The CONEG DMU Workshop
The need to address
moderate volume rural and suburban commuter services has led to a revival of interest in
the diesel multiple unit (DMU) car as a cost efficient, clean transportation mode. The
long term availability of low cost fossil fuels has also encouraged the study of fuel
alternatives from renewable sources. To encourage a productive exchange of ideas on these
subjects, the CONEG High Speed Rail Task Force sponsored a DMU Workshop on October 18
& 19, 1995, to review non-traditional solutions to intercity passenger needs. The
workshop, which drew over 100 people from the region, across the United States, Canada and
western Europe, examined technical advances in this equipment; its operating and financial
feasibility; and policy issues dealing with mixed passenger/freight service and safety
issues. This issue of Transportation Matters is devoted to a technical summary of the
workshop proceedings.A Short History of the Rail Diesel
Multiple Unit Car in North America
Guest Editor: Jerome R. Pier, PE, Technical Consultant,
Allied International Corporation. Mr. Pier has been active in the rail transportation
industry since his graduation from Penn State in 1950. He has written numerous technical
papers dealing with energy use and air pollution in the rail industry and has been a
supporter of the CONEG High Speed Rail Task Force since its inception.
RDC-1 during an excursion on Cape Cod in 1995 (photo
provided by Cape Cad Railroad, Marion, Massachusetts.)
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While the first diesel powered unit train, the Budd-built Pioneer
Zephyr, appeared in 1934 and was followed by a number of similar light-weight diesel unit
trains without locomotives, the DMU as we know it first appeared in 1949. Built by the
Budd Company and designated the RDC or Rail Diesel Car, it was intended to offer MU
service in non-electrified territory, providing performance suitable for schedules similar
to electric MU cars with minimum capital and maintenance costs. The implementation of
these goals resulted in the RDC-1 shown here.
The power train consisted of two Detroit Diesel 275 Hp engines connected to
reversing Allison torque converter transmissions driving gear boxes on the inboard axles
through cardan shafts. This provided a Hp/T ratio of 8.68:1, sufficient to produce an
initial acceleration of 1.4 mphps and a maximum governed speed of 85 mph. The engine power
was upgraded to 300 Hp in subsequent production and Twin Disc Transmissions replaced the
Allison Transmission. Braking was provided with two inboard disc brakes/axle. The system
provided retardation as high as 3.5 mphps in emergency and 2.8 mphps in service. The RDC
was suitable for multiple unit control in consists up to 6 cars. One of the obvious
advantages of the concept was that a train could be operated with a crew consisting of a
motorman and a conductor and, being doubled ended, could operate without turnaround
facilities.
When RDC production stopped in 1962, more than 400 units had been delivered
worldwide with the majority of these being in North America. The RDC met most of the goals
set forth above, not the least of these being a claimed return on investment of 25%. It
was well liked by the railroads' passenger operations people, but the railroads by this |
