Many such couplings are known. Thus there are many different forms of key couplings, spring couplings, clamp couplings, pin couplings in which a pin extends through the second part and the shaft and gear couplings and couplings with spined or specially profiled shafts.
Especially easy to produce are couplings in which the shaft is inserted in a cylindrical bore in the second part and then a hole is bored to receive a connecting bolt. In such case the connecting bolt can be a cross pin, a tangential pin, or a longitudinal pin. With a cross pin, the hole for the connecting pin is bored through the shaft and the second member perpendicular to the longitudinal axis of the shaft and the cross pin is inserted into the hole. With a tangential pin, a hole for the pin is likewise bored perpendicular to the longitudinal axis of the shaft but so that the longitudinal axis of the hole lies tangential to the shaft. The tangential pin is then inserted in the hole bored in the shaft and the second part. With a longitudinal pin, a hole for the pin is bored parallel to the longitudinal axis of the shaft generally from the end of the shaft so that the axis of the hole coincides with a generatrix of the shaft. The longitudinal pin is inserted in this hole so that it lies half in the shaft and half in the second part. Cross pins and tangential pins can suitably be used only when the dimensions of the second part are not too large since otherwise an excessively long hole must be bored. The longitudinal pin can only be used when the end of the shaft is not covered by another part. This requirement is frequently not fulfilled. As the aforementioned single pins cannot be used in many cases, a more complicated kind of fastening is required. These other kinds of fastening no longer have only a simple bore to receive the connecting bolt in an otherwise unworked part to be connected but the connecting bolt and the shaft or the other part have also plane surfaces for making the connection. Frequently used are rectangular springs which lie in grooves in the shaft and the second part. Somewhat simpler on the other hand is a form which is partly round. For this purpose connecting springs are known which lie in a groove in the shaft and in the portion which lies in the groove have a rectangular cross section fitting the shape of the groove. In the part extending out of the groove the spring has, on the other hand, a circular cross section. This rounded part of the spring engages in a round groove in the art having a bore. The latter part thus has a cylindrical bore for the shaft and a likewise cylindrical bore for the connecting spring, the two bores intersecting with one another. Other torque transmitting couplings between a cylindrical shaft and a part having a bore are more complicated to produce than that described above. In particular, end gear couplings or couplings with splined or profiled shafts are expensive to produce.