October 2009

The Workhorses of Waste

Collection vehicles vary according to type and specification.

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Refuse Truck

Photo: Mcneilus

By Daniel P. Duffy

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It’s been said that the cowboys working the range would pamper their mustangs and often neglect their own comfort for the sake of their workhorses. They made sure that the horses got clean water while the cowboys drank brackish water. The horses were given sweet grass to eat while their riders made do with a cold plate of beans. The cowpokes sacrificed their own well being for the sake of their mounts. And they did so with good reason: Their livelihoods (even their lives) depended on the care of their horses.

The waste industry has its own workhorses, the waste collection vehicles, and they come in various “breeds.” Like the cowboys of old, their riders perform a physically demanding, gritty, unappreciated but absolutely necessary job. Hollywood portrayals notwithstanding, cowboys back in the day were not glamorous; they were workingmen like everyone else. Being a cowboy was a tough way to make a living, something modern waste collectors can appreciate. And like the cowboys of the past, today’s waste collectors need the appropriate mounts with the right capabilities in order to do their jobs.

Basic Types of Vehicles
There are three basics types of waste collection vehicles and three specialized types. Each services a different kind of customer: industrial, residential, recycling, or specialized. The three basic types are classified by the location and manner of their loading operation and include front loaders, rear loaders, and side loaders. The two specialized collection vehicles collect either with a vacuum attachment or with a grappler arm. The third specialized type is classified according to the overall function of recycling.

Front loaders (not to be confused with front-end loaders used for earthmoving and stockpile material management) are used to collect waste from dumpsters that collect and temporarily store debris that is typically generated by businesses, retail operations, restaurants, and industry. These trucks combine a forklift with a waste hopper for containment during transport. As the truck approaches a dumpster, it inserts its fork lift arms into metal loops designed for the purpose and located on either side of the dumpster box. Once secured, the forklift arms lift the box up and over the truck cab, turning it upside down as it goes. The top of the dumpster will fall open and allow its contents to spill into the hopper below. Once emptied, the forklift arms return the now empty dumpster back to its position on the ground. Inside the hopper, the waste is compacted by a “packer blade” that pushes the waste back to the rear of the hopper. This increases its density and opens up more free space for the next load. Trucks that are equipped with “pack and go” hydraulics, have superior operational efficiency since the truck can be compacting waste as it moves to its next pickup, removing delays as the truck would wait motionless until the compaction process was completed.

Rear loaders typically accept residential waste from individual trash cans that are emptied manually into the rear of the truck. These trucks are usually serviced by a small crew consisting of the driver and two or more loaders. They are designed to take and compact smaller individual loads of waste, compared with the large bulk loads handled by the front loaders. Partially automated loading systems are available in addition to manual loading. Waste containers larger than the typical waste cans (often referred to as toters) can be lifted and dumped by an auxiliary loading mechanism. Sometimes this loading mechanism consists of a special grove slot in the truck that is sized to receive a standardized waste container. A chain that tightens and wraps itself around the waste container can then lift and tilt it to empty the contents into the back of the truck. No matter how the waste is loaded, it gets compacted within the truck. This is done by means of a hydraulically powered sweep-and-slide blade that shifts out and down to position itself for compaction and then sweeps the waste forward to the front of the tuck. This action effectively compacts the loaded waste and frees up space in the back end for additional loading.

Automated side loaders are collection trucks that pick up intermediate-size mobile garbage bins. Some models have mechanical arms that can reach out 9 feet from the side of the truck to grab adjacent bins. The arm is operated from within the cab by a joystick and is articulated so that it can be operated around obstacles. This allows the entire waste collection effort to be performed by a single worker instead of the typical driver and one to two loaders required by less-advanced collection vehicles.

Recycling trucksare a kind of specialized vehicle used by standard hauling routes. They are designed to manage source-separated waste, collecting and hauling it to a local multistream (“clean”) materials recovery facility (MRF). However, since most waste collection operations nowadays also include a pickup of source-separated recyclable materials, recycling trucks have become an integral part of the standard waste collection vehicle fleet. No compaction is typically performed in these trucks either, but they do come with multiple (usually four) containers, each of which holds a different kind of source-separated waste.

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Pneumatic collection trucks are specialized vehicles equipped with flexible pneumatic tubes controlled and positioned by attached cranes or booms. The engines of these trucks can be used to generate a suction force that applies negative pressure to the mouth of the tube. The tube is positioned over an opening (typically a hole to an underground storage unit) and proceeds to suck up the waste into the holding tank on the back of the truck. The tube’s flexibility allows for effective operation even around nearby obstacles.

Grapple trucks are another type of specialized waste collector used primarily in large-scale industrial and recycling activities. These trucks come equipped with a hydraulically operated boom serviced by a clamshell bucket or an orange-peel grapple. The boom reaches out to an adjacent pile of debris or large and heavy waste items and grabs them with the grappling attachment. The oversized waste is then deposited into a dump container on the back of the truck for hauling offsite. Given the size, weight, and irregularity of the waste handled by grapple trucks, they do not typically compact their waste loads during transit. Next Page >

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