1955 saw the first major revision of the Packmaster, with an enlargement of the tailgate assembly. The spacious 1.5 cubic yard hopper was now the biggest in the industry, and new loading width of 71" provided plenty of room for two men to load simultaneously. Body sizes of 13, 16 and 20 yards were soon joined by a monster 25 yard job that just bested Gar Woods new 24 yard Load-Packer. The original Packmaster was still available, with its one yard hopper and narrow tailgate, as a 10 yard model for small routes.
71" width opened up Packmasters true potential. Awesome crushing power remained, as this 55 gallon drum shows
Clearly, the earliest of these next generation Packmasters were transitional models, sharing minor details with the original version. The bi-fold hopper door, interlocked to the packer linkage was still standard, but would be soon replaced by a more conventional (and optional) one-piece cover. Despite narrower riding steps, the large grab bars remained at first, but shortly gave way to smaller hand grips. The rounded edges of the body also would become more angular, particularly along the lower edge.
The Packmaster would remain virtually unchanged for the rest of its very long life span, which lasted well into the 1990s. The biggest change occurred in 1963, when all Leach bodies were produced with ejection discharge, but no major changes were made to the packer mechanism. Packmaster became a major success, selling 541 units in 1955, and almost doubling that figure the following year with 936 copies sold. There would be ups and downs, but the Packmaster was clearly the most powerful, best all-around rear loader on the market, which Leach was slowly beginning to dominate.
Inside the belly of the beast reveals the heavy duty packer blade, made of high tensile steel with replaceable edge
Bi-fold door was carried over from '54 and was integrated with the packer linkage, but was soon replaced by one-piece door
Front view contrasts squared off '55 Packmaster body (left) with rounded body of pre-55 model
Packmaster Packing Cycle
Refuse is first loaded into hopper, in front of packer blade which rests in its 'home' position in the passage leading into the body. To avoid interference with the automatic door, refuse was not to be piled any higher than the hopper loading sill
Cycle is started automatically by closing hopper door, which actuates packer cylinder valve. Massive 5" diameter x 45" stroke cylinders begin to extend. Holding cylinder (not shown) prevents movement of swing links causing blade to pivot rearward over the load
Once blade has contacted extreme rear edge of tailgate, the packer rams overcome the pressure in the holding cylinder, allowing the links to swing downward and the packer blade lowers to the bottom of the hopper behind the load.
At this point, spring loaded rollers (not shown), which had been held inward by the side walls, are aligned with the bottom of the recessed roller tracks (not shown) and spring outward to lock into the track channels
Then, the packing cylinders are reversed, pulling the blade rearward into the body. The rollers, locked into the track path, keep the lower edge of the blade close to the contour of the hopper floor, preventing it from 'riding up' over the load.
Hopper door opens automatically, allowing for immediate reloading by crew
At their upward end, the path of the roller tracks levels out, causing the blade to travel inward horizontally a full 12 inches to solidly pack the body. Risers in the upper tracks force the spring-loaded rollers inward, ready for the next cycle
Above: Video of the Packmaster in operation. This 1980s model S-III Packmaster illustrates how little had changed on this model over the course of thrity-plus years of production, and thus provides us with an accurate demonstration of how it functioned. One significant change in these later versions is that the cycle automatically stops before leading edge of the blade passes by the hopper sill. This safety feature was applied to all American-built packers during the 1970's.
CRT contributor Bruce Polit provided the video of this truck, still in limited service with the City of Chicago as of early 2010. A picture of the S-III Packmaster appears later in this article (Chapter 13).
A spectacular Packmaster on a REO truck from Woodside, Queens
This small army of Packmasters went to National Disposal Service for a new Seattle, Washington branch
Second generation Packmaster was the first Leach available with a 25-cubic yard body