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A drawbar is a solid coupling between a hauling vehicle and its hauled load. Drawbars are in common use with rail transport, road trailers, both large and small, industrial and recreational, and with agricultural equipment.
Agricultural equipment is hauled by a tractor-mounted drawbar. Specialist agricultural tools such as ploughs are attached to specialist drawbars which have functions in addition to transmitting tractive force. This was partly made redundant with Ferguson's development of the three-point linkage in his famous TE20. A wooden drawbar extends from the front of a wagon, cart, chariot or other horse-drawn vehicles to between the horses. A steel drawbar attaches a three-point hitch or other farm implement to a tractor.
A drawbar is a towing or pushing connection between a tractive vehicle and its load.
On light vehicles, the most common coupling is an A-frame drawbar coupled to a 1 7/8 inch or 50 mm tow ball. These drawbars transmit around 10% of the gross trailer weight through the coupling.
The direction of haulage may be push or pull, though pushing tends to be for a pair of ballast tractors working together, one pulling and the other pushing an exceptional load on a specialist trailer. The most common drawbar configuration for heavy vehicles is an A-frame drawbar at the front of a full trailer that connects to a tow coupling on a hauling vehicle [1]
On heavy vehicles, the drawbar is coupled using a drawbar eye, typically of 40 mm or 50 mm diameter, connected to a bolt and pin coupling. Commonly seen brands include Ringfeder, V. Orlandi and Jost Rockinger . These drawbars transmit little or no downwards force through the coupling.
The drawbar should not be confused with the fifth wheel coupling. The drawbar requires a trailer which either loads the drawbar lightly (for example a small boat trailer, or caravan, or the load is the weight of the coupling components only (larger trailers, usually but not always with a steerable hauled axle, front or rear). By contrast, the fifth wheel is designed to transmit a proportion of the load's weight to the hauling vehicle. Drawbar configuration is mostly seen on hydraulic modular trailer and ballast tractor combination to haul oversize loads which require special trailer and tractor.
A drawbar eye, also called tow eye, is a mechanical part to connect an independent trailer/dolly via a drawbar coupling to a tractor. [2] the eye is connected to the front end of a drawbar with bolt, flange-mounting or welding. [3] Most are made from high tension material to bear heavy loads while being pulled by the tractor. The eye is made in the shape of an "i" with a hole at top which is locked in the drawbar coupling and the lower part is mounted to the drawbar making it an essential connector between the drawbar and drawbar coupling. The drawbar eye is used in many heavy transport operations around the world. It is mostly used for agriculture equipment, construction equipment, road trains, dolly trailers, full trailer and hydraulic modular trailers.
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Two or more passenger or freight cars may be attached by means of a drawbar. At both extremes there is a regular coupler such as the North American Janney coupler or the Russian SA3 coupler. This drawbar eliminates slack action.
A semi-trailer truck, also known as a semi-truck, (or semi, big rig, tractor-trailer, or eighteen-wheeler) is the combination of a tractor unit and one or more semi-trailers to carry freight. A semi-trailer attaches to the tractor with a type of hitch called a fifth wheel.
A road train, land train or long combination vehicle (LCV) is a trucking vehicle used to move road freight more efficiently than semi-trailer trucks. It consists of two or more trailers or semi-trailers hauled by a prime mover.
A tractor is an engineering vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery such as that used in agriculture, mining or construction. Most commonly, the term is used to describe a farm vehicle that provides the power and traction to mechanize agricultural tasks, especially tillage, and now many more. Agricultural implements may be towed behind or mounted on the tractor, and the tractor may also provide a source of power if the implement is mechanised.
A trackless train — or tram, road train, land train, or parking lot train is a road-going articulated vehicle used for the transport of passengers, comprising a driving vehicle pulling one or more carriages connected by drawbar couplings, in the manner of a road-going railway train. Similar vehicles may be used for transport of freight or baggage for short distances, such as at a factory or airport.
A trailer is an unpowered vehicle towed by a powered vehicle. It is commonly used for the transport of goods and materials.
Scammell Lorries Limited was a British manufacturer of trucks, particularly specialist and military off-highway vehicles, between 1921 and 1988. From 1955 Scammell was part of Leyland Motors.
