Service Manual

Groundsmaster 4500 --D/4700--DHydraulic System Page 4 -- 44
Testing
The most effective method for isolating problems in the
hydraulic system is by using hydraulic test equipment
such as pressure gauges and flow m eters in the circuits
during various operational checks (See the Special
Tools section in this chapter).
IMPORTANT: All o b vious areas such as hydraulic
oil supp ly, oil filters, binding components, loose
fasteners or improper adjustments must be
checked before assuming that a hydraulic compo-
nent is the source of the problem.
CAUTION
Failure to use gauges with recommended pres-
sure (PSI) rating as listed in test procedures
could result in damage to the gauge and possible
personal injury from leaking hot oil.
CAUTION
All testing should be performed by two (2)
people. One person should be in the seat to oper-
ate the machine and the other should read and
record test results.
Keep body and hands away from pin hole leaks
or nozzles that eject hydraulic fluid under high
pressure. Do not use hands to search for leaks;
use paper or cardboard. Hydraulic fluid escap-
ing under pressure can have sufficient force to
penetrate the skin and cause serious injury. If
fluid is injected into the skin, it must be surgical-
ly removed within a few hours by a doctor famil-
iar with this type of injury. Gangrene may result
from such an injury.
WA RNING
Before disconnecting or performing any work on
the hydraulic system, all p ressure in the system
must be relieved and all rotating machine parts
must be stopped. See Relieving Hydraulic Sys-
tem Pressure in t he General Information section
of this chapter.
WARNING
Precautions for Hydraulic Testing
1. Clean machine thoroughly before disconnecting or
disassembling any hydraulic components. Always keep
in mind the need for cleanliness when working on hy-
draulic equipment. Hydraulic system contamination will
cause excessive wear of hydraulic components.
2. Before conducting a hydraulic test, make sure hy-
draulic oil is at normal operating temperature by operat-
ing the machine under load for approximately ten (10)
minutes. Also, make sure the hydraulic reservoir is full.
3. Check control linkages for improper adjustment,
binding or broken parts.
4. Put m etal caps or plugs o n all hydraulic lines left
open or exposed during testing or removal of compo-
nents.
5. Theenginemustbeingoodoperatingcondition.Use
a phototac to determine engine speed when performing
a hydraulic test. Engine speed will affect the accuracy of
the tester readings. See Chapter 3 -- Yanmar Diesel En-
gine for engine speed specifications.
6. When using hydraulic tester with pressure and flow
capabilities, the inlet and the outlet hoses must be p rop-
erly connected and not reversed to prevent damage to
the hydraulic tester or machine components.
7. When using hydraulic tester with pressure and flow
capabilities, open load valveinthetestercompletelyto
minimize the possibility of damaging components.
8. Install fittings finger tight a nd far enough to make
sure that they are not cross --threaded before tightening
them with a wrench.
9. To prevent damage, position tester hoses so that ro-
tating or moving machine parts do not contact the hoses
or tester.
10.After connecting test equipment, make sure hydrau-
lic reservoir is full.
11. After installing test equipment, start engine and run
at idle speed. Check for hydraulic leakage and correct
before proceeding with test.
12.Before returning machine to use after testing, make
sure that hydraulic reservoir has correct fluid level.