Diamond Technical Corner

To start, we should clarify that working load, also known as chain pull, and tensile strength are not the same. Working load describes the amount of linear pull exerted on a chain by a drive while tensile strength is the amount of force required for that chain to fail. While these measurements can be related, the two terms are not interchangeable.

For drives operating at speeds lower than those shown in Diamond's horsepower ratings charts, chain pull, in combination with tensile strength, can be used to select the appropriate roller chain. Here are several equations used to determine working load or chain pull:



Generally, chain pull should not exceed 1/6th of the ultimate, or maximum, tensile strength for chain with press-fit connecting links or non offset links or 1/9th of the maximum for slip-fit connecting links or offset links. By comparing chain pull against rated tensile strength, the appropriate chain can be selected.

Have more questions about working load? Drop us a note at asktheengineer@diamondchain.com.

To answer this question, let's do a quick refresher on the ANSI part numbering system. The first digit(s) in each standard roller chain part number tells us the pitch of a chain in eighths of an inch. That means that an ANSI 120 chain, for example, has a pitch of 12/8s of an inch or 1.5 inches.

Let's say then that we wanted to know how many feet of chain are in an application of ANSI 120 that is 180 pitches in length?

Again, we know that ANSI 120 chain has a pitch of 1.5". For an application with 180 pitch, we simply multiply 1.5 inches by 180 to get 270 inches or convert to feet 270/12 = 22.5.

But what if we want to convert from feet into pitch? Let's say we have an application that uses 10 feet of ANSI 40 chain. We know that from the ANSI numbering system, ANSI 40 chain has a pitch of 4/8s of an inch or .5 inches. For an application of ten feet, we do a quick conversion from feet into inches (10 x 12 = 120) and then divide 120/.5 to get 240 pitches.

Knowing how to convert between pitch and feet can be useful, especially when double checking an order, but don't worry if you need additional help. Diamond Chain's customer service and application engineering teams are available to assist you. You can contact both groups by calling us at 1-800-872-4246.

Have additional questions about converting pitch to feet and vice versa? Drop us a note at asktheengineer@diamondchain.com. To find an authorized dealer in your area that can assist with cut-to-length orders, please click here for our distributor finder.

While "one at a time" and "correctly" seemed to be the most frequent, and apparently most amusing, answers from our engineering team - after some consideration, we thought this deserved an answer that was a bit more practical.

One mistake that is commonly made when counting the number of pitches in a strand of roller chain is to include only exterior link plates. By counting only the exterior plates, only half the number of pitches end up being counted.

So then how should the number of pitches be counted? Taking a quick time out for a review of definitions - the pitch of a roller chain is the distance between the center of one pin to the center of the next pin. To count the number of pitches in a strand of chain, we would start our count from the first pin on one end of the piece of chain and move to the next pin, which would be one pitch, and then on to the next pin, which would be another pitch, and so on until the end of the strand of chain is reached.

Here's a quick visual to help illustrate:


Have additional questions about counting the number of pitch in a strand of chain? Send us an email at asktheengineer@diamondchain.com. For more information on the maintenance and installation of roller chain, check out our maintenance guide here.

Q - In the late 1940s, Harley Davidson made a lightweight 2 stroke motorcycle that used Diamond #35 chain in the front and #40 in the rear. What was the last year that Diamond Chain manufactured this bi-color (blue inner links and gray outer plates) #40 roller chain?

A - Diamond Chain discontinued the use of the "bluing" process for the production of inner plates for standard #35 and #40 roller chains in 1987. Although still a process in use today as a means of passive rust protection, Diamond Chain discontinued the use of the bluing process in favor of more effective means of rust protection through Diamond's proprietary lubricant.

Although Duralube's sintered bushing and rollers have lubricant drawn in under vacuum, the additional external lubricant applied prior to shipping provides additional protection for the roller chain. In addition to providing overall lubrication that will maximize the service life of the chain, the proprietary Diamond Chain lubricant is also a rust preventative in case the chain is not intended to be used immediately.

Q - I want to make sure I'm getting the real "McCoy" and not an inferior company's chain.

A - Diamond Chain uses three distinct product marks to differentiate between its Diamond, Infinity, and Sapphire product series. Diamond Chain's flagship Diamond series includes a stamp of the words "Diamond Chain" along with the Diamond graphic element. The Infinity series includes only the Diamond graphic element stamp while Sapphire has a RSC stamp for Sapphire roller chain.

In order to guarantee that you are purchasing authentic Diamond Chain products, you should always buy from an authorized Diamond distributor.

For help locating an authorized distributor, you can use our distributor locator available here for our North American customers and here for our European customers.

The number stamped on the side of a chain is the ANSI (American National Standards Institute) model number. Roller chain can be manufactured in many different sizes; the most common ANSI sizes are 40, 50, 60, and 80.

The first digit indicates the pitch of the chain measured in eights of an inch. The last digit can either be a 0, 1, or 5. A "0" is used for standard chain, a "1" is used for lightweight chain, and a "5" for bushed chain with no rollers.

For reference, here is the full list of ANSI models and the corresponding length for one pitch of chain.

ANSI	Pitch
25	.250
35	.375
40	.500
41	.500
50	.625
60	.750
80	1.000
100	1.250
120	1.500
140	1.750
160	2.000
180	2.250
200	2.500
240	3.000

Have additional questions about roller chain? Drop us an email at asktheengineer@diamondchain.com. For further assistance, please contact Diamond Chain's customer service and application engineering teams at 1-800-872-4246.