A stressed member engine is a vehicle engine used as an active

structural element In structural engineering, structural elements are used in structural analysis to split a complex structure into simple elements (each bearing a structural load). Within a structure, an element cannot be broken down (decomposed) into parts of dif ...

of the

chassis A chassis (, ; plural ''chassis'' from French châssis ) is the load-bearing framework of a manufactured object, which structurally supports the object in its construction and function. An example of a chassis is a vehicle frame, the underpart ...

to transmit forces and torques, rather than being passively contained by the chassis with anti-vibration mounts. Automotive engineers use the method for weight reduction and mass centralization in

vehicle A vehicle () is a machine designed for self-propulsion, usually to transport people, cargo, or both. The term "vehicle" typically refers to land vehicles such as human-powered land vehicle, human-powered vehicles (e.g. bicycles, tricycles, velo ...

s. Applications are found in several vehicles where mass reduction is critical for performance reasons, usually after several iterations of conventional frame/chassis designs have been employed.

Applications

Motorcycles

Stressed member engines was patented in 1900 by Joah ("John") Carver Phelon and his nephew Harry Rayner. and were pioneered at least as early as the 1916 Harley-Davidson 8-valve racer, and incorporated in the production Harley-Davidson Model W by 1919. The technique was developed in the 20th century by

Vincent Vincent (Latin: ''Vincentius'') is a masculine given name originating from the Roman name ''Vincentius'', which itself comes from the Latin verb ''vincere'', meaning "to conquer." People with the given name Artists *Vincent Apap (1909–2003) ...

and others, and by the end of the century was common feature of chassis built by

Ducati Ducati Motor Holding S.p.A () is an Italian motorcycle manufacturing company headquartered in Bologna, Italy. History Barely a month after the official liberation of Italy in 1944, SIATA announced its intention to sell this engine, called ...

BMW Bayerische Motoren Werke AG, trading as BMW Group (commonly abbreviated to BMW (), sometimes anglicised as Bavarian Motor Works), is a German multinational manufacturer of vehicles and motorcycles headquartered in Munich, Bavaria, Germany. Th ...

and others. In 2019, KTM Duke 790's engine is used as a stressed member.

Automobiles

Many

mid-engine In automotive engineering, a mid-engine layout describes the placement of an automobile engine in front of the rear-wheel axles, but behind the front axle. History The mid-engine, rear-wheel-drive format can be considered the original layout ...

sport cars have used stressed engine design.

Race cars

The 1967 Lotus 49 is credited for establishing a solution copied by "everyone" in

Formula One Formula One (F1) is the highest class of worldwide racing for open-wheel single-seater formula Auto racing, racing cars sanctioned by the Fédération Internationale de l'Automobile (FIA). The FIA Formula One World Championship has been one ...

. This requirement is cited as a reason the rules committee changed from an inline-four to a V-6 configuration for the 2014 Formula One season.

Production automobiles

The limited-production

De Tomaso Vallelunga The De Tomaso Vallelunga is a mid-engine sports car produced from 1964 until 1967. It was the first road going automobile manufactured by the company. History The prototype has a backbone chassis with stressed member engine and formula car susp ...

mid-engine car prototyped in 1963 used the engine as a stressed member. In GM's Chevrolet Bolt and Tesla Motors Model S and Roadster electric cars, the battery pack is a stressed member to increase rigidity.

Tractors

The Fordson tractor Model F, designed during World War I, eliminated the frame to reduce cost of materials and assembly, and was probably influenced by the similar design of the 1913 Wallis Cub.

References

{{Motorcycle components Automotive chassis types Structural system Motorcycle frames