A Series Short pitch Precision Simplex Roller Chains & Bush Chains
|Width between inner plates
|Pin length||Inner plate depth
| Plate thickness
|Average tensile strength
|Weight per meter
*Bush chain:d1 in the table indicates the external diameter of the bush
Roller chain or bush roller chain is the type of chain drive most commonly used for transmission of mechanical power on many kinds of domestic, industrial and agricultural machinery, including conveyors, wire- and tube-drawing machines, printing presses, cars, motorcycles, and bicycles. It consists of a series of short cylindrical rollers held together by side links. It is driven by a toothed wheel called a sprocket. It is a simple, reliable, and efficient means of power transmission.
CONSTRUCTION OF THE CHAIN
Two different sizes of roller chain, showing construction.
There are 2 types of links alternating in the bush roller chain. The first type is inner links, having 2 inner plates held together by 2 sleeves or bushings CZPT which rotate 2 rollers. Inner links alternate with the second type, the outer links, consisting of 2 outer plates held together by pins passing through the bushings of the inner links. The “bushingless” roller chain is similar in operation though not in construction; instead of separate bushings or sleeves holding the inner plates together, the plate has a tube stamped into it protruding from the hole which serves the same purpose. This has the advantage of removing 1 step in assembly of the chain.
The roller chain design reduces friction compared to simpler designs, resulting in higher efficiency and less wear. The original power transmission chain varieties lacked rollers and bushings, with both the inner and outer plates held by pins which directly contacted the sprocket teeth; however this configuration exhibited extremely rapid wear of both the sprocket teeth, and the plates where they pivoted on the pins. This problem was partially solved by the development of bushed chains, with the pins holding the outer plates passing through bushings or sleeves connecting the inner plates. This distributed the wear over a greater area; however the teeth of the sprockets still wore more rapidly than is desirable, from the sliding friction against the bushings. The addition of rollers surrounding the bushing sleeves of the chain and provided rolling contact with the teeth of the sprockets resulting in excellent resistance to wear of both sprockets and chain as well. There is even very low friction, as long as the chain is sufficiently lubricated. Continuous, clean, lubrication of roller chains is of primary importance for efficient operation as well as correct tensioning.
Many driving chains (for example, in factory equipment, or driving a camshaft inside an internal combustion engine) operate in clean environments, and thus the wearing surfaces (that is, the pins and bushings) are safe from precipitation and airborne grit, many even in a sealed environment such as an oil bath. Some roller chains are designed to have o-rings built into the space between the outside link plate and the inside roller link plates. Chain manufacturers began to include this feature in 1971 after the application was invented by Joseph Montano while working for Whitney Chain of Hartford, Connecticut. O-rings were included as a way to improve lubrication to the links of power transmission chains, a service that is vitally important to extending their working life. These rubber fixtures form a barrier that holds factory applied lubricating grease inside the pin and bushing wear areas. Further, the rubber o-rings prevent dirt and other contaminants from entering inside the chain linkages, where such particles would otherwise cause significant wear.
There are also many chains that have to operate in dirty conditions, and for size or operational reasons cannot be sealed. Examples include chains on farm equipment, bicycles, and chain saws. These chains will necessarily have relatively high rates of wear, particularly when the operators are prepared to accept more friction, less efficiency, more noise and more frequent replacement as they neglect lubrication and adjustment.
Many oil-based lubricants attract dirt and other particles, eventually forming an CZPT paste that will compound wear on chains. This problem can be circumvented by use of a “dry” PTFE spray, which forms a solid film after application and repels both particles and moisture.
Layout of a roller chain: 1. Outer plate, 2. Inner plate, 3. Pin, 4. Bushing, 5. Roller
If the chain is not being used for a high wear application (for instance if it is just transmitting motion from a hand-operated lever to a control shaft on a machine, or a sliding door on an oven), then 1 of the simpler types of chain may still be used. Conversely, where extra strength but the smooth drive of a smaller pitch is required, the chain may be “siamesed”; instead of just 2 rows of plates on the outer sides of the chain, there may be 3 (“duplex”), 4 (“triplex”), or more rows of plates running parallel, with bushings and rollers between each adjacent pair, and the same number of rows of teeth running in parallel on the sprockets to match. Timing chains on automotive engines, for example, typically have multiple rows of plates called strands.
