Truck

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A truck (lorry in British English) is a vehicle used to transport goods. The word "truck" comes from the Greek word "trochos", which means "wheel". They usually use diesel fuel.

Daimler-Lastwagen, 1896

Types of trucks by size[change | change source]

Light trucks[change | change source]

Light trucks are trucks the size of cars. They are used by individuals and also companies. In the United States, a truck is a light truck if it weighs less than 6,300 kg (13,000 lb). Light trucks are only a little heavier than vans or pickup trucks, but require a special driver's license.

Medium trucks[change | change source]

Medium trucks are heavier than light trucks but lighter than heavy trucks. In the United States, a truck is a medium truck if it weighs between 6,300 kg (13,000 lb) and 15,000 kg (33,000 lb). Trucks that are used for local delivery and public service (dump trucks, garbage trucks) are normally around this size. Medium trucks have usually two axles: one at front and one at rear. The rear wheels may be coupled (that is: two wheels hitched together) to enable heavier load, but they may also be single.

Heavy trucks[change | change source]

Heavy trucks are the heaviest trucks that are allowed on the road. In the U.K. they are known as lorries. Usually heavy trucks have three axles: one at front and two at rear, and the rear axles have coupled wheels to enable heavy loads. Often heavy trucks pull trailers. They can be either full trailers which have both front and rear axles or boggies and their own brakes, and are connected to the towing truck with a towbar, or semi-trailers, which are attached to a special kind of a truck called tractor unit with a turntable coupling ("fifth wheel"). A semi-trailer is a kind of trailer which has wheels only in the back and the front rides on the back of the tractor unit. The tractor unit has an engine and the semi-trailer does not. Driving a heavy truck requires a professional driver's license. Truck drivers are called truckers.

The laws of various countries say what kind of vehicle combinations are allowed. A semi-trailer can be converted into a full trailer with using a dolly. A dolly is a small trailer which has only a bogie (= set of wheels), fifth wheel coupling for the semi-trailer and a towbar. Using a dolly, the semi-trailer can now be hitched to an ordinary cargo-carrying truck and does not need a tractor unit.

A heavy truck-trailer combination is often called big rig or eighteen-wheeler.

The largest heavy trucks are the Australian road trains which may have up to four semi-trailers coupled to a tractor in a train-like fashion and may carry up to 200 tonnes of cargo.

Body types[change | change source]

Box trucks ("tilts" in the UK) have walls and a roof, making a closed cargo room. The rear has doors and there is sometimes a side door too.

Concrete mixers have a turning drum on back. Turning one way mixes the concrete and turning it the other way pushes the concrete out. The concrete goes down "chutes" (like large pipes with an open top). On most trucks the concrete comes out the back but some new types have the concrete goes over the cab and down chutes in the front. Because concrete is very heavy and hard to mix concrete mixers have to be very heavy duty.[1]

Dump trucks ("tippers" in the UK) carry loose loads like sand, gravel, and dirt. Most dump trucks have an open-top box bed and an opening "tail-gate" door on the back. It lifts up at the front so the load can fall out the tailgate and be "dumped" on the ground behind the truck.[2]

Flatbed trucks have a level body with no sides. This lets the truck be loaded from the side or top but does not cover the load. Some have sides that can be taken off or folded down. Many times the load is covered with tarps.

Garbage trucks pick up garbage and trash from homes and some businesses and haul it away. Most were loaded from the rear but now some load from the front or side. The same type of truck is often used to pick up recycling.

Semi-tractors ("artics" in the UK) have no bodies, instead they have a "fifth wheel" for towing a semi-trailer.

Tank trucks ("tankers" in the UK) are designed to carry liquids or gases. They usually have a round tank (like a food can) lying down on the chassis. There are many types of tanks because there are so many liquids and gasses. Most tankers are built for only one type of liquid.

Wreckers ("recovery lorries" in the UK)(sometimes "tow trucks" in the US) are used to lift and tow broken cars and trucks. They usually have a boom with a cable. Cars are now often carried on special flatbeds.

Semi-trucks[change | change source]

Semi-truck with "box" trailer. Blue is the axles, differentials, drive shafts, and fifth wheel.
1. Semi-tractor
2. Semi-trailer
3. Engine compartment
4. Cab
5. Sleeper (not on all trucks)
6. Air dam (not on all trucks)
7. Fuel tanks
8. Fifth wheel coupling
9. Inside cargo space
10. Landing gear - legs for parking trailer
11. Tandem axles

References[change | change source]

Carroll, John; Davies, Peter (2015). The Illustrated Encyclopedia of Tractors and Trucks. Hermes House. ISBN 978-1-84309-689-5.