capable of pulling a three-ton load at 18 mph and capable of restarting on a gradient of one in eight. Production tractors powered by Jowett engines were displayed on the Karrier stand at Olympia's Motor Transport Show. A Karrier "Cob" Major, a 4-ton three-wheeled tractor, was also displayed Ro-Railer Karrier's Ro-Railer was a hybrid single decker bus, capable of running on both road and rail, intended for towns and villages distant from a railway. Also designed by J Shearman, road motor engineer to London, Midland and Scottish Railway it was tested by the chairman and board of directors of LM & S in January 1931 by travelling between Redbourn and Hemel Hempstead. Though it was not a success, Karrier's road railbus looked like a bus and could be changed from road to rail in 2½ to 5 minutes. With a six-cylinder engine and a body by Craven it ran at up to 50 mph. Said to be very rough-riding it ran for 1930–31 on the Stratford-on-Avon and Midland joint line. Finally it became a vehicle used to transport track ballast on the West Highland Line. Trolleybuses In 1925, Karrier became the first British manufacturer to produce a three-axle passenger vehicle, aided by the availability of larger pneumatic tyres, and in 1926, entered into an agreement with Clough, Smith & Co. Ltd. to produce the 'Karrier-Clough' trolley-omnibus which Clough would market. This arrangement continued until 1933, when Karrier began marketing the trolleybuses themselves. Despite receiving multiple orders in 1933–4, Karrier went into receivership, leading to the takeover by Humber in 1934, thus becoming part of the Rootes Group. Trolleybus manufacture was moved to Rootes's Sunbeam subsidiary's factory at Wolverhampton, where it continued up until World War II. During the periods in wartime, when production was allowed, only one model was produced, the W4, which could be badged either as Sunbeam or Karrier. Post-war, production continued briefly before the trolleybus portion of the company was sold to Brockhouse in 1946. Rootes Group products In the late 1950s and 1960s some Karrier vehicles were fitted with the Rootes TS3 two-stroke opposed piston diesel engine. Other engines used in this period include Humber Hawk 4-cylinder petrol engines (L-Head and OHC), Humber Super Snipe 6-cylinder (L-Head and OHV) and Perkins Diesels. At Luton, the only designs carried over from the previous era were the three wheeler and the six-wheel trolleybus chassis. The trolleybus business became