Troubleshooting (Continued)
Problem | Cause | Correction |
Slow operation of machine | Relief valve setting in backhoe | Relief pressure will have to be checked |
(lack of power) all cylinders | control valve too low or defective | and corrections made. Backhoe |
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| system pressure is 2400 PSI. Relief |
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| valve may need cleaning and over- |
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| hauling, or entire cartridge must be |
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| replaced. |
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Spongy or jerking action | Low oil supply in reservoir | Fill to proper level. |
of cylinders and/or noisy |
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operation | Air in system | Bleed all circuits of air by operating |
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| machine at maximum oil flow and |
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| through full movements. |
| Oil viscosity too heavy, or | Use recommended hydralic fluid. Run |
| oil is not at operating | machine until oil reaches operating |
| temperature | temperature. |
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| Pump not running | Check pump drive to be sure it is |
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| engaged. |
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Lift, crowd or bucket | Damaged or worn spool | Replace spool end seals. |
cylinders drop under load | seals |
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when control spools |
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shifted from neutral | Problems involving the control | This valve is a precision device and is |
| valve | not intended for any extensive field |
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| adjustment or repair. Field replace- |
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| ment parts are limited to seal kits, |
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| cartridges, valve sections and tie rods. |
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| Replacement of these parts, the |
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| opening of check cavities and certain |
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| relief cavities to examine for trapped |
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| dirt, or resetting of the main relief valve |
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| with the use of good pressure gauge, |
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| should be referred to qualified service |
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| personnel. |
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| Dirt and shreds of packing material are |
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| the usual causes of valve malfunction. |
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| Be sure the reservoir oil supply is kept |
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| clean and only factory supplied |
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| packings are used in cylinder repair. |
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| Everything must be clean and free of |
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| dirt during the oil line removal and |
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| replacement, and during any cylinder |
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| work. |
Load drops or settles | Loose oil line connections, | Tighten all hose connections and |
| leaks in line or broken lines | replace any damaged |
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| leaking |
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| replace any damaged hoses and lines. |
| Oil is bypassing cylinder piston, | Replace or rebuild the cylinder; replace |
| scored piston, worn piston | damaged parts. |
| packing, or defective piston |
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| assembly |
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| Worn or damaged rod seals on | Repack cylinder. Rebuild cylinder, |
| cylinder; external leaks | replacing damaged parts as necessary. |
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| Worn control valve | Replace the control valve. |
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| Damaged or worn spool seals | Replace spool end seals. |
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