GWR AEC Railcar

Several railway companies experimented with petrol and diesel railcars in the early part of the twentieth century, the GWR had a fleet of AEC powered railcars which were arguably the most successful type to be built until the advent of the British Railway DMU in the 1950s. Indeed it can be said that the success of these railcars established the viability of diesel railcar for operation on Britain's railways in the future [1]. The first railcar entered service in 1933 operating between London Paddington and Reading though with just a single engine was considered rather underpowered having a top speed of just 45 mp/h (72 km/h), all subsequent railcars had two engines and subsequently much better performance.

Preserved W4W, a Park Royal example, at NRM York

Information
Number built:	38
Built:	1934-42
Builder:	Park Royal, Gloucester Railway Carriage & Wagon Company, GWR Swindon
Motor:	1 or 2 AEC 6-cylinder diesel
Power:	121 / 242 hp (90 / 180 kW)

The railcars were built in a number of batches throughout the 1930s and early 1940s. Park Royal built the first four, the Gloucester Railway Carriage & Wagon Company building the next thirteen. One of these was a dedicated parcels van, later railcars also had buffers and draw gear to haul stock. The rest of the fleet was built at the GWR's own Swindon works in the early 1940s. These differed from the earlier railcars in having an angular boxy exterior [2] as opposed to the Art Deco streamlined look of the earlier railcars (which had earned them the nickname of "Flying Banana"). The last few railcars built had cabs at one end only (gangways at the other) and were used in two-car sets [3].

The railcars remained in service until the 1960s used on Western Region branch lines. Three have been preserved.

Side view of W4W

W31W at London Paddington (KD Collection)

Front view of W4W

[1] Brian Haresnape, Diesel Multiple Units: the First Generation (Ian Allan, 1985) p. 11
[2] Colin J Marsden, DMU and EMU Recognition Guide (Ian Allan, 2013) p. 4
[3] Haresnape p. 10