Classic Refuse Trucks DEMPSTER

Dempster in the 1960's
Many cities had adopted the Dumpster system in the forties and fifties, a time when landfill and dump space was often a short distance from the collection point. But short runs too the disposal site soon became a thing of the past for many communities as dumps filled up, land prices soared and public opposition to even sanitary landfill methods became acute. The "short haul" Dumpster system could be costly and time consuming when longer runs to rural landfills became necessary. The combination of transfer trailers and the GRD hoist helped solve this problem, but the new front loading container system was even more versatile. In 1961, Dempster offered conversion kits for the old Dumpster containers, allowing cities who had already invested in Dumpster System equipment to convert to front loader service. The kit required removal of the top of the box over which a top dumping door assembly was welded, as well as a pair of side fork pockets. The fork pocket assemblies were actually slideable; in one position locking the bottom dump door for Dumpmaster front loader service, and in the other unlocking the bottom door for hauling with a standard LFW or GRD hoist.

New conversion kits adapted older containers for use with either top dumping Dumpmaster System, or traditional Dumpster bottom dump method. Note sliding fork pockets on container. Super Dumpmaster body handled standard or converted containers up to 12 cubic yards and featured optional hopper cover door.

To service the converted containers, some up to twelve cubic yards capacity, a new heavy duty Super Dumpmaster was available with a 30 cubic yard body and a packer blade delivering a force of 85,000 pounds against the load. With this new model, cities could now build a Dumpmaster container system while still servicing their existing converted Dumpster containers with a single unit. A ten cubic yard container may not seem unusual in commercial collections today, but consider that some fleets once consisted of open body or packer trucks of the same capacity. In this sense, a high-capacity Super Dumpmaster and one operator could possibly replace a small fleet of older trucks and several crew members.

Dempster refuse systems became increasingly popular during the 1960's, as both contractors and municipalities realized the benefits on containerized refuse systems. Dempster's long association with container systems, coupled with brilliant engineering and aggressive marketing easily made them the most recognizable name in the field. The new decade brought new additions to the Dinosaur roll off family, most notably the DinoPacker stationary compaction unit. The face of refuse collection, particularly commercial and bulk handling, had changed forever, and Dempster now sat squarely at the top of the heap.

As can be seen above, the Dumpmaster was perfectly suited to snow removal duty, compacting snow and ejecting a giant ice cube!

In late 1961, another major engineering change to the Dumpmaster loading arm mechanism was unveiled. Since the first hydraulic truck loaders had appeared nearly two decades prior, the common practice was to actuate the lift arms with set of hydraulic cylinders, mounted under the front of the truck body roughly parallel to the chassis. These cylinders were connected on their rod ends to bell crank affixed to cross shaft which carried a loader arm on each outboard end. The cylinders were relatively short, but gained mechanical advantage through the bell cranks though this placed a significant torsional load on the cross shaft carrying the arms. Dempster's new design featured long stroke cylinders, with the piston end mounted to the outside of the truck body and the rod end coupled directly to each lift arm. By acting directly on each lift arm, working pressures could be lowered resulting in less damaging heat within the hydraulic system. The lift cylinders were now out of the way of potential damage from landfill hazards, and ever higher lift capacities were now possible. It was another triumph for the Dempster team, and best of all it was and idea that was adaptable only to curved lift arms for which they also held the patent! These two features would be Dempster's lasting legacy to front loader design, and it is hard to find many examples even today that do not have these features.

The new style lift cylinders acting directly on the lift arm (left) are contrasted with the underbody hoist (right) as used on previous models. Also note the hand load container for use on residential collection, an accessory offered since the very first Dumpmaster was built in the mid 1950's.

1/7/06