Hirth-tooth profile (ground)

As a detachable coupling, the Hirth tooth profile offers a self-centering and form-fitting connection for rotationally symmetrical parts such as shafts, rotor disks or indexing plates on rotary indexing tables in the smallest of spaces. Torque transmission is limited by the available axial tension. Thanks to the high-precision grinding of the teeth, the contact area can be increased and, as a result, the surface pressure can be reduced.

If the elements to be coupled can be easily moved axially, the Hirth coupling is designed in two parts. For other applications, such as non-lifting rotary indexing tables or tool holders, the coupling can also be designed in three parts, consisting of an outer, inner and bridge ring.

The Hirth serrations are available in a non-hardened version produced by milling (up to a material strength of 1100 N/mm²) or in a hardened version.



The tooth profile is pre-milled hardened and and ground with high precision, taking into account the required hardening depth, so that the Hirth tooth profile shows almost no change in the indexing and centering accuracy even after multiple switching operations. While a contact area of ​​up to approx. 70% can be achieved in the milled version, a contact area of ​​up to 80% is achieved with the ground version. This not only increases the accuracy, but also the transmittable torque.

Hirth Verzahnung

Thanks to our many years of experience in milling and grinding Hirth gears, we achieve optimal results for our customers. With the state-of-the-art, newly upgraded jig grinding center of the type Kehren Ri6-4, we are able to grind Hirth gears with high precision.


  • Form-fit and force-fit joint
  • Self-centering
  • Lower axial and radial runout tolerances
  • Space saving
  • High torque capacity
  • Very precise positioning reproducibility
  • Repeatable accuracy of less than 0.001 mm
  • Indexing accuracy of +/- 2" (guaranteed +/- 3")
  • Wear resistant
  • Durable



Summary of geometry data (standard version)

Diameter max. 950 mm
Number of teeth 24, 36, 48, 72, 96, 144, 288, 360, 720

We also manufacture Hirth spur gears according to individual customer drawings. We deliver precision technology at the highest level.

Flohr Industrietechnik GmbH - Im Unteren Tal 1 - D-79761 Waldshut-Tiengen - Phone: +49 (0)7751 / 8731-0 - info@flohr-industrietechnik.de

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