Garbage truck
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Image:Wastemanagementtruck.jpg A garbage truck in US English; or dustcart, or sometimes dustbin wagon in Commonwealth English, is a truck specially designed to haul waste to landfills and other recycling / disposal facilities. They are a common sight in most urban areas.
There are four basic models of garbage truck:
- Front loaders generally service commercial and industrial sites using dumpsters (US term for large wheelie bins). They have large prongs on the front which are carefully aligned with arms on the dumpster. The dumpster is then lifted over the truck, until it is upside-down and the trash will then fall out into the receptacle.
- Rear loaders commonly service residential areas. They have an opening at the rear that a trash collector can throw garbage bags or empty the contents of trash cans into. Often (particularly in Europe) they have a lifting mechanism to automatically empty wheeled bins (from both residential and commercial premises) without the operator having to lift the waste by hand. Another popular system for the rear loader is a rear load container specially built to fit a groove in the truck. The truck will have a wire / chain or strap system for lifting in the two "eyes" on the rear top. The waste will then slide into the tray of the truck. Normal sizes are 8 to 22 m³.
The rear loader is usually equipped with some type of compactor that will compress the garbage, and move it towards the front of the vehicle.
- Side loaders are versions of either front or rear loaders that lift small trash containers or have openings on either side to deposit trash. Some side loaders are equipped with a mechanical remote-control arm that grasps a trash container such as a wheeled bin and empties it into the truck in the same manner as front loaders. This type of garbage truck requires only one arm-operator/driver but residents must position their wheelie bins carefully near the curb and at least two metres away from nearby objects.
- Pneumatic collection, almost a 24 ton vacuum cleaner. On the top it has a crane with a tube and a mouthpiece that fits in a hole, usually hidden under a plate under the sidewalk. From here it will suck up garbage from an underground installation. The system usually allows the driver to "pick up" the garbage, even if the access is blocked by cars, snow or other barriers.
There are also larger trucks that carry trash over long distances, usually modified dump trucks.
Garbage trucks empty their trash in landfills or combustion facilities. Most rear loaders lift the rear section so that the garbage will spill out. Front loaders more commonly have a moving wall that pushes the garbage out. Some larger landfills will have large contraptions that tip the entire truck, thus allowing the trucks to not have to carry their own method of emptying the garbage.
History
Wagons and other means had been used for centuries to haul away solid waste. Trucks were first used for this purpose soon after their invention. The 1920s first saw open topped dump trucks used for the purpose, but soon covered vehicles became used more often. The open tops tended to drop waste and had poor odours. These covered trucks were first introduced in more densely populated Europe than in North America, but were soon used everywhere.
The covered vehicles were still modified dump trucks, however. The main difficulty was that the garbage collectors needed to lift the trash to shoulder height. The first technique developed in the late 20s to solve this problem was to build round compartments with massive corkscrews that would lift the load and bring it away from the rear. A more efficient model was the development of the hopper in 1929. It solved this problem by developed a cable system that a could pull garbage into the truck.
In 1937 George Dempster invented the Dempster-Dumpster system in which wheeled garbage containers were mechanically tipped into the garbage truck. His containers were known as Dumpsters, which led to the word dumpster entering the language.
In 1938 the Garwood Load Packer revolutionized the industry when the notion of including a compactor in the truck was implemented. The first primitive compactor could double a truck's capacity. This was made possible by the availability of relatively cheap hydraulic presses.
1955 saw the Dempster Dumpmaster the first front loader introduced. They do not become common until the 1970s, however. The 1970s also saw the introduction of smaller dumpsters, often known as wheelie bins which were also emptied mechanically.
Since that time there has been little dramatic change. Compactor designs however, have been many and varied, one of the most popular being the traditional "sweep and slide" system where hydraulically-powered plates scoop out the garbage from a loading hopper and subsequently compact it against the material already loaded. The Heil Colectomatic used a combination of a lifting loading hopper and a sweeper blade to clear and compact garbage in anticipation of the next load.
So-called "continuous" compactors were popular in the 1960s and 1970s. The German Shark design (later Rotopress) used a huge rotating drum, analogous to a cement mixer, in conjunction with a serrated auger to grind down and compact the garbage. SEMAT-Rey of France pioneered the rotating rake system (also used in the British Shelvoke and Drewry Revopak) to both mutilate waste and break down large items. High fuel consumption has seen a decline in the popularity of continuously compacting garbage trucks.
There has long been the dream of the fully automated garbage truck that could do away with all but the driver. Some cities do have these systems (see Side Loader above), but they are generally unable to deal with unexpected situations.
In 1995 a freak accident occurred when a 12 foot hydraulic arm punched through the side of a Los Angeles garbage truck and raked a school bus, killing two eight year old school children [1].
See also
External links
- History of refuse collection - Historical information and many pictures of garbage trucks.
- Heil Garbage Trucks - Heil Environmental, history of the oldest U.S. garbage truck maker, modern garbage trucks
- Freightliner Garbage Trucks - Information and images of Freightliner garbage trucks and how they work.
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