A ''giubo'' ( ; etymology: giunto Boschi, "Boschi joint"), also known as a 'flexdisc', and sometimes misspelled as guibo, is a flexible

coupling A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end mov ...

used to transmit rotational

torque In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of th ...

between the

drive shaft A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power (physics), power and torque and rotation, usually ...

and the companion

flange A flange is a protruded ridge, lip or rim (wheel), rim, either external or internal, that serves to increase shear strength, strength (as the flange of an iron beam (structure), beam such as an I-beam or a T-beam); for easy attachment/transfer of ...

mechanical device A machine is a physical system using power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromolecul ...

s, such as an automobile engine. The giubo is made from flexible

synthetic rubber A synthetic rubber is an artificial elastomer. They are polymers synthesized from petroleum byproducts. About 32-million metric tons of rubbers are produced annually in the United States, and of that amount two thirds are synthetic. Synthetic rubbe ...

and is designed to allow some angular and axial misalignment while reducing driveline vibration in mechanical power transmission applications.

How it works

Input and output shaft flanges are bolted to the giubo on either side using alternating hole positions, so that the flanges are not connected directly to one another but instead only through the rubber material of the coupling. The

elasticity Elasticity often refers to: *Elasticity (physics), continuum mechanics of bodies that deform reversibly under stress Elasticity may also refer to: Information technology * Elasticity (data store), the flexibility of the data model and the cl ...

of the rubber absorbs vibration and flexes for alignment. It follows that the rubber must withstand the application's full transmitted torque, for which reason the rubber is often reinforced internally using moulded-in fibre material. The giubo may also have a harmonically "phased" design, typically requiring arrows that are marked on it to point to the corresponding flange arms.

Name

''Giubo'' is a portmanteau of the

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, an ethnic group or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance language *** Regional Ita ...

words ''giunto'' ('joint' or 'coupling') and ''boschi'' (the surname of the Italian engineer who designed and patented the first flex disc,

Antonio Boschi Antonio is a masculine given name of Etruscan language, Etruscan origin deriving from the root name Antonius. It is a common name among Romance language-speaking populations as well as the Balkans and Lusophone Africa. It has been among the top 40 ...

(1896–1988)). Boschi later founded GIUBO

SpA A spa is a location where mineral-rich spring water (and sometimes seawater) is used to give medicinal baths. Spa towns or spa resorts (including hot springs resorts) typically offer various health treatments, which are also known as balneoth ...

, a company solely dedicated to manufacturing flex discs.

Use

The giubo is believed first to have been used for this purpose on the

Alfa Romeo Alfa Romeo Automobiles S.p.A. () is an Italian luxury car manufacturer and a subsidiary of Stellantis. The company was founded on 24 June 1910, in Milan, Italy. "Alfa" is an acronym of its founding name, "Anonima Lombarda Fabbrica Automobili." ...

model 1900, produced between 1950 and 1959. As used on several British cars, such as the

Hillman Imp The Hillman Imp is a small economy car that was made by the Rootes Group and its successor Chrysler Europe from 1963 until 1976. Revealed on 3 May 1963, after much advance publicity, it was the first British mass-produced car with the engine blo ...

, Triumph GT6 MKII/GT6+,

Lotus Elan Lotus Elan is the name of two separate ranges of automobiles produced by Lotus Cars. The first series of cars was produced between 1962 and 1975 as a rear-wheel drive vehicle. The second series was produced between 1989 and 1995 as a front-wheel ...

and some early versions of the

Land Rover Discovery Land, also known as dry land, ground, or earth, is the solid terrestrial surface of the planet Earth that is not submerged by the ocean or other bodies of water. It makes up 29% of Earth's surface and includes the continents and various isla ...

, the item is known as a Rotoflex coupling.gt6mk2.com
/ref> The

Porsche 917 The Porsche 917 is a sports prototype race car developed by German manufacturer Porsche to exploit the regulations regarding the construction of 5-litre sports cars. Powered by a Type 912 flat-12 engine which was progressively enlarged from ...

used a Giubo centered on the rear half-shaft, but in a manner that did not require the joint to laterally flex.

Mercedes-Benz Mercedes-Benz (), commonly referred to as Mercedes and sometimes as Benz, is a German luxury and commercial vehicle automotive brand established in 1926. Mercedes-Benz AG (a Mercedes-Benz Group subsidiary established in 2019) is headquartere ...

cars have used Giubos throughout the line, starting with the W114 and W115 chassis. The

Saab 92 The Saab 92 was the first production car from Saab Automobile, Saab. The design was very aerodynamic for its time, with a drag coefficient (''cx'' or ''cw'') of 0.30. The entire body was stamped out of one piece of sheet metal and then cut to ac ...

, 93 and 96 use this type of joint in the drive shafts from the transmission to the front wheels, on the

steering column The automotive steering column is a device intended primarily for connecting the steering wheel to the steering mechanism. Secondary functions A steering column may also perform the following secondary functions: *energy dissipation management ...

connection to the steering housing, and on the gear change lever to the gear box connection.

References

{{Powertrain Rotating shaft couplings Automotive transmission technologies de:Hardyscheibe

How it works

Name

Use

See also

References