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 mo ...

used to transmit rotational

torque In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. Wh ...

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, 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 a steel beam (structure), beam such as an I-beam or a T-beam); for easy attachment/transfer o ...

mechanical device A machine is a physical system that uses 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 macromolec ...

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 of rubber is produced annually in the United States, and of that amount two thirds are synthetic. Synthetic rubber, just like natural ru ...

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 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, a Romance ethnic group related to or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance languag ...

words ''giunto'' ('joint' or 'coupling') and ''boschi'' (the surname of the Italian engineer who designed and patented the first flex disc, Antonio Boschi (1896–1988)). Boschi later founded GIUBO

SpA A spa is a location where mineral-rich spring water (sometimes seawater) is used to give medicinal baths. Spa health treatments are known as balneotherapy. The belief in the curative powers of mineral waters and hot springs goes back to pre ...

, 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 carmaker known for its sports-oriented vehicles, strong auto racing heritage, and iconic design. Headquartered in Turin, Italy, it is a subsidiary of Stellantis Europe and one of 14 brands of mu ...

model 1900, produced between 1950 and 1959. As used on several British cars, such as the Hillman Imp, 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 The Land Rover Discovery is a series of five or seven-seater family SUVs, produced under the Land Rover marque, from the British manufacturer Land Rover, and later Jaguar Land Rover. The series is currently in its fifth iteration (or generat ...

, 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 4. ...

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 simply as Mercedes and occasionally as Benz, is a German automotive brand that was founded in 1926. Mercedes-Benz AG (a subsidiary of the Mercedes-Benz Group, established in 2019) is based in Stuttgart, ...

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. 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 accommodate doors ...

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