The Rolls-Royce 30 hp was one of four cars to be produced as a result of an agreement of 23 December 1904 between Charles Rolls and Henry Royce. Badged as a Rolls-Royce, the 30 hp was produced during 1905 and 1906 by Royce's company, Royce Ltd. at its factory in Trafford Park, Manchester. It was sold exclusively by Rolls' motor dealership, C.S.Rolls & Co., at a price of GBP890. The engine was exhibited at the Paris Salon in December 1904, along with the 10 hp, 15 hp and 20 hp models. Claude Johnson was keen that a six-cylinder model was included in the Rolls-Royce line-up as other "quality" makers, especially Napier, were adding them to their ranges. The 30 hp was discontinued when the company changed to a single model policy and launched the 40/50 (Silver Ghost). The engine was made of three separately cast two-cylinder units which were common with the two-cylinder 10 hp and four-cylinder 20 hp types sharing their bore of 4 in (102 mm) and stroke of 5 in (127 mm). It is water-cooled and of 6000 cc capacity with overhead inlet and side exhaust valves. The crankshaft was carried in seven main bearings in an attempt to keep vibration to a minimum, a problem on many early six-cylinder engines, as the dynamics of the layout were still not fully understood. Early cars had a high-tension ignition system using pre-charged accumulators, a trembler and a coil ignition system; on later cars this was supplemented by a magneto which could be used as an alternative. As the lighting supplied uses oil for the side and tail and acetylene for the headlights, there is no other drain on the accumulators, which need to be recharged between outings. The power output is 30 bhp (22 kW) at 1000 rpm. The engine speed is controlled by a governor that can be over-ridden by the pedal-controlled accelerator. A three-speed gearbox was fitted at first, later changed to four-speed, connected to the engine via a short shaft and a leather cone clutch is used. On the four-speed type, third gear is direct and fourth speed an overdrive ratio. The car has a top speed of 55 mph (89 km/h). There is a transmission brake operating on a drum fitted behind the gearbox operated by foot pedal and internal expanding drum brakes on the back axle operated by the handbrake lever. Suspension is by semi-elliptic leaf springs on both front and rear axles with an additional crossways helper spring on the rear. Artillery type wheels with wooden spokes were fitted. Two chassis lengths were made, the short was 112 in (2,845 mm) long and the long 118 in (2,997 mm). the track was the same on both lengths at 56 in (1,422 mm). Rolls-Royce did not provide the coachwork. Instead, the cars were sold in chassis form for the customer to arrange their own body supplier. Both closed and open cars were made. Only one car, chassis number 26355 is known to survive.

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Rolls-Royce vehicles
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