BYLINE: Dipl-Ing Gerd Ahne and

Dipl-Ing Gerd Truckenbrodt*

BYLINE: * Dipl-Ing Ahne is PumA Project Manager and Dipl-Ing Tuckenbrodt is Head of Projects at PFA GmbH

ON SHOW at the InnoTrans exhibition this month in Berlin will be the first production version of a PumA coach for German Railway’s regional services. The PumA concept of rebodying old vehicles was developed by Partner für Fahrzeug Austattung GmbH, which built a prototype in 1995.

After intensive negotiations with German Railway, the company won an order in 1996 for 55 PumA cars. PFA had previously been refurbishing former German State Railway Type Bmh2329 coaches for Regional Express routes, but the discussions with DB concluded that rebodying using PumA technology was a better option. As a result, PFA’s Regional Express refurbishing programme begun in 1994 was wound up.

Starting point for the PumA rebuild was a study of the work required for the previous refurbishment programme. Analysis revealed that high costs were incurred in restoring the bodyshell and underframe to good condition, but there was no technical improvement to show for the expense.

This led to the idea of replacing the old 26·4m body with a structure that could be prefabricated in a cost-effective way. Body segments assembled in adjacent workshops would be mounted on the old underframe in place of the old sidewalls and roof. The advantages included: avoiding the cost of reconditioning bodyshells; the ability to automate assembly of the prefabricated elements and to use industrial production methods for fitting the interior; reduction of the time taken to complete the process; and a much more attractive exterior.

Materials choice

Once the basic decision had been taken, PFA investigated the merits of steel and aluminium bodyshells. Using criteria ranging from the need to fit in with the existing production process to weight reduction potential and minimal technical risk, Alusuisse was chosen as a development partner. Other considerations included low investment costs and the need for the body elements to form part of the load-bearing structure. The result was the concept chosen for the 1994 prototype which retained the steel underframe, used prefabricated aluminium sidewalls, bolted joints between the body sections, and a roof formed of glued sandwich elements.

Cost savings were immediately obvious in terms of a shorter assembly time, but an overall saving was not achieved because of a decision to incorporate air-conditioning and a passenger information system. Analysis reveals that the total cost of rebodying is the same as refurbishment, but rebodied cars should be much more attractive to passengers.

Two types

The build of 55 vehicles includes 11 driving trailers. Starting again from a Type Bmh2329 second class DR coach, the underframe has to be modified for the different door configuration. A steel profile is added to form the link with the aluminium sidewalls. The driving trailers also receive a block structure to which the self-supporting driver’s cab is later glued.

The side and end walls are assembled from welded aluminium extruded profiles which are bolted to the steel profile on the undeframe. Structural strength is increased by cross-members at roof level; the roof is formed of glued sandwich elements.

To allow standard fittings for all the intermediate second class coaches, the driving trailers incorporate the first class accommodation and special requirements such as features for disabled people. Behind the cab is a 22-seat first class saloon, an entrance area with single-leaf sliding plug doors, and two five-seat first class compartments; the saloon’s location means that passengers will not be disturbed by people walking through the train. Those seated facing forward will enjoy a view of the track ahead through a glass partition at the rear of the cab.

A multi-purpose area with folding seats and space for cycles is located in the centre of the car, and at the rear is an office and wheelchair-accessible toilet. An eight-seat second class saloon with wheelchair space completes the accommodation.

The intermediate cars are divided into three saloons with 25, 38 and 23 seats. Twin-leaf sliding-plug doors are controlled by the driver. Passengers need only move the handle to activate internal doors.

Compact air-conditioning modules are mounted in the roof over the entrances with deep air intakes over the doors so that there is little risk of the equipment sucking in exhaust fumes from a diesel loco. The cab is also air-conditioned.

Ribbon glazing is glued to the sidewalls, and the first class windows are fitted with roller blinds. Post-formed interior panelling is used.

The passenger information system includes screens in all saloons and exterior displays for passengers on the platform. An emergency call point is provided at each entrance and in the wheelchair-accessible toilet; all toilets are of the vacuum-retention type.

Reconditioned bogies with disc brakes are taken from Type Bm281 cars converted to Intercity driving trailers which have been fitted with new running gear and load-sensitive brake equipment.

Spin-off benefits

The rationale behind the PumA programme was entirely based on economic considerations, but there were a number of environmental spin-off benefits. Compared with scrapping and remanufacture, reuse of the bogies and underframe achieves an energy saving equivalent to the needs of an average German household over 30 years. As many as 150 components such as buffers and brake valves were recovered from other vehicles and reconditioned; the benefit of this compared with straight use of replacement parts is substantial, but difficult to quantify.

Thanks to use of aluminium and other light materials, weight of the intermediate cars was reduced from 40 to 39 tonnes, despite the addition of air-conditioning, a closed toilet system and other equipment. Assuming each car runs 225000 km a year, annual energy savings equate to the amount of energy consumed annually by three average German households. In practice, the saving is not achieved, as energy is required to power the air-conditioning.

Co-operation between PFA and DB in the rebodying programme suggests that there is a considerable future for PumA-based technology. Experience gained with the project highlighted the limits and possibilities, revealing that major work on the underframe or bogie quickly notches up high costs. It is clear that options for refurbishment, rebodying or new build depend on different circumstances and requirements, but the ability to produce as-new vehicles on a series production basis is an important success criterion. o

CAPTION: Driving trailers nearing completion in the PFA works at Weiden

CAPTION: Before and after. An old DR coach has been transformed into an attractive air-conditioned vehicle

CAPTION: Aluminium sidewalls have been bolted to the steel underframe; the roof is formed of glued sandwich elements


1. Günther Dr D, Ansätze beim Umbau von Reisezugwagen. VDI Berichte 1089, VDI-Verlag 1993.

2. Schwarz, Schlosser, K