GWR railcars

GWR railcars
standard gauge

In 1933, the Great Western Railway introduced the first of what was to become a successful series of diesel railcars, which survived in regular use into the 1960s, when they were replaced with the new British Rail "first generation" type diesel multiple units.

The original design featured streamlined bodywork, which was very much the fashion at the time. The rounded lines of the first examples built led to their nickname: "flying banana". The preserved W4W is an example of the original, rounded body shape. Later "razor edge" examples, such as No. 27 (pictured), had much more angular (and practical) bodywork, yet the nickname persisted for these too.

The interiors of railcars No. 1 to No. 18 were heated by using waste heat from the engine cooling water. This system proved unreliable in service due to issues with the thermostatic valves employed. Later vehicles from No. 19 onward abandoned this system due to its unreliability and because their revised specification demanded that they be able to haul steam-heated rolling stock.^[1]

These later vehicles, No. 19 onwards, were equipped with steam heating systems which were capable of heating both the vehicle's interior and that of any additional trailed vehicles, via a steam supply to the standard steam heating equipment. Steam was produced by a fully automatic Vapor Clarkson steam generator manufactured by Gresham and Craven Ltd under licence from the Vapor car co. The generator was of the water tube with counterflow arrangement type, and could supply up to 300 lb of steam per hour, at 45 lb per square inch. The quantity of steam supplied could be varied by the driver to suit the demand required by a solo railcar, or plus one, or plus two, trailer vehicles. The fuel was the same diesel as was used by the railcar's engines, drawn from a separate 45-gallon tank. The water supply for the heating system was a single 100-gallon tank.^[1]

Railcars No. 1 to No. 18 were powered by a high-speed diesel engine manufactured by A.E.C, producing a maximum brake power output of 130 hp (97 kW). The engine was of the straight 6 configuration, with a bore of 115 mm diameter and a stroke of 142 mm. This gave a total displacement of 8.85 litres. The maximum operating speed was 1,800 rpm.^[1]

Railcars No. 19 onwards were powered by a modified version of the previous engine. This engine was equipped with direct injection and the bore diameter was enlarged to 120 mm, the stroke remaining at 142 mm. This engine produced a lower brake power output of 105 hp at 1,650 rpm.^[1]

An unusual feature was the external

drive from the gearbox on the rear of a horizontally mounted engine to road-vehicle style reduction boxes outboard of the two axles on one bogie. Later units had two such engine-and-drive combinations placed on opposite sides. Railcars 19–20 were fitted with a separate high-low ratio gearbox on the final drive side of the gearbox, which allowed a top speed of about 60–70 mph (97–113 km/h) in high and about 40–45 mph (64–72 km/h) in low. Railcar W20W retains this in preservation.

The brake system on railcars No. 2, 3 and 4 was unconventional. Instead of the usual

to the inside circumference of the drums. The 20 inch internal diameter cast steel brake drums were bolted to the inside face of one wheel per axle.

The vacuum necessary for brake operation was created by three rotary exhausters, two being driven directly from the engines (one by each engine). The third exhauster was chain-driven by the final drive shaft. This arrangement allowed vacuum to be maintained during coasting, when the engines would be shut down. The system operated at a vacuum of 22 to 24 inches of mercury, stored in four reservoirs on the chassis. Another unusual aspect to this system was that vacuum was increased in the vacuum brake cylinder to apply the brakes,^[1] this being contrary to normal British railway practice, in which the vacuum is reduced to apply the brakes.^[2]

The prototype unit, No. 1, made its first run on 1 December 1933 between

Soon after this, the GWR ordered the next three production units, Nos. 2 to 4, which were built with two engines (instead of one) which allowed them to reach a maximum speed of 80 mph (130 km/h), and included a buffet. These units were delivered in July 1934 and entered service on 15 July 1934 between

The next three units, Nos. 5 to 7, entered service in July 1935 and had 70 seats. They were used on services between

The earlier units operated as single railcars. The final four, numbered 35 to 38, were twin coupled units with the driving cabs at the outer ends of the set, and were the forerunners of today's diesel multiple units. These had the capacity for 104 passengers, and a standard corridor coach could be installed between the two cars to increase the seating capacity to 184. These were introduced in November 1941 and worked the Birmingham-Cardiff service.^[5]

