By 1927, John I Thornycroft & Co Ltd had been well-established as a major manufacturing company for many years. The firm had factories in Basingstoke and Southampton and its products, which were widely exported, included commercial and military vehicles, various types of boats and ships, marine engines, water-tube boilers and other items. The following timeline covers Thornycroft’s activities from 1927 to 1932, and looks at the company’s lorries.
Thornycroft introduced new models and continued producing existing types inherited from the previous year, production included four-wheelers and RSWs. These vehicles covered the load range 1.5 tons (1,524kg) to 7 tons (7,112kg) and were all powered by large in-line L-head four-cylinder engines.
Among others, new types included the JJ 5 tonner (5,080kg) and CC 7 tons (7,112kg), both four-wheelers, and the XB RSW - 5 tons (5,080kg) on-road and 3 tons (3,048kg) off-road. The JJ was introduced as a replacement for the immortal J 4 tonner (4,064kg), although Thornycroft was still taking orders this year for the J as well as for the pre-1927 Type Q.
The firm announced that all its power units should have in-unit engines, gearboxes and clutches, and the engine range was rationalised into three sizes, the MB/4 (3,620cc, 36bhp@1,500rpm), HB/4 (5,420cc, 46bhp@1,500rpm) and BB/4 (6,970cc, 58bhp@1,600rpm).
Mercedes Benz caused a stir when it exhibited a diesel 5 tonner (5,080kg) at the 1927 Commercial Motor Show, held at Olympia.
Thornycroft’s lorry capacity range remained unchanged at 1.5 tons (1,524kg) to 7 tons (7,112kg), with the following vehicles: A1 (1.5 tons/1,524kg), A2 (2 tons/2,032kg), KB (3 tons/3,048kg), A3 RSW (3 tons/3,048kg on-road, 2 tons/2,032kg off-road), PB (4 tons/4,064kg), JJ (5 tons/5,080kg), XB RSW and XB RSW lwb (5 tons/5,080kg on-road, 3 tons/3,048kg off-road), JJ lwb (6 tons/6,096kg) and CC (7 tons/7,112kg).
Mercedes Benz started marketing its diesel 5 tonner (5,080kg) in the UK as the first diesel lorry to be put on sale in this country. British manufacturers were criticised in the press for ignoring diesel lorries while foreign manufacturers were pushing ahead. Another German diesel product, the Cologne-built Deutz lorry engine, was given press coverage in the UK.
Thornycroft discontinued the CC, a move which reduced the upper limit of the four-wheel capacity range to 6 tons (6,096kg). Type JJ options now included 5 and 6 tonners (5,080 and 6,096kg), with a choice of standard, forward control and lwb models.
Having used relatively low-powered four-cylinder engines for its entire model range hitherto, Thornycroft introduced its first six-cylinder lorry engine in order to extend the upper limit of the load capacity range. The new six-cylinder WB/6 engine offered 78bhp, considerably more than the company’s previous maximum of 60bhp. The big ‘six’ enabled Thornycroft to increase the upper limit of its capacity range from 6 tons (6,096kg) to no less than 10 tons (10,160kg), resulting in the 10 ton (10,160kg) JC RSW. So far, Thornycroft’s RSWs had been able to travel off-road. However, not all RSW customers needed off-road capability, and the JC was for on-road use only.
Interest in diesel-engined commercial vehicles was intensifying, and developments by Continental manufacturers were being reported. Three diesel commercial vehicles were listed in the UK at the end of the year, these being Berna (Swiss), Mercedes Benz (German) and Saurer (Swiss).
A new development on Thornycroft lorries was the fitting of a Westinghouse vacuum servo-assisted braking system to at least one of its lorries (JC RSW 10 tonner/10,160kg), in which the servo effect was proportional to brake pedal pressure.
The capacity range of Thornycroft’s four-wheelers remained at 1.5 tons to 6 tons (1,524 to 6,096kg). The well-tried 2 ton (2,032kg) A2 was supplemented, and eventually replaced, by the more powerful A10 2 tonner (2,032kg), while new 2.5 ton (2,540kg) and 4 ton (4,064kg) classes were introduced, represented by the A7 and PC respectively. Unlike Thornycroft’s other four-wheelers, the A7 was fitted with brakes on all four-wheels, starting a general move to all-wheel braking on the firm’s four-wheelers. The small A1 continued representing the 1.5 ton (1,524kg) capacity, while the JJ 5-6 tonner (5,080-6,096kg) continued representing the heavy end of the four-wheel class.
Although introduced the previous year, the JC RSW 10 tonner (10,160kg) was withdrawn after a short innings, and was replaced by the 12 ton (12,192kg) QC with the 11,330cc NC/6 six-cylinder engine giving no less than 104hp @ 1,700rpm. Like the defunct JC, the QC was for on-road use only. Also withdrawn was the A3 RSW 3 tonner (3,048kg), replaced by newer models.
