In this module, we will learn about the failures of power transmission components in a machine. We’ll also learn about how to troubleshoot these failures. Skip to Quiz!
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Recall that we need energy to drive machines and equipment. The energy available is required to achieve the desired motion and work.
When energy is transmitted from input to output using mechanical elements, we call that mechanical power transmission. The mechanical elements used in power transmission are:
Gears
Belt and pulley systems, and
Chain and sprocket systems.
Machinery breakdowns are often the result of gear failure. The cause of gear failure can be:
Wear,
Overload, and
Misalignment.
Let’s discuss each of them in detail.
Wear is uniform metal removal from the surface of gear teeth. This condition is caused by metal-to-metal contact during operation.
The remedy to avoid wear failure in gears is to provide proper lubrication. Lubricant forms a thin film that prevents metal-to-metal contact between gears.
We often push our machines to their limits and beyond. For example, a two-seater bike designed for a capacity of two people is often driven with more than two persons sitting on it. This can result in excessive tooth loads on the gearbox inside our two wheeler.
When gears are loaded in this manner and subjected to stress, the gear tooth fails. To avoid this failure, we need to ensure that a machine is not overloaded.
Shaft misalignment is considered one of the common repeated problems in most rotating machinery. Misalignment leads to vibrations and additional load on a transmitting gear’s teeth.
A gear’s teeth will not mesh the way they were designed to, resulting in excessive loads on the weaker parts of the teeth. This will result in wearing of the gears and failure.
A gear must mesh properly to avoid gear failure.
We need to adjust a gear mesh by adjusting the location of the motor. Loosen the fasteners that lock the motor in position. Once the motor is loose, be sure it is to move in the direction that would allow for gear mesh adjustment.
As belts, along with gears, are a critical component of power transmission, we often encounter their failures. Belt drive failure can result in a machine breakdown.
A belt drive system can have problems like:
Belt cracks,
Loud noises during startup, and
Pulleys that wear out prematurely.
If we notice any of these issues while examining our drive symptoms, then a possible cause could be improper belt tension.
A belt that’s too loose on a pulley will cause slippage, which leads to heat build-up from friction. This heat will damage our rubber belts and cause the belts to crack and break. A belt that’s too tight can add stress to our bearings leading to motor failure.
We need to make sure that our belts are correctly tensioned. This can help us prevent added costs associated with electric motor or belt failure.
We use a tension gauge to check belt tension. We need to measure a belt’s span length. Set a measured distance in the gauge by displacing the bottom O-ring. Set the top O-ring at zero position.
Next, press down on the belt in the approximate center of its span. We need to press down the belt until it deflects to the desired level on the O-ring. The desired level is compared with a reference belt or by aligning the bottom O-ring to the straight edge of the string.
Now that we have deflected the belt, the recommended amount for the top O-ring will have moved up the plunger. This will give us the tension measurement. We need to compare this with the force chart.
The chart shows recommended deflection force. For example, for a speed range of - RPM, the recommended force of a new belt should be 7.6 lbs.
Pulleys need to be appropriately aligned to prevent premature wear on belts and pulleys. Always check the alignment of pulleys after tensioning a belt because sometimes during tensioning the pulleys can move.
Much like gear drives and belt drives, power can be transmitted by a roller chain. These chains are made up of several rigid links that are held together. A roller chain passes over a sprocket that pulls the chain.
Most often, a chain drive is susceptible to corrosion. A symptom of corrosion is surface pitting, and this is generally noticed on the sides of the links. To prevent corrosion, we will need to lubricate a chain often.
If we notice a roller chain is vibrating excessively, then the possible causes could be:
High speed,
Chain sag, and
Sprocket misalignment.
Let’s discuss each of them.
Any rotating piece of machinery has a critical speed, and roller chains are no exception. We need to ensure that a chain is running below critical speed to avoid vibration.
Excessive chain sag can cause vibration or excessive noise and prevent a chain from properly engaging its sprocket. This can prevent the chain from operating smoothly. On the other hand, an over-tightened chain can cause premature wear or elongation of the chain.
Sprocket alignment is also essential when we are first installing our chain drive. We need to ensure that both the drive socket and the drive sprocket tooth centerlines are straight to each other.
First, we will install the sprocket on the drive shaft. We need to make sure the ends of the chain are lined up with the sprocket. Now we’re ready to check the chain tension.
We can use the same tension gauge that we used when setting up a belt tension. We’ll place our straight edge or scale from sprocket to sprocket on the slack side of the chain drive.
From the straight edge, the distance of the O-ring gives sag present in the chain. A chain should be installed with sag from two to four percent of the sprocket center distance for most applications. If the chain sag is not within these limits, we need to remove the link of the chain.
The mechanical elements used in power transmission are:
Gears,
Chain and sprocket systems, and
Belt and pulley systems.
