| Mode |
Symptoms |
Possible Causes |
| Fatigue |
Wire break is transverse
-- either straight across or Z shape. Broken ends will appear
grainy. |
Check for rope bend around
too small a radius; vibration or whipping; damaged sheaves; rollers
too small; reverse bends; bent shafts; tight grooves; corrosion;
small drums & sheaves; incorrect rope construction and size
(too big); improper installation; poor end termindations. (In
the absence of other modes of degradation, all rope will eventually
fail in fatigue). |
| Tension |
Wire break reveals a mixture
of cup and cone fracture and shear breaks. |
Check for overloads; sticky,
grabby clutches; jerky conditions; loose bearing on drum; fast
starts, fast stops, broken sheave flange; wrong rope size &
grade; poor end terminations. Check for too great a strain on
rope after factors of degradation have weakened it. |
| Abrasion |
Wire break mainly displays
outer wires worn smooth to knife edge thinness. Wire broken by
abrasion in combination with another factor will show a combination
break. |
Check for change in rope
or sheave size; change in load; overburden change; frozen or
stuck sheaves; soft rollers; sheaves or drums; excessive fleet
angle; misalignment of sheaves; kinks; improperly attached fittings;
gift & sand; objects imbedded in rope; improper grooving. |
| Abrasion plus
Fatigue |
Reduced cross-section is
broken off square thereby producing a chisel shape. |
A long term condition normal
to the operating process. Short term: see "Abrasion." |
| Cut or Gouged
or Rough Wire |
Wire ends cross-section
is necked down as in a cup and cone configuration. Tensile break
produces a chisel shape. |
Check on all the above conditions
for mechanical abuse, or either abnormal or accidental forces
during installation. |
| Torsion of Twisting |
Wire ends show evidence
of twist and/or cork-screw effect. |
Check on all the above conditions
for mechanical abuse, or either abnormal or accidental forces
during installation. |
Mashing
or
Crushing |
Wires are flattened and
spread at broken ends. |
Check on all the above conditions
for mechanical abuse, or either abnormal or accidental forces
during installation. This is a common occurrence on the drum
when the lower layer is installed with less tension than the
layer going on top. |
| Corrosion |
Wire surfaces are pitted
with break showing evidence either of fatigue tension or abrasion. |
Indicates improper lubrication
or storage, or a corrosive environment. |
P.O. Box 33170
5250 River Road
Cincinnati, OH 45233
Phone: (513) 941-2443
Fax: (513) 941-2445