Working Load Limit

The WLL (Working Load Limit) for each hoist
has been calculated to suit the maximum travel and wire rope selection stated. The term ‘Travel’ indicates the extent (in metres) for which the hoist is designed to raise or lower, e.g. the distance between the top and bottom limit settings. This would also indicate the maximum amount of wire rope that can be applied to the drum assembly. The WLL is calculated at the hoist. All potential loads being applied within the application should be considered when selection is made.

The factor of safety for hoist wire ropes is subject to the number of ropes used and how the load is distributed. Based on a uniformly distributed load a minimum factor of 10:1 is maintained. Individual ropes are sized to sustain up to 40% of the WLL, still maintaining a factor of 10:1. Typically on a 3 line suspension bar, the centre line shall sustain up to 70% of the WLL and still have a minimum safety factor of 10:1.

Limit Switches

Rotary limits for, top and bottom (working) and ultimate switches are mounted on each unit, chain driven to govern the extent of travel required. The limits are easily adjustable and should be set and tested on installation.

5 5        Limits