Popular Terminology for Roller Chains

Overview of Chain Terminology

There are several key components that make up a standard roller chain:

• Roller Link: Inner Link composed of 2 Roller Link Plates, 2 Bushings, and 2 Rollers
• Pin Link: Outer Link composed of 2 Pin Link Plates and 2 Pins
• Spring Clip Style Connecting Link: Outer Link composed of 1 Press Fit Plate with 2 Pins, 1 Detachable Slip Fit Plate and 1 Spring Clip
• Cottered Style Connecting Link: Outer Link composed of 1 Press Fit Plate with 2 Cotter Pins, 1 Detachable Slip Fit Plate and 2 Cotter Keys
• Offset Link: Link composed of 2 Offset Plates, 1 Cotter Pin with 1 Cotter Key, 1 Bushing, and 1 Roller (Note: #25 and 35 chains are rollerless chains)

Together, these components make up a completed roller chain. Roller chains can be either single-strand or multiple-strand and come in a range of sizes, with different tensile strength and working loads. Together, the tensile strength and chain load ratings help buyers determine which chain is right for their unique needs.

Additional terms that are used to describe chains include:

• Chain Pitch describes the distance between the pin center points on a single Pin Link. The number to the left of the right-hand digit in a standard roller chain size denotes the number of ⅛ inches in the pitch. (Ex: 40 Riv = 4/8 = ½” Pitch)
• Heavy Series Chain differs from standard series in the thickness of the plates.
• Chain Preloading refers to preloading during the manufacturing process. This also is sometimes referred to as Pre-Stretching.
• Minimum Ultimate Tensile Strength is the minimum force at which an unused, undamaged chain could break when subjected to a single tensile loading test.
• Attachments are adaptations to standard roller chain components to modify the chain for use in multitudes of applications. Attachments are commonly seen on pin links, roller links, and connecting links.
• Chain elongation is defined as the difference in length of a chain due to wear.  During normal operation, the pins articulate within the bushings. The outside diameter of the pin decreases as the inside diameter of the bushing increases from wear.