# Giubo

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{{Short description|Type of flexible coupling used to transmit rotational torque}}
{{More citations needed|date=November 2018}}thumb|A driveshaft coupling. Note the split damage beginning to appear, likely due to the large axial displacement.
thumb|A giubo

A '''''giubo''''' ({{IPAc-en|ˈ|dʒ|uː|b|oʊ}} {{respell|JOO|boh}}; etymology: '''giu'''nto '''Bo'''schi, "Boschi joint"), also known as a 'flexdisc', and sometimes misspelled as '''guibo''', is a flexible [coupling](/source/coupling) used to transmit rotational [torque](/source/torque) between the [drive shaft](/source/drive_shaft) and the companion [flange](/source/flange) on [mechanical device](/source/mechanical_device)s, such as an automobile engine.

The giubo is made from flexible [synthetic rubber](/source/synthetic_rubber) and is designed to allow some angular and axial misalignment while [reducing driveline vibration](/source/vibration_damping) 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](/source/Elasticity_(physics)) 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](/source/Italian_language) words ''giunto'' ('joint' or 'coupling') and ''boschi'' (the surname of the Italian engineer who designed and patented the first flex disc, [Antonio Boschi](/source/Antonio_Boschi) (1896–1988)).<ref>[http://www.fondazioneboschidistefano.it/ws/ fondazioneboschidistefano.it]</ref> Boschi later founded GIUBO [SpA](/source/Limited_liability_company), a company solely dedicated to manufacturing flex discs.<ref>{{cite web |url=http://www.digest.net/alfa/archive/v9/msg09114.html |title= Giubo spelling and pronunciation |publisher=[Alfa Romeo](/source/Alfa_Romeo) Owners' Club digest |date=2003-06-17 |access-date=2004-04-27}}</ref>

==Use==
The giubo is believed{{fact|date=November 2014}} first to have been used for this purpose on the [Alfa Romeo](/source/Alfa_Romeo) [model 1900](/source/Alfa_Romeo_1900), produced between 1950 and 1959. As used on several British cars, such as the [Hillman Imp](/source/Hillman_Imp), [Triumph GT6 MKII/GT6+](/source/Triumph_GT6), [Lotus Elan](/source/Lotus_Elan) and some early versions of the [Land Rover Discovery](/source/Land_Rover_Discovery), the item is known as a '''Rotoflex''' coupling.<ref>{{Cite book |url=https://books.google.com/books?id=kJJ8AwAAQBAJ&q=rotoflex+coupling&pg=PT127 |title = Lotus Elan: The Complete Story |isbn = 9781847976345 |last1 = Vale |first1 = Matthew |date = 2013-08-31|publisher = Crowood }}</ref><ref>{{Cite web |url=http://www.gt6mk2.com/rotoflex.html |title = Rotoflex}}</ref><ref>[http://www.gt6mk2.com/Articles/Dunlop%20Rotoflex%20Brochure.pdf gt6mk2.com]</ref> The [Porsche 917](/source/Porsche_917) used a Giubo centered on the rear half-shaft, but in a manner that did not require the joint to laterally flex. [Mercedes-Benz](/source/Mercedes-Benz) cars have used Giubos throughout the line, starting with the [W114 and W115](/source/Mercedes-Benz_W114%2FW115) chassis. The [Saab 92](/source/Saab_92), [93](/source/Saab_93) and [96](/source/Saab_96) use this type of joint in the drive shafts from the transmission to the front wheels, on the [steering column](/source/steering_column) connection to the steering housing, and on the gear change lever to the gear box connection.

== See also ==
*[Rag joint](/source/Rag_joint)

==References==
{{Commons category|Giubo}}
{{reflist}}

{{Powertrain}}

Category:Rotating shaft couplings
Category:Automotive transmission technologies

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Adapted from the Wikipedia article [Giubo](https://en.wikipedia.org/wiki/Giubo) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Giubo?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.