The Screw Pin Anchor Shackle Design

The shackle is a load bearing devise with a removable pin that allows the user to connect different types of slings - from Chain Slings, to wire rope, to synthetic slings. 

The Screw Pin Anchor Shackle is one, if not, the most popular shackle & rigging hardware around.  It’s used by a variety of industries from Marine, Towing, Material Handling, Construction, Stage Rigging, Landscaping, Mining, and on.  Its design is so simple and so effective.

The Design

It is a U-shaped design with a pin.  It is made up of 2 main separate components:  The Shackle Body & the Removable Pin

The Bow - is the U-shape body of the shackle.  It’s curved and is referred to by several names: The body or the Bow.  

The Ears - are the bottom sides of the bow where the pin screws in.

The Pin - also know as the load bearing pin, is the removable part of the shackle that screws into the ears.  It is a bolt with a small nob at the end which allows the user to turn (tighten it).

The Shoulder - is on the pin.  It’s the part of the pin that stops the pin from going all the way through the shackle bottoms.  Most importantly it makes contact with the shackle when the pin is fully engaged (tightened & fully threaded).  One should only use a shackle after it’s been properly and fully engaged (per OSHA)  - meaning the shoulder is in contact with the shackle body.

Rigging anchor Shackles are quick and easy to use.  They are popular because of their convenience and simple mechanism, and ideal in applications when users need to connect and dis-connect them.  

Measurements & Definitions

When a shackle size is mentioned, it is usually the shackle body diameter measurement one refers to, not the pin size.

Example:  3/8" Screw Pin Anchor Shackle.  The 3/8" refers to the body diameter (see picture below)

The above picture shows all the key shackle measurements and their definitions.  All shackles should also have body identification by the manufacturer:  The name or trademark of the manufacturer, the size, and the rated load.  These identifications are usually cast, forged, or stamped markings on the shackle.  There are a variety of shackle styles available depending on the application needs.

For a more in depth look at the different types of shackles available - check out our previous blog: https://www.baremotion.com/blogs/news-towing-trucking-lifting-equipment/the-different-styles-types-of-shackles

Safety precautions should always be followed when using shackles or any other rigging equipment.  There are certain guidelines users need to follow to ensure safe operations. 

Shackles should always be inspected before use:

• Make sure all markings are legible
• The body and pin are both identifiable as being of the same size, type and make
• Never use a Bolt Type Anchor Shackle without using a securing nut and cotter pin
• It’s free from nicks, cracks and corrosion.  Visual inspections should be done to make sure there is no wear, cracks, or deformation.
• Shackles may not be heat treated as the may affect their working load limit. 
• Shackles should also be properly stored when not in use.  Kept away from any corrosive materials or direct heating (including sunlight).  In a dry environment.
• Never modify, repair or reshape a shackle by machining, welding, heating or bending, as this will affect the working load limit.

At Baremotion we supply such brands as Crosby Shackles, CM, and import shackles.

This information only covers the general design.  For specific applications and safety precautions other supplemental information is necessary.  

Safety Note:  Never use products beyond their working load limits.  Make sure to always inspect products before use.  Failure to read the proper warning and application information may result in serious injury or death.