A chain hook is a device located on the end of a chain which makes it possible to attach the chain to an object. Made of heavy forged steel, the chain hook can be attached to a chain by one of several methods. The chain hook can be attached using a split chain link, a welded chain link or a clevis pin. The clevis pin is a preferred method of attaching a chain hook since it can be removed and swapped with another hook should the need arise.
There are two basic styles of chain hook found on most chains. The first is an open hook, which has a wide gap in the hook. The open hook style allows it to be used to pull or lift an object similar to the hook found on a crane. With an open hook, ropes, clevises and other chains can be placed inside of the hook and lifted or pulled. The second type of hook is the closed hook. This style of hook is tight and is typically used to lock a hook onto another chain link.
Some open-style hooks are actually safety hooks. A safety chain hook has a metal, spring-loaded flapper attached to it. The flapper is mounted on the shank of the hook and bridges the gap to the point of the hook. As a chain or similar object is placed on the hook, the flapper folds down, allowing the object to pass through and rest in the belly of the chain hook. The flapper then springs closed, thereby preventing the object from being able to come out of the hook without first pressing the flapper down and out of the way.
Some small-scale chains such as a dog chain use a spring clip in the hook that must be pressed down in order to remove the chain. This is a smaller version of the safety hook. A safety chain hook is commonly found on construction sites or other places where crew and bystander safety is a concern. Some aftermarket manufacturers sell conversion kits that turn regular hooks into safety hooks.
When attaching a chain hook onto a chain that has no hook, it is best to use a clevis. The clevis uses a bolt that slides through the end link of a chain and screws into the fitting on the bottom of the hook. This method creates the strongest form of chain building outside of splitting and re-welding a link.