Geared steam locomotive
A geared steam locomotive is a type of steam locomotive which uses gearing, usually reduction gearing, in the drivetrain, as opposed to the common directly driven design.
Locomotive
A gas turbine locomotive is an internal combustion engine locomotive consisting of a gas turbine. ICE engines require a transmission to power the wheels. The engine must be allowed to continue to run when the locomotive is stopped.
Gas turbine-mechanical locomotives, use a mechanical transmission to deliver the power output of gas turbines to the wheels. A gas turbine locomotive was patented in 1861 by Marc Antoine Francois Mennons (British patent no. 1633). There is no evidence that the locomotive was actually built but the design includes the essential features of gas turbine locomotives built in the 20th century, including compressor, combustion chamber, turbine and air pre-heater. In 1952, Renault delivered a prototype four-axle 1150 hp gas-turbine-mechanical locomotive fitted with the Pescara "free turbine" gas- and compressed-air producing system, rather than a co-axial multi-stage compressor integral to the turbine. This model was succeeded by a pair of six-axle 2400 hp locomotives with two turbines and Pescara feeds in 1959. Several similar locomotives were built in USSR by Kharkov Locomotive Works.
Gas turbine-electric locomotives, use a gas turbine to drive an electrical generator or alternator which produced electric current powers the traction motor which drive the wheels. In 1939 the Swiss Federal Railways ordered Am 4/6, a GTEL with a of maximum engine power from Brown Boveri. It was completed in 1941, and then underwent testing before entering regular service. The Am 4/6 was the first gas turbine – electric locomotive. British Rail 18000 was built by Brown Boveri and delivered in 1949. British Rail 18100 was built by Metropolitan-Vickers and delivered in 1951. A third locomotive, the British Rail GT3, was constructed in 1961. Union Pacific ran a large fleet of turbine-powered freight locomotives starting in the 1950s. These were widely used on long-haul routes, and were cost-effective despite their poor fuel economy due to their use of "leftover" fuels from the petroleum industry. At their height the railroad estimated that they powered about 10% of Union Pacific's freight trains, a much wider use than any other example of this class.