Wire Rope Technical Parameters

Wire ropes, like the machines and hoists on which they are used, require careful use, handling and maintenance for satisfactory performance, long life and adequate safety.

Precautions Should Be Observed To Meet These Requirements:



Causes-Rope Damage

  Fault

  Possible Cause

  Fault

  Possible Cause

Accelerated Wear
Severe abrasion from being dragged over the ground or obstructions.
Rope wires too small for appication or wrong construction or grade.
Poorly aligned sheaves.
Large fleet angle.
Worn sheaves with incorrect groove size or shape.
Sheaves, rollers and faileads having rough wear surfaces.
Stiff or seized sheave bearings.
High bearing and cotact pressures.
Broken wires or undue wear on one side of rope
Incorrect alignment.
Damaged sheaves and drums.
Broken wires near fittings.
Rope vibration.
Burns
Sheave grove too small.
Sheaves too heavy.
Sheave bearings seized.
Rope dragged over obstacle.
Rapid appearance of broken wires.
Rope is not flexible enough.
Sheaves, rollers, drums twoo small in diameter.
Overload and shock load.
Excessive rope vibration.
Rope speed too high.
Kinks that have formed and been straightened out.
Crussing and flattening of the rope.
Reverse bends.
Sheave wobble.
Rope core charred
Excessive heat.
Corrugation and excessive wear
Rollers too soft.
Sheave and drum material too soft.
Distortation of lay
Rollers too soft.
Sheave and drum material too soft.
Pinching and crushing
Sheave grooves too small.
Rope broken off square
Overload, shock load.
Kink
Broken or craked sheave flange.
Rope chatters
Rollers too small
Strand break
Overlaod, shock load.
Local wear.
Slack in 1 or more strands.
Rope unlays
Swivel fitting on langs lay ropes.
Rope dragging against stationary object.
Crushing and nicking
Rope struck or hit during handling.
Corrosion
Inadequate lubricant.
Incorrect type of lubricant.
Incorrect storage.
Exposure to acids or alkalis.
High stranding
Fittings incorrectly attached
Broken strand.
Kinks, dog legs.
Incorrect seizing.
Kinks, dog lengs, distortions
Incorrect installation.
Incorrect handling
Reduction in diameter
Broken core
Overload
Corrosion
Severe wear.
Excessive wear in spots
Kinks or bends in rope due to incorrect handling in service or during installation.
Vibration or rope on drums or sheaves.
Bird cage
Sudden release of load.
Crushing and flattening
Overload, shock load.
Uneven spooling
Cross winding rope
Rope bigger than drum
Loose bearing on drum
Faulty clutches
Rope dragged over obstacles.
Strand nicking
Core failure due to contined operation under high load.
Core Stretch
Overload
Untwist of Langs lay ropes.
Core prostrusion
Shock loading
Disturbed rope lay
Rope unlays
Load spins
 
Relative Fatigue Life Of End Fittings:
End attachments of wire rope installation are of the greatest importance of safety and it is important to know that many wire rope attachments, even when properly made and installed, develop less than the full strength of the rope.
 
Type of Splicing
Cycles @25% Strength of Splice (Thousands)
Cycles @35% Strength of Splice (Thousands)
H/S
15
30
Zine
30
60
M/S FB
30
70
M/S FL
40
110
SWGD
50
200
 
  H/S

  Hand Tucked (Liverpool) Eyesplice.

  Zinc

  Zinc Socket

  M/S FB

  Foldback Eye & Aluminum Sleeve

  M/S FL

  Flemish Spliced Eye & Mechanical
  Sleeve

  SWGD

  Swaged Socket



Wire Rope Lay

Left-hand ordinary lay (LHOL) wire rope (close-up). Right-hand lay strands are laid into a left-hand lay rope.



Right-hand Lang's lay (RHLL) wire rope (close-up). Right-hand lay strands are laid into a right-hand lay rope. The lay of a wire rope describes the manner in which either the wires in a strand, or the strands in the rope, are laid in a helix

Left & Right Hand Lay

Ordinary and Lang's lay describe the manner in which the wires are laid to form a strand of the wire rope. To determine which has been used first identify if left or
right hand lay has been used to make the rope. Then identify if a right or left hand lay has been used to twist the wires in each strand.
 

  Ordinary lay

  The lay of wires in each strand is in the opposite direction to the
  lay of the strands that form the wire.

  Lang's lay

  The lay of wires in each strand is in the same direction as the lay
  of the strands that form the wire.

  Alternate lay

  The lay of wires in the strands alternate around the rope between
  being in the opposite and same direction to the lay of the strands
  that form the wire rope.

  Regular lay

  Alternate term for ordinary lay.

  Albert's lay

  Archaic term for Lang's lay.

  Reverse lay

  Alternate term for alternate lay.

  Spring lay

  This is not a term used to classify a lay as defined in this section.
  It refers to a specific construction type of wire rope.

Wire Rope Construction & Specification

This image of a fraying wire rope shows some individual wires. The specification of a wire rope type – including the number of wires per strand, the number of strands, and the lay of the rope – is documented using a commonly accepted coding system, consisting of a number of abbreviations.

This is easily demonstrated with a simple example. The rope shown in the figure "Wire rope construction" is designated thus: 6x19 FC RH OL FSWR

  6

  Number of strands that make up the
  rope

Photograph

  19

  Number of wires that make up each
  strand

  FC

  Fibre core

  RH

  Right hand lay

  OL

  Ordinary lay

  FSWR

  Flexible steel wire rope

 
Each of the sections of the wire rope designation described above is variable. There are therefore a large number of combinations of wire rope that can be specified in this manner. The following abbreviations are commonly used to specify a wire rope.
Abbreviation
  FC         Fibre core   FSWR       Flexible steel wire rope
  FW        Filler wire   IWR       Independent wire rope
  IWRC   Independent wire rope core   J   Jute (fibre)
  LH   Left hand lay   LL   Lang's lay
  NR   Non-rotating   OL   Ordinary lay
  RH   Right hand lay   S   Seale
  SF   Seale filler wire   SW   Seale Warrington
  SWL   Safe working load   TS   Triangular strand
  W   Warrington   WF   Warriflex
  WLL   Working load limit   WS   Warrington Seale
 

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