A transmission joint with a coupling having frontal teeth (20,21) is inserted between an output shaft of a gear motor and a worm screw. A release element is associated in a radial way to the coupling so that the coupling can be manually released in an emergency. The release element includes an eccentric pin that engages the coupling element in a radial way so that the coupling element can be moved from an engagement position to a release position by being turned by a lock barrel (26) with its key.