or spongy cylinder operation are
signs of air in the hydraulic system.
If air in the hydraulic system is suspected, you will
hear air leakage when hydraulic fittings are loosened
and see air bubbles in the hydraulic fluid.
Loose fittings, faulty o-rings or seals, trapped oil,
leaks, system opened for service, etc., can cause air
in the system. Determine what is causing air to enter
the system and correct it. Bleed air from the system.
8.4.1 Hydraulic Pressures
a. Checking Pressure
1. Start the machine and warm the hydraulic system to
operating temperature.
2. Shut off the machine and install a gauge of suitable
pressure rating according to the following chart to
the appropriate test port.
3. Start the machine, run the engine and follow the
procedures in Section 8.4.1, e. “Pressure
Specifications (8042, 10042 & 10054).”
b. Adjusting Hydraulic Pressure
1. Shut the machine off. Remove the cap on the relief
(if necessary).
2. Start machine and loosen the jam nut on the relief.
Turn the relief clockwise to increase pressure or
counter-clockwise to decrease pressure. Set to the
correct pressure.
3. Tighten jam nut and recheck pressure at full throttle.
If reading is within specification, shut machine off,
install safety cap and remove gauge from test port.
4. If the proper pressure cannot be set, use the
accompanying hydraulic schematic and/or the
electrical schematic to help troubleshoot and correct
the problem.
Test
Location
Gauge Fittings
2, 3, 4, 5
4000 psi gauge
(280 bar gauge)
Unit equipped with
fittings from factory.
6, 7, 8, 10
1000 psi gauge
(70 bar gauge)
Unit equipped with
fittings from factory.
9
4000 psi gauge
(280 bar gauge)
Requires a male or
female quick
disconnect coupler.
CAUTION
GAUGE DAMAGE may occur. Malfunctioning
hydraulic system circuits may have excessive
pressure and can cause hydraulic pressure spikes.
Test circuit with the highest reading pressure gauge
first. If this gauge cannot record an accurate pressure
reading, use the next lower pressure gauge.