A stressed member engine is a vehicle engine used as an active structural element of the

chassis A chassis (, ; plural ''chassis'' from French châssis ) is the load-bearing framework of an artificial 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 mount A bushing or rubber bushing is a type of vibration isolator. It provides an interface between two parts, damping the energy transmitted through the bushing. A common application is in vehicle suspension systems, where a bushing made of rubber ...

s. Automotive engineers use the method for weight reduction and mass centralization in vehicles. 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 ( 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 Ducati Motor Holding S.p.A. () is the motorcycle-manufacturing division of Italian company Ducati, headquartered in Bologna, Italy. The company is directly owned by Italian automotive manufacturer Lamborghini, whose German parent company is Au ...

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

Automobiles

Many mid-engine 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. 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 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