Product Description

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.

BICYCLE CHAIN WEAR

The lightweight chain of a bicycle with derailleur gears can snap (or rather, come apart at the side-plates, since it is normal for the “riveting” to fail first) because the pins inside are not cylindrical, they are barrel-shaped. Contact between the pin and the bushing is not the regular line, but a point which allows the chain’s pins to work its way through the bushing, and finally the roller, ultimately causing the chain to snap. This form of construction is necessary because the gear-changing action of this form of transmission requires the chain to both bend sideways and to twist, but this can occur with the flexibility of such a narrow chain and relatively large free lengths on a bicycle.

Chain failure is much less of a problem on hub-geared systems (e.g. Bendix 2-speed, Sturmey-Archer AW) since the parallel pins have a much bigger wearing surface in contact with the bush. The hub-gear system also allows complete enclosure, a great aid to lubrication and protection from grit.

CHAIN STRENGTH

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)^{[citation needed]}. 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.

CHAIN STHangZhouRDS

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^[8][9][10] for additional information.

ASME/ANSI B29.1-2011 Roller Chain Standard SizesSizePitchMaximum Roller DiameterMinimum Ultimate Tensile StrengthMeasuring Load25

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):

Notes:
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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What to Look for in a Belt Tensioner

If you notice the power steering, air conditioning, or power steering stops working, chances are that your belt tensioner has been compromised. A compromised belt tensioner can be completely destroyed overnight, or it can last for a long time before it breaks. Either way, you should never drive with a faulty belt tensioner. It’s far better to have it replaced before the engine shuts down completely. In addition, replacing a belt tensioner will prevent other complications, such as power steering or air conditioning, from occurring.

Misaligned idler pulley

If the tensioner arm is not rotating freely or has an abnormal chirping noise, it could be the result of a misaligned idler pulley. If this is the case, replace the idler. If the idler does not move, you may need to adjust the accessory mount points or use a laser alignment tool. The tensioner arm is only 1 part of the tensioner.
A misaligned idler pulley on a belt tensioner is usually the cause of a squeaking noise. If this noise continues even after a replacement of the belt, it’s time to replace the whole belt. A misaligned idler pulley can also be the cause of premature belt wear. If the idler pulley is out of alignment, it could also cause the belt to wear too fast and lead to the premature failure of the timing belt.
The tensioner pulley is made of nylon, steel, or plastic. It may be flat or grooved. Before replacing it, check for any cracks, dents, or debris on the pulley’s surface. Plastic pulleys may have broken sidewalls. If the idler pulley is worn out, you might also notice squealing noises when the vehicle is in motion.
The misalignment of a belt is most pronounced when the span between the 2 pulleys is short. When the span is long, however, diagnosing the problem becomes more complicated. Small degrees of offset may not be visible to the naked eye, but a laser alignment tool can help identify these subtle variations. In order to identify a misaligned idler pulley on a belt tensioner, you must first determine its cause.
When the tensioner’s idler pulleys are out of line, a belt tensioner will not be able to properly adjust the torque that the belt is under. This may result in squealing noises. If this is the case, it is time to call a mechanic. He or she will be able to determine the cause and correct it. If you suspect the problem, your next step is to replace the idler pulley on the belt tensioner.
If the ribbed belt is not properly aligned, you may have a misaligned idler pulley. To fix the misalignment, locate the belt adjustment bolt underneath the hood. You should be careful not to damage the alternator or battery terminal while doing this task. If you do accidentally connect the battery positive to the earth, you might be able to damage the ribbed belt and ruin your vehicle’s timing.
Besides a misaligned idler pulley on the belt tensioner, another problem may be the alternator’s serpentine belt. If your car’s alternator belt is not aligned properly, you could have misaligned the alternator’s pulley or a worn-out bearing. Regardless of the cause of your problem, you should have the belt inspected.