By the end of the year, the number of manufacturers listing diesel commercial vehicles for the UK market had grown to seven from the previous year’s three, these being AEC (British), Berna (Swiss), Laffly (French), Mercedes Benz (German), Pagefield (British), Peerless (British of US origin) and Saurer (Swiss).
Thornycroft’s absence from diesel listings could not continue indefinitely, and Sir John I Thornycroft announced at his firm’s 29th AGM that Thornycroft had been running experimental diesel vehicles for some time and would be able to supply diesel vehicles as soon as any general demand arose.
During the latter part of the year, Thornycroft began to adopt class names for its lorries while retaining existing designations. Thus, for example, the A10 2 tonner (2,032kg) became the A10 Bulldog, the A7 2.5 tonner (2,540kg) became the A7 Speedy, and there were also the PC Sturdy (4 tons/4,064kg), QD Colossus (10-11 tons/10,160-11,176kg) and others.
Six-cylinder engines were spreading down the load capacity range, and the smallest lorries to be powered by ‘sixes’ were both the A7 and A14 versions of the four-wheel Speedy 2.5 tonner (2,540kg). Capacity ranged from 2 tons (2,032kg) for the Bulldog four-wheeler) to 10-11 tons (10,160- 11,176kg) for Dreadnought and Colossus RSWs).
By the end of the year, the majority of Thornycroft’s four-wheelers had all-wheel braking; also, vacuum servo-assisted brakes had come into use on most of the firm’s lorries.
Thornycroft’s first vehicle diesel engine, a 10,741cc ‘six’ developing 90hp at 1,800rpm, was shown at an exhibition of diesel-engined vehicles held in Manchester. In certain respects, this engine resembled the NC6 petrol engine. Although the engine was displayed in a four-wheel 6 ton (6,096kg) normal control chassis, it was obvious that the unit had been designed to suit forward control vehicles because all components, such as dynamo, governor, fuel pump and injectors etc were located on the near side of the engine. Thornycroft’s new diesel was offered in the Type QD Colossus RSW 10-11 tonner (10,016-11,176kg). Other British exhibitors at Manchester’s diesel exhibition included AEC, Blackstone, Crossley, Gardner and Leyland.
Thornycroft took a cautious, perhaps rather negative view of the future for diesel vehicles. At the firm’s 30th AGM, held in November, Sir John I Thornycroft said of diesels that it was no use obtaining great improvements in fuel consumption if the savings were offset by increased maintenance charges. He went on to say that people forecasting widespread use of diesels were neglecting to take account of the effect which a special form of taxation might have on diesel fuel.
Changes were made to Thornycroft’s model range towards the end of the year (i.e. for the 1933 model year). The previously four-cylinder Strenuous four-wheel 5 tonner (5,080kg) gained a new six-cylinder option, the forward control LD/ZD6, powered by the 6,901cc ZD6 engine giving 76bhp. The Jupiter JD was replaced by the Taurus JD, with a capacity of 6.75 tons (6,858kg). In the RSW class, the new Wolfhound plugged the 4 ton (4,064kg) gap in the capacity range and was available in normal and forward control versions, with a choice of four or six cylinder engines. Similarly, the Mastiff SD was introduced to plug the 7 ton (7,112kg) gap, again with four and six-cylinder engine options. The 10-11 ton (10,016-11,176kg) Colossus was dropped, leaving the six-cylinder Dreadnought 11 tonner (11,176kg) to represent the heavy end of the range; this vehicle was for on-road use only. Both the Wolfhound and the Mastiff were fitted with all-wheel brakes, for the first time on Thornycroft’s RSWs.
All Thornycroft lorries listed at the end of the year had vacuum servo-assisted braking. Thornycroft standardised on the Westinghouse system.
In late 1932, it was announced that Thornycroft had been developing another vehicle diesel engine which was, by then, out of the experimental stage and in production. This engine was said to be entirely different from Thornycroft’s original diesel which was little more than an adaptation of the NC6 petrol engine. Two versions of the new diesel engine were offered, the 92bhp four-cylinder CIND4 and 147bhp six-cylinder CIND6, both outputs being given at 1,800rpm. Swept volumes were 7,500cc, and 11,250cc, respectively, and both versions of the engine gave no less than 56 per cent more bhp/litre than Thornycroft’s original NC6-based diesel. A Taurus chassis fitted with a CIND4 was demonstrated to The Commercial Motor journal and the diesel Taurus went into production as the JD/CI-ND4, alongside four and six-cylinder petrol-engined versions of the lorry which included vehicles with the 60bhp MB4 ‘four’ and the 75bhp ZD6 ‘six’.
A 1930 A2 cattlewagon displayed at Milestones
An MB4 engine powers HMS’s 1930 Iron Duke
Photos above: Nick Corrie
The 6.5 ton Jupiter was introduced in 1931
A 3 ton Speedy of c1932