ASME B18.25.3M-98 (R2008)

This standard covers requirements for square and rectangular parallel keys and keyways intended for both alignment of shafts and hubs, and transmitting torque between shafts and hubs. Keys covered by this standard have a relatively loose width tolerance. All width tolerances are positive. Keys with minus width tolerances and a smaller tolerance range are covered by ASME B18.25.1M. The inclusion of dimensional data in this standard is not intended to imply that all sizes described are production stock items. Consumers should consult with suppliers concerning lists of stock items.