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Double engagement design with intermediate shaft to realize particular torsion spring stiffnesses

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 spacer can be radially mounted and dismounted without having to move the connected machines. The distance dimension ‘E’ between the flange hubs can then be used, for example, to service connected machines. Avoid pollution of the environment due to leaking lubricants. When the spacer is dismounted, a check of the rotational direction of the drive can easily be performed. 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.


CAD Size D1 D2 D3 D4 Emin Lmin L4 L6 L7min l1
    mm mm mm mm mm mm mm mm mm mm
  106 171 106 129.5 126 162 278 47.5 61.5 124 62
  130 210 130 156 152 188 336 56 77.5 152 76
  151 234 151 181 178 220 394 65.5 90.5 180 90
  178 274 178 209 208 257 459 77 104.5 210 105
  213 312 213 247 245 289 515 87.5 116.5 240 120
  235 337 235 273 270 328 586 99 133 270 135
  263 380 263 307 305 364 664 110 154 300 150
  286 405 286 338 330 428 778 129.5 179 350 175
  316 444 316 368 362 476 856 143 196 380 190
  372 506 372 426 419 532 972 160.5 228 440 220
  394 591 394 472 472 626 1186 93 288 560 280
  432 640 432 518 518 653 1237 103 300 584 292

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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