A type of steam-electric railway locomotive designed by Jean-Jacques Heilmann
1890 Heilmann took out a patent for a steam-electric locomotive
1892-3 The first prototype was built. It had a horizontally-opposed two-cylinder steam engine driving a DC generator. An exciter dynamo with its own little vertical steam engine was mounted just in front of the generator.
An excellent source of information on Heilmann's first locomotive is here [1]
Two further locomotives were built improving on the initial design:
No. 8001 had a conventional Belpaire boiler supplying a Willans high-speed vertical steam engine to drive the DC generators at 400 rpm. The exciter dynamo was driven by a small engine developing 18 kW at 550 rpm. The electrical equipment was once again supplied by Brown Boveri.
The locomotive made its initial test run on 12 November 1897. The entire weight was available for adhesion, and engine produced very little hammer blow. [2]
Zoomable photograph of the Willans engine at the Willans and Robinson works at Rugby here.