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A “Transformer” for maintaining tube trains used by London Underground

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A “Transformer” from Pfaff Rail Systems for maintaining tube trains used by London Underground

At Ealing Common depot, a railway service workshop of London Underground, the Tube trains used on the District line will now be maintained with the aid of a lifting system from Pfaff Verkehrstechnik GmbH, Kissing (Germany). On account of its futuristic design, the maintenance staff have nicknamed the versatile and unique dual-purpose system the “Transformer.” A total of 28 stationary hybrid lifting jacks from Pfaff Verkehrstechnik with bogie lifting beams and body supports raise and hold the trains measuring up to 117 m long up to 1.44 m high, thus granting the engineers the greatest possible and safe access underneath the vehicle.

Frequency converters ensure precision lifting
The versatility of the lifting system from Pfaff Verkehrstechnik lies with its ability to lift the Tube trains either as one complete unit or individual carriages for maintenance purposes to an infinitely adjustable, ergonomic height. The 28 jacks lift up to 280 tonnes total weight and the supports can carry a load of up to 196 tonnes. This is a task that requires utmost precision. If a complete train is lifted, the lifting process of the Pfaff-silberblau jacks runs precisely synchronized with a deviation of less than ± 2 mm. The worm gear screw jacks owe this precision to a series of frequency converters, which also permit differing lifting speeds within the system.

Pfaff_Verkehrstechnik_LondonMetro03Once the vehicle has been lifted, the next components of the hybrid system are ready to go into action. The jacks feature additional, motor-driven supports for holding up the carriage bodies. This in turn makes it possible to lower the individual bogies back down onto the rails and to roll them out from underneath the raised vehicle. Large, bright LED lights integrated into the lifting beams ensure the effective illumination of the work area under the raised vehicle.

Once the Pfaff-silberblau system is lowered, the lifting beams mesh together with the main rail and sit flush with the floor. As soon as the lifting beams go up, they are followed by gap covers, thereby resealing the recesses (which would otherwise remain open), such that they can be stood on.


The lifting system and the work processes are controlled via an easy-to-use touch display, which also enables the maintenance staff to check the status of all the major system components at all times.

Cost-efficient concept hybrid lifting jack system
Pfaff Verkehrstechnik has developed the new concept of a hybrid lifting jack system as a cost-effective alternative to the established underfloor lifting and support systems. It offers excellent value for money, not least due to the fact that the extremely shallow pit depths require significantly less foundation work.

The motion technology for the lifting system from Pfaff Verkehrstechnik GmbH was developed by the sister company also based in Kissing: Columbus McKinnon Engineered Products delivered the sophisticated Pfaff-silberblau screw jacks as an integral component of the system used for lifting and supporting the London Underground Tube trains.

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