Roger Waller

Dipl. Ing. Roger Waller and his company DLM

After graduating in Switzerland, Waller was employed by the Swiss Locomotive Machine Works (SLM) at Winterthur. In 1982 he joined the South African Railways and worked as an assistant to David Wardale during the latter stages of the tuning-up and testing work on the Red Devil.

He returned to SLM in 1984 and was responsible for the development of the Class H2/3 rack locomotives, first built in 1992 and now in service in Switzerland (on the Brienz Rothorn Bahn) and in Austria (on the Schneeberg Schafberg railway). These engines embody a number of advanced features, including light oil firing giving very low exhaust emissions and allowing one-man operation on the low-speed mountain railways on which the locomotives are used. By comparison with the 1933 design from which they were developed, the new locomotives are 25% lighter and develop 36% more power, this resulting in 61% less fuel being consumed per passenger trip, with a top speed 56% higher. They are thus operationally equivalent to diesel locomotives yet retain the commercially important appeal of steam traction.

In Feb 2003 Waller presented a paper titled “Modern Steam – An Economic and Environmental Alternative to Diesel Traction” to the Institution of Mechanical Engineers Railway Division under the auspice of the “Sir Seymour Biscoe Tritton Lecture”.

Following on the success of these locomotives, Waller and his team at SLM extensively rebuilt ex-Deutsche Reichsbahn 52 Class 2-10-0 No. 8055, which incorporates some of the features of the rack tanks, such as light oil firing and ultra-thick thermal insulation. This rebuild was first tested in 1999 and after a period of inactivity in Germany (caused by regulatory authorities), the locomotive returned to Switzerland in 2003 under the ownership of DLM where it is expected to operate regularly on Orient Express and other special services.

S/S Montreux

In 2000 the steam group at SLM (by that time re-named Sulzer Winpro Ltd.) separated from the main company through a management buy-out, the new company, Steam Locomotive & Machine Works DLM Ltd. (DLM), concentrating entirely on steam technology, with Waller as its Vice President and CEO.

In addition to work on steam locomotives, DLM inherited a contract for the supply of a new steam power unit to replace a life-expired diesel engine on the paddle-steamer S/S Montreux.   – see for further information.

Puffing Billy Railway No 14A newly fitted with oil-firing.

In recent years, Waller purchased two fireless steam locomotives for the purpose of promoting this form of traction for industrial use.  One of these has been modified with a few modern features including solar panels on its cab roof to replace its steam turbogenerator.  See for further information.


Most recently, Roger was engaged by the Puffing Billy Railway in Victoria, Australia, to convert one of their locomotives to oil-firing.  This work was completed in 2018.  See for further information.