The JD’s most controversial feature was its snout type layout, in which the front axle was set well back, behind the engine, giving considerable forward overhang of the bonnet. This feature allowed ample load-carrying area in relation to wheelbase, and the snout layout was also used by other manufacturers. Whether or not it was aesthetically appealing was a matter of personal choice, but it gave the JD a certain thrusting grandeur!
While British (and other) lorry manufacturers had complacently continued producing petrol-driven vehicles during the ’twenties, Mercedes Benz put the diesel cat among the petrol pigeons when it introduced a diesel 5 tonner (5,080kg) to the UK at the 1927 Commercial Motor Show, held at Olympia. Not long afterwards, diesel Mercedes lorries were offered for sale in the UK. Sections of the British specialist press rebuked our commercial vehicle manufacturers for ignoring diesel engines, and at least one journal complained that the first diesel lorry to have received anything like real tests in this country was foreign! Fortunately, British manufacturers entered the diesel field over the next few years, and, in 1930, Thornycroft announced at its 29th AGM that it had been running experimental diesel vehicles for some time. British exhibitors at an exhibition of diesel-engined vehicles held in Manchester in 1931 included newcomers Leyland and Thornycroft, and existing manufacturers Crossley, Gardner, AEC and Blackstone. Thornycroft’s first diesel engine, shown at Manchester, was a 10,741cc six-cylinder engine developing 90hp at 1,800rpm which was offered in the Type QD Colossus.
Diesel engines for lorries were here to stay, Thornycroft was firmly in the diesel market after a belated start and production of Thornycroft’s latest diesel engine was announced in October 1932. This engine was of different construction to the firm’s first diesel, mentioned above, and was available in four and six-cylinder versions, the CIND4 and CIND6. The four-cylinder version gave 92bhp at 1,800rpm from 7,500cc, while, at the same rpm, the big 11,250cc ‘six’ gave 147bhp. A Taurus chassis fitted with a CIND4 was demonstrated to The Commercial Motor journal, loaded with around 6 tons of ballast. The journal’s representative was impressed with the ease with which the engine started, finding that the 24 volt CAV-Bosch starter motor turned the engine effortlessly, and regular firing occurred almost immediately. A decompressor was fitted to ease starting in cold weather, and the driver was provided with a manual injection timing control. The Commercial Motor was also impressed with the engine’s flexibility, finding that the Taurus would trickle along at 6mph in top gear without signs of distress. The engine was governed to a maximum of 1,800rpm, but could run satisfactorily up to 2,200rpm. Thornycroft claimed a fuel consumption of 12.5mpg (22.6 litres per 100km). The diesel Taurus went into production as the JD/CI-ND4, and was offered alongside four and six-cylinder petrol-engined versions of the lorry. Standard and long-wheelbase vehicles were also offered with each engine option.
The Taurus JD followed Thornycroft’s usual lorry design formula. The vehicle had a steel chassis frame supporting the front-mounted, fore-and-aft engine, and power was taken to the back axle from a dry single-plate clutch via a four-speed sliding pinion gearbox (i.e. no synchromesh) and a two piece open propeller shaft, transmitting power to the differential through an overhead worm drive. A clutch stop was fitted to ease upward gear changes in the absence of synchromesh, as was usual on Thornycrofts. Disc type wheels were fitted, twins at the rear and singles at the front; pneumatic tyres were standard.