1. How do I calculate the WLL (working load limit) of my wire rope?


    The working load of a wire rope depends on the intended use for the wire rope.

    For lifting slings, the safety factor is 5 to 1. So, to calculate, the minimum break load is divided by 5, then allowances for the type of end termination or the way it is being used must also be considered (I.E.: if choked a reduction of 20% is applied). 

    Ropes used in other applications may have differing safety factors applied. Those used in staying applications or the forestry sector work on a 3 to 1 safety factor. For ropes used on cranes, the safety factor depends on the classification of the cranes, which can be found in ISO 16625.

  2. Which wire rope should I use on my crane?


    This will depend on what type of crane is it and which rope on the crane are you looking to replace.

    For auxiliary hoist ropes and most main hoist rope applications, a low rotation rope such as Dyform 34LR should be selected. For boom hoist applications Dyform 8PI or Dyform 6 are the best options. 

    Always refer to the manufacturer’s specifications or refer to the test certificate for the current rope on the crane.

    For more information about the crane ropes that Cookes offer, browse our crane ropes or download our wire rope brochure to learn more.

  3. Does the type of end fitting alter the rope's capacity?


    Yes, most end termination will reduce the WLL of your wire rope although there are some that give 100% efficiency.

    • Turn back eyes with a ferrule termination give a 90% efficiency rating.

    • Wedge socket terminations and hand splices give a 80% efficiency rating.

    • Spelter sockets fitted with either resin or white metal give a 100% efficiency rating.

    • Swage studs & Swage sockets give a 90% efficiency rating.

  4. How can I extend the life of my wire rope?


    There are a number of ways to extend the life of a working rope:

    1) Lubrication – wire rope is a machine usually made up of 200 to 300 wire which move independently to one another whenever a rope operates around a sheave or spools off a drum, therefore ensuring ropes are lubricated internally reduces the level of friction between the individual wires optimizing the ropes bend fatigue performance. 

    2) Dyform – Dyform ropes are manufactured with strands that have been manufactured oversize and are then drawn through a series of rollers before being closed around the core to make the finished rope. This compaction shapes the wires allowing them to move more smoothly when operating around a sheave or spooling off a drum thus increasing the bend fatigue life. The smooth outer surface of the strand has a better contact area with the sheave or drum which also adds to the rope life.   

    3) Increasing the diameter of the sheave or winch drum. The larger the sheave or winch drum the less stress the rope is under the longer its service life will be. 

    4) Increasing the number of wires in each strand – simply put the more wires that there are the easier they will bend meaning the longer your ropes service life will be. However always take into account smaller wire do not offer good resistance to abrasion so if wear is one of your ropes’ key failures, then a compromise might be your best option (refer the X Chart below).


    For more information about extending the life of your wire ropes, download our guide. 

  5. What diameter of sheave or drum should I use?


    When designing any rope operating equipment, designers should consider the relevant national and/or international standards based upon the application/industry ETC. 

    The diameter of the sheaves and drums together with the tension are normally associated with the overall service life of the rope. In simple terms, the larger the diameter, the longer the service life. 

    Typical diameter of sheaves and drums for crane applications are 16 to 28 times the nominal rope diameter.