Applicant has discovered that the use of plastic gears in connection with metal gears on a main gear reduces the amount of friction between gear teeth and in addition reduces noise resulting from the assembly. Applicant's shaker herein requires a minimal amount of maintenance and will operate for long periods of time. Moreover, Applicant's shaker requires little or no lubrication. The gears may be disposed between the two parts of the housing and the eccentric weights outside the housing or visa versa.