A tow hitch is a device attached to the chassis of a vehicle for towing, or a towbar to an aircraft nose gear. It can take the form of a tow ball to allow swiveling and articulation of a trailer, or a tow pin, or a tow hook with a trailer loop, often used for large or agricultural vehicles where slack in the pivot pin allows similar movements. Another category is the towing pintle used on military vehicles worldwide.
A dolly is an unpowered vehicle designed for connection to a tractor unit, truck or prime mover vehicle with strong traction power.
An articulated vehicle is a vehicle which has a permanent or semi-permanent pivot joint in its construction, allowing it to turn more sharply. There are many kinds, from heavy equipment to buses, trams and trains. Steam locomotives were sometimes articulated so the driving wheels could pivot around corners.
A tractor unit is a characteristically heavy-duty towing engine that provides motive power for hauling a towed or trailered load. These fall into two categories: heavy- and medium-duty military and commercial rear-wheel-drive semi-tractors used for hauling semi-trailers, and very heavy-duty typically off-road-capable, often 6×6, military and commercial tractor units, including ballast tractors.
A semi-trailer is a trailer without a front axle. The combination of a semi-trailer and a tractor truck is called a semi-trailer truck.
The fifth-wheel coupling provides the link between a semi-trailer and the towing truck, tractor unit, leading trailer or dolly. The coupling consists of a kingpin, a 2-or-3+1⁄2-inch-diameter vertical steel pin protruding from the bottom of the front of the semi-trailer, and a horseshoe-shaped coupling device called a fifth wheel on the rear of the towing vehicle. As the connected truck turns, the downward-facing surface of the semi-trailer rotates against the upward-facing surface of the fixed fifth wheel, which does not rotate. To reduce friction, grease is applied to the surface of the fifth wheel. The configuration is sometimes called a turn-table in Australia and New Zealand, especially if it is a rotating ball-race-bearing type. The advantage of this type of coupling is towing stability.
Towing is coupling two or more objects together so that they may be pulled by a designated power source or sources. The towing source may be a motorized land vehicle, vessel, animal, or human, and the load being anything that can be pulled. These may be joined by a chain, rope, bar, hitch, three-point, fifth wheel, coupling, drawbar, integrated platform, or other means of keeping the objects together while in motion.
A motorcycle trailer is either a trailer used to carry motorcycles or one to be pulled by a motorcycle in order to carry additional gear.
Ringfeder name is a German brand based in Krefeld founded in 1922. The brand manufactures bolt couplings, hook couplings, drawbar eyes, underrun protections and accessories. Ringfeder is part of VBG Truck Equipment, one of the divisions in the VBG Group, a large international industrial group.
A ballast tractor is a specially weighted tractor unit of a heavy hauler combination. It is designed to utilize a drawbar to pull or push heavy or exceptionally large trailer loads which are loaded in a hydraulic modular trailer. When feasible, lowboy-style semi-trailers are used to minimize a load's center of gravity. Typical drivetrains are 6×4 and 6×6 but also available in 8×6 and 8×8. Typical ballast tractor loads include oil rig modules, bridge sections, buildings, ship sections, and industrial machinery such as generators and turbines.
An overrun brake is a brake system commonly used on small trailers, where the motion of the trailer with respect to the towing vehicle is used to actuate the brake.
A tank transporter is a combination of a heavy tractor unit or a ballast tractor and a mating full trailer, hydraulic modular trailer or semi-trailer, used for transporting tanks and other armoured fighting vehicles. Some also function as tank recovery vehicles, the tractors of which may be armoured for protection in combat conditions.
A hydraulic modular trailer (HMT) is a special platform trailer unit which feature swing axles, hydraulic suspension, independently steerable axles, two or more axle rows, compatible to join two or more units longitudinally and laterally and uses power pack unit (PPU) to steer and adjust height. These trailer units are used to transport oversized load, which are difficult to disassemble and are overweight. These trailers are manufactured using high tensile steel, which makes it possible to bear the weight of the load with the help of one or more ballast tractors which push and pull these units via drawbar or gooseneck this combination of tractor and trailer is also termed as heavy hauler.