Have you heard about idler gear before? Then what is an idler gear? An idler gear is a gear between two gears to transfer the motion.
It can also be defined as a gear that is put into a gear train to change the direction of rotation of the output wheel.
Years ago, I noticed my car’s reverse gear was no longer engaging. After troubleshooting, I discovered that the idler gear teeth had broken, so they were no longer engaging.
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Keep reading below for more details.
Definition Of Idler Gear
The idler gear is between two gears, mostly the input or output gear. The idler gear is usually a small diameter toothed wheel with few teeth. Its function is not to increase or reduce the rotation speed, as other types of gears do, but rather, the idler gear is used to alternate the direction of rotation of the output wheel.
Therefore, the idler gear does not affect the transmission ratio of the gear system since it is a driving wheel and a driven wheel at the same time and, therefore, does not modify the output angular velocity.
Motion is produced when two gears are placed immediately next to one another and move in opposite directions.
An idler gear is positioned between two gears when they must both travel in the same direction. It only changes the direction the second gear rotates when it transmits motion from one gear to another.
You can refer to the gears that link the idler wheel as the “driven gear,” which receives motion, and the “driving gear,” which transmits motion.
The gear ratio between the driven and driving gears is computed similarly as it would be in the absence of the idler gear.
Additionally, using idler gears can create space between the shafts that attach