As the 1970s approached, Heil Company was in a most advantageous position. In the fifteen years since the original Colectomatic was launched, they had steadily assembled the most complete refuse collection and disposal product lineup in history. The Colectomatic Mark III with its revolutionary Duo-Press compaction-ejection system was the flagship rear loader, which had been recently joined by a modern new front loader. There were bulk-handling container hoists and roll-offs with the acquisition of Load-Lugger, including stationary compactors, both portable and permanent. There was even equipment for the receiving end, with the Bowles line of transfer station equipment and trailers, and the Heil Pulverizer for the shredding of municipal refuse.
The Mark II/III had shown the future of rear loaders as far as the principle of compaction and ejection as cooperative forces, but its hinged-hopper packer mechanism was being overshadowed by the new slide-sweep rear loader designs that followed in the wake of the 1960 Leach 2-R Packmaster. Load-Master fielded the first one in 1964, the powerful and economical LM-100 with ejection-discharge and a cavernous hopper that would swallow almost anything. Pak-Mor followed in 1967, mostly abandoning their rotary-blade model for an all-new Load-Liner series. Gar Wood came out with the first swing-link rear loader the same year, the powerful LP-800. The 2-R itself had received the crude but effective Leach Push-Out ejector system in 1963, and was becoming legendary within the industry. Having slowly built its reputation with private haulers in the midwest and northeast, the big Leach rear loader was finding many new customers, including municipalities. Leach had essentially spawned a whole new class of rear loaders; the heavy-duty "bulk" loader, capable of collecting household refuse, commercial containers and even bulk refuse (water heaters, washers, stoves, etc.) on a single pass, all the while while packing loads of up to 1,000 pounds per cubic yard.
Heil's Colectomatic Mark III was by no means an inferior packer, and still delivered high-density payloads and economical operation. However, it would always be limited in its crushing capability due to the hinged hopper design. Likewise, slide-sweep rear loaders were far more efficient in container service, especially with cans bigger than 2-cubic yards. The competitors models had hoppers which could be reloaded in mid-cycle, while the Mark III was the only rear loader requiring the complete cycle to finish before reloading could begin. Heil would have to field a bulk loader soon, or risk being left behind in the 1970s. There are indications that the alarm had been sounded as early as 1965, when a patent was filed for a new rear loader with a more-or-less sweeping type action. It was never built, probably because it would never have have been able to truly compete with the 2-R. And the Mark III was still selling quite well, which at least gave Heil time to develop a worthy successor.
Although having built much of its refuse equipment empire by way of acquisition (including both individual designs and whole companies), Heil now turned to their own engineering team to create the new bulk rear loader. John Wieschel, Jerald Zanzig, Robert Czarnecki and Claire Murray all contributed to what would become one of the most interesting rear loaders ever conceived, and exactly what Heil needed; a massive machine that would compete with the 2-R on every level, without simply copying the Leach design. The Colectomatic Mark V was announced in August of 1971, based on a patent filed in March of that year. The patent described two embodiments of a single concept, one of which would be the Mark V heavy-duty rear loader which was needed immediately. The other variant would go into production a year later, and would be a lighter-duty version called the Mark IV. Thus, Heil skipped a "Mark" series in order to put their large bulk rear loader on the streets as soon as possible.
DESCRIPTION OF THE MARK V PACKING MECHANISM
The foundation for the Mark V started with the Duo-Press compaction-ejection body, although dimensionally larger than the Mark III and initially only in the 25-cubic yard size (a 20-yard body would be added later). The massive new tailgate structure could hold 3.2 cubic yards in its hopper, and featured a packer mechanism which was unlike any method used on a rear loader before or since. The upper panel (called the slide) was itself a two-piece assembly. The upper slide section was a reinforced sheet affixed to the top of the tailgate by hinges, replacing the fixed bulkhead partition used by the 2-R. The lower slide section enveloped the upper panel, its forward section being a solid steel sheet (working against the refuse), wrapping around the upper section, and a rearward section that was open in the middle. These two panels forming the slide section "telescoped" in-and-out, and also pivoted back and forth against the upper hinge. Power to the slide came via 5" x 30" double-acting rams, with their cylinder ends affixed high up in the tailgate (near the hinge), and their rod ends connected to the lower slide section. Connected to the slide was what Heil called blade (commonly known as the "sweep" panel today), which resembled a larger version of the Mark III packer blade. It was hinged to the slide, and was operated by 5.5" x 34" double-acting rams, with cylinder ends mounted to the lower slide section, and their rod ends affixed to crank arms welded to the blade.