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Number Range	Introduced	Builder	Engine	Weight (long tons)	Seats	Withdrawn	Notes
1	1934	Park Royal	1 AEC of 130 hp (97 kW)	24 long tons (24.4 t; 26.9 short tons)	69	1955	Prototype railcar
2–4	1934		2 AEC of 130 hp (97 kW)	26.2 long tons (26.6 t; 29.3 short tons)	44	1954–1958	Buffet fitted
5–7	1935	Gloucester RCW		25.3 long tons (25.7 t; 28.3 short tons)	70	1957–59	Standard single car
8–9, 13–16	1936			29.5 long tons (30.0 t; 33.0 short tons)	70	1957–60	9 withdrawn in 1946 after fire
10–12	1936			29.9 long tons (30.4 t; 33.5 short tons)	63	1956–57	Lavatory fitted
17	1936			28.85 long tons (29.31 t; 32.31 short tons)	None	1959	Parcels car, capacity 10 long tons (10.2 t; 11.2 short tons)
18	1937			33.6 long tons (34.1 t; 37.6 short tons)	49	1957	Prototype, with buffers & draw gear for hauling vans
19–33	1940–41	GWR, Swindon	2 AEC of 105 hp (78 kW)	35.65 long tons (36.22 t; 39.93 short tons)	48	1960–62	33 rebuilt in 1954 to replace 37
34	1941			34.9 long tons (35.5 t; 39.1 short tons)	None	1960	Parcels car, capacity 10 long tons (10.2 t; 11.2 short tons)
35–38	1941–42			36.7 long tons (37.3 t; 41.1 short tons) + 37.6 long tons (38.2 t; 42.1 short tons)	60 + 44	1957, 1962	Power twins with buffet and lavatory 35+36 and 37+38 37 withdrawn in 1949 after fire and replaced by 33

Five of the 38 railcars were destroyed by fires:^[6]

• No 9 was burnt out at Heyford in July 1945; officially condemned in May 1946
• No 10 was burnt out at Bridgnorth in March 1956; officially condemned in May 1956
• No 35 and No 36 were destroyed by fire at St Anne's Park, Bristol in April 1956; officially condemned in April 1957
• No 37 was damaged by fire in February 1949 and was stored until being scrapped; officially condemned in September 1949

Three of the GWR railcars have survived into preservation:

Vehicle no.	Builder	Year built	Location	Comments	Photograph
W4W	Park Royal	1934	National Railway Museum, York[7]	Static display
W20W	GWR Swindon	1940	Kent & East Sussex Railway	Under restoration at Tenterden since 1983
W22W	GWR Swindon	1940	Didcot Railway Centre	Operational

Hornby Railways manufacture a model of the 1940-style railcar in OO gauge, using tooling acquired in their takeover of Lima.^[8] In late 2017, Dapol released an OO model of the streamlined 1936 Gloucester RCW railcars in a variety of liveries and numbers. Heljan manufacture a model of the 1940-style railcar in OO gauge, using new tooling, that includes internal lighting and front and rear lighting.^[9]

Graham Farish produced an N-gauge model (with various numbers, e.g. 19, 22, and 20), both before and after their takeover by Bachmann.

• GWR petrol-electric railcar
• GWR steam rail motors
• GNR(I) AEC Class railcars
• ČSD Class M 290.0

Further reading

• Allen, Geoffrey Freeman (February 1983). "The GWR's Flying Bananas".
  OCLC 49957965
  .
• Leigh, Chris; Hammond, Pat (January 2006). "Purr, not puff!".
  OCLC 173324502
  .
• Riley, Dick (May 1983). "Railcars remembered".
  OCLC 49957965
  .
• Thackray, Brian (2012). "23 The Great Western Railcars Numbers 1 to 17". The AEC Story – From the Regent to the Monarch. Amberley Publishing. pp. 224–239.
  ISBN 9781445603902
  .

External links

Wikimedia Commons has media related to GWR railcars.

• The Great Western Archive
• British Diesel Rail Coaches