Case Studies

Zwiehoff Shunters

June 2, 2023



At a steel plant in Bremen, Germany, operating company, Hansebahn, has the job of moving so-called torpedo cars, containing molten pig iron, from the works to the rolling mill, where it is processed. After they are emptied, they need shunting back to begin the process again.


For efficiency reasons, the client wished to use electric shunters and approached the manufacturer of our innovative ROTRAC products, Zwiehoff, who agreed to begin trialling its largest unit, the E4, to meet Hansebahn’s capacity requirements. Fully loaded, each torpedo car has a gross weight of 1,000 tons.

The ROTRAC E4 can trail loads of up to 500 tons, so Zwiehoff coupled two units together, using a master/slave configuration on the remote control. Both machines could then be operated simultaneously by one user.


Initially, Zwiehoff’s approach proved satisfactory, however, over time, it became apparent that the E4’s standard batteries did not hold enough power to complete all shunting manoeuvres. Partial charging was necessary whilst the torpedo cars were being loaded or unloaded, but unfortunately, this is not possible with the lead acid batteries used as standard on the ROTRACs.

Zwiehoff worked closely with Hansebahn to find a solution and create a bespoke product that met its requirements. Larger capacity lithium-ion batteries, which are already being used in the forklift sector, were sourced. Their compatibility with incomplete charging makes them ideal for this application and allowed the shunters to perform perfectly in these challenging conditions.

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