Technical Specs for Farm accessories

Hitch Pin and Linch Pin Operation

All of the types of pins listed in this selection guide require at least one predrilled hole that is meant to hold and retain objects in place. For coupling applications, two mating segments are aligned and then held in position by the pin. Hitch pins and clevis pins require an additional cotter pin inserted perpendicularly to lock the pin in position. Linch pins, detent pins, snapper pins, safety spring pins, and toggle pins all contain integral locking mechanisms.

Like other pins, these devices are meant to resist shear forces, which make them fundamentally different than bolts and screws. Sometimes these can be used as shear pins in mechanical overload situations.

Hitch Pin and Linch Pin Production

Since hitch and linch pins are meant to resist shearing under heavy loads, their material of construction is almost exclusively metal.

Hardened and ground steel undergoes a heat treatment process that compacts carbon atoms, resulting in a stronger but more brittle version of the metal. If uncoated, it is likely to oxidize under certain conditions.
Unhardened steel is more malleable and less expensive, but also cannot handle extreme loads. It is vulnerable to corrosion.
Stainless steel is corrosion resistant, aesthetically appealing, and exceptionally strong, but is also more expensive than other steel options.
Brass provides quality strength, conductivity, corrosion resistance, and low-magnetic permeability, but is limited to a lower working load.

Production of hitch and linch pins is represented by the infographic below.

Hitch Pin and Linch Pin Configurations

Several types of hitch and linch pins exist, mostly differentiated by their locking mechanism. Hybrid styles of two pin types covered below are very common.

Hitch pins link two mating components and are held in position on one end by the use of cotter pin. These pins have a non-removable bend or handle to prevent removal from the other side. The cotter pin should not handle a significant load.
Variations of hitch pins include hitch pins locked with a linch pin, or a hitch pin with a detent locking mechanism. Some hitch pins will have a cotter pin attached via chain to prevent misplacement. Another form of hitch pin is held in place by a safety spring pin. Some hitch pins may have keyed locks to prevent unauthorized removal.
A linch pin (also linchpin, lynch pin, and click pin) employs a locking ring into the pin design that fastens the pin in place. An audible 'snap' ensures a firm clasp.
A clevis pin is a hardware piece with a cylindrical head, a point, and a hole that is routed through a mating clevis fastener to assemble components within the fastener. A cotter pin prevents the clevis pin from loosening. Variations are used in everything from crane attachments to plowing equipment.
Clevis pins with multiple holes and clevis pins held in place by welding are deviations from generic clevis pins.
Detent pins contain a hallowed section of the pin with a perpendicular spring that extrudes one or two ball bearings from the pin's shaft. When the ball is aligned with a hole, it locks the pin into place. The pin can be finger released.
For toggle pins, the locking mechanism is a hinged device that prevents the pin from being withdrawn until the lock is aligned with the pin by hand.
Snapper pins consist of a pin with a hand-deformable, tempered, spring steel wire that slips over the end of the pin. It is easy to remove, so this positioning wire cannot hold any load.

Hitch Pin and Linch Pin Applications

Hitch pin and linch pins are recognizable from their common usage in towable trailers, such as boat trailers and campers. Snapper pins are sometimes used on trailer jacks as well. Clevis pins are common in many industries and are identifiable in rigging for sailboats and in servos for model aircraft. Detent pins are common in exercise equipment. Toggle pins are an easy way to assemble and disassemble scaffolding.

Different type pins showing: