Experienced crane and hoist customers know that rope guides are an expensive component and prone to regular failure on some models of hoists.
When unloaded, the stiffness of steel wire rope creates a natural de-coiling force which can pull a rope through a single-band rope guide causing the rope to become unseated from the machined scroll. This is known as “slack rope”.
Slack rope can occur during transportation or inadvertently during use as the operator lowers the hook block onto an object. This condition is not always obvious to the operator as it is often hidden behind the covers on the hoist but if it is not removed before continuing, the guide can gather the slack rope and collide with it damaging the rope, the guide or even the hoist unit itself!
ZX design prevents slack rope occurring.
The ZX hoist has a unique rope guide design consisting of two bands which prevent a slack rope condition from forming on the drum. An inner band clamps tight onto the rope preventing de-coiling whilst an outer band seats around it ensuring the rope is guided into the correct drum scroll. Both parts of the rope guide are machined to allow easy removal and fitting during a rope replacement and manufactured from a tough, wear-resistant synthetic polymer designed to last the lifetime of the hoist.
We don’t believe you will find many suppliers who include a double band.
There is a tendency to jump to the conclusion that a rope guide has failed due to the operator side pulling. In our experience, “slack rope” is a far more common cause of failure in those hoists with single-band rope guides.
In relation to side pulling, cast iron rope guides have long been considered the least resistant to failure followed by steel rope guides because they have very limited flexibility before they break or permanently distort. Due to their characteristics, cast iron and steel rope guides are more prone to permanently damaging the strands of a steel wire rope.
We’ve also included a summary of these points in our ZX hoist brochure shown below.
If you would like more information or advice on how our ZX range can benefit your business please complete the form below or contact a member of our sales team.