Cardan joints

We currently have devices whose vocation is :

• for gimbals, to ensure a fixed-point movement with two degrees of angular freedom (this is the case for radar antenna mounting, Ariane's cryogenic engine, where the inclination of the jet allows the trajectory to be inflected, etc.);

• for a universal joint, to transmit mechanical power between two shafts which may or may not intersect, and whose relative position may vary during operation. If the shafts have the same angular velocity, the joint will operate homokinetically.

  The qualities expected of a drive seal are :

  • adapt to relative variations in shaft position, both linear and angular;

  • be homokinetic, so as not to generate pulsating torque, a source of vibration;

  • dampen or even isolate vibrations;

  • not to generate vibrations;

  • to achieve the highest possible yield;

  • be easy to maintain, with wear parts easily replaceable;

  • not to overload the connections, either because of the assembly conditions (the assembly must be isostatic) or because of unbalance due to a lack of joint balance.

  Note :

  For a better understanding of this article, please refer to the article on homokinetic joints in this volume.

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