What really sets the Mark V apart from all other rear loaders is the unusual eccentric action of the blade. Both the blade and slide were stabilized by large swinging links in the tailgate, which was already the practice of the Gar Wood LP-800 and Dempster Route King. However, the Mark V links were not connected to the fulcrum of the blade and slide, but rather to offset bores in the front of the blade. The effect of this novel arrangement is that pivotal movement of the blade causes the entire packer assembly to move back and forth. As a result, the trajectory of the blade tip changes as it moves through the hopper. The result was an unusually low and deep tub-shaped hopper, swept by a large blade with relatively short-stroke hydraulic cylinders. The travel path of the mechanism was roughly elliptical, and the distance between the edge of the blade and hopper floor increased as it packed the load in the body, helping eliminate jams. The stabilizer links eliminated the need for tracks and rollers and the wear associated with them.
The elliptical path of the Mark V packer was the result of the offset pivot/suspension point of the swing links
The hopper is low and deep with very a very slight incline up to the body floor level
The cavernous Mark V hopper could accept virtually any type of material, and was dubbed the "Big Bite" in early Heil literature, foreshadowing a trade name which see widespread use on the European version. The cycle commenced with the blade going up, causing the slide to press inward against the load and lessening the tendency of the blade to knock refuse out of the hopper. Phase 2 is slide out, covering the load in the hopper. In phase 3, the blade goes down and sweeps the hopper floor while the slide simultaneously pivots outward away from the load. The final phase is slide in, where the contents of the hopper are packed into the body.
The Mark V continued Heil's practice of using pilot-operated valves with pushbutton electric controls to operate the packer. The packer was actually started and stopped by a lever, with electric pre-selector switches which determined the movements of the mechanism. Moving the lever would complete the entire cycle, or the "full circle" of compaction as Heil literature stated. The operator could choose normal mode, for typical hand-loaded residential routes, or container mode, with the mechanism starting and stopping at the blade up/slide out position. This was done so that lifting cables (drawn by the slide) could be attached to a container before resuming the cycle. Pulling the lever with the mechanism already in operation causes a short-cycle, with the blade immediately going down and then slide in. A blade button could be pushed causing the blade to go up immediately, as well as a stop button for emergencies.
An automatic crowd feature helped protect the unit from damage caused by incompressible objects. If the blade struck such an object, hydraulic pressure buildup triggered a pressure switch, causing the blade to rise up slightly to clear the obstruction. This would occur continuously as needed, resulting in "chopping" movement of the blade and slide to find a clear path through the refuse. Heil was virtually alone in the U.S. industry with their use of electric controls for rear loaders, for better or for worse, and this did add complexity to troubleshooting procedures. In addition to the usual hydraulic plumbing, service men would have to be familiar with the function of relays, limit switches and holding coils used in the Mark V, not to mention diodes and even a circuit board!
Two container hoists were available for the Mark V, the most basic being a set of wire cables anchored to the tailgate and looped around pulleys on the slide blade. Using the packer hydraulic cylinders to do the lifting, this hoist could empty containers up to 3-cubic yards. For the bigger jobs, an overhead hydraulic winch could be installed for handling containers up to 10-cubic yards. The loading sill edge of the hopper was hinged, and was normally kept up during container dumping, but could lowered for ease of loading bulky objects by hand.
By 1973, the Mark V received a new design body with vertical reinforcing ribs, as did all of Heil's rear loaders. The change was likely dictated by production economies, since it weighed in 300 pounds heavier. Until curved-side bodies became standard, the vertical rib was common throughout most of the refuse body industry from the 1970s forward. The only other major update during the Mark V production involved repositioning the tailgate lift cylinders from their original vertical orientation to a horizontal layout which decreased strain. For 1977, manual-linkage packer controls were made optional, indicating possible negative customer reaction to the pushbutton controls.
On the streets, the Mark V more than lived up to Heil's expectations and earned a reputation as a formidable bulk packer. Along the the Leach 2-R and Loadmaster LM-400, it was even able to crack into the fiercely competitive New York City contractor market. John Thomas worked on the introduction, marketing and promotion of the Mark V for Heil during the 1970s. He recalled how one contractor developed a very special version for the severe duty of commercial service;
"One of my greatest satisfactions was the conversion of New York Carting in Manhattan from the 2R to a way overbuilt special version of the Mark V. I worked closely with the Macaluso Family (Joe, Chuck and Bobby) in the design of their special units. The "gold standard" back in those days was to pack 1,000 pounds per cubic yard of household refuse. The Macaluso Mark V ("Metro" as they called it) consistently packed in excess of 1,600 pounds per cubic yard!"
Mark V with the "Full Circle" logo on a rare Walter all-wheel drive cabover, most likely at the 1971 APWA show
MARK V COMPACTION CYCLE
Cycle commences with blade moving up. As the blade pivots, the offset position of the lower link pins moves the slide panel slightly inward against the load in the body
Telescopic slide moves out, and blade covers refuse in hopper. When the controls are set to "container" operation, this is the position from which the cycle start and stops, allowing the operator to hook up and remove container hoist cables
Blade moves down, sweeping contents of hopper. As the blade pivots, the offset position of the lower link pins moves the slide panel slightly outward, away from the load in the body.