Roller chain is made in several sizes, the most common American National Standards Institute (ANSI) standards being 40, 50, 60, and 80. The first digit(s) indicate the pitch of the chain in eighths of an inch, with the last digit being 0 for standard chain, 1 for lightweight chain, and 5 for bushed chain with no rollers. Thus, a chain with half-inch pitch would be a #40 while a #160 sprocket would have teeth spaced 2 inches apart, etc. Metric pitches are expressed in sixteenths of an inch; thus a metric #8 chain (08B-1) would be equivalent to an ANSI #40. Most roller chain is made from plain carbon or alloy steel, but stainless steel is used in food processing machinery or other places where lubrication is a problem, and nylon or brass are occasionally seen for the same reason.
Roller chain is ordinarily hooked up using a master link (also known as a connecting link), which typically has 1 pin held by a horseshoe clip rather than friction fit, allowing it to be inserted or removed with simple tools. Chain with a removable link or pin is also known as cottered chain, which allows the length of the chain to be adjusted. Half links (also known as offsets) are available and are used to increase the length of the chain by a single roller. Riveted roller chain has the master link (also known as a connecting link) “riveted” or mashed on the ends. These pins are made to be durable and are not removable.
An example of 2 ‘ghost’ sprockets tensioning a triplex roller chain system
Roller chains are used in low- to mid-speed drives at around 600 to 800 feet per minute; however, at higher speeds, around 2,000 to 3,000 feet per minute, V-belts are normally used due to wear and noise issues.
A bicycle chain is a form of roller chain. Bicycle chains may have a master link, or may require a chain tool for removal and installation. A similar but larger and thus stronger chain is used on most motorcycles although it is sometimes replaced by either a toothed belt or a shaft drive, which offer lower noise level and fewer maintenance requirements.
The great majority of automobile engines use roller chains to drive the camshaft(s). Very high performance engines often use gear drive, and starting in the early 1960s toothed belts were used by some manufacturers.
Chains are also used in forklifts using hydraulic rams as a pulley to raise and lower the carriage; however, these chains are not considered roller chains, but are classified as lift or leaf chains.
Chainsaw cutting chains superficially resemble roller chains but are more closely related to leaf chains. They are driven by projecting drive links which also serve to locate the chain CZPT the bar.
Sea Harrier FA.2 ZA195 front (cold) vector thrust nozzle – the nozzle is rotated by a chain drive from an air motor
A perhaps unusual use of a pair of motorcycle chains is in the Harrier Jump Jet, where a chain drive from an air motor is used to rotate the movable engine nozzles, allowing them to be pointed downwards for hovering flight, or to the rear for normal CZPT flight, a system known as Thrust vectoring.
The effect of wear on a roller chain is to increase the pitch (spacing of the links), causing the chain to grow longer. Note that this is due to wear at the pivoting pins and bushes, not from actual stretching of the metal (as does happen to some flexible steel components such as the hand-brake cable of a motor vehicle).
With modern chains it is unusual for a chain (other than that of a bicycle) to wear until it breaks, since a worn chain leads to the rapid onset of wear on the teeth of the sprockets, with ultimate failure being the loss of all the teeth on the sprocket. The sprockets (in particular the smaller of the two) suffer a grinding motion that puts a characteristic hook shape into the driven face of the teeth. (This effect is made worse by a chain improperly tensioned, but is unavoidable no matter what care is taken). The worn teeth (and chain) no longer provides smooth transmission of power and this may become evident from the noise, the vibration or (in car engines using a timing chain) the variation in ignition timing seen with a timing light. Both sprockets and chain should be replaced in these cases, since a new chain on worn sprockets will not last long. However, in less severe cases it may be possible to save the larger of the 2 sprockets, since it is always the smaller 1 that suffers the most wear. Only in very light-weight applications such as a bicycle, or in extreme cases of improper tension, will the chain normally jump off the sprockets.
