Hirth joint

Hirth joint

A Hirth joint or Hirth coupling is a type of mechanical connection named after its developer Hellmuth Hirth. It is used to connect two pieces of a shaft together and is characterized by teeth that mesh together on the end faces of each half shaft.

Construction

Hirth joints consist of radial grooves milled or ground (or both) into the end face of a cylindrical feature of a part. Grooves are made one by one into the part tilted by the bottom angle of the grooves, and rotated from groove to groove until the serration is complete.

Usually the grooves mesh together within a ring, because the load bearing capacity of teeth is rapidly decreasing at smaller diameters. For instance a shaft of 60 mm diameter can be toothed in a 12 mm wide ring only (inner diameter is 36 mm) without jeopardizing the load bearing capacity of the shaft.

Theoretically a number of kinds of matching serrations can be made on the end faces of shafts. Only symmetric serrations are used in practice: the profile of a tooth is a symmetric triangle, and the the tooth's head and bottom angle is the same too.Even the profile angles are not arbitrary: angles of 60 and 90 degrees are used.

The coupling is defined by the number of grooves, the outer diameter of the cylindrical feature, the bottom angle of the grooves (to the axis of the cylindric feature), and the depth of grooves.

Finally, an axially oriented bolt holds the two parts together.

Advantages

:- very high loads can be transferred in a small enclosure of only a few parts (two serrated faces and a bolt fixing them together):- there is no lag:- self centering (because of this the Hirth coupling is used in very high RPM gas turbines also)

Disadvantages

:- the manufacturing process is complex and time consuming -- i.e. expensive.

Uses

Hirth joints were first used in gasoline engine crankshafts [cite web
url = http://pardo.net/bike/pic/fail-005/000.html
title = Cranks -- Center Clamp
accessdate = 2007-04-27
] and are now used in jet engine shafts, in accessories for surgical operating tables, in agricultural machines for fixing tools etc, and in bikes parts/frames such as Campagnolo's "Ultra-Torque" bicycle crankset, and in Bicycle Torque Couplings.

References


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Hellmuth Hirth — (April 24 1886 – July 1 1938) was a German engineer who founded the Mahle and Hirth companies, manufacturing engine components and complete aircraft engines respectively.Hirth was born in Heilbronn, the son of an engineer and tool maker. He was… …   Wikipedia

  • Schempp-Hirth Nimbus-4 — infobox Aircraft name = Nimbus 4 type = high performance FAI Open Class glider manufacturer = Schempp Hirth Flugzeugbau GmbH caption = Nimbus 4M with powerplant deployed designer = Klaus Holighaus first flight = 1990 introduction = retired =… …   Wikipedia

  • Coupling — This article is about a mechanical connection between two objects. For other uses, see Coupling (disambiguation). Rotating coupling A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power.… …   Wikipedia

  • Bottom bracket — A square taper cartridge bottom bracket. The bottom bracket on a bicycle connects the crankset to the bicycle and allows the crankset to rotate freely. It contains a spindle that the crankset attaches to, and the bearings that allow the spindle… …   Wikipedia

  • Crankset — A Shimano Deore right crankset, showing crank arm, spider, three chainrings and chainring guard …   Wikipedia

  • Bicycle Torque Coupling — An S and S Coupling also known as a Bicycle Torque Coupling or BTC is a coupling which enables bicycle frames to be separated into smaller pieces, usually to facilitate packing and transporting. They can be built into the frame by the frame… …   Wikipedia

  • Liste des moteurs d'avions — Maintenance sur un General Electric TF39 turbofan d un C 5 Galaxy Cet article est la liste des moteurs d avions par type et constructeur. Voir aussi la Catégorie:Moteur d aviation. Sommaire …   Wikipédia en Français

  • List of military aircraft of the United States — This list of military aircraft of the United States includes prototype, pre production and operational types. For aircraft in service, see the List of active United States military aircraft. Prototypes are normally prefixed with X and are often… …   Wikipedia

  • Dick Johnson (glider pilot) — Dick Johnson Born Richard H. Johnson January 10, 1923(1923 01 10) Medicine Hat, Alberta, Canada Died July 23, 2008(2008 07 23) (aged 85) Midlothian, Texas, United States Alma mater …   Wikipedia

  • Challenge International de Tourisme 1932 — The Challenge 1932 was the third FAI International Tourist Plane Contest (French: Challenge International de Tourisme), that took place between 12 and August 28, 1932 in Berlin, Germany. The four Challenges, from 1929 to 1934, were major aviation …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”