Rolls-Royce 20 hp (1905)

Infobox Automobile


name = Rolls-Royce 20 hp
manufacturer = Rolls-Royce Ltd
production = 1905-1906
40 madeThe Rolls-Royce Motor Car. Anthony Bird and Ian Hallows. Batsford Books. 2002 ISBN 07134 8749 6]
class =
body_style =
engine = 4118cc 4 cylinder.
transmission = three or four speed
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wheelbase = Auto in|106|0 or Auto in|114|0
successor =
designer = Sir Henry RoyceThe Rolls-Royce 20 hp is an early car model produced by Rolls-Royce at their Manchester works and made in 1905 and 1906. The car was exhibited at the 1904 Paris Motor Salon along with the 10hp and 15hp cars and 30hp engine.

The engine was made of two separately cast two cylinder unit which were common with the two cylinder 10 hp and six cylinder 30 hp types sharing their bore of Auto in|4|0 and stroke of Auto in|5|0. It is water-cooled and of 4118 cc capacity with overhead inlet and side exhaust valves. 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 Auto bhp|20|0 at 1000 rpm. Rolls-Royce Motor Cars website http://www.rolls-roycemotorcars.com] 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 with the introduction of the Light 20 and subsequently fitted to all cars, connected to the engine via a short shaft and a leather lined cone clutch is used. On the four speed type, third gear is direct and fourth speed an overdrive ratio.

Two of the cars ran in the 1905 Isle of Man TT race and one driven by Percy Northey came second overall, the other driven by C.S. Rolls failed to finish after gearbox problems. Rolls tried again in 1906 and won. In December 1906 he took a car to the United States and won a race at Yonkers.cite book |last=Georgano |first=N. |title=Beaulieu Encyclopedia of the Automobile |year=2000 |publisher=HMSO |location=London |id=ISBN 1-57958-293-1]

The first cars had a chassis length of Auto in|114|0 but following the special lightweight cars made for the TT Race a shorter Auto in|106|0 version became available. These would become known as the Heavy 20 and Light 20. The track on the Light 20 was also narrower at Auto in|52|0 compared with the the Heavy 20's Auto in|56|0. Rolls-Royce did not provide the coachwork. Instead, the cars were sold in chassis form for the customer to arrange his own body supplier. Both closed and open cars were made.

The Light 20 has a top speed of Auto mph|50|0 (Auto mph|52|0 on the TT versions) and the Heavy 20 Auto mph|47|0 . This speed would be reduced if a heavy body was fitted. 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.

The car in chassis only form cost £650. Three cars, chassis number 26350, 40509 and 40520 are known to survive.

References