The lengthening due to wear of a chain is calculated by the following formula:
M = the length of a number of links measured
S = the number of links measured
P = Pitch
In industry, it is usual to monitor the movement of the chain tensioner (whether manual or automatic) or the exact length of a drive chain (one rule of thumb is to replace a roller chain which has elongated 3% on an adjustable drive or 1.5% on a fixed-center drive). A simpler method, particularly suitable for the cycle or motorcycle user, is to attempt to pull the chain away from the larger of the 2 sprockets, whilst ensuring the chain is taut. Any significant movement (e.g. making it possible to see through a gap) probably indicates a chain worn up to and beyond the limit. Sprocket damage will result if the problem is ignored. Sprocket wear cancels this effect, and may mask chain wear.
The most common measure of roller chain’s strength is tensile strength. Tensile strength represents how much load a chain can withstand under a one-time load before breaking. Just as important as tensile strength is a chain’s fatigue strength. The critical factors in a chain’s fatigue strength is the quality of steel used to manufacture the chain, the heat treatment of the chain components, the quality of the pitch hole fabrication of the linkplates, and the type of shot plus the intensity of shot peen coverage on the linkplates. Other factors can include the thickness of the linkplates and the design (contour) of the linkplates. The rule of thumb for roller chain operating on a continuous drive is for the chain load to not exceed a mere 1/6 or 1/9 of the chain’s tensile strength, depending on the type of master links used (press-fit vs. slip-fit). Roller chains operating on a continuous drive beyond these thresholds can and typically do fail prematurely via linkplate fatigue failure.
The standard minimum ultimate strength of the ANSI 29.1 steel chain is 12,500 x (pitch, in inches)2. X-ring and O-Ring chains greatly decrease wear by means of internal lubricants, increasing chain life. The internal lubrication is inserted by means of a vacuum when riveting the chain together.
Standards organizations (such as ANSI and ISO) maintain standards for design, dimensions, and interchangeability of transmission chains. For example, the following Table shows data from ANSI standard B29.1-2011 (Precision Power Transmission Roller Chains, Attachments, and Sprockets) developed by the American Society of Mechanical Engineers (ASME). See the references for additional information.
ASME/ANSI B29.1-2011 Roller Chain Standard SizesSizePitchMaximum Roller DiameterMinimum Ultimate Tensile StrengthMeasuring Load25
|ASME/ANSI B29.1-2011 Roller Chain Standard Sizes|
|Size||Pitch||Maximum Roller Diameter||Minimum Ultimate Tensile Strength||Measuring Load|
|25||0.250 in (6.35 mm)||0.130 in (3.30 mm)||780 lb (350 kg)||18 lb (8.2 kg)|
|35||0.375 in (9.53 mm)||0.200 in (5.08 mm)||1,760 lb (800 kg)||18 lb (8.2 kg)|
|41||0.500 in (12.70 mm)||0.306 in (7.77 mm)||1,500 lb (680 kg)||18 lb (8.2 kg)|
|40||0.500 in (12.70 mm)||0.312 in (7.92 mm)||3,125 lb (1,417 kg)||31 lb (14 kg)|
|50||0.625 in (15.88 mm)||0.400 in (10.16 mm)||4,880 lb (2,210 kg)||49 lb (22 kg)|
|60||0.750 in (19.05 mm)||0.469 in (11.91 mm)||7,030 lb (3,190 kg)||70 lb (32 kg)|
|80||1.000 in (25.40 mm)||0.625 in (15.88 mm)||12,500 lb (5,700 kg)||125 lb (57 kg)|
|100||1.250 in (31.75 mm)||0.750 in (19.05 mm)||19,531 lb (8,859 kg)||195 lb (88 kg)|
|120||1.500 in (38.10 mm)||0.875 in (22.23 mm)||28,125 lb (12,757 kg)||281 lb (127 kg)|
|140||1.750 in (44.45 mm)||1.000 in (25.40 mm)||38,280 lb (17,360 kg)||383 lb (174 kg)|
|160||2.000 in (50.80 mm)||1.125 in (28.58 mm)||50,000 lb (23,000 kg)||500 lb (230 kg)|
|180||2.250 in (57.15 mm)||1.460 in (37.08 mm)||63,280 lb (28,700 kg)||633 lb (287 kg)|
|200||2.500 in (63.50 mm)||1.562 in (39.67 mm)||78,175 lb (35,460 kg)||781 lb (354 kg)|
|240||3.000 in (76.20 mm)||1.875 in (47.63 mm)||112,500 lb (51,000 kg)||1,000 lb (450 kg|
For mnemonic purposes, below is another presentation of key dimensions from the same standard, expressed in fractions of an inch (which was part of the thinking behind the choice of preferred numbers in the ANSI standard):
|Pitch (inches)||Pitch expressed
1. The pitch is the distance between roller centers. The width is the distance between the link plates (i.e. slightly more than the roller width to allow for clearance).
