Jump to content

Tow hitch

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by JGC (talk | contribs) at 01:17, 2 December 2007 (interwiki, da). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Template:Histinfo

A tow hitch (or tow bar or recovery point) is a device attached to the chassis of a vehicle for towing or a towbar to an aircraft nose gear, or paired main gears. See TowHitch.com

It can take the form of a tow-ball to allow swivelling and articulation of a trailer, or a tow pin and jaw with a trailer loop - often used for large or agricultural vehicles where slack in the pivot pin allows the same movements. A further category is the towing pintle used for military vehicles around the world with a hook and locking catch.

In the US the vehicle attachment is known as the tow-hitch. It is the receiver which bolts to the chassis of the vehicle. In the U.S. there are a few common classes: I, II, III and IV that are defined by the SAE. Class I (to 2000 lbs / 909.1 kg) and II (to 3500 lbs / 1591 kg) are for light loads, and the receiver is a square hole 1.25 inch / 31.7 mm x 1.25 inch. Class III (to 5000 lbs / 2272.7 kg) and IV (to 10,000 lbs / 4545.5 kg) can accommodate much larger trailers such as campers, boats, etc. A Class III/IV receiver is 2 inches / 50.1 mm square and in some cases 2 1/2inch / 63.5 mm.

The trailer tongue [US] or coupling [non US] slips over a tow-ball. Tow-balls come in various sizes (1 7/8 in / 47.6 mm, 50 mm / 1.97 in, 2 in / 50.1 mm and 2 5/16 in / 58.7 mm), depending on the load they carry and the country of operation.

Outside the US the vehicle mounting for the tow-ball is referred to as the tow-bracket. The mounting points for all recent passenger vehicles are defined by the vehicle manufacturer and the tow-bracket manufacturer has to use these mount points and prove the efficacy of eir bracket for each vehicle by a full rig-based fatigue test.

In order to tow safely the right combination of vehicle and trailer has to be combined with correct loading horizontally and vertically on the tow-ball. Advice should be taken [see references] to avoid any potential problems as an unstable combination can kill.

In North America the ball attaches to a ballmount. The ballmount must match the US hitch class. The ballmount is a rectangular bar that fits into a receiver attached to the vehicle. It may drop down to get the ball closer to the ground so the trailer will ride level.

In the European Union, towbars must be a type approved to European Union directive 94/20/EC to be fitted to automobiles first registered on or after 1st August 1998.

The ISO standard tow-ball is 50mm in diameter and conforms to a standard BS AU 113b. The ISO standard has been adopted in most of the world outside North America.

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 sticking out from the vehicle when not required. Some manufacturers are now introducing retractable tow-balls as a further option.

Across Europe around 25% of the vehicle park have tow-balls fitted - but there are distinct regional variations with Benelux and Scandinavia having 70 to 90% of vehicles with tow-balls.

Trailer Tow hitch

Cars can include 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 under tension to distribute part of the trailer's hitch weight to the tow vehicle's front axle. It can help reduce trailer sway and hop. Trailer hop can jerk the tow vehicle which makes an unpleasant trip. Trailer sway is sometimes called "fish tailing". At high speeds, trailer sway can become extremely dangerous. Most vehicle manufactures will only allow a maximum trailer capacity of 5000#'s and 500#'s of tongue weight without using a weight distributing hitch. Tow vehicles often have the square receiver tow bars to accept the weight distributing hitch.

Lunette Ring

A Lunette ring is a type of trailer hitch that works in combination with a pintle hook on the tow vehicle. A pintle hook and lunette ring makes a more secure coupling when used on rough terrain, compared to the traditional ball-type trailer hitch.

References

See also

Retrieved from "https://en.wikipedia.org/w/index.php?title=Tow_hitch&oldid=175170794"