LINEAR BALL-BEARING MOTOR

The acceleration of a steel ball running on parallel steel rails has b een measured. When the rails are connected, respectively, to the posit ive and negative terminals of a DC supply, the ball completing and ele ctrical circuit, the acceleration increases as the current is raised. Three components of acceleration have been recognised: a frictional re tardation; an electromagnetic acceleration which increases with curren t but is independent of speed; and an electromagnetic retardation whic h increases with both current and speed. The characteristics of this l inear ball-bearing motor are compared with those of the cylindrical ba li-bearing motor, and with the predictions of electromagnetic theories .