February 1906: The valveless motor car

The early 20th century was awash with automotive innovations, some of which went onto to dominate the industry over the following decades, whilst others didn’t quite have the transformative impact their inventors expected.

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One such curiosity is the valveless motor car  – an unusual vehicle which featured a valveless, two-cylinder engine and a transmission mechanism without the usual change speed gearbox  – developed by London engineer Ralph Lucas .

Explaining the operation of the engine (which is pictured) The Engineer wrote that ‘when the pistons ascend, air is drawn into the crankcase through the carburettor and passage G. The petrol is in the meantime dropping into the chamber. The pistons then descend, compressing the air in the crankcase and forcing it though the throttle and chamber where it becomes mixed with petrol vapour, and when the piston has uncovered the ports, is admitted into the cylinders driving before it the products of combustion of the previous explosion through the exhaust ports and replacing them with a new charge. On the next upstroke the pistons compress the charge prior to its ignition and downward movement of the pistons.’

The car itself boasts an unusual layout, with engine placed beneath the driving seat and the space beneath the bonnet utilised for a cone-shaped petrol tank. ‘The framework of the car resembles somewhat a punt,’ commented The Engineer.

The article reports on a number of claimed advantages for the novel design including greater reliability than engines with valves, silent running thanks to the fact hat that the connecting rods are in constant thrust, high torque at low speeds and ease of manufacture.  

Some of these claims were put to the test by The Engineer in ‘the hilly neighbourhood of Blackheath’ and the journal was duly impressed.  ‘On the high gear the car travelled up long and steep gradients without necessitating change to the low gear’ it wrote, hailing the vehicle as ‘a highly meritorious attempt to adapt a two-cycle internal combustion engine to the propulsion of road vehicles.’

The full original article can be read here