Troubleshooting

Problem     Cause/ Action

Mechanical damage caused by the rope contacting the structure of the crane or appliance on which it is operating – usually of a localised nature.

  • Generally results from operational conditions.
  • Check sheave guards and support/guide sheaves to ensure that the rope has not “jumped out” of the intended reeving system.
  • Check sheave and drum grooving for evidence of damage or “tracking”. Given sufficient tension over a prolonged period the rope can cut an imprint into the sheave groove causing damage particularly when the rope is changed.
  • Review operating conditions.

Opening of strands in rotation resistant, low rotation and parallel closed ropes – in extreme circumstances the rope may develop a “birdcage” or “basket” distortion or protrusion of inner strands.

Note- rotation resistant and low rotation ropes are designed with a specific strand gap which may be apparent on delivery in an off tension condition. These gaps will close under load and will have no effect on the operational performance of the rope.

  • Check sheave and drum groove radii using a sheave gauge to ensure that they are no smaller than nominal rope radius +5% - Carl Stahl Evita recommends that the sheave and groove radii are checked prior to any rope installation.
  • Repair or replace drum/sheaves if necessary .
  • Check fleet angles in the reeving system - a fleet angle in excess of 1.5 degrees may cause distortion.
  • Check installation method – turn induced during installation can cause excessive rope rotation resulting in distortion.
  • Check if the rope has been cut “on site” prior to installation or cut to remove a damaged portion from the end of the rope. If so, was the correct cutting procedure used? Incorrect cutting of rotation resistant, low rotation and parallel closed ropes can cause distortion in operation.
  • Rope may have experienced a shock load.

Broken wires or crushed or flattened rope on lower layers at crossover points in multi -layer coiling situations.

Wire breaks usually resulting from crushing or abrasion.

  • Check tension on underlying layers. Carl Stahl Evita recommends an installation tension of between 2% and 10% of the minimum breaking force of the wire rope. Care should be taken to ensure that tension is retained in service. Insufficient tension will result in these lower layers being more prone to crushing damage.
  • Review wire rope construction Wire ropes with a relatively high fill factor resist crushing. Moving from a fibre core to a steel core will increase fill factor. Moving to a compacted rope construction will increase fill factor.
  • Do not use more rope than necessary.

Wires looping from strands.

  • Insufficient service dressing.
  • Consider alternative rope construction.
  • If wires are looping out of the rope underneath a crossover point, there may be insufficient tension on the lower wraps on the drum.

“Pigtail” or severe spiralling in rope.

  • Check that the sheave and drum diameter is large enough. Carl Stahl Evita recommends a minimum ratio of the drum/sheave to nominal rope diameter of 18:1.
  • Indicates that the trope has run over a small radius or edge.

Two single axial lines of broken wires running along the length of the rope approximately 120 degrees apart indicating that the rope is being “nipped” in a tight sheave.

  • Check sheave and drum groove radii using sheave gauge to ensure that they are no smaller than nominal rope radius +5%. Carl Stahl Evita would recommend that the sheave/drum groove radii are checked prior to any rope installation.
  • Repair or replace drum/sheaves if necessary.

One line of broken wires running along the length of the rope indicating insufficient support for the rope, generally caused by oversize sheave or drum grooving.

  • Check the groove diameter is no greater than 15% greater than the nominal rope diameter.
  • Repair or replace drum/sheaves if necessary
  • Check for contact damage at base of sheave groove.

Short rope life resulting from evenly/ randomly distributed bend fatigue wire breaks caused by bending through the reeving system.

Fatigue induced wire breaks are characterised by flat ends on the broken wires.

  • Bending fatigue is accelerated as the load is increased and as the bending radius decreases. Consider whether either factor can be improved.
  • Check wire rope construction – compacted ropes are capable of doubling the bending fatigue life of a conventional steel wire rope.

Broken Rope – ropes are likely to break when subjected to substantial overload or misuse particularly when a rope has already been subjected to mechanical damage.

  • Review operating conditions. Possible causes include: extreme overload, internal external corrosion of the rope, loading the rope when bent over tight radius. Rotation of a single layer rope.

Wave or corkscrew deformation normally associated with rotation resistant or low rotation ropes.

  • Check sheave and drum groove radii using sheave gauge to ensure that they are no smaller than nominal rope radius +5%. Carl Stahl Evita recommends that the sheave/ drum groove radii are checked prior to any rope installation.
  • Repair/replace drum/sheaves if necessary.
  • Check fleet angles in the reeving system – a fleet angle in excess of 1.5 degrees may cause distortion.
  • Check that the rope end has been secured correctly.
  • Check operating conditions for induced turn.

Short rope life resulting from localised bending fatigue wire breaks.

Fatigue induced wire breaks are characterised by flat ends on the broken wires.

  • Bending fatigue is accelerated as the load is increased and as the bending radius decreases. Consider whether either factor can be improved.
  • Check wire rope construction – compacted ropes are capable of doubling the bending fatigue life of a conventional steel wire rope.
  • Localised fatigue breaks indicate continuous repetitive bends over a short length. Consider whether it is economic to periodically shorten the rope in order to move the rope through the system and progressively expose fresh rope to the severe bending zone.

Rotation of the load in a single fall system.

  • Review rope selection.
  • Consider use of rotation resistant rope.

Rotation of the load in a multi – fall system resulting in “cabling” of the rope falls.

  • Possibly due to induced turn during installation or operation.
  • Review rope selection.
  • Review installation procedure and/ or operating procedure.

Core protrusion or broken core in single layer six or eight strand rope.

  • Caused by repetitive shock loading- review operating conditions.

Rope accumulating or “stacking” at drum flange- due to insufficient fleet angle.

  • Review drum design with original equipment manufacturer – consider adding rope kicker, fleeting sheave etc.

Sunken wraps of rope on the drum normally associated with insufficient support from lower layers of rope or grooving.

  • Check correct rope diameter
  • If grooved drum check groove pitch
  • Check tension on underlying layers. Carl Stahl Evita recommends an installation tension of between 2% and 10% of the minimum breaking force of the wire rope. Care should be taken to ensure that tension is retained in service. Insufficient tension will result in these lower layers being more prone to crushing damage.
  • Make sure that the correct rope length is being used. Too much rope may aggravate the problem.

Short rope life due to wear and abrasion.

  • Check fleet angles and sheave alignment throughout the reeving system.
  • Check that all sheaves are free to rotate.
  • High rope tension will accelerate wear and abrasion.
  • Review rope selection. Compacted rope will resist wear and abrasion better than conventional wire rope.
  • Consider shortening the rope or turning the rope around within the reeving system.

External Corrosion.

  • Consider selection of galvanised rope.
  • Review level and type of service dressing.

Internal Corrosion.

  • Consider selection of galvanised rope.
  • Review level and type of service dressing.
  • Consider selection of plastic impregnated rope.