The cause of gear failure can be:
Wear,
Overload, and
Misalignment.
A belt drive system can fail due to:
Belt cracks,
Loud noises during startup, and
Pulleys that wear out prematurely.
If we notice a roller chain is vibrating excessively, then the possible cause could be:
High speed,
Chain sag, and
Sprocket misalignment.
Question #1: What are the elements of power transmission? (select all that apply)
Gears
Belt and pulley systems
Nuts and bolts
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Chain and sprocket systems
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Answer: Gears
Belt and pulley systems
Chain and sprocket systems
Some external signs that indicate potential coupling failure include:
Abnormal noise,
Excessive vibration, and
Failed seals indicated by lubricant leakage.
Question #2: How can we avoid wear failure in gears? (select all that apply)
By spraying water on the gear
By lubricating gears
By using baking soda
By using wear pad
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Answer: By lubricating gears
The remedy to avoid wear failure in gears is to provide proper lubrication. Lubricant forms a thin film that prevents metal-to-metal contact between gears.
Question #3: How do we troubleshoot a gear that is not meshing properly?
By using multimeter
By checking centre distance
By adjusting the location of the motor
By measuring number of teeth on gears
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Loud noises during startup
Bent pulleys
Pulleys that wear out prematurely
Belt cracks
Answer: Loud noises during startup
Pulleys that wear out prematurely
Belt cracks
Belt cracks,
Loud noises during startup, and
Pulleys that wear out prematurely.
Question #5: How do we check belt tension?
Using a multimeter
Using a slip gauge
Using a scale
Using a tension gauge
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Answer: Using a tension gauge
We use a tension gauge to check belt tension.
Question #6: What is the cause of excessive vibration of a roller chain? (select all that apply)
High speed
Rigid links
Chain sag
Sprocket misalignment
Scroll down for the answer...
Answer: High speed
Chain sag
Sprocket misalignment
If we notice a roller chain is vibrating excessively, then the possible causes could be:
High speed,
Chain sag, and
Sprocket misalignment.
Other References:
Your car’s transmission is a complex system that controls the application of power from the engine to the driveshaft. It experiences more wear and tear than many other parts of your vehicle due to the heat and friction produced by its many moving components. Problems range from simple leaks to complete failure, but it can be hard to tell when a seemingly small problem signals a bigger issue.
Do you have an issue with your transmission? Here are some common questions and their solutions.
In every vehicle, the transmission is one of the things that directly affect competency. Usually, following proper transmission maintenance procedures will keep it running smooth, but even with all your precautions, problems may still happen. Here are 5 common transmission questions and their answers:
If you add too much transmission fluid, you may notice it foaming, which can cause erratic gear shifting. Some other problems that may arise include oil starvation and transmission damage. A common issue with overfilling is that people notice fluid underneath their vehicle and think there’s a leak. To remedy this, they’ll add more fluid, contributing to the problem.
If you have noticed a very fine powder deposit of metal clinging to the pan, that’s normal. However, if you have actual shavings or chunks, then you have a potentially serious issue. Shavings are a sign of internal wear beyond what would be considered normal. The actual cause, if these are actual shavings, could be from a lot of things, and none of them are good. Metal shavings are a clear sign that the transmission is ready for a full transmission rebuild.
Make sure you only use the recommended transmission fluid for your engine, since using the wrong kind can damage other parts of your vehicle. The most common situation where the wrong transmission fluid is used is in the case of using automatic transmission fluid (ATF) in place of variable transmission fluid (VTF) and vice versa. If you happen to use the wrong kind of fluid, you will need to remove it as soon as possible to try to minimize the amount of damage to your transmission. If your car has already been driving with the wrong fluid for many miles you will need to get it services to assess any damage.
There are many causes of transmission mystery noises. If your transmission is making a grinding or brushing sound while in gear, the problem may be damaged needle bearings associated with your torque converter. If the needle bearings become damaged, you will generally hear strange noises coming from the transmission while in driving gears, but not when the vehicle is in neutral.
A transmission in trouble will give you various warning signs. You might notice a burning smell, dirty fluid, or see transmission fluid on your driveway or garage floor, which could be caused by a leak. Hearing unexpected sounds while the vehicle is in neutral is another signal that you need to get your transmission serviced or scheduled in for repair. Unusual sounds while you’re in gear could also be warning you of a transmission problem.
Pro Tip: If your transmission starts to do anything out of the ordinary, don’t wait and hope for the best. Take it in!
Identifying problems with your industrial vehicle isn’t always the easiest thing to do. Remember, if you hear or see something strange, don’t wait to see if the problem goes away. Make sure to get your vehicle checked by a transmission service expert before any further damage occurs. Not only will it save you time and money, but it could also save you and others from harm.