US Patent 7153214 Universal joint

A universal joint to transmit force from a tool to a workpiece. A driver attachable to the tool has a spherical cavity. A plurality of inwardly facing protrusions is formed in the cavity. Each protrusion has a pair of conical sidewalls separated by an angled ramp. A driven socket has a sphere formed on one end. The sphere has a plurality of channels. The sphere is received in the spherical cavity in the driver and the protrusions in the cavity are received in the channels. The drive webs forming the channel engage the protrusions when the driver is angularly offset from the driven socket.