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

structural element Structural elements are used in structural analysis to split a complex structure into simple elements. Within a structure, an element cannot be broken down (decomposed) into parts of different kinds (e.g., beam or column). Structural elements can ...

of the chassis 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 (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), ...

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 The Harley-Davidson Model W, also known as the ''Sport Twin'', is a motorcycle made by Harley-Davidson from 1919 to 1923. Unusually for a Harley-Davidson motorcycle, the Model W had a flat-twin engine and a trailing link fork. The Model W set spe ...

by 1919. The technique was developed in the 20th century by

Vincent Vincent ( la, Vincentius) is a male given name derived from the Roman name Vincentius, which is derived from the Latin word (''to conquer''). People with the given name Artists *Vincent Apap (1909–2003), Maltese sculptor *Vincent van Gogh ...

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

sport cars have used stressed engine design.

Race cars

The 1967

Lotus 49 The Lotus 49 was a Formula One racing car designed by Colin Chapman and Maurice Philippe for the 1967 F1 season. It was designed around the Cosworth DFV engine that would power most of the Formula One grid through the 1970s. It was one of the fi ...

is credited for establishing a solution copied by "everyone" in

Formula One Formula One (also known as Formula 1 or F1) is the highest class of international racing for open-wheel single-seater formula racing cars sanctioned by the Fédération Internationale de l'Automobile (FIA). The World Drivers' Championship, ...

. 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 suspe ...

mid-engine car prototyped in 1963 used the engine as a stressed member. In GM's Chevrolet Bolt and Tesla Motors

Model S The Tesla Model S is a battery-powered liftback car serving as the flagship model of Tesla, Inc. The Model S features a dual-motor, all-wheel drive layout, although earlier versions of the Model S featured a rear-motor and rear-wheel drive l ...

and Roadster electric cars, the battery pack is a stressed member to increase rigidity.

Tractors

The

Fordson tractor Fordson was a brand name of tractors and trucks. It was used on a range of mass-produced general-purpose tractors manufactured by Henry Ford & Son Inc from 1917 to 1920, by Ford Motor Company (U.S.) and Ford Motor Company Ltd (U.K.) from 1920 to ...

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