Rapido Trains Inc. has a reputation in North America for the exceptional level of fine detail incorporated into its rolling stock. Our partnership with  Rails of Sheffield and the National Railway Museum to produce a ‘OO’ gauge model of the LNER’s record-breaking dynamometer car No. 23591 gave us the opportunity to bring this high level of detail to the UK market.

Best known as the vehicle that recorded the 126mph run of LNER ‘A4’ No. 4468 Mallard  on July 3 1938, the North Eastern Railway’s test car, built at Darlington Works in 1906, is now on display at the National Railway Museum, where it has been reunited with Mallard.

A Dynamometer Car scientifically measures the performance of locomotives in order to effect improvements. Inside, instruments measure the speed, power and other statistics of locomotive performance, many of which were applied to a paper trace operated mechanically from the movement of the vehicle. The NER’s vehicle was also equipped with a drop-down bed hanging in the ceiling for operators to sleep in. It was also fitted with equipment to allow operators to speak to the driver. 

No. 23591 passed into LNER ownership after the Grouping of 1923 where Chief Mechanical Engineer Sir Nigel Gresley used it extensively to test his new designs and modifications against established locomotives. It was even used behind the UK’s only steam-diesel hybrid locomotive! 

The Dynamometer car and its paper trace recorded Mallard’s top speed of 126mph on Stoke Bank in 1938. The vehicle eventually passed into British Railway ownership and continued to be used for scientific testing including the famous 1948 Locomotive Exchange Trials. The Dynamometer Car is now preserved as part of the National Collection at the NRM in York. 

Two versions have been produced, depicting No. 23591 in July 1938 LNER teak condition, as it was during Mallard’s world speed record run; and post-1946 LNER teak with its later number – No. 905202 – as seen during the famous 1948 Locomotive Interchange trials. 

This ‘OO’ gauge model of No. 23591 was the first of a series of products released under the ‘Rails Exclusive’ brand of high-quality, collectable ready-to-run models, produced exclusively for one of the UK’s largest model railway retailers, Rails of Sheffield. Based on detailed research of the prototype, archive photographs and official drawings, the ‘Rails Exclusive’ model featured exceptional interior and underframe detail, including depictions of the recording equipment and the additional speed recording wheel between the bogies. The model was critically acclaimed by modellers and the modelling press and, in 2019, was voted by the readers of Model Rail magazine as ‘Coach of the Decade’ in its Model of the Decade awards! 

It’s perhaps no surprise that all Dynamometer Cars have sold out but you can click HERE to explore the range of exclusive products from Rails of Sheffield. 

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