clevises

A clevis is a U-shaped fastening device that forms a hinged connection between two components. The ends of the clevis fork are drilled to accept a pin or bolt, which passes through aligned holes in the linked parts to secure them together. Clevises are used in mechanical linkages, towing, lifting, and rigging where a quick-disconnect, pivoting joint is needed.

Construction and components: The main parts are the clevis (the U-shaped yoke), the clevis pin (or bolt), and a retaining device such as a cotter pin, hairpin cotter, or threaded nut and washer. The mating part has a hole that lines up with the clevis holes; the pin is inserted and secured to prevent separation.

Materials and ratings: Clevises are typically forged or cast steel, often with protective coatings; stainless steel and aluminum versions are used for corrosion resistance or lighter weight. They come in various sizes, defined by pin diameter and overall width, and are rated by a working load limit (WLL) or safe working load.

Variants and usage: In addition to standard clevis fittings used with clevis pins, there are clevis straps, clevis hangers, and clevis yokes used in machinery, drawbars, and rigging assemblies. They are common in towing hitches, forklift attachments, agricultural implements, and aerial lifting gear. The term is often used alongside other hardware such as shackles, hooks, and eye bolts.

Safety and maintenance: Use the correct size and material for the load; ensure the pin and retaining clip are properly engaged; avoid side loading, which can reduce strength; inspect for wear, corrosion, elongation of holes, and cracks. Replace parts showing damage or excessive wear.