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Double engagement design with sliding hub to compensate for greater axial misalignments

The TSCHAN® POSIFLEX®-coupling is a torsionally stiff gear coupling with a certain backlash. It compensates for angular, parallel and axial shaft misalignments within defined ranges. Parallel shaft offset can only be compensated by the double engagement design with two toothing planes. The coupling transmits the torque via hubs with crowned gear teeth which are in permanent mesh with the straight gear teeth of the sleeves. There must be a certain gear tooth circumferential clearance in order to compensate misalignments of the connected machines. The coupling is suitable for horizontal installation in each direction of rotation. For applications involving other than horizontal position, it may be necessary to support the housing or the spacer. Please contact RINGFEDER POWER TRANSMISSION, if this has not been taken into account when selecting the coupling size. It is imperative to use a lubricant that is appropriate for the specific requirements of the gear coupling in order to ensure reliable and continuous operation. Avoid pollution by leaking lubricant.


CAD Size D1 D2 D3 D5 D6 E L L4 L9 l1
mm mm mm mm mm mm mm mm mm mm
106 171 106 129.5 98 129.5 8 210 47.5 18.5 62
130 210 130 156 115 156 10 231 56 13 76
151 234 151 181 140 181 10 250 65.5 14.5 90
178 274 178 209 165 209 11 276 77 17 105
213 312 213 247 195 247 11 291 87.5 6.5 120
235 337 235 273 230 270 14 319 99 7 135
263 380 263 307 260 305 14 344 110 6 150
286 405 286 338 280 330 16 381 129.5 ?0,5 175

General features

  • Torsionally rigid gear coupling made of high-quality steel
  • Compensates for angular,radial and axial shaft offset
  • Suitable for use in temperatures up to +130°C if special seals are used
  • Available with split sleeve (ZEA / ZEB - ZEA model range also available in ZEB design) and single-piece sleeve (ZEH)
  • The elastic ring can be replaced without having to move the coupled machines (multi-part models)
  • Bores up to 320 mm
  • Torques up to TKn = 290,000 Nm / TKmax = 580,000 Nm
  • Speeds up to nmax = 5,000 rpm

General description

The POSIFLEX® coupling is a torsionally rigid twin cardanic gear coupling.


The coupling housings have a straight internal toothing whilst the hubs have an external toothing with a chased variable radius. As a result, the hubs can move spatially within the housing and thus compensate angular, radial and axial shaft misalignment of the adjoined shaft ends within specified tolerances. Depending on coupling type and size, the standard toothing permits an angular misalignment of up to 0.75 degrees per toothing-plane and an axial movement of several millimetres. The max. possible radial shaft displacement is dependent on the distance between the two toothing planes. Other toothing geometries can be used for further specific applications.


High-grade tooth profiles and grease with ultra high-pressure additives guarantee low-restoring forces and a long serviceable life. The material used is forged steel with an apparent yielding point of at least 350 N/mm2. Special materials can be used for further specific applications. Sealing is carried out using O-rings and lip-seals of buna N. The housings are centred and held together by fit-bolts and self-locking nuts.


The use of special seals permits the temperature limit to be raised to 130 °C.


At peripheral speeds upwards of 30 m/s it is advisable to dynamically balance the coupling.

Special applications

If greater misalignements are anticipated at higher speeds and torques, an examination is necessary, performed with the assistance of a special computing programme. This is independent of the determined size. The value TKmax may not be exceeded in any state of operation (start-up, electrical short circuit, blocking, etc.).

Tolerances and standards

The bore tolerance is ISO H7, if not differently ordered. The bore diameters listed refer to keyways to DIN 6885/1.

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