Accumulator with transport override

This invention discloses an accumulator conveyor having a powered propelling member passing through a plurality of independent operating zones arranged in tandem along the conveyor. In each zone, the propelling member is shiftable between an article propelling and an article non-propelling position by pneumatically actuated pressure rollers acting on the propelling member. A valve operated by an article detecting sensor in each zone operates to supply or exhaust fluid pressure to the actuators. An auxiliary valve system connected between a secondary pressure source and the actuators operates to shift all of the operating zones into an article propelling position thereby overriding the accumulator function of the conveyor.