The International Steam Pages


Brief case for an investigation to be made into the suitability of modern
steam locomotive production in areas with heavy production capability.

Ted Pritchard. writes:

Synopsis. Opportunities for employment are required in certain areas where there is availability of heavy production capability. The production of modern steam locomotives would suit these conditions. Following, it is briefly set out why this type of locomotive is now a very desirable product with regard to:- Low pollution, Multi-fuel capability, High Power, High Tractive Effort, Moderate Initial cost and "User-friendliness" to the rail track. Some features of two main design improvements leading to these enhancements of the "classic" steam locomotive are discussed initially.

DESIGN IMPROVEMENT NO. 1. Use of 90 degree " Vee" 2 cylinder Uniflow Engines on each driving axle. The drive would be through bevel gears like a road truck or rear- wheel drive automobile. The engines would be compact and weigh no more than half of the weight of the electric final- drive motors in diesel-electric and electric locomotives.

Use of Uniflow engine gives high efficiency. Conventional locomotive steam engines use the same valving and steam passages handling both the hot inlet steam and the relatively much cooler exhaust steam. This leads to cooling of incoming steam and is so wasteful that it cannot usefully [efficiency-wise] expand steam to a ratio more than approximately 2.5 to 1. The Uniflow engine is designed differently and has minimal wasteful effects and can operate at 10 to 1 expansion ratio. It will out- perform a "simple" conventional engine at all cut-offs. It also compares well against multiple- expansion steam engines. {Ref. Low's "Heat Engines" 1942.] In earlier days, the newly-developed Uniflow engine began to compete well against the steam turbine and the diesel. See P258, "Power From Steam", by R L Hills, 1995.

DESIGN IMPROVEMENT NO 2. Use of Powdered Coal Burner as tested in the 1950s by the Victorian Railways Dept and the State Electricity Commission. This was very favourably reported on:- "..during trials .. no trouble was experienced with the operation of the [Stug/Henschel] dust firing equipment……Advantages:- [of powdered brown coal as against grate fired black coal]..improved cab cleanliness, reduced noise, no hand firing and fire cleaning, uniformity of fuel, improved steaming, elimination of smoke, spark hazard and spark arrestor cleaning, less arduous and more congenial work for the fireman…" Written by the former Engineer in charge of Research, State Electricity Commission of Victoria, Mr H Herman in his book "Brown Coal." 1952.

A. LOW POLLUTION. It has been discovered that utilising diesel fuel in diesel engines produces what could be the most cancerous substance known to man in the minute particulate material in the exhaust called- "nitrobenzanthrone." ["New Scientist," 25th Oct, 97.] It is thus of great concern to utilise diesel engines in populated areas.

It is generally accepted that "external combustion" as used in steam plants minimises emissions. In fact "external combustors" known as "thermal reactors" or "catalytic converters" are added-on in the exhausts of practically all petrol motor cars sold in Australia.

B. MULTI-FUEL CAPABILITY. Steam power can be designed to utilise more different fuels than any other power unit. Wood, bagasse, straw, peat, brown and black coal, petrol, kerosene, distillate, crude oil, alcohol, gas and also solar heating have been used. Wood fuel, grown in plantations along the track, has been used. This is now considered an environmentally excellent system as the carbon dioxide generated by combustion in the locomotive is countered by the carbon dioxide taken up by the growing of the wood fuel crop. The fuel supply is of course sustainable.

Petroleum fuel is in increasing short supply. However, coal supply is expected to last at least several hundred years. Thus coal fuel is valuable and can be considered as a "stop-gap" fuel for use until practical sustainable fuel systems are developed and in full use.

C. HIGH POWER. High power has been available even with conventional classic steam locomotives. The world record breaker "Mallard" which achieved 126 MPH in 1939 used a standard old fashioned grate system and hand firing. With design improvements such as the two above, leading to approximately double the power to ratio as compared to the classic design, there should be little trouble in achieving the required high power in the modern design.

D. HIGH TRACTIVE EFFORT. Without the limitations of the rigid wheelbase of wheels driven via coupling rods which applied to the classic steam locomotive, there is greater freedom in the design. Higher tractive effort per ton of locomotive is now possible. For freight work which requires very high tractive effort, the Garratt type may be chosen. Eg.- with 2-8-2 / 2-8-2 or even 0-8-0 / 0-8-0 wheel arrangement. With higher power and tractive effort available, fewer locomotives would be required on heavy trains.

E. MODERATE INITIAL COST. Because of "Low" or "Moderate" technology used in steam locomotives as against the "High tech." in diesel locomotives with their electric transmissions, cost per unit power for steam has been 30 to 50% lower in the past. With the two design improvements [above] incorporated in the modern steam locomotives, this cost advantage should be at least maintained.

F. TRACK USER-FRIENDLINESS. With a balanced Vee engine geared to each axle, large driving wheels are no longer required - saving space and weight. "Hammer Blow" on the track from balance weights on the wheels which are no longer required, is eliminated. The vertical component of the connecting rod force on the track, which on classic steam can increase wheel loads 40%, is eliminated. Coupling rods are not required. More weight is saved. However, wheel slip control is now desirable. Governor-throttles on each engine are recommended.

Compared to diesel, halving the weight of the unit driving each axle [Vee engine versus electric motor] greatly eases unsprung weight per wheel causing less track impact.

CONCLUSION. The two main improvements are shown above to transform the steam locomotive to give superior performance in all vital areas like power, low pollution, low cost and multi-fuel capability. It is well worthy of further study to confirm its suitability for production thus assisting in creating valuable employment and rejuvenating business.

Ted Pritchard, FMTC Mech Eng, Auto Eng., Hartnett Award., Grad Dip Ed., 22nd January, 2001.


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