Manual of Engineering Drawing, 3rd Edition

Chapter Keys and key ways

A key, Fig. 17.1, is usually made from steel and is inserted between the joint of two parts to prevent relative movement; it is also inserted between a shaft and a hub in an axial direction, to prevent relative rotation. A keyway, Figs. 17.2, 17.3 and 17.4, is a recess in a shaft or hub to receive a key, and these recesses are commonly cut on key-seating machines or by broaching, milling, planning, shaping and slotting. The proportions of cross-sections of keys vary with the shaft size, and reference should be made to BS 4235 for the exact dimensions. The length of the key controls the area of the cross-section subject to shear, and will need to be calculated from the knowledge of the forces being transmitted or, in ...