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Appearance
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Cause
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Remedy
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Fact
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Conditions
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Hardening
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Hardening of the whole sliding face. Glazing and cracks on the face. Push with a finger, and a crack is detected. |
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(1) Heat generation by high speed or excessive internal pressure. |
(1) In case of piston, change to SPG.
(2) In case of rod, use buffer ring together. |
| The whole packing hardens and changes into shape of groove and when bent with a finger, a crack occurs. |
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(1) High oil temperature
(2) Influence of oil
(a) Incompatibility of oil and rubber material
(b) Deterioration of oil |
(1) Lower oil temperature or change to hear resistant material (fluoro rubber).
(2a) Change to oil resistant rubber material.
(2b) Renew oil. |
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Wear
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The sliding face is worn into a flossy mirror-like face. |
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(1) Sliding was extremely short stroke and caused insufficient lubrication. |
(1) In case of piston, change to SPG.
(2) In case of rod, use buffer ring together. |
| The size of sliding width continuously differs on the circumference and the position of minimum width and the position of maximum width are roughly symmetrical. |
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(1) Eccentricity of rod and cylinder head and cylinder and piston head. |
(1) Make eccentricity of installation within the tolerance of packings. |
| Abnormal wear of part of the circumference of the sliding lip (matching the direction lateral load). |
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(1) Abnormal wear of wear ring and bearing by excessive lateral load. |
(1) Change wear ring and bearing material to those which can withstand for large load. |
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Scars
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Partial cut, dent on the top end of the lip. |
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(1) By external force such as by hanging on a nail or wire for storage.
(2) Insufficient chamfering of the mating material when fitting.
(3) By driver, etc. when fitting. |
(1) Improvement to storage method.
(2) Increase chamfering of the mating material and make it smooth so as not to cause overturn.
(3) Use fitting tool. |
| Scratch on sliding face. |
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(1) There was a scar on the mating sliding face.
(2) Due to overturn.
(3) By embedded foreign material. |
(1) Check fully before fitting.
(2) Make sufficient chamfering of the mating material and make it smooth so as not to cause overturn.
(3) Make sure to clean. |
