28
Ⅳ
. Maintenance
2) Hook
Must have a latch to keep binding wire rope or chain from slipping off the hook.
Areas most subject to abrasion are gateway and center of hook on which weight lays.
4) Gears
When abrasion value(a) reaches 0.15t, it is time to replace it.
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Methods for Recognizing Value Limits of Pulley Groove by Naked Eye
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After processed and heat-treated, surface of pulley groove is coated with black zinc.
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When working load, black zinc coating is scratched off down to the point where wire rope does not move
toward bottom of groove any more.
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As the equipment is continuously used, the scratch line moves toward bottom of groove. The reason that the
scratch line nears toward bottom may be either wire ropeʼs diameter is reduced or pulley groove is worn off.
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Value Limits of Hook
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Normal value
Limit value
Item
Gateway
A (mm)
Genter of hook
T (mm)
in.
mm
in.
mm
0.72
18.3
0.52
13.15
0.8
20.5
0.46
11.8
Worn Wire Rope touching
bottom off Pulley Groove
1. Replace Wire Rope
2. Paint groove with magic pen
New Wire Rope touching
bottom off Pulley Groove
Replace pulley
Item
Measures
3) Pulley
Since abrasion at pulley groove occurs by wire rope, check wire rope too when abrasion is detected at pulley groove.
Time to Replace:
If a new wire rope hanging maximum
load touches bottom of groove, it is time to replace pulley.
