The Morgan Expansion truck was first introduced in 1915 by the Cowan Company. These trucks were designed to handle the problem of expansion/contraction of rollers made from composition, a product made from animal glue, glycerin, and molassas. This mixture, besides being edible, also will absorb moisture during high humidity days and shrink during low humidity periods, like winter. Because composition rollers were so unpredictable, the Morgan expansion truck could be adjusted to compensate. With modern rollers made from synthetic rubber, and accurate height plate materials like photopolymer, adjustable trucks are not really necessary--all the trucks should be the same diameter and any variation in roller height should be made by adding our hard plastic tape to the bed rails, especially for C&P presses.
See the listings on the Composing Room page for the appropriate Sterling Toggle Hooks and key that are required to use these bases. When plates are ordered (quarter inch thick, or .250")for use on these bases, advise your photoengraver that the plate will be used on a Sterling Honeycomb base and they will saw the appropriate bevel on each side of the plate. Magnesium or copper plates may be used that will provide the best base and sharpest image for letterpress.
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