Abstract: A torque coupling comprising two non-metallic inserts linked together by a lip-fitted shaft having a multi-sided cross-section. One of the inserts is press-fitted into the internal involute shaft of a driving mechanism, such as a gear box, while the other is similarly fitted into the internal involute shaft of a driven mechanism, such as a pump. The multi-sided configuration of the slip fitted shaft permits the torque load to be distributed compressively on the inserts. Consequently, greater torque loads can be transmitted by the coupling with the benefit of the low-wear, self-lubricating characteristics of certain non-metallic insert materials.