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A Fire Engine Meets a Luxury Car Maker – the Dennis Rolls-Royce

The name Rolls-Royce tends to conjure up images of prestige and luxury and has certainly been synonymous with these terms since the turn of the twentieth century.

Rolls-Royce: A Brief History

Rolls-Royce Symbol

With humble beginnings in 1884 as an electrical and mechanical business established by Henry Royce, its successful dive into the London car market came about in 1904 when Royce met with Charles Rolls – a London quality car dealer. Such a fortuitous encounter evolved into an agreement between the two parties, which entailed the manufacturing of a range of cars to be exclusively sold by CS Rolls and Co. bearing the name of Rolls-Royce. Two years later, in 1906, the Rolls-Royce company was formed and their ‘Silver Ghost’ – a six-cylinder car, was declared the ‘best car in the world’ within 12 months of the duo's foray into the car market.

Rolls-Royce would go on to expand their mechanical ingenuity at the beginning of the First World War designing aero engines – specifically ‘the Eagle’, which provided almost half of the total horsepower used by the Allies in the air war. Similarly, by the time World War II was well underway, Rolls-Royce again stepped in with the development of the Merlin, powered by the Hawker Hurricane and Supermarine Spitfire in the Battle of Britain.

It is important to note that, while Rolls-Royce dabbled in private and commercial mechanical designs, the company never built fire engines of any description. Nor did they produce chassis designed for the purpose of firefighting. This, however, did not stop the company being associated with British fire engines production for over thirty years. Post WWII, the British Military Forces attempted to unify their equipment and machinery. Up to this post, a wide variety of vehicle makes and models made up the military fleet. As such, the Forces charged Rolls-Royce with developing a range of engines, which could be utilised across a wide gamut of vehicles and equipment, with the main criteria being low weight, high power, reliability, ease of service, commonality of parts, the capacity to start and run immediately in extreme temperatures, and to operate on low grade fuels. This was no easy task.

The resultant engine was known as the ‘B range’. It was produced in four, six and (straight) eight cylinder versions, using many common parts. The most unusual feature of this engine was probably its ‘F-head’ valve arrangement, and its exhaust valves in the block. Rover had also developed a similar engine type for its Land Rover range, with the layout allowing larger valves for better airflow, lubrication, cooling and quieter running. In its military role, the B range was intended primarily for use in specialised combat vehicles.

The Rolls-Royce Silver Ghost, 1906. Credit: Rolls-Royce company website.

Dennis F2 Has Entered the Game

Following the end of WWII, Dennis Bros began to upgrade and refine their product range, with the modernisation of some of their existing pre-war fleet designs, as well as the introduction of completely new models. Interestingly, Dennis also changed the way its models were designated, doing away with the engine or pump capacity descriptions, for example, the ‘Big 4’ and ‘500/700’, and instead adopting a numerical sequence prefixed by ‘F’. The numbers were simply allocated in order as each model was introduced, so there is no indicative feature as to the type of vehicle.

Engine sketches from the Dennis F1-F12 Specifications and Brochures, 1948-1954. [Museum of Fire collection]

The Dennis F2 was a completely new model, powered by the Rolls-Royce B80 series petrol engine. The B80 engine was chosen for the first Rolls-Royce powered Dennis appliances, with the F2 (normal control) and F7 (forward control) models announced in 1948. The B80 was available in 4, 6 and 8 cylinder versions, “which developed 150 bhp at 3,000 rpm and employs overhead inlet and side exhaust valves. Both the crankshaft and connecting rods are machined all over – the former being counterbalanced and fitted with a torsional vibration damper. The bearings are of copper lead, indium faced. Rolls-Royce also utilised special light alloy tinplated pistons working in chromium, which protected bores, ensuring maximum life expectancy. The cylinder head of light alloy had inserted valve seats of nickel chrome molybdenum and of exceptionally large diameter. Austenitic exhaust valves with Stellite faced seatings were situated in the cylinder block. Force feed lubrication was by a submerged pump, which draws oil from the sump through a filter floating near the surface of the oil and a replaceable filter element fitted externally. The double venturi carburettor equipped with a large capacity air cleaner was designed for balanced mixture distribution. Easy starting was ensured by the automatic choke control” (8000-001693 Dennis F1 – F12 Specifications and Brochures, 1948 – 1954). Drive was through a four-speed crash gearbox and a No. 3 Dennis pump was fitted (mounted centrally or at the rear) with an output of around 800 gpm. A ‘first aid pump’ was also available as an option.

The New South Wales Fire Brigades (now Fire and Rescue NSW) acquired six Dennis F2 models between 1948 and 1957. The first was bodied by the Brigade, but the others were supplied complete from the factory. They originally entered service at Headquarters, George Street West and Crows Nest, but later entered district stations. The first chassis to arrive in November 1948 underwent customary acceptance tests in respect to its specifications, performance and pumping capabilities.

Dennis F2, ME No 290 at The Rocks. [Museum of Fire collection]

Up until this period, Brigade vehicles had been fitted with 19th century style ‘Braidwood’ bodies, with the crews sitting on the rear. In Europe, however, designs with uncovered inward facing seats or fully enclosed ‘limousine’ bodies, had rapidly been gaining favour. The F2 was chosen to receive the limousine style due to the expected prestige of becoming the ‘Flying Squad Motor’ at Headquarters in Sydney city. By the time the design was finally settled on, a decision had been made to standardise this new world design. The F2 appliance was allocated and stationed at Headquarters in May 1952.

The Brigade also commissioned a number of other Dennis models, powered by the Rolls-Royce engine up until the 1970s. The subsequent B81 engine replaced the B80 from the early 1960s and continued to be offered by Dennis until the late 1970s. Automatic transmissions had become the standard design offered at this time. A novelty of the late 1960s was the option of Dunlop disc brakes on the F44 model. The Board continued to commission further Dennis appliances, with a total of 87 new fire engines delivered in 1972 – a mixture of both Jaguar and Rolls-Royce F49 series engines. The F49s were allocated to Headquarters, the Rocks, and Wollongong. The F49 series with ratings of 1,000 gal/min, whilst the remaining 37 were Jaguar ‘D’ series 600 gal/min pumping capacity.

- Story by Museum of Fire Heritage Team


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