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A tow hitch (or tow bar or trailer hitch in North America) is a device attached to the
chassis A chassis (, ; plural ''chassis'' from French châssis ) is the load-bearing framework of an artificial object, which structurally supports the object in its construction and function. An example of a chassis is a vehicle frame, the underpar ...
of a vehicle for towing, or a towbar to an
aircraft An aircraft is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or by using the Lift (force), dynamic lift of an airfoil, or in ...
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 A pintle is a pin or bolt, usually inserted into a gudgeon, which is used as part of a pivot or hinge. Other applications include pintle and lunette ring for towing, and pintle pins securing casters in furniture. Use Pintle/gudgeon sets have ma ...
used on military vehicles worldwide. To tow safely, the correct combination of vehicle and trailer must be combined with correct loading horizontally and vertically on the tow ball. Advice should be heeded (see references) to avoid problems.


Regional variations


North America

Trailer hitches for conventional passenger cars, light-duty commercial vehicles, light trucks, and multipurpose passenger vehicles come in two main OEM or aftermarket types: receiver and bumper/fixed-drawbar. Receiver-type hitches consist of a portion with a rearward-facing opening that accepts removable aftermarket hitch-mounted accessories: trailer hitch ball mounts, hitch bike racks, cargo carriers, etc. Bumper/fixed-drawbar type hitches typically are built as one piece, have an integrated hole (sometimes more than one hole on pickup trucks) for the trailer ball mount, and are generally not compatible with aftermarket hitch-mounted accessories. Outside North America, the vehicle mounting for the tow ball is called the tow bracket. The mounting points for all recent passenger vehicles are defined by the vehicle manufacturer and the tow-bracket manufacturer must use these mount points and prove the efficacy of their bracket for each vehicle by a full rig-based fatigue test.


Ball Mounts

The trailer hitch ball attaches to a ball mount; with a diameter typically " larger than the ball bolt/shank diameter. The ball mount must match the SAE hitch class. The ballmount for a receiver-type hitch is a square bar that fits into a receiver attached to the vehicle. Removable ball mounts are offered with a varying rise or drop to accommodate variations in the height of the vehicle and trailer to provide for level towing.


Load classes

A trailer hitch typically bolts to the chassis of the vehicle. In North America, there are a few common trailer hitch classes (I, II, III, and IV) that are defined by the Society of Automotive Engineers (SAE). : Class I – up to – light loads : Class II – up to – light loads : Class III – up to – larger loads (campers, boats, etc.) : Class IV – up to – larger loads (campers, boats, etc.) Some manufacturers market Class V hitches, but there was no such standard listed in the 2014 version of SAE J684. : "Class V" – up to – larger loads (construction equipment, etc.)


Receiver tube sizes

A receiver hitch can accommodate a variety of different tow hitches when the tow hook/ball may be attached via a receiver tube attached to the tow vehicle. Trailer hitch receiver tubes may be bolted, welded, or integral to the vehicle chassis, and come in various sizes depending on the load they are designed to carry and the country of operation. The US standards are: :Class I & II - light or medium duty receiver tube :Class III & IV - heavy duty receiver tube :Class V - receiver tube


Ball sizes

Trailer hitch balls come in various sizes depending on the load they carry and the country of operation with removable types consisting of a bolt/shank to attach to the ball mount. The trailer tongue (North America) or coupling (outside North America) slips over a trailer hitch ball attached to a receiver hitch mount or integral with the hitch. A larger, heavy-duty gooseneck ball size: is typically used for towing greater than 10,000 pounds and this towing capacity falls outside of the scope of SAE J684 trailer hitch classes.


Truck variants

Weight ratings for both bumper-mounted and frame-mounted receiver hitches can be found on the bumper of pickup trucks (for bumper-mounted tow balls) and on the receiver hitch (for frame-mounted receiver hitches). For flat deck and pickup trucks towing
trailers Trailer may refer to: a Transportation * Trailer (vehicle), an unpowered vehicle pulled by a powered vehicle ** Bicycle trailer, a wheeled frame for hitching to a bicycle to tow cargo or passengers ** Full-trailer ** Semi-trailer **Horse traile ...
there are fifth wheel and gooseneck hitches. These are used for agriculture, industry, and large recreational trailers. Front trailer hitches are also used on pickup trucks, full-size SUVs, and RVs for multiple purposes. A front-mounted hitch can accommodate additional truck equipment such as front mount bike carriers, fishing/hunting gear, winches, step plates, and snowplows. It also allows a driver to maneuver a trailer with better visibility into a parking site. Front trailer hitches are mounted directly to the frame of a vehicle to ensure a reliable connection. Front hitches are typically equipped with standard-sized receiver tubes to accommodate a variety of removable aftermarket hitch mounted accessories.


