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TERMINOLOGY

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Trailer drawings are not on scale and are for illustration purposes only

BASIC TRAILER DESCRIPTIONS

Semi-trailer	A trailer without a front axle. A large proportion of its weight is supported either by a TRUCK or by a detachable front axle assembly known as a DOLLY or by the tail of another trailer. A semi-trailer is normally equipped with LEGS which can be lowered to support it when it is uncoupled. A truck coupled to a semi-trailer is often called a semi-trailer truck or semi. A SEMI does not necessarily refer to a specific axle usage. In our case it refers to a TRIDEM / TRI-AXLE, but can be used to describe any single trailer-truck combination.



Single-axle	Single trailer with only one (1) axle



Tandem / 2-Axle	Single trailer with two (2) axles 2-Axle Trailers are also known as EIGHTEEN WHEELERS (although not commonly used in RSA). This description is calculated from the total number of ALL the wheels of the truck and trailer unit combined. Truck: 1 front axle with SINGLE TYRES (equals 2 wheels), 2 rear axles with DUAL TYRES (equals 8 wheels). Trailer: 2 axles with DUAL TYRES (equals 8 wheels) TOTAL WHEELS: 18 wheels However - if the trailer had SINGLE tyres on, the description FOURTEEN WHEELER would refer to the same trailer


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Tri-axle / Tridem	Single trailer with three (3) axles



Tandem-Tandem Interlink Link	Two (2) separate trailers each with two (2) axles linked together by 5th WHEEL or DOLLY



Interlink Link	Two (2) separate trailers with any combination of axles linked together by 5th WHEEL or DOLLY. (Generally 2 x 2-Axle trailers - see above TANDEM-TANDEM)

A-Z
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Air suspension	air suspension is a suspension which supports the load on air-filled rubber bags rather than steel springs. Compressed air is supplied by the same engine-driven air compressor and reservoir tanks which provide air to the air brake system.

Axle	that which attaches wheels to trailer

Bobtail	a bobtail is a tractor operating without a trailer. Also refers to a straight truck.

Chassis	the frame of a vehicle. This is the structure of a vehicle, which all other parts attach to regardless whether it is unibody or frame construction.

Dolly	an auxiliary axle assembly having a fifth wheel used for purpose of converting a semi trailer to a full trailer. Dollies can be used to haul multiple trailers behind a single power unit. (also referred to as bogie).

Dry Van	a van that doesn't have a reefer unit.

Extendable flatbed trailer	a flatbed trailer whose length may be readily increased or decreased within prescribed limits and with prescribed variations in load carrying capability. Used mainly for oversized loads. The truck, and a pin on the trailer.

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Fifth wheel	coupling device attached to a truck or dolly which supports the front of a semi trailer and locks it to the tractor or dolly. The fifth wheel's center is designed to accept a trailer's kingpin, around which the trailer and truck or dolly pivot in turns.

Flatbed / flatdeck	trailer with a flat deck and no sides.

Gooseneck	on a drop frame trailer, that portion of the trailer which extends upward and forward from the front of the loading deck to, and including, the upper coupler and front crossmember.

Gooseneck, removable	a gooseneck which can be separated from the trailer and reconnected, usually through the use of large hooks or removable pins. The motive force required to remove such goosenecks is usually obtained through the use of the tractor winch line or hydraulic cylinders.

Kingpin	a kingpin is an anchor pin at the center of a semi trailer's upper coupler which is captured by the locking jaws of a tractor's fifth wheel to attach the tractor to the semi trailer.

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Landing legs / gear	legs which can be lowered to support trailer when it is uncoupled from truck or additional trailer

Load binder	a mechanical device, consisting of a lever-operated toggle and lock, generally used to tighten a cargo securing system. Winches are sometimes used as load binders.

Load straps	canvas belts that are long enough to go over the top of a load and used to hold the cargo onto the deck of a flatbed trailer. Load straps are also used on the inside of an enclosed van to secure freight.

Pallet	wooden board for carrying goods

Refrigeration unit	a mechanical device designed to be mounted on a refrigerated trailer or container for the purpose of cooling the cargo area.

Stepdeck	a trailer that has a main deck that is lower than the deck above the fifth wheel, but not as low as that of a double drop. The back of the deck is usually level with the top of the trailer tires.

Tarp / tarpaulin	a water resistant fabric cover used to protect the cargo on an open trailer

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Truck	a motor vehicle designed to carry an entire load. It may consist of a chassis and body; a chassis, cab and body;

Tyres - SINGLES	1 tyre per side of axle (total of 2 tyres per 1 axle)

Tyres - DUALS	2 tyres per side of axle (total of 4 tyres per 1 axle)

Dry Van	standard trailer or truck with all sides enclosed.


	If any of the above terms / descriptions are incorrect, or if you wish to add to our list, please e-mail the details to info@satb.co.za