Abstract:
An automatic changing apparatus for sample vials and like regularized objects is provided, wherein a rectilinear array of vials is indexed along an X-axis, rows of the array are indexed seriatim along a Z-axis, and individual vials of the Z-axis indexed rows are indexed seriatim past a counting station along a Y-axis. Photoelectric sensors are provided to override portions of the indexing mechanism if no sample vials are present in array rows or individual compartments.