Tow hitch

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A tow hitch (or tow bar or recovery point) is a device attached to the chassis of a vehicle for towing.

It can take the form of a tow-ball to allow w: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 their 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.