Screening apparatus

Abstract

A screening plant having a feed plate located between a grizzly grate and a conveyor driven by a hydraulic motor. A first source of fluid supplies hydraulic fluid to a first cylinder to open the feed plate and to a second hydraulic cylinder to swing the grizzly grate. A second source of fluid provides hydraulic fluid to the hydraulic motor driving the conveyor and to a sequence valve at a pressure determined by the load on the motor. The sequence valve stops the flow of fluid to the second cylinder stopping the feed plate when the pressure of fluid from the second source of fluid reaches a predetermined value so that the conveyor will not be overloaded. The feed plate has to open at a preset speed and is started and stopped by the discharging conveyor, as the conveyor meets its capacity. When the feed plate reaches full open position, it activates a control that lifts the grizzly grate and dumps off large pieces of material. The grizzly grate is also controlled by the discharge conveyor. The grizzly grate completes its cycle by returning to the start position automatically.

Dependencies are inferred from the claim text.