Europe

In the
European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...
, tow hitches must be a type approved by European Union directive 94/20/EC requirements and fitted to vehicles first registered on or after 1 August 1998.Outside of North America, the ISO standard tow ball that has been adopted in most of the world is in diameter and conforms to a standard BS AU 113b (replaced by BS ISO 1103:2007). With a minor modification, it was published by UNECE on 15 June 2018, as class A. There are two main categories of ISO tow ball: the flange fitting and the swan-neck which has an extended neck fitting into the tow-bracket. Swan-neck tow balls are often removable to avoid the inconvenience of a tow ball protruding from the vehicle when not required. Some manufacturers are introducing retractable tow balls as an option. Across Europe around 25% of vehicles have tow balls fitted—but there are distinct regional variations, being more common in
Benelux The Benelux Union ( nl, Benelux Unie; french: Union Benelux; lb, Benelux-Unioun), also known as simply Benelux, is a politico- economic union and formal international intergovernmental cooperation of three neighboring states in western Europe ...
and
Scandinavia Scandinavia; Sámi languages: /. ( ) is a subregion in Northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. In English usage, ''Scandinavia'' most commonly refers to Denmark, Norway, and S ...
. In Sweden, around 2.2 million cars of around 4.3 million (just over 50%) have tow balls. In the United Kingdom the popularity of caravans is responsible for a large proportion of
four-wheel drive Four-wheel drive, also called 4×4 ("four by four") or 4WD, refers to a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer ca ...
( SUV) vehicles being fitted with tow hitches.


Electrical connector

The vehicle must also be electrically connected to the trailer.
Trailer connector A trailer connector is a multi-pole electrical connector between a towing vehicle such as a car or truck and a trailer. It is intended primarily to supply automotive lighting on the trailer, but also provide management and supply to other consume ...
variants are standardised at the regional or national and local levels. Some variants are defined by the ISO standards for trailer connectors.


Trailer tow hitch

A car can be equipped with a trailer tow hitch with a removable tow ball.


Weight-distributing hitch

A weight-distributing hitch is a "load leveling" hitch. It is a hitch setup mounted on the tow vehicle that uses spring bars and chains under tension to distribute part of the trailer's hitch weight from the towing vehicle's rear axle to the towing vehicle's front axle and to the trailer's axle(s). It can help reduce trailer sway and hop. Trailer hop can jerk the tow vehicle. Trailer sway is also called fishtailing. At high speeds, trailer sway can become dangerous. Most vehicle manufacturers will only allow a maximum trailer capacity of and of tongue weight without using a weight-distributing hitch. Tow vehicles often have square receiver sockets to accept weight distributing hitches.


Pintle hook and lunette ring

A lunette ring is a type of trailer hitch that works in combination with a
pintle A pintle is a pin or bolt, usually inserted into a gudgeon, which is used as part of a pivot or hinge. Other applications include pintle and lunette ring for towing, and pintle pins securing casters in furniture. Use Pintle/gudgeon sets have ma ...
hook on the tow vehicle. A pintle hook and lunette ring make a more secure coupling, desirable on rough terrain, compared to ball-type trailer hitches. It is commonly seen in towing applications in agriculture, industry, and the
military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distinct ...
. The clearance between the lunette and pintle allows for more relative motion between the trailer and tow vehicle than a ball coupling does. A disadvantage of that is the "slam" transmitted into the towing vehicle with each push/pull load reversal. This becomes a tradeoff between a more secure coupling and a more comfortable towing experience.


Gooseneck hitch

The gooseneck hitch mounts in the middle of the truck bed. This hitch is designed to be paired with a gooseneck trailer, which can manage heavier loads than a hitch at the back of the tow vehicle. An advantage of the gooseneck hitch is its tighter turning radius, which helps when towing a big flatbed or car hauler. Gooseneck hitches also enable use of the entire truck bed when not towing.towing
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Mobile crane tow hitch

An AAR Type "E" coupler serving as a tow hitch on a mobile crane. Pulling up on the link at the rear releases the knuckle allowing uncoupling.


See also

*
Drawbar (haulage) 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. Agriculture an ...
*
Electronic stability control Electronic stability control (ESC), also referred to as electronic stability program (ESP) or dynamic stability control (DSC), is a computerized technology that improves a vehicle's stability by detecting and reducing loss of traction ( skiddi ...
*
Fifth-wheel coupling 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 vertical steel pin protruding from the bottom of the front of the semi- ...
* Fifth Wheel and Gooseneck * ISO standards for trailer connectors *
Ringfeder Ringfeder name (pronounced in English ) 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 ...
* Semi-trailer * Tow truck * Tractor * Tractor unit * Trailer brake controller *
Trailer connector A trailer connector is a multi-pole electrical connector between a towing vehicle such as a car or truck and a trailer. It is intended primarily to supply automotive lighting on the trailer, but also provide management and supply to other consume ...
* Trailer (vehicle) * Truck nuts


References


External links


Directive 94/20/EC of the European Parliament


{{DEFAULTSORT:Tow Hitch Automotive accessories