Deflection is a problem as it changes the radius of the crane. Luffing tower cranes and lattice boom mobile cranes are less susceptible to deflection than hammerhead tower cranes and telescopic boom mobile cranes, flat top tower cranes perform worse than tower cranes with an A frame. Although deflection will vary amongst brands and models.
Other things influencing deflection levels are the tower height (the higher the tower the more deflection) whether the crane is tied in to a structure or free standing and working radius (the higher the working radius the more deflection) and the weight being lifted (more weight = more deflection)
The most common objects to cause deflection on a construction site are
Bobcats and excavators - 3t plus
Stressing cable - 3t
Precast concrete - 3t to 10t generally
When lifting with deflection the cranes tower will start to lean towards the object being lifted. Although when hooking up the load the dogman has positioned the hook block above the load, now due to deflection the hook block will be further out than the load, causing the load to swing and potentially damaging objects and structures in close proximity or even causing injury.
To rectify this the dogman should keep an eye out of the position of the cranes hook block and trolley and adjust the radius if effected by trolleying in to the centre of the load again or jibbing up if on a luffing crane.
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