8.55
Model 644E-42/944E-42
Rev. 6/04
Hydraulic System
8.8
HYDRAULIC CIRCUITS AND
TROUBLESHOOTING
This section covers the hydraulic circuits and includes a
circuit drawing, troubleshooting chart, and description of
the circuit for each function.
Typically, the circuit drawings illustrate the flow of oil for
the hydraulic function being shown.
The troubleshooting charts cover some common
problems that can occur during the operation of the
hydraulic system. Electrical and hydraulic functions are
often related. Verify that the 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 the hydraulic oil level in the reservoir. Oil level
should be in the middle of the 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.
WARNING:
Wait for hydraulic fluid to
cool before servicing any hydraulic component.
Hot hydraulic fluid can cause severe burns.
WARNING:
Relieve hydraulic pressure
before servicing any hydraulic component.
Escaping hydraulic fluid under pressure can
penetrate the skin causing death or serious
injury. When checking for air in the hydraulic
system, wear safety glasses and gloves to help
provide protection from spraying hydraulic oil.
Summary of Contents for 944E-42
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Page 14: ...Safety Practices 1 8 Model 644E 42 944E 42 Rev 6 04 This Page Intentionally Left Blank...
Page 102: ...Boom 3 56 Model 644E 42 944E 42 Rev 6 04 This Page Intentionally Left Blank...
Page 139: ...4 37 Model 644E 42 944E 42 Rev 6 04 Cab and Covers This Page Intentionally Left Blank...
Page 144: ...Cab and Covers 4 42 Model 644E 42 944E 42 Rev 6 04 This Page Intentionally Left Blank...
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Page 501: ...8 251 Model 644E 42 944E 42 Rev 6 04 Hydraulic System MT1950 2 3 4 5 6 7 8 5 5...
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Page 508: ...Hydraulic System 8 258 Model 644E 42 944E 42 Rev 6 04 This Page Intentionally Left Blank...
Page 525: ...9 17 Model 644E 42 944E 42 Rev 6 04 Electrical System This Page Intentionally Left Blank...
Page 554: ...Electrical System 9 46 Model 644E 42 944E 42 Rev 6 04 This Page Intentionally Left Blank...
Page 759: ...10 3 Model 644E 42 944E 42 Rev 6 04 Stabil TRAK System This Page Intentionally Left Blank...
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Page 800: ...Stabil TRAK System 10 44 Model 644E 42 944E 42 Rev 6 04 This Page Intentionally Left Blank...
Page 832: ...Transfer Carriage 11 32 Model 644E 42 944E 42 Rev 6 04 This Page Intentionally Left Blank...
Page 840: ...12 8 Model 644E 42 944E 42 Rev 6 04 Index...
Page 841: ...Accident Prevention Tags OS2180 8990403 Origin 5 00 Accident Prevention Tags...
Page 842: ...Accident Prevention Tags OS2180 8990403 Origin 5 00...
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