Accumulator with automatic override

This invention relates to a powered roller accumulator conveyor having a powered propelling member passing through a plurality of independent accumulating zones arranged along the conveyor. The propelled member is shiftable between driving and non-driving positions with respect to the powered rollers by means of vertically shiftable supporting rollers operated by pneumatically powered actuators. Each of the actuators are controlled by means of a series of valves connected to a source of fluid pressure. In an accumulating position, each of the actuators are connected through an article detecting sensor-operated valve to the source of fluid pressure. In an override or discharge position, shuttle valves associated with each actuator are series connected to the source of fluid pressure through a main control valve and are operative to direct the flow of fluid from the sensor operated valve to energize each of the actuators in each of the zones to shift all of the operating zones into driving position.