Steam diesel hybrid locomotive

Examples were built in the United Kingdom, Soviet Union and Italy but the relatively high cost of fuel oil, or failure to resolve problems caused by technical complexity, meant that the designs were not pursued.

In 1926 Kitson and Company, Leeds, built an experimental example for the London and North Eastern Railway, using as their model the Still engine already in use for stationary and marine applications.

[3] Because steam power provided the torque required for starting, no form of variable transmission was necessary and a permanent reduction geartrain of ratio 1·878 to 1 was fitted.

During the trials it was used successfully with coal trains and it proved very efficient in terms of fuel used, because the waste heat from the diesel power was recovered.

Patents for the system were held by Severino Cristiani and Secondo Sacerdole in Italy and it was promoted in England by Captain William Peter Durtnall.

[7] The first prototype, numbered 8000, a 2-8-2 from the Vorishilovgrad works, had two pairs of outside double-acting opposing pistons; when diesel power was initiated, at about 20 km/h (12 mph), diesel fuel was injected into the centre portion between the pistons which thus became the compression-ignition chamber, while the outer ends of the cylinders continued to receive steam in the normal way.

It was also a 2-10-2 configuration and had the centre space in the cylinders, between the opposed pistons, intended to combine compression ignition and steam expansive working in the same chamber.

This differed from the Kitson-Still system in that there was no waste heat recovery and the steam and internal combustion engines had separate cylinders (vertically mounted in the tender), but both driving the same traction wheels.

His claimed advantages were the reduced complexity of a combined transmission system, the improved comfort of the operators being separated from the driving cylinders and the differing maintenance requirements of steam and diesel (such as boiler washouts) being more easily accommodated when the units were detachable.

In 1954 Chicago inventor Charles Denker patented a system whereby the exhaust from a conventional four-stroke diesel engine was directed into a large-diameter steam cylinder.