Semi Trailers from American Trailer Exchange
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Information About a Semi Trailer or Truck Trailer

Definition of a semitrailer or semi-trailer:

semitrailer [ˌsɛmı'treılə]
noun  a type of trailer that has wheels only at the rear, the front end being supported by the towing vehicle (the towing vehicle is known as a tractor)
Source: The Collins English Dictionary � 2000 HarperCollins Publishers

General Information
A semi-trailer is a trailer without a front axle. A large proportion of its weight is supported either by a road tractor or by a detachable front axle assembly called a dolly. A semi-trailer is equipped with legs that can be lowered to support it when it is unhooked from the tractor. When coupled together, the tractor- trailer combination is often referred to as a semi, 18-wheeler, big-rig, articulated lorry, or truck and trailer.

The purpose of a semi-trailer is to carry freight. There are several types of semi-trailers including dry freight vans, refrigerated vans (reefers), flatbeds (standard, step-deck, lowboy, double drop, etc.) and tank trailers. Trailer sizes vary, but the most common sizes today are 53' or 48' in length and 102" or 96" in width.

Semi trailers are also referred to as truck trailers and are typically listed under the Heading: Trailers-Truck in most phone directory yellow pages.

Weight and Size Limits in the United States
Although some states and localities vary, a loaded truck (tractor & trailer combination) in the U.S. is typically limited to the following size and weight restriction:
    Maximum Width: 8'6" (102")
    Maximum Height: 13'6"
    Maximum Overall Length: 80'
    Maximum Total Weight: 80, 000 lbs (including weight of equipment & load)

Shipments that exceed these limits may require special permits and other regulations may be required

What is a Fifth-Wheel?:
Originally, a fifth wheel was a steering bearing that enabled the front axle of a horse-drawn wagon to rotate. Today, a fifth wheel is a wheel or portion of a wheel placed horizontally over the rear axle or axles of a tractor or pickup truck, serving as a coupling for a semitrailer that allows it to rotate for turns and better stability.

To find the Year of a trailer, look at the 10th digit of the Vehicle Identification Number (also known as the VIN) and follow the Chart below:

A	1980	J	1988	T	1996	4	2004
B	1981	K	1989	V	1997	5	2005
C	1982	L	1990	W	1998	6	2006
D	1983	M	1991	X	1999	7	2007
E	1984	N	1992	Y	2000	8	2008
F	1985	P	1993	1	2001	9	2009
G	1986	R	1994	2	2002	A	2010
H	1987	S	1995	3	2003	B	2011

Brief History of the Semi-trailer
Fruehauf
August Charles Fruehauf (1868-1930), was a blacksmith and carriage builder in the Detroit area. In 1914,  he built a trailer to carry a merchant's pleasure boat, which was to be hauled by a Ford automobile. The trailer was a success. The merchant asked Fruehauf to build additional trailers to haul lumber. These trailers, which Fruehauf called "semi-trailers", became very popular. In 1918, Fruehauf incorporated his semi-trailer manufacturing company, and the Fruehauf Trailer Company was was formed.

Trailmobile
John C. Endebrock began work at the Sechler Company, a carriage maker, in 1889 as an office boy, working his way through the ranks to the position of foreign sales representative. It was Endebrock who, around 1910, saw that the future lay in building "truck trailers," and that the days of the horse-drawn wagon were  coming to an end. No one had yet developed a satisfactory device for coupling a truck-trailer to a truck. Endebrock decided to concentrate on a vehicle that could be pulled by a Ford Model "T" passenger car.

A totally new trailer had to be designed using the principles of automobile  dynamics. This new unit featured an angle iron chassis frame with crossmembers, horn-type front spring hangers, a knuckle-type front axle, automobile springs,  artillery wheels, roller bearings, and a draw bar with housed spring sections.  In 1915, after months of rigorous road testing, the new trailer was introduced  to the world. The name "Trailmobile" was chosen since the unit would "trail" an automobile. The wide acceptance of these first automotive trailers prompted the  Sechler organization to change its name to the Trailmobile Company.

Endebrock pondered the possibility of easing the task of coupling and uncoupling semi-trailers, which required three men with jacks to lift the trailer. He  wondered if a coupler similar to those used on railroad cars could be devised for the semi-trailer, eliminating the need for two extra men. During 1918-1919,  he developed a jaw coupled with a spring-plunger locking device, mounted on a "lower fifth wheel" plate attached to the tractor frame. The fifth wheel mechanism locked into a "king pin" on the bottom of the front end of the semi-trailers. Only one man, the driver of the tractor, was needed to couple and  uncouple the automatic trailer. Endebrock's handmade prototype fifth wheel, patented in 1919, differed very little from present semi-trailer fifth wheels. (Copyright 1997, 1998, 1999, 2000, 2001 Trailmobile Corporation)

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