What is a clevis joint?
A fork, a pin and the part between them.
A clevis joint is a simple mechanical connection: a forked part (the clevis) and a pin hold a mating part in place. The mating part sits between the two prongs of the fork and is held by the pin, and it can pivot only in a single plane. The clevis is an element for transmitting force in simple linear movements such as pushing and pulling.
The geometry explains both the strength and the limit. The pin is supported on both sides by the fork, so it is loaded in double shear and carries the same force over twice the area of a single-shear pin (K01-Q1-05). The same geometry holds the pin axis fixed in the fork, so the joint cannot tilt out of its plane without loading the fork and the pin edgewise. That is why a clevis suits a load and a pivot that stay in one plane, and a spherical rod end suits a linkage that moves in more than one (Q1-03).
What are the parts called?
Names overlap, so check the drawing.
- Clevis rod end, rod clevis, fork head, fork end. The fork on a threaded shank or with a threaded hole, fitted to a cylinder rod or a linkage rod.
- Clevis pin (bolt). The pin through the fork. It is held by a spring-loaded bolt or a split pin (Q1-07).
Be careful with "yoke end". Some suppliers use it for a fitting that holds a cable or rod in lifting work. In a machine linkage it means the same fork as a clevis, so confirm which part your supplier means.
How do the types differ?
By how they connect and how heavy they are. Catalogues usually separate three:
| Type | Connection | Typical use |
|---|---|---|
| Female-thread clevis (often abbreviated FK) | Internal thread | Fits the externally threaded end of a pneumatic or hydraulic cylinder rod; the common cylinder type, standardised in DIN 71752 and ISO 8140 |
| Male-thread clevis (often FT) | External thread | Screws into a tapped rod or tube; for adjustable linkages and actuator rods |
| Heavier-fork pattern | Internal thread, larger fork | For larger cylinders; check the dimensions on the drawing, because the pattern name differs between catalogues |
Clevises are normally made with an internal thread, right-hand as the standard; a left-hand thread is a request item. The common materials are free-cutting steel (galvanised) and stainless steel. Fine-pitch and left-hand versions are usually listed separately from the standard pitch. Confirm whether a quotation covers the fork head alone or also the pin and retaining clip (Q1-04, Q1-02).
How does a clevis differ from a rod end?
A clevis turns in one plane and is simple. A rod end tilts. Clevis joints are typically limited to a single plane, give high load capacity in shear, and are easy to assemble and take apart; a rod end bearing is a spherical bearing in a threaded housing and accommodates angular misalignment. The choice is in Q1-03.
Which article answers which question?
| If you need to… | Read |
|---|---|
| Know which standard the part follows and what it covers | Q1-02 |
| Decide between a clevis and a spherical rod end, and align the clevis through the stroke | Q1-03 |
| Choose the size and thread for a cylinder, set the engagement, lock it | Q1-04 |
| Check what limits the load of the joint | Q1-05 |
| Choose the pin diameter, fit and hardness | Q1-06 |
| Retain the pin | Q1-07 |
| Pick material and finish for wet or washdown service | Q1-09 |
| Find out why a clevis wears, rattles or cracks | Q1-12 |
Where do clevis rod ends appear on vehicles?
Wherever a push-pull link swings in one plane: pedal assemblies (clutch, brake and throttle pedals), the pushrod from a pedal to a master cylinder, and throttle or shift links in a bracket-and-lever layout. The reasons are the ones above. The pin gives a double-shear connection, the fork comes apart quickly, and the thread lets the length be adjusted.
What differs is the load and the surroundings. The load comes from a person pressing through a lever ratio, with shock on top when something is dropped or forced. The fork sits in vibration, dirt and sometimes road spray, which brings in the retention, corrosion and wear questions in Q1-07, Q1-09 and Q1-12.
Because a clevis is held to one plane, it does not suit a link whose end moves in several planes, such as most suspension and steering links. Those use spherical ends (Q1-03).
Pedal and pushrod joints are safety parts. The vehicle maker decides their size, pin retention and acceptable parts. For the product range, see SYZ's clevis rod ends page and its clevis buyers guide.