Slide moves in, compacting refuse against load in body, and hopper is ready for refuse to be loaded. When the controls are set to "normal" operation, this is the position from which the cycle start and stops, allowing normal hand loading of hopper
Mark V Electric Controls: (1) Start lever: move right to start and complete entire cycle. Move left for short cycle, to take smaller bites of the load. (2) Stop button, press to stop at any point in cycle. (3) Blade up switch, press to raise blade at any point in cycle. (4) Pre-selector switch, move left for container cycle, move right for normal cycle
WHY THE HEIL MARK V IS UNLIKE ANY OTHER PACKER
Although it uses links to support the packer mechanism, the Mark V is not a true swing-link style packer, such as the Dempster Route King and E-Z Pack Goliath. It could be referred to as a semi-swing link type packer, having a pivoting telescopic slide with the links serving as stabilizers. It is a truly unique method used only by the Heil Mark V.
In the comparison graphic above, we first see the Dempster, which is the purest type of swing-link packer. It has a single pivot point (A), and two sets of links which are welded to the upper panel. The lower links carry most of the load force, while the upper links are for control. The the entire assembly swings in an perfect arc around pivot point (A), and the lower (sweep) blade pivots around a hinge (B). The E-Z Pack method (first used by Gar Wood) is similar to Dempster, but uses two sets of independent links, pivotally connected to the tailgate and the upper panel. The upper panel moves in more vertical path, swinging outward slightly towards the lower end of the arc. Like Dempster, the lower (sweep) panel pivots at hinge point (B).
The Mark V links are pivotally connected to the tailgate at (A), but the opposite ends are not connected to the upper (slide) panel. Instead, they are connected to the lower (sweep) panel face (B) at a point behind the blade pivot hinge (C). Thus, the lower end of the packer assembly is supported without tracks, while the upper end is supported and pivots slightly on a hinge (D). When the lower (sweep) blade rotates around its pivot point, the offset placement of the link (B) causes the entire slide panel to pivot back-and-forth around its upper hinge (D). As a result, the Mark V has a hopper floor shaped like a deep tub, with the blade following an elliptical path.
In the video below, the concept is visible, although it is a very subtle movement; watch as the lower sweep panel opens, and notice that the slide moves inward (towards the load in the body) simultaneously. Then the slide moves out during the second phase of the cycle. Next, as the lower (sweep) panel closes and begins crushing the load, the slide moves outward, rising slightly away from the load in the body.
Video courtesy of Erick Zucconi
The Mark V packer with its blade "down" and slide "in"...
...and then with blade "up" and slide "out"; note how the swing links connect to the sweep panel, not the slide panel
An early version Mark V with horizontal rib body on a Chevrolet or GMC tilt-cab tandem
This Mark V on a Kenworth Hustler has unusual extra reinforcements at mid-body
Overhead winch hoisting 8-yard container. The Mark V received an all-new vertical-rib body for 1973.
Ford C-8000 tilt cab handling a residential route
Jefferson Parish, Louisiana went to the Mark V to combine pickup of bulk items with regular collection routes.
The Parish Disposal Service painted many of their trucks in wild schemes, such as this tiger-striped Mark V.
This truck has the horizontally-mounted tailgate lift cylinders, a running change made around 1976
Another late-model version with the improved tailgate cylinders; heavy-duty trucks like this Volvo N10 were needed to carry the Mark V payload
Heil's Colectomatic Mark III was by no means an inferior packer, and still delivered high-density payloads and economical operation. However, it would always be limited in its crushing capability due to the hinged hopper design. Likewise, slide-sweep rear loaders were far more efficient in container service, especially with cans bigger than 2-cubic yards. The competitors models had hoppers which could be reloaded in mid-cycle, while the Mark III was the only rear loader requiring the complete cycle to finish before reloading could begin. Heil would have to field a bulk loader soon, or risk being left behind in the 1970s. There are indications that the alarm had been sounded as early as 1965, when a patent was filed for a new rear loader with a more-or-less sweeping type action. It was never built, probably because it would never have have been able to truly compete with the 2-R. And the Mark III was still selling quite well, which at least gave Heil time to develop a worthy successor.
Although having built much of its refuse equipment empire by way of acquisition (including both individual designs and whole companies), Heil now turned to their own engineering team to create the new bulk rear loader. John Wieschel, Jerald Zanzig, Robert Czarnecki and Claire Murray all contributed to what would become one of the most interesting rear loaders ever conceived, and exactly what Heil needed; a massive machine that would compete with the 2-R on every level, without simply copying the Leach design. The Colectomatic Mark V was announced in August of 1971, based on a patent filed in March of that year. The patent described two embodiments of a single concept, one of which would be the Mark V heavy-duty rear loader which was needed immediately. The other variant would go into production a year later, and would be a lighter-duty version called the Mark IV. Thus, Heil skipped a "Mark" series in order to put their large bulk rear loader on the streets as soon as possible.
