This post was written by Ryan Graham from Work Safety QLD – View Original Post Here
High winds pose a risk to tower cranes when they are not in operation. If a tower crane is left with its slew brake engaged or with the jib parked at too small a radius, it could potentially result in very high loadings being placed on the crane causing a collapse of the jib or even the whole crane.
To mitigate the risks, our procedure at Falcon Cranes is to weathervane our tower cranes when they are not in use, as per the manufacturers recommendations.
What Is Weathervaning?
Activating weathervaning or “free slewing” mode on a tower crane essentially allows the crane to slew with its full 360 degree radius freely in the wind, just like a flag.
Due to the surface area of the front jib being much larger than that of the rear or the counter jib, the front jib will follow the wind direction, and the counter jib will point against the wind.
This orientation minimises the surface area exposed to the force of the wind, which reduces the wind “pressure” exerted on the crane structure, thus minimising the risk that the wind could “push the crane over”, or cause damage to the super structure under high loadings.
What Are Falcon Cranes Procedures?
Falcon Cranes operate a fleet of Comansa and Potain tower cranes that can be placed into weathervane both manually, with a lever and push button on the top of the slew motor, and also automatically with the use of a dedicated pushbutton, either in the cabin or on the base electrical panel.
Both manual and automatic weathervane procedures are explained in the manufacturer’s manuals present with the cranes on all sites and are also explained in the plant specific Operator Inductions.
How To Tell If A Crane Is In Weathervane Mode
It is possible to tell from the ground whether or not a tower crane is in weathervane mode simply by looking for tell-tale signs, e.g. the direction of roof-top flags or other tower cranes nearby.
Please note that all Falcon Cranes tower cranes will be left in weathervane mode over the Christmas break!