Abstract: The present invention is a gravity separator for classifying particulate matter as to weight. The invention herein uses a screened vibrating deck having a flow of air therethrough for separating the particulate matter placed thereon. The air flow is provided by a fan, located centrally of the housing below the deck and, which fan rotates about a vertical axis. Movement is imparted to the deck by a drive rod connected to an eccentric shaft. The eccentric shaft rotates about an axis transverse to the fan shaft. A single drive motor is used to operate both the eccentric shaft and the fan.