CSR was retained by the Harzer Schmalspurbahnen, GmbH (HSB) of Wernigerode, Germany, to engineer a new "front end" on a 1918-built steam locomotive. The steam engine number 99-5906, is an 0-4-4-0T "Mallet"-type steam locomotive that has been modified many times over its service life.

The subject locomotive 99 5906 shown at Alexisbad during instrumented temperature and pressure testing.

"The management at HSB saw the need to replace the stack on the 5906 as an opportunity to provide an operational and mechanical improvement to the locomotive," said Bernd Seiler, Department Head of Equipment Technology at HSB. "The current stack had been made in-house by staff sometime in the last few decades, and the poor design, inclusive of some 30 facets, has resulted in a locomotive that could use some improvement."

CSR was brought in by HSB to provide engineering support to the railways' mechanics. Work began in July 2014, with the instrumentation and testing of the 5906. CSR employed National Instruments software and a variety of digital instruments to record the 5906 under real world test conditions. The successful completion of such tests is something which CSR believes has yet to be accomplished with such granularity on any steam locomotive.

"The opportunity to outfit a working steam locomotive with a host of temperature and pressure sensors, all of which fed into a monitoring computer system, is the type of innovative research we strive to make a reality here at CSR," explained Wolfgang A. Fengler, MSME, a Technical Advisor for CSR. "The results of the instrumentation and testing on locomotive 5906 is a second-by-second digital report of the Rankine cycle at work. The tools we have at our disposal now are something the engineers designing these locomotives could have only dreamed about a hundred years ago."

Testing was completed in August 2014, since which time CSR has been completing detailed engineering of an advanced, "Lempor" exhaust nozzle and stack. Key to the work on behalf of HSB is that improvements performed on the steam locomotive not impact the historic appearance of the engine. That in mind, it is anticipated the Lempor exhaust will increase the power of the locomotive and decrease fuel consumption.

In addition to adding a Lempor exhaust, CSR is designing what is known as a "Master Mechanics Front End," a system of baffles and spark-abating netting commonly used in the smokeboxes of U.S. steam locomotives but which saw little use in Germany. This new system will decrease the risk of starting lineside forest fires while improving the flow of hot gases through the smokebox.

"We have a locomotive that was designed in the 1890's to operate some 25 to 30 km between service stops that is being used here on the HSB to run 180 km or more before servicing," explained Seiler. "We view our work with CSR as an opportunity to minimize wear and tear on the engine, decrease coal consumption and increase the power and reliability of our motive power. If we can make the locomotive a better tool without impacting the historic integrity, we get a win-win."