A bar screen consists of a stationary bar rack that is automatically cleaned by one or more power operated rakes. Bar screens are usually categorized according to the type of raking mechanism used to remove debris from the bar rack. The operating cycle of a reciprocating rake screen begins with the rake in the standby, or parked, position at the discharge elevation. The most popular reciprocating rake design uses a cogwheel and pin rack drive arrangement to operate the cleaning rake. The chain-driven reciprocating rake bar screen utilizes a chain-driven rake mechanism to clean the stationary bar rack. The screen is protected against rake overloads through the use of sensing devices in the circuits of the screen drive and actuator motors. The cable-operated reciprocating rake bar screen is one of the oldest types of mechanically cleaned screens. Operation is controlled by a level switch, and the hydraulically driven cleaning mechanism is located on the downstream side of the bar grid.