A dual-roller conveyor belt comprising: a top side and an opposite bottom side, with a plurality of cavities extending from the top side to the bottom side; an array of roller sets including: a top roller at the top side for supporting conveyed articles; a bottom roller at the bottom side in contact with the top roller such that rotation of the bottom roller in a first direction causes rotation of the top roller in an opposite second direction; wherein each top roller and bottom roller are arranged in a vertical stack in one of the cavities; characterised in that the conveyor belt comprises channels (42, 43, 44) along which the roller sets are translated from a first position in which the top roller extends to a maximum level above the top side and a second position in which the top roller extends to a minimum level below the maximum level; and in that the conveyor belt further comprises a braking surface lying below the top roller so that the weight of a conveyed article resting on the top roller pushes the top roller against the braking surface. a top side and an opposite bottom side, with a plurality of cavities extending from the top side to the bottom side; an array of roller sets including: a top roller at the top side for supporting conveyed articles; a bottom roller at the bottom side in contact with the top roller such that rotation of the bottom roller in a first direction causes rotation of the top roller in an opposite second direction; wherein each top roller and bottom roller are arranged in a vertical stack in one of the cavities; characterised in that the conveyor belt comprises channels (42, 43, 44) along which the roller sets are translated from a first position in which the top roller extends to a maximum level above the top side and a second position in which the top roller extends to a minimum level below the maximum level; and in that the conveyor belt further comprises a braking surface lying below the top roller so that the weight of a conveyed article resting on the top roller pushes the top roller against the braking surface. a top roller at the top side for supporting conveyed articles; a bottom roller at the bottom side in contact with the top roller such that rotation of the bottom roller in a first direction causes rotation of the top roller in an opposite second direction; wherein each top roller and bottom roller are arranged in a vertical stack in one of the cavities; characterised in that the conveyor belt comprises channels (42, 43, 44) along which the roller sets are translated from a first position in which the top roller extends to a maximum level above the top side and a second position in which the top roller extends to a minimum level below the maximum level; and in that the conveyor belt further comprises a braking surface lying below the top roller so that the weight of a conveyed article resting on the top roller pushes the top roller against the braking surface. the conveyor belt comprises channels (42, 43, 44) along which the roller sets are translated from a first position in which the top roller extends to a maximum level above the top side and a second position in which the top roller extends to a minimum level below the maximum level; and in that the conveyor belt further comprises a braking surface lying below the top roller so that the weight of a conveyed article resting on the top roller pushes the top roller against the braking surface.