Keyless Locking Devices are mainly applied to the joints between the mechanical parts (such as gears, belt pulleys) and shaft so as to realize load transmission, which is achieved by the large tightening force between Inner Ring and shaft and between Outer Ring and hub produced by the twisting force of high-tension bolt in Keyless Locking Devices; While running under load, it transmits torque, axial force or their compound load depending on joint pressure and friction force from Keyless Locking Devices and mechanical parts.