Bad idler pulley

Having a Bad Idler Pulley on a Belt Tensioner? If this sounds familiar, then it’s probably time to change it. Idler pulleys slowly take hits while the engine is running, causing the belt to wrap and bend. Eventually, the belt will slip, and a new idler pulley should be installed to ensure optimal tension. But before you spend a dime on a new one, let’s talk about what to look for.
Symptoms of a Bad Idler Pulley: If the noise persists, there is a problem with the idler pulley or its bearing. These parts wear out over time and may eventually cause a cracked idler pulley or serpentine belt. Not only will the idler pulley create an irritating noise, but it will also damage the belt itself, leading to overheating, stalled engine, and even damage the head gaskets. Thankfully, a Bad Idler Pulley on a Belt Tensioner is easily replaced and will only cost about $40.
Although the Idler Pulley is not the most popular component on a car, it’s a critical part that ensures that the engine runs smoothly. It’s easy to overlook this part, but its failure can make it impossible for your vehicle to operate at its optimal level. Moreover, a Bad Idler Pulley on a Belt Tensioner will cause your engine to malfunction, so it’s essential that you check it at regular intervals.
If you notice a squealing noise while driving, the Idler Pulley is likely the culprit. Because of friction between the engine belt and idler pulley, the engine belt rubs against the pulley, causing it to squeak and make a clicking noise. This squealing noise will continue until the problem is repaired or replaced. It’s time to start addressing the problem before it becomes too late.
If you notice the tensioner pulley moving away from the engine, it’s most likely that the pulley is malfunctioning. A belt that is loose or slack may make it difficult to start the car, or your engine may even overheat. If this occurs, it’s crucial to replace the Idler Pulley as soon as possible, because a Bad Idler Pulley on a Belt Tensioner can seriously damage your vehicle.
The Idler Pulley facilitates the motion of the engine belt. It serves as a smooth rotating point that allows the belt to loop without a barrier. Over time, this part of the system will begin to show signs of wear and tear, and replacement is vital to protect your engine, serpentine belt, and other accessories. An early warning sign of a problem is a squealing sound coming from the engine area.

Broken tensioner arm

The belt tensioner is a piece of machinery that is used to keep the belt tight. If this part breaks, you can easily repair it yourself using a long-handled ratchet, serpentine belt tool, or a socket. To repair the tensioner, simply remove the drive belt from the pulley and rotate it to release tension. Check for roughness, resistance, or binding of the drive belt.
Noises caused by the tensioner are a sign of a damaged component or excessive oscillation. These noises are usually caused by worn internal components or the tensioner’s pivot bushing. In some cases, the vibration damping system or a worn-out alternator pulley could also be to blame. If this is the case, replace the pulley and tensioner together. To check the condition of your belt tensioner, follow these steps.
In addition to worn-out springs, a loose or broken pivot arm could be causing your belt to misalign. A worn-out tensioner pulley bushing will also cause vibrations, noise, and seizing. Lastly, a broken tensioner spring could be preventing the belt from maintaining proper tension. Broken springs are also prone to loss of tension due to heat. Damaged tensioner housing can also affect belt tension.
Once the belt is installed, you need to check the condition of the pulley and the tensioner arm. Make sure that the pulley is moving and that the arm is moving smoothly with the cranking and releasing. If the arm is wobbling, the tensioner is failing. If the pulley wobbles or excessive chattering occurs, the tensioner is failing. It can also be seized or jammed.
If the tensioner arm has broken, replace it. Replacing the tensioner can be a tedious task. Be sure to use a suitable tool to tighten the pulley and tensioner. If you are not sure of how to replace the pulley, try using a serp belt tool. Another good option is to purchase a 3/8 drive ratchet. If you don’t have this tool, you can use a long 3/8 extension and a deep socket.
The belt tensioner assembly can fall off the engine, causing damage to the timing belt. If you are replacing it, you must replace it with a new one, and tighten all of the mounting bolts before reinstalling it. To avoid further damage to the engine, ensure you replace the belt with a new tensioner and a new belt. The tensioner is bolted to the engine’s timing cover, so make sure you carefully tighten the bolts when replacing it.