Electromagnetic screen drives are known which utilize an electromagnetic drive unit directly connected to the wire screen cloth which is vibrated but these units are noisy and have to be tuned to a desired frequency, and the amplitude of the vibration produced is affected by varying loads on the screening surface because of the tuned vibration system.  The present invention utilizes a motor driven mechanical vibrator which does not need to be tuned, and which is quieter than the electromagnetic screener and varying loads on the screening surface do not affect its amplitude of vibration, since it is not a tuned vibration system. 
An object of the present invention is to provide a vibrating screener, using eccentrically mounted rotating weights, directly connected to the intermediate portion of the screening surface which produces a device which is quieter in operation than the electromagnetic screening apparatus, which requires no tuning, which transmits a full vibratory effect to the screen surface, which utilizes a unique isolation system, which requires very low maintenance, and which, in case of malfunction of the vibrator, permits replacement of the vibrator in 5 to 10 minutes.