HYDRAULICS
8M-57
SECTION 8M. HYDRAULIC 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 is installed in-line
with the component to determine how much (gpm/lpm)
oil is flowing to and from the component 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.
Figure 8M-1. In-Line Flow Tester
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.
CAUTION
When using a plug to block a pressure line the plug
must be able to withstand the pressure developed in
the circuit.
NOTICE
An in-line tester (Figure 8M-1) is used in this section
to measure oil flow. When using a tester with vari-
able gpm settings, make sure the tester is set for the
proper flow range to avoid damage to the tester.
Record all readings obtained during the test. Perform
all tests at the same engine speed (rpm) and the
hydraulic oil at operating temperature.
NOTICE
The instrument tests described in this section are
intended as a guide only and may not include every
problem encountered within a hydraulic system.
Contact your local Jacobsen dealer for additional
information and assistance.
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