ASA Chains Single, Double and Triple: Pitch, How to Measure a Worn Chain and How to Order It

ASA chains are roller chains that follow the American standard (ASA, for American Standards Association). They are used in power transmission: they connect a driving sprocket with a driven one to transmit motion and torque in industrial, agricultural and transport machinery.

Among roller chains, ASA chains are distinguished by their dimensions in inches. The pitch is the distance between centers of two consecutive pins and defines the size of the chain. The most common pitches range from 1/4" to 3", although in Argentine industry intermediate pitches such as 1/2", 5/8", 3/4" and 1" are widely used.

At MR Accesorios Industriales we work with ASA chains from brands such as SKF, Tsubaki, Donghua and Emmar. If you need a chain for a specific equipment, we help you identify the correct model from the sample or measurements.

ASA chains are manufactured in single, double and triple versions, depending on the number of rows of rollers. A single chain has one row, a double has two rows joined by common pins and a triple has three. The more rows, the greater the load capacity and the greater the total width.

The choice depends on the power to be transmitted and the available space. Single chains are the most economical and cover most applications. Double and triple are used when more strength is needed without increasing the pitch, for example in heavy conveyors or agricultural machinery.

An important detail: a double chain cannot be replaced by two single chains side by side, because the pins and plates do not match. Always order the chain with the original number of rows.

Chain wear manifests as elongation due to wear on pins and bushings. To measure it, place the chain on a flat surface and measure the distance between a given number of links, comparing it with the theoretical measurement.

A practical method is to measure 10 links (11 pins) and compare with the nominal pitch multiplied by 10. If the measurement exceeds the theoretical by 2% or more, the chain is worn and should be replaced. For example, in a chain with pitch 1/2", 10 links should measure 5". If it measures 5.1" or more, it is already out of specification.

You can also use a chain gauge, which directly indicates the percentage of elongation. If you do not have that instrument, with a metal ruler and patience you can make an approximate measurement. If in doubt, we recommend sending us a photo of the chain and the measurements so we can guide you.

The series number of an ASA chain indicates the pitch in eighths of an inch. For example, an ASA 40 chain has a pitch of 4/8" = 1/2". An ASA 50 has a pitch of 5/8", an ASA 60 of 6/8" = 3/4", and so on. Larger chains, such as ASA 80, 100, 120, correspond to pitches of 1", 1 1/4" and 1 1/2" respectively.

To identify an unmarked chain, measure the pitch with a caliper: distance between centers of two pins. Then compare with the ASA pitch table. It is also useful to measure the roller diameter and inner width, because there are chains with similar pitch but different roller (for example, ASA 40 and ASA 41).

At MR we help you identify the chain from those measurements or a photo. If you have the sprocket, you can also count the teeth and measure the outer diameter to deduce the pitch.

We sell ASA chains from recognized brands such as SKF, Tsubaki, Donghua and Emmar. Each has its own designation system, but all follow the ASA standard in dimensions.

For example, in SKF chains are identified with the prefix PHC and a code that includes the pitch and type. The code PHC 40-2C/L corresponds to a double chain with pitch 1/2" with clip connection. In Tsubaki, the designation is more direct: RS60 is a single chain with pitch 3/4" and RS25 has pitch 1/4".

In Emmar, codes such as 12-C1 or 10-C2 indicate the pitch in eighths and the number of rows (C1 single, C2 double). If you have a chain from another brand, we can find the equivalent according to measurements.

To quote an ASA chain, we need some basic data: pitch (or ASA series number), number of rows (single, double or triple), length (in links or meters) and whether it includes a connection (connecting link) or not.

If you do not know the pitch, you can measure the distance between pins and send us a photo of the chain next to a ruler or caliper. The code engraved on the side plates also helps, if visible.

With that data we will quote the chain and its accessories (connecting links, half links) promptly. We ship throughout the country from Buenos Aires, Argentina.

A well-lubricated and aligned chain lasts much longer. Lack of lubrication accelerates wear between pins and bushings, causing premature elongation. Use the recommended lubricant for chains and apply it regularly.

Alignment between sprockets is critical: if the shafts are not parallel or the sprockets misaligned, the chain works twisted and wears unevenly. Check alignment with a ruler or a laser.

Also check tension: a too loose chain can jump teeth and a too tight one overloads the bearings. The practical rule is to leave a sag of approximately 2% of the distance between centers.