DEUTSCHE BAHN and Stemmann-Technik are collaborating on a project to develop an actively-controlled single-arm pantograph capable of operation at up to 400 km/h.

The design will be an evolution of Stemmann's existing DSA380 model that is already in production, which is approved for speeds in excess of 320 km/h. The company has decided that developing a new pantograph to meet the required specification for each incremental increase in operating speed beyond 320 km/h would not be cost-effective, therefore a product range that can operate comfortably at up to 400 km/h is envisaged.

Initial technical studies into active pantograph development were carried out by DB in co-operation with Bombardier, but in 2005 Stemmann-Technik took over Bombardier's share of the project, and it is now working with DB to assess the product's suitability for series production.

The basic technical parameters such as mass distribution, kinematics and collector head configuration form the basis for all pantograph design. However, for a pantograph capable of speeds above 320 km/h, Stemmann has set a number of additional objectives that must be achieved. These focus on a decrease in contact force variations by means of an active control, a decrease in acoustic emissions achieved through modified pantograph design, and continuous online diagnosis of the contact wire and associated catenary.

The active pantograph employs a closed-loop system that controls force maxima and minima resulting from the aerodynamic conditions and vibration. This should enable the pantograph to operate at higher speed without modification as existing infrastructure is upgraded or new lines built.

The active control also reduces static contact force and thus the wear at the catenary wire and contact strips. This should reduce the maintenance costs for both the pantograph and overhead line equipment. Continuous online condition monitoring of the overhead line is also possible using sensors that are attached to the pantograph.

Stemmann currently has five examples of the design undergoing static testing. Aerodynamic evaluation is taking place in a wind tunnel, while operational tests are being carried out on DB Systemtechnik's test rig in München. Stemmann-Technik anticipates fitting the pantograph to a DB high speed trainset in the second half of the year for a two year programme of in-service testing.