Classic Refuse Trucks FRONT LOADERS

U.S. FRONT LOADER DEVELOPMENT

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Bowles and Dempster were now the unofficial front runners in the battle for front loader supremecy, but the latter could not have been entirely satisfied with their current Dumpmaster system. They were essentially selling a system that was Dempster in name only, with the Holmes-designed lift arm mated to a packer body that was a fully badged Pak-Mor. The claw and pin coupling method was novel, but presented drivers with a small target to grab, and mastering this hook up may have proved to be a difficult task. Though a smaller-sized builder may have been satisfied with this product, Dempster had a fair amount of experience in designing, manufacturing and selling truck equipment, as the sheer number of patents awarded to the firm show. Instead of developing the existing product, they instead used their engineering prowess to basically start all over again, and by 1957 had come up with a brand new machine that had nothing in common with the first Dumpmaster except that they were both front loaders. It would be a milestone, and the foundation of their growth into one of the biggest refuse body builders in the world.

Regardless of brand, all front loaders of the late fifties had at least one nagging problem in common. The lift arms invariably passed by the vehicle cab during their cycle, which represented a hazard to the driver who, if he was not careful, could be injured by the arm passing in such close proximity. The same was true for rear view mirrors (an absolute necessity in this application) which had to be retracted during the loading cycle. On some models, if the arms were to become stuck while in the elevated position, the cab doors would not open leaving the driver trapped inside. George R. Dempster and William Herpich teamed up to design a new type of lift arm that truly revolutionized the industry. The new arms were attached and pivoted at the lower front edge of the truck body. Each arm was of a single piece (that is to say not articulated as with the Holmes system), but rather than pass straight by the cab, they curved up sharply and crossed over the cab doors, then back down again to a point near the front bumper where they were joined together by a Harbers-type rock shaft arrangement. The new arm never passed by the doors or windows at any point during the lift cycle, ushering in a new era in safety, and eliminating the need for mirror retracting devices as with straight arm loaders. It remains one of the most important development in the entire history of the front loader, and is almost universal in use to this day.

Left: Curved lift arm introduced in 1957 solved major safety hazard inherent to front loaders, and secured Dempster's position in the industry. Right: Large, external lift arm cylinders debuted in early 1960's giving the Dumpmaster tremendous lifting power

To go with their modern new curved lift arms, Dempster also introduced their first fork type coupler, which differed from the "California" method by engaging slots in the sides of the container, rather than the bottom. The side fork system had a great advantage in driver visibility, making for easier coupling, no small matter considering that many refuse operators where still using long-hood conventional cab trucks. With forks stored in the "up" position, the curved lift arms could be left in the lowered position while the vehicle was driven. A third radical change came in the form of an all new rectangular compaction/ejection body. It had a full-travel packer plate powered by a four stage, telescopic hydraulic ram. Co-inventor Herpich had actually designed the similar Hydro E-Z Pack side loader for Hercules-Galion. This was a fantastic leap in power over mechanical type packers, as the heavily braced body construction indicated. Each batch of refuse could be compacted and crushed against the rear door as it was loaded, with a force of 58,000 pounds. Even higher pressures would be realized with later models, and of course full ejection discharge eliminated any tip over worries at the disposal point.

As Bowles and Gentile had brought forth the "California Half Pack", Depmster and Herpich had now created the "Eastern Full-Pack", a type of truck which would enjoy decades of success until nationwide weight consciousness took hold during the 1980's. Even then, the Dempster curved arm and side fork have become industry standards worldwide. The 1957 Dumpmaster was so revolutionary, that it saw very few major changes over the years, though many minor improvements were added. The most important change came in the early 1960's, when the underbody lift cylinders were replaced by long stroke "pulling" cylinders fastened to the body sides, resulting in increased lifting capacity and again setting a standard that would become near universal on front loaders. Herpich went on to design the vast majority of the E-Z Pack product line during the 1960's and 1970's.

Also debuting in 1957 was a new entry by Michigan-based Lodal Inc., who paired their truck loader mechanism with a full compaction refuse body sold as the Load-a-Matic. The heart of this new front loader was a novel coupling method employing a triangular bracket which engaged a correspondingly shaped slot made into the container. An early version, illustrated at left, shows the ease with which the "self-aligning" triangle engaged cans even from less-than-ideal appraches. Servo-controlled cylinder (orange highlight) controlled pitch if necessary. When inverted, containers were positively retained by sliding lock plates (yellow) which engaged lugs welded on the container (green) automatically as lift arms raised through linkage (blue) in loader frame. Another cylinder could move a pivot arm ninety degrees to "snatch" containers at right angles to the front of the truck, though it is not clear if this feature actually went into production. Designed by John R. Brisson, the triangle coupling method would go through some refinements and enjoyed a fair degree of success for more than twenty years. Brisson has been awarded several refuse truck patents, including his unorthodox Lodal EVO unitized side loader.

By the end of the decade, the dust was starting to settle somewhat. After a flurry of new designs in close succession, a sort of holding pattern can be seen to have emerged. The west coasters, led by Bowles championed the straight loader arm and lightweight half-pack, hoist dumped bodies. The eastern school would be dominated by the Dempster method using curved arms and heavy, high-compaction bodies with full ejection. The 1960's would see more manufacturers coming aboard the front loader "bandwagon", and the emergence of some interesting new ideas. With few exceptions, most of what was to come would merely be refinements of what was first tried and tested in the fifties.

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11/6/05