2. The right-hand digit of the standard denotes 0 = normal chain, 1 = lightweight chain, 5 = rollerless bushing chain.
3. The left-hand digit denotes the number of eighths of an inch that make up the pitch.
4. An “H” following the standard number denotes heavyweight chain. A hyphenated number following the standard number denotes double-strand (2), triple-strand (3), and so on. Thus 60H-3 denotes number 60 heavyweight triple-strand chain.
A typical bicycle chain (for derailleur gears) uses narrow 1⁄2-inch-pitch chain. The width of the chain is variable, and does not affect the load capacity. The more sprockets at the rear wheel (historically 3-6, nowadays 7-12 sprockets), the narrower the chain. Chains are sold according to the number of speeds they are designed to work with, for example, “10 speed chain”. Hub gear or single speed bicycles use 1/2″ x 1/8″ chains, where 1/8″ refers to the maximum thickness of a sprocket that can be used with the chain.
Typically chains with parallel shaped links have an even number of links, with each narrow link followed by a broad one. Chains built up with a uniform type of link, narrow at 1 and broad at the other end, can be made with an odd number of links, which can be an advantage to adapt to a special chainwheel-distance; on the other side such a chain tends to be not so strong.
Roller chains made using ISO standard are sometimes called as isochains.
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|Standard or Nonstandard:||Standard|
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Can transmission chains be used in material handling systems?
Yes, transmission chains can be used in material handling systems. Here’s a detailed answer to the question:
Material handling systems involve the movement, storage, control, and protection of materials and products within a manufacturing or distribution facility. These systems often require reliable and efficient power transmission to move conveyors, lifters, hoists, and other equipment used in material handling operations.
Transmission chains offer several advantages for material handling applications:
1. High Load Capacity: Transmission chains are designed to handle heavy loads and provide robust power transmission capabilities. They are capable of transmitting high torque, making them suitable for lifting and moving heavy objects in material handling systems.
2. Durability: Transmission chains are constructed with high-quality materials and undergo stringent manufacturing processes to ensure durability and longevity. They are designed to withstand the demanding operating conditions typically encountered in material handling systems, including continuous operation and exposure to various loads and environments.
3. Versatility: Transmission chains are available in various sizes, configurations, and materials to accommodate different material handling applications. They can be customized to meet specific requirements such as load capacity, speed, and environmental conditions.
4. Precision and Efficiency: Transmission chains offer precise and efficient power transmission, allowing for smooth and reliable movement of materials. They have minimal backlash and provide accurate positioning, ensuring the precise handling of materials within the system.
5. Adaptability: Transmission chains can be easily integrated into different types of material handling equipment and systems. They can be used in conveyor systems, overhead cranes, stackers, palletizers, and many other applications commonly found in material handling operations.
6. Maintenance and Serviceability: Transmission chains are designed for easy maintenance and replacement. Regular lubrication and inspection can help ensure optimal performance and extend the chain’s lifespan. When necessary, worn or damaged components can be replaced, minimizing downtime and maintenance costs.
It’s important to select the appropriate type and size of transmission chain based on the specific requirements of the material handling system. Factors to consider include the load capacity, operating speed, environmental conditions, and maintenance considerations. Consulting with experts or manufacturers can help determine the most suitable transmission chain for reliable and efficient material handling operations.
How does the speed of rotation affect the choice of transmission chain?
The speed of rotation is an important factor to consider when selecting a transmission chain for a specific application. Here’s a detailed answer to the question:
1. Fatigue and Wear: The speed of rotation directly affects the fatigue and wear characteristics of a transmission chain. Higher rotational speeds result in increased cyclic loading and wear on the chain’s components. Therefore, it is crucial to choose a chain that is designed to handle the anticipated speed and associated fatigue stresses.
2. Lubrication and Cooling: Faster rotational speeds generate more heat due to friction between the chain and the sprockets. Adequate lubrication is essential to minimize friction, reduce heat buildup, and maintain the chain’s performance and longevity. Additionally, some high-speed applications may require additional cooling mechanisms to dissipate heat effectively.
3. Centrifugal Forces: As the rotational speed increases, centrifugal forces become more significant. These forces can affect the chain’s stability, tension, and overall performance. Chains designed for high-speed applications are engineered to withstand the increased centrifugal forces and maintain proper tension during operation.
4. Dynamic Balance: High-speed rotation may introduce dynamic imbalances in the transmission system, leading to vibrations and decreased system efficiency. Special attention should be given to selecting a transmission chain with proper dynamic balance characteristics to minimize vibrations and ensure smooth operation.
5. Material and Design: Chains for high-speed applications often require specific materials and design features to accommodate the increased rotational forces and maintain reliability. High-strength alloys, precise manufacturing tolerances, and advanced surface treatments may be employed to enhance the chain’s performance and durability at high speeds.
When selecting a transmission chain, it is crucial to consider the manufacturer’s recommendations and specifications regarding maximum allowable speeds. Factors such as the application’s operational requirements, anticipated rotational speed, load, and environmental conditions should all be taken into account to ensure the chosen chain is suitable for the specific high-speed application.
What are the common causes of failure in transmission chains?
Transmission chains are subject to various factors that can contribute to their failure over time. Here’s a detailed explanation:
1. Insufficient Lubrication: Inadequate or improper lubrication is one of the leading causes of chain failure. Insufficient lubrication can lead to increased friction, heat generation, and accelerated wear between the chain’s components, such as pins, bushings, and rollers.
2. Contamination: Contaminants like dirt, dust, debris, and moisture can enter the chain system, affecting its performance and causing accelerated wear. Contamination can hinder proper lubrication, increase friction, and cause corrosion, leading to chain failure.
3. Overloading: Applying excessive loads beyond the chain’s rated capacity can lead to overloading, which causes stress and deformation of the chain’s components. Overloading can result in chain elongation, accelerated wear, and ultimately, chain failure.
4. Misalignment: Improper alignment of the chain and sprockets can cause uneven distribution of forces, leading to localized wear and increased stress on certain areas of the chain. Misalignment can result from incorrect installation or wear and tear of sprockets, leading to premature chain failure.
5. Fatigue: Repeated cyclic loading and stress can cause fatigue in the chain, leading to cracks, fractures, and ultimately, chain failure. Fatigue failure is more likely to occur when the chain is subjected to high-speed or high-frequency applications.
6. Corrosion: Exposure to corrosive environments, such as high humidity, chemicals, or extreme temperatures, can cause corrosion on the chain’s components. Corrosion weakens the chain’s structural integrity, leading to premature failure.
7. Poor Maintenance: Inadequate maintenance practices, such as infrequent inspections, lack of lubrication, and neglecting to address potential issues, can contribute to chain failure. Regular maintenance, including lubrication, cleaning, and proper tensioning, is essential for the longevity and reliable performance of transmission chains.
It is important to address these factors to prevent chain failure. Proper lubrication, regular inspections, cleaning, and alignment checks are essential maintenance practices. Selecting the right chain for the application, following manufacturer guidelines, and adhering to industry standards can also help mitigate the risk of failure and ensure the optimal performance and longevity of transmission chains.
editor by CX 2023-07-27