Stacking up

A Swiss distributor of plumbing materials uses an electric overhead travelling crane to handle steel and copper tubing, bar profile and other long sections at its warehouse in Geneva.

An innovative solution needed to be found to the problem of handling and storing unwieldy loads of both ferrous and non-ferrous material without having to make time-consuming alterations to the crane each time the load material changed. The crane was designed, built and installed by Brun (now called Brun-Mech Kransysteme).

Inside the building, which is 17m wide and 55m long, bar and tube sections up to 6m long are handled and sorted for redistribution. Brun-Mech’s solution was to put the bundles in cradles or baskets which are stacked on top of each other to save floor space.

The crane is an underslung design which allows the crab or trolley to leave the crane and move to a gantry to travel outside the building for unloading and loading trucks and railway wagons.

Most of the loads are ferrous material so handling is mainly carried out by two electro-magnets which each have a safe working load of 2t. The crab uses Brun-mech’s standard compact heavy duty hoist, the BM 11, which is built to class FEM 2. A special rope fall arrangement restricts swaying of the load when the crane accelerates or slows down, thus helping the operator to accurately position the cradles for easier stacking. Each magnet has a pair of studs at the end which, when swivelled through 90°, allows the baskets to be hooked on and used instead of the magnets.

The traverse which holds the electro-magnets has a rotating mechanism and is also fitted with auxiliary hooks which enables the crane to handle other loads which cannot be taken by a magnet or in the cradles.

A voltage regulator housed in the pendant push-button control station allows the crane operator to increase or reduce the flux to alter the force of the magnet. The operator can thus choose exactly how many ferrous pieces to extract from the cradle without having to pick them out from the pile one by one. An illuminated signal indicates when the electro-magnet is under power and starts flashing when the operation begins.

Since the installation of this stacking crane, and its subsequent successful operation, Brun-Mech – which is based in Nebikon, Switzerland – has installed three similar systems in the Czech Republic for steel merchant Ferona.