reference numerals used to denote the corresponding parts of the representative clamp mechanism 36 driving the clamp mechanism 36 is another dc servomotor 80 fig1 positioned outside the clamp and lift mechanism housing 34 the dc servomotor 80 will be called the clamp motor hereafter the clamp motor 80 is coupled to a bevel gear assembly 82 fig1 and 6 via a speed reducer 84 and timing belt or like drive linkage 86 mounted to the underside of the clamp and lift mechanism housing 34 the bevel gear assembly 82 has an output shaft 88 extending upwardly into the housing a pinion 90 is fixedly mounted on the top end of the bevel gear assembly output shaft 88 and so is positioned centrally between the pair of transfer bars 22 a pair of racks 92 extending parallel to each other from respective clamp carriages 94 which are coupled to the respective terminal segments 22 3 of the transfer bars 22 in a manner yet to be described the racks 92 mesh with the pinion 90 on its opposite sides an inspection of fig1 and 7 will reveal that each clamp carriage 94 is slidably mounted on a pair of guide rods 96 arranged at right angles with transfer bars 22 disposed opposite to each other.