Bedford SB

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Bedford SB
A preserved Bedford SB in the United Kingdom
Manufacturer Bedford (General Motors)
Body and chassis
Doors One behind front axle
Floor type Step entrance
Chassis Straight Ladder frame
Engine Bedford
Capacity 33-41 Seats
Transmission 4-speed synchromesh
Length 27ft 6in, later 30ft
Width 7ft 6in, optionally 8ft and later 2.5m

The Bedford SB is a front-engined bus chassis that was built by Bedford in the United Kingdom. It was launched at the 1950 Commercial Motor Show[1] as the replacement for the Bedford OB.

It was the first Bedford vehicle to have a "forward control" design, with the driver's seat located at the right of the engine and the front axle underneath. It used a four-speed synchromesh gearbox, with five-speed gearboxes offered later. It could be fitted with Bedford's own petrol or diesel engine, with the Perkins R6 and Leyland O.350 and O.370 engines also being offered during the 1950s and 1960s.[2]

Wheelbase length was originally 17 ft 2in (5.23 m), but from 1955 an 18 ft (5.49 m) option was also offered. Bodywork was provided by a wide range of builders, including Duple, Plaxton, Harrington, Willowbrook and Marshall of the United Kingdom, Hawke Coachwork, Coachwork International and New Zealand Motor Bodies of New Zealand, and many more.

There were numerous variants of the SB, each determined by the engine fitted:

Variant Engine
SB Bedford petrol 4.927 L
SBG Bedford petrol 4.927 L
SB3 Bedford petrol 4.927 L
SBO Perkins R6
SB1 Bedford diesel 4.927 L
SB5 Bedford diesel 5.42 L
SB8 Leyland O.350
SB13 Leyland O.370

From 1968, the SB series used computer classification codes from Bedford's parent company General Motors, with the petrol-engined SB3 variant becoming NFM, and the diesel-engined SB5 variant becoming NJM. However, they were rarely referred to under these codes.

The SB was built for the UK market and export, and production spanned 37 years - longer than any other Bedford bus chassis - until the sale of Bedford Vehicles in 1987.

Versions of the Bedford SB exported to New Zealand were powered by the standard petrol or diesel engines, except the last batch sold to New Zealand Railways Department, which used Caterpillar C7 engines and Allison transmissions. The use of Caterpillar C7 engines and Allison transmissions by New Zealand Railways Road Services is not supported. All the NZRRS SB buses had Bedford petrol or diesel engines. 40 of the Bedford YMT buses had Caterpillar C7 engines. Many were later powered by Caterpillar, Leyland, Scammell, Cummins, Detroit, Isuzu, Mitsubishi, Gardner and GMC engines. While most retained the standard gearbox, many later ran with Eaton/fuller manual, Allison automatic or Daimler epicyclic gearboxes. NZR buses were also fitted with 2 speed Eaton differentials for the country's hilly terrain and mountain passes.