The Valveless was an English automobile

Automobile

An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...

 manufactured from 1908 until 1915 in Huddersfield, Yorkshire. The successor to the Ralph Lucas

Ralph Lucas

The Ralph Lucas was an English automobile manufactured by its namesake from 1901 until around 1908. The first model was an odd two-stroke car powered by paraffin; it had a piston and a crankshaft at either end of its one cylinder. A button in the steering wheel controlled the speed of the engine....

 Valveless, the car marked the entry of the David Brown

David Brown (entrepreneur)

Sir David Brown was an English entrepreneur, managing director of his family firm David Brown Limited and one time owner of shipbuilders Vosper Thornycroft and automobile manufacturer Aston Martin....

 group into the manufacture of motors. Its engine

Engine

An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines burn a fuel to create heat which is then used to create motion...

 was a 25 hp duplex two-stroke model which was advertised as having "only six working parts"; these included two piston

Piston

A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from...

s, two connecting rod

Connecting rod

In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion....

s, and two crankshaft

Crankshaft

The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...

s, which were geared together and counter-rotated. This is a type of engine configuration known as a split single

Split-single

The split-single , is a variant on the two-stroke engine with two cylinders sharing a single combustion chamber.There have been "single" and "twin" The split-single (Doppelkolbenmotor to its German and Austrian manufacturers), is a variant on the two-stroke engine with two cylinders sharing a...

since it is effectively a single cylinder split into two.