Classic Refuse Trucks ROTO-PAC

Roto-Pac Experimental Hydraulic Rear Loader

Following the improvements which resulted in the wide-hopper Roto-Pac of 1957, City Tank Corporation engineers Robert Brown and Cletus Bamber drew up an improved design for the Roto-Pac compactor, which was also adaptable as a stand-alone rear loader tailgate without the usual escalator loader. A patent was filed in 1959, for the all-hydraulic packing system, but the improvement was never known to have been incorporated into the standard Roto-Pac model, which continued to use a chain-driven cam to operate its small compactor blade. In light of this, it has been assumed that the stand-alone hydraulic rear loader concept of the patent was shelved as well.

However, a photograph has recently surfaced which shows New York Department of Sanitation (DSNY) employees loading what appears a packer very much like the one described in the 1959 Brown & Bamber patent. The photo, shown below, was taken at Coney Island in 1962, and offers only a rear view of the truck, with its fairly well-battered packer blade. Regardless of the poor view angle, this photo reveals important clues that strongly suggest this is indeed a real-life version of the patent packer.

The packer blade appears stopped at the top of the hopper opening, which was a feature of the design (as will be seen in the patent drawings and description). Other clues that lead me to believe this is the patent truck include:

-What appears to be a mounting gusset for one of the packer rams (visible at left, above the blade edge)

-Twin hydraulic hoses (supply and return) passing through the roof of the tailgate, which would have operated the packer lift link cylinder.

-An open "access hatch" atop the tailgate, and rounded corners reminiscent of similar features common to the standard Roto-Pac

COMPARISON WITH THE BROWN & BAMBER PATENT

    The patent drawing above shows the blade in the loading position, packer cylinders (40) extended, and lift ram/link (30) retracted. Refuse was loaded under the open blade until the hopper was filled (just as is seen in the Coney Island image). When the packing cycle commenced, the link cylinder extended, closing the load behind the blade, and then the packer cylinders retracted, dragging and packing the load into the body. In the final phase, the link cylinder then opened the blade, ready to receive the next batch. The patent covered a hydraulic circuit which used pilot-operated and relieved valving so that the cycle was not only automatic, but also able to ride up and over incompressible obstructions between packer and hopper which would have damaged the unit. A very similar design was used on City Tank's later Load-Master rear loaders from 1964 until well into the 1970s.

    The patent makes no reference to how the tailgate was opened and the load ejected. Most likely, it was a tilt-to-dump just like the standard Roto-Pac was throughout its existence. The problem of opening the tailgate away from the body (with the long packing cylinders mounted inside) could be easily overcome. This would simply involve providing a locking means for the packing blade (24) to prevent if from moving rearward, such as a spring-loaded clevis pin arrangement. Thus locked in the inward position, the extension of the packing rams (40) could be used to push open the tailgate on a hinge. A piano-type hinge is visible on the truck in the Coney Island photo. Also, Gar Wood patented just such a blade-locking method on their Load-Packer 600 series.

    The fact that is the DSNY using this truck is further anecdotal evidence to support identification. The Department was City Tank's biggest customer, a relationship that didn't change even after the company relocated from the New York City area to Virginia in 1960. The DSNY has a long history of trying out all types of refuse equipment, and even designed its own bodies in 1938. If City Tank wanted to test a new model, New York would have been the most likely location.

    Finally, the Coney Island truck does not match any other known refuse packer of that era. Although conclusive evidence has not been found, I believe the Coney Island truck is indeed the City Tank patent of Brown & Bamber, and was most likely a one-off experimental unit, or was in very limited production (possibly exclusive to the DSNY). The Department is known to have kept accurate records of the number of vehicles it has owned, as well as the composition of the fleet. Perhaps the DSNY archives will one day confirm the identification once and for all.

Rear view of the patent packer blade. Except for cylinder placement, a similar method was used on the Gar Wood T-100 in 1965.

Patent #	Description	Inventor	Assignee	Date
US3092269	Packer Assembly	Brown, et al	City Tank Corp	April 28, 1959

REFERENCES

Vintage Roto-Pac Literature in PDF at the Classic Refuse Trucks Library

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2/9/19