How Does a Semi Tractor Work?
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Semi-Tractors
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Semi-trailer trucks are also know as tractor-trailers. Within the United States, they are also referred to as semis, big rigs or 18-wheelers. In Australia and Canada, they are referred to as semis. In the United Kingdom and Ireland, they are known as artics or articulated lorries. Semi-tractor trailers are vehicles that are specially designed for the purpose of pulling, towing and hauling a trailer or some other machinery device that is used for construction or agricultural use. The trailer used for agricultural or construction use generally carries large amounts of freight cargo. Many of today's current tractors have numerous electrical buttons and switches within the tractor cab to maneuver the many different functions that they are capable of.
Semi-Tractor Trailer Brakes and Transmissions
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The majority of semi-tractor trucks utilize air pressure instead of hydraulic fluid to activate the brakes on the units. This is generally because semis require a much greater braking force and air pressure makes it easier to brake. The use of air pressure to activate the brakes also helps to make it easier to connect and disengage trailers and tractor units. In addition, in comparison to using hydraulic systems, it also lessens brake failures such as leaking or failures due to overheated brake fluid fumes within the hydraulic lines. Semi-tractors usually have manual transmissions. This permits the driver to have more control. This is needed when hauling various types of loads.
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North American Vs. European Semi-Tractors
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Semi-tractors in North America generally consist of three axles. The front or steer axle consists of two wheels and the rear drive axles each consists of a pair of double (dualies) wheels on every side. However, the most common structure of a tractor consists of ten wheels. There are some that have tires called super singles or wide-base singles instead of the dual wheels. This is for the purpose of lessening the tractors weight. In these cases, the tractor is equipped with only six wheels. Cargo trailers generally consist of three axles in the rear, with each of those axles consisting of dual wheels. All of the wheels on the entire vehicle total 18 wheels. However, trailers may vary in the quantity of wheels they have. There are various rules that govern the maximum size and weight of tractor-trailers. The rules differ between states. The United States permits two-axle tractors to tow two 1-axle 28.5-foot semi-trailers. A European tractor unit consists of a sheer face on the front of the unit for improved maneuverability. The driver of the tractor only needs to measure distances from his seating position. This provides maximum total length maneuverability for shorter trucks that have long trailers and great cargo capacity. The complete length of tractor vehicles in Europe are measured as maximum total length; however, in the United States, the cabin part of the tractor is generally not included in the measurement of the vehicle.
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Resources
- Photo Credit Flickr, RICarr, Chris in NE, Roadsidepictures
