Cable strand broken

Jul 27, 2008 4 Replies

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kashif_ashkar 17 years ago

Dear group members,

i have encountered one problem and need to analyzed it before taking any preventive action.

Contorl cable (1/8", 7X19, steel cable) strands wires were found broken in the area where it run overs pulleys (phenolic). I have came to know that these area are critical to fatigue but couldnt figured out the reason and mechanism which led to such damage near pulleys. if some one can explain me the propbable causes / reason which can led to such occurrences or reasons which can aggravate the situation, so that i can based my maintenance procedures and frequency to avoid future recurrence.

hope for a sound engineering / scientific reply from group members.

thanks

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jim beam 17 years ago

simple bending fatigue. try a larger radius on the pulley. if that's not possible, better material/surface finish quality on the cable [strands] might help.

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deu 17 years ago

Possibly groove radius on the pulley as well, either too tight or too slack can do it.

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kashif_ashkar 17 years ago

well i have checked pulleys as well, in some pulleys i have observed cable groove marks in the pulley. however, i have tested the cable sample with broken wire strands and their breaking strenght was passing the ASTM standard with the exception of one sample that failed to qualify the tests.

Bending loads can cause this problem, but in my case the lap angle on the pulleys is around 10-20 degree,which i think can not contribute much in my case.

hope that this new infomartion might help the members in further assisting me in correct analysis.

regards

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jim beam 17 years ago

breaking strength is not fatigue strength - fatigue is your problem.

angle is not radius. radius defines bending stress. see point above.

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