THE APT in the course of time

The history of the mobile flash-butt welding machine

At first, electrical flash-butt welding was only possible in stationary plants, whereas the alumino-thermic procedure was reserved for mobile welding. In view of the outstanding quality of the flash-butt welding machine, the call came very early to be able to use this method on track work sites too.

1973: K 355 PT

In 1973, Plasser & Theurer built the first mobile flash-butt welding machine: the K 355 PT. Austrian Federal Railways (ÖBB) was the first railway company to operate it. The K 355 welding unit was supplied from Ukraine and installed in a Plasser & Theurer machine.

1986: K 355 APT LKW

To extend the field of application of the APT 500, a mobile welding machine, travelling not only by rail but also by road, was required.

1995: APT 500

In 1995, the new, improved APT 500 series was put into operation. Both the design of the welding head and the electronic equipment and controller had been improved.

1998: APT 500 S

The rail pulling device makes it possible to perform closure welds of long-welded rails far below the neutral rail temperature.

2002: APT 600 S

The four-axle APT 600 is built in standard railway vehicle design. The use of the rail tensioning unit makes it possible to perform closure welds below the target temperature.

2011: APT 1500 RA

Development and construction of the APT 1500 R welding robot allows for the automatic geometrical alignment of the rails and the automatic welding process. Closure welding without pulling device, approval in compliance with EN 14587-2, automatic analysis.

2013: APT 1500 RL

Following the successful market launch of the on-track APT 1500 RA, the road/rail welding machine APT 1500 RL was implemented. Thanks to its low weight of 32 t, the permissible maximum weight for transport by road is not exceeded. This allows the machine to travel on roads without additional permits.

APT 1500 RC

The APT 1500 RC is a welding machine in container design: the welding head and all its components – drive engine, generator and electronic controls – are mounted on a standard container (30 ft or 9,125 mm). This allows the welding machine to be transported easily to any work site either on a flat bed trailer or using a semi-trailer truck.


More than 20 machines of the APT 1500 series have been supplied. The prototype of the APT 1500 R welding robot has performed more than 12,000 welds.

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