1950 Roto-Pac Escalator/Compactor Early example of the second generation Roto-Pac escaalator-compactor loader from City Tank Corporation     Gar Wood winning the bulk of the 1949 DSNY equipment bid had left City Tank in an unfortunate position. Having tooled-up to build the original version Roto-Pac, they had at least temporarily lost their best sales prospect for the new body. What the company did next was fairly phenomenal; they essentially abandoned the original design and started over again, and by mid-1950 had an entirely new refuse body on the market.     The new body was still badged as the Roto-Pac, but replaced the rotary drum pulverizer with an escalator-compactor system. The new Roto-Pac was similar to the early Kurtz Conveyor loaders of the 1930s, utilizing an endless roller chain with flights attached was used to continuously lift the refuse from the hopper to the top of the body. However, the new Roto-Pac featured an oscillating packer panel at the inside top of the tailgate, driven mechanically via roller chain by the conveyor motor. The small packer blade, always in motion when the conveyor was operating, cleared the area at the top end of the body where the conveyor unloaded its refuse. In addition to keeping the conveyor discharge opening cleared, it also provided a small degree of compaction. Body capacities of 14 or 16 cubic yards were initially offered for the new Roto-Pac. The mechanism of the second generation Roto-Pac was fairly simple for a loader of this type. A reversible hydraulic motor mounted to the upper tailgate (red highlights) provides the power for all loading and packing functions. The motor drives a common jackshaft (green highlights) that turns the escalator chains. The escalators chains are connected to each other by a series of flights, which carry refuse from the hopper upward through an enclosed passageway to the top of the tailgate. The common jackshaft simultaneously turns a set of crank wheels, pivotally connected to the packer plate (yellow highlights), which is in turn supported on its upper end by a set of stabilizer links. The oscillation of the packer blade continually clears the area where the escalator discharges, and packs the load once the body becomes filled. The function of the oscillating packer blade is very similar to that of the later SEMAT Superpac and SD Revopak rear loaders.     John P. Calamore designed the new refuse body for City Tank, which improved upon the earlier types of conveyor-loaders by increasing load density. DSNY mechanic Thomas Baldt had actually filed patent number 2496192 for a similar device in 1946, and at least one prototype of the Baldt-type conveyor loader was built by Heil, and underwent testing by the Department. The Baldt system used a conveyor that fed a rotary packer blade scraped by an internal retaining plate. Baldt's design was fairly complex, which is probably why it was not adopted. Roto-Pac component locations: A) escalator chains with flights, B) oscillating packer blade, C) tailgate lift cylinders, D) body hoist, E) snow-loading doors (specified by the DSNY on refuse packers of this period)     Despite the continuing advances being made by competitors batch-type packers, the DSNY still liked the ability of conveyor-type loaders to handle household rubbish and coal ash, the latter making up a large portion of city waste stream. Besides City Tank Corporation, the only other major builder of conveyor-loaders was Heil, who did sell 50 of their Conveyo-Pak bodies to the City. But the redesigned Roto-Pac was evidently just what the DSNY wanted, and an order for 210 of the new style bodies was delivered in 1951. It was to be the beginning of a long relationship, with the Roto-Pac becoming the dominant refuse body in the Department fleet through the late 1960s. Early 1950's DSNY Roto-Pac bodies on International Harvester 210 series trucks Patent # Description Inventor Assignee Date US2660326 Tail Gate Loader and Packer John P. Calamore City Tank Corp November 10, 1949 US2746240 Pump and Motor Hydraulic Transmission... Brown, et al City Tank Corp October 19, 1950 US2692062 Loader and Packer for Refuse Trucks John P. Calamore City Tank Corp January 18, 1951 7/4/10 © 2010 All Rights Reserved Photos from factory brochures/advertisements except as noted Logos shown are the trademarks of respective manufacturers