Abstract: Successive, juxtaposed, outwardly extending, receiving cradles are arranged in a continuous belt by having at their proximal ends, link like bases which are connected together hingedly in tandem by their leading and trailing edges which form hinge members. Opposed wedged shaped, sidewise protruding trunnions extend from the proximal end plates of each cradle and these trunnions are received within laterally opposed, linear channels in the upstanding side panels of a support member. The channels thus confine the wedge shaped trunnions to form adjacent parallel upper and lower flights so that the cradles protrude upwardly generally parallel to each other in the upper flight and downwardly generally parallel to each other in the lower flight.