Frequently Asked Questions
Roller Chain Components
What is a roller chain roller link?
What is a roller chain offset link?
Single-pitch offset links, slip-fit type, are furnished with a slip-fit pin unassembled in the linkplates. A flat is milled on one end of the pin preventing it from turning in the linkplate once installed.
Two-pitch offset links, press-fit type, are an offset link and a roller link assembled together. The press-fit construction of this assembly greatly increases its structural rigidity, reliability, and durability. For these reasons, the two-pitch offset assembly is recommended in preference to the single-pitch offset. However, due to the reduction in the chain’s working capacity, offset links, of either type, are not recommended in performance oriented drives.
What is a roller chain connecting link used for and what is its impact on the chain’s load capacity?
Slip-fit links, the most common and most popular, are provided for general chain applications and allow the easy slip fit assembly of the cover plate over the pin ends. This slip-fit construction does not have the same integrity found in the assembled chain and can reduce the chain’s working load capacity by as much as 30%.
Press-fit connecting links are provided when the integrity of the connecting link needs to be equal to that of the base chain. This design uses pitch holes in the cover plate that are smaller than the chain pins, requiring the user to press the cover plate onto the pins before installing the spring clip or cotter. While more difficult to install, this type of connection provides the greatest load carrying capability.
What is the difference between riveted and cottered chain?
Cottered chain is constructed using pins that extended through one plate and are sidemashed and through the second side a further distance than through the first plate, with a cross-drilled hole for inserting a cotter pin. Note: cottered chain is also manufactured using an interference fit between the plate hole size and pin diameter. However, the plate is easier to remove following removal of the cotter, because grinding of the riveted pin end is not necessary.
What is the smallest suggested sprocket size to minimize the effects of chordal action?
- Slow speed drive (drip type lubrication) – 12 teeth
- Medium speed drive (oil bath type lubrication) – 17 teeth
- High speed drive (pumped lubrication) – 25 teeth
What is the recommended minimum chain wrap in a roller chain drive?
Note: For a sprocket ratio of 3:1 or less there will always be 120° more wrap on the small sprocket, regardless of the center distance.
When are hardened tooth sprockets recommended?
Roller Chain Lubrication
What type of lubrication is recommended at various ambient temperatures?
Ambient temperature: 40-100 F – SUS Viscosity 400-650, SAE Engine Oil of 30 Weight, SAE Gear Oil 85 W, ISO 100, and AGMA lubrication 3.
Ambient Temperature 100-120 F – SUS Viscosity 650-950, SAE Engine Oil of 40 Weight, SAE Gear Oil 90, ISO 150, and AGMA lubrication 4.
Ambient Temperature 120-140 F – SUS Viscosity 950-1450, SAE Engine Oil of 50 Weight, SAE Gear Oil 90, ISO 220, and AGMA lubrication 5.
In what application would forced or circulated type lubrication be most appropriate?
In what application would bath type lubrication be most appropriate?
In what application would drip type lubrication be most appropriate?
Roller Chain Failure
A chain failed in service. Inspection of the failure revealed a bent or broken pin, or pins that appear to be turned within the outer (pin) link plates. Why?
Shock loads that are greater than the component’s yield strength, approximately 55-60% of the chain’s tensile, are the cause of this problem. Changing to high strength Series chain, increasing the chain size (i.e. #80 up to #100), or working to eliminate the shock load on the drive system are some of the ways the chain’s performance may be improved.
A roller chain failed in service and upon inspection of the failure it was determined to be a “crack” in an inner (roller) plate. Why did this happen?
Rough Roller Chain Operation
Roller chain is not operating smoothly. The chain appears to be climbing the sprocket teeth.
The chain does not travel smoothly during operation. Marks appear on the interior of the inner linkplates. Why?
What is the tensile strength and load rating for ANSI 60 and ANSI 60 Heavy roller chain?
The average tensile strength of ANSI 60 and ANSI 60 Heavy Series chain is 8500 pounds. We calculate the average tensile strength based on current and historical test data taken from each production lot of ANSI 60 and ANSI 60 Heavy roller chain.
Generally, working load for any chain should not exceed 1/6th of the average tensile strength when using press-fit connecting links, or 1/9th of the average when using slip-fit connecting links or offset links.
When calculating working load based on a manufacturer’s ultimate or maximum tensile strength data, it’s important to remember that these numbers may not reflect the expected tensile strength for each chain of that given size. Tensile strength described as ultimate or maximum merely indicates the highest level recorded in their test procedures, which may not be repeatable.
What is meant by “pre-loading” roller chain, why is it done, and is it important?
Following assembly, an initial load is applied to the chain, which is called a pre-load. This loading approximates the recommended maximum loading in service and is done to align the various chain components such as pins, bushings, and link plates. The benefit of pre-loading is that it greatly helps eliminate the initial elongation often found in “lesser” chains. Elimination of this initial elongation can increase the chain’s useable service life, and therefore pre-loading is very important.
How can the wear in a roller chain be accurately measured and when is the chain considered worn out?
How is proper chain tension measured and why is it important?
What is the difference between slip-fit and press-fit multiple strand chain?
Multiple strand chains manufactured using slip-fit center plates are most common and are well suited for drives of moderate severity. These chains are designed for ease of disassembly throughout the entire length of chain. The chains can be shortened or sections can be added quickly with minimal effort. However, with the slip-fit center plate design, the user may experience accelerated fatigue failures in exchange for the ease of alteration in the field.
Multiple strand chains manufactured using press-fit center plates were originally developed for service in applications that require the utmost in multiple strand chain capacity. Multiple strand chains with press-fit center plates have significantly greater fatigue strength than their slip-fit center plate counterparts, because press-fit construction assures rigid, permanent support for the pins at each tension point with no relative movement, which can cause wear or fatigue. While the press-fit construction does provide the increased fatigue resistance that is often essential in critical applications, the user does give up some convenience because the chain’s length cannot readily be altered in the field. For this reason, press-fit riveted multiple strand chain should always be ordered in the exact pitch length required, including a Bushed Center Plate Link (BCL) connecting link.
What is roller chain length matching and why is it used?
Many applications require two or more chains, normally with attachments, to run in parallel with “flights” joining the chains together forming a conveyor- or transfer-type system. In these cases, it is critical to have the chains ordered as a set, matched for length, and installed on the machinery with the same relationship to one another as when they were matched.
We offer two degrees of precision matching for chains used in parallel operation. Class I matching insures the chains within a given set will not vary in overall length by more than .006″/ft. Class II matching is much more stringent, and assures that the longest and the shortest chain in a given set will not vary in overall length by more than .002″/ft.
What are the temperature limitations of roller chain?
Why is my chain elongating too quickly?
My roller chain is rusting in service. What should I do?
Will the typical chain breaker (pin extractor) break multiple strand roller chain?
Do your connecting tools work for multiple strand roller chains?
How is the drive ratio of a roller chain drive calculated and what is the maximum recommended single reduction?
The maximum recommended ratio for a single reduction is 7:1. In practice, the practical single reduction limit is affect by the minimum size of the small sprocket, the maximum size of the large sprocket, and the need for sufficient wrap on the small sprocket. For ratios larger than 7:1, a double reduction is preferred.