A rod end bearing, also known as a heim joint (North America) or rose joint (UK and elsewhere), is a mechanical articulating

joint A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...

. Such joints are used on the ends of control rods, steering links,

tie rod A tie rod or tie bar (also known as a hanger rod if vertical) is a slender structural unit used as a tie and (in most applications) capable of carrying tensile loads only. It is any rod or bar-shaped structural member designed to prevent the separ ...

s, or anywhere a precision articulating joint is required, and where a clevis end (which requires perfect alignment between the components) is unsuitable. A ball

swivel A swivel is a connection that allows the connected object, such as a swivel gun, gun, swivel chair, chair, Caster, swivel caster, or an anchor rode to rotate horizontally or vertically. Swivel designs A common design for a swivel is a cylindr ...

with an opening through which a bolt or other attaching hardware may pass is pressed into a circular casing with a threaded shaft attached. The threaded portion may be either male or female. The heim joint's advantage is that the ball insert permits the rod or bolt passing through it to be misaligned to a limited degree. A link terminated in two heim joints permits misalignment of their attached shafts. A linkage with heim joints on both of its ends transmits force in one direction only: directly along its long axis. It cannot transmit forces in any other direction, or any moments. This makes these types of joints useful for statically determinate structures.

History

The spherical rod end bearing was developed by

Nazi Germany Nazi Germany, officially known as the German Reich and later the Greater German Reich, was the German Reich, German state between 1933 and 1945, when Adolf Hitler and the Nazi Party controlled the country, transforming it into a Totalit ...

during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. When one of the first German planes to be shot down by the

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories and Crown Dependencies. * British national identity, the characteristics of British people and culture ...

in early 1940 was examined, they found this joint in use in the aircraft's control systems. Following this discovery, the Allied governments gave the '' H.G. Heim Company'' an exclusive

patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling discl ...

to manufacture these joints in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, while in the UK the patent passed to '' Rose Bearings Ltd''.Howard, K. 1999. ''Technofile: The rod end bearing''. Motor Sport. LXXV/8 (August 1999), 70-71 The ubiquity of these manufacturers in their respective markets led to the terms ''heim joint'' and ''rose joint'' becoming synonymous with their product. After the patents ran out the common names stuck, although , ''rosejoint'' remains a registered trademark of Minebea Mitsumi Inc., successor to Rose Bearings Ltd. Originally used in aircraft, the rod end bearing may be found in cars, trucks, race cars, motorcycles, lawn tractors, boats, industrial machines, go-karts, radio-control helicopters, formula cars, and many more applications.

Adjustability

Heim joints allow adjustability of the linkage length that they are attached to after assembly and installation. Rod ends are usually manufactured with slightly longer threads than are absolutely necessary, so they can be threaded further onto their mating shaft if needed. This is useful for maintenance, to correct for wear after a period of use, adjusting the link length to compensate for manufacturing tolerances, or fine tuning the performance of a mechanism after it is assembled. After adjustment, the new position is then locked in place with a jam nut.

References

{{reflist Linkages (mechanical)

History

Adjustability

See also

References