Jacobsen SLF 1880, Technical/Repair Manual

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8G-43
SECTION 8G. TRACTION CIRCUIT INSTRUMENT TESTS
GENERAL
The tests in this section are provided as a means of
isolating problems in the hydraulic system
This section uses two test methods to identify a prob-
lem or to evaluate a hydraulic circuit. The first test is a
pressure test. The pressure test determines how much
force (pounds per square inch – psi (kPa)) is being
used to force the available hydraulic oil through the cir-
cuit. The second test (flow) determines how much oil is
flowing through the circuit and how long it takes for the
oil to flow through the circuit (gallons per minute – gpm
(lpm)).
During the pressure test a pressure gauge is installed
in-line with the component pressure inlet. The test
determines how much pressure is being exerted on the
oil flowing to the component.
In the flow test a flow/pressure tester (Figure 8G-1) is
installed in-line with the component to determine how
much (gpm/lpm) oil is flowing to and from the compo-
nent and how much force (psi/kPa) is being exerted on
the oil.
The flow test is more complete and can isolate a prob-
lem within a circuit.
Make sure the mower is secured and cannot roll. If
interlock systems are bypassed, exercise caution when
performing each test.
Follow the instructions carefully and completely. Plug
lines and cap ports as directed.
A test record has been provided at the end of this sec-
tion. Make copies of the record for future use. Use the
form to record test results Page 8G-49(Figure 8G-13).
CAUTION
If interlock safety features are bypassed during a
test, use extreme caution when performing tests and
make sure the interlock system is functional after the
test has been completed.
CAUTION
When using a plug to block a pressure line the plug
must be able to withstand the pressure developed in
the circuit.
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WARNING
To avoid serious bodily injury, always lower mower
fully, place all controls in neutral and shut off the
engine before inspecting the hydraulic lines or
hoses. Never run hands across tubes, hoses, or fit-
tings to check for leaks. Hydraulic fluid escaping
under pressure can have sufficient force to penetrate
skin and may cause infection in a minor cut or open-
ing in the skin.
WARNING
The hydraulic system is under pressure, and the oil
may be hot.
• Always relieve pressure in the hydraulic system
before performing service.
• Do not block, plug or cap a hydraulic line or
component that is not protected with a relief
valve.
• Failure to follow appropriate safety precautions
may result in death or serious injury.
NOTICE
An in-line tester (Figure 8G-1) is used in this section
to measure oil flow. When using a tester with vari-
able gpm settings, make sure tester is set for the
proper flow range to avoid damage to the tester.
Record all readings obtained during the test. Per-
form all tests at the same engine speed (rpm) and
the hydraulic oil at operating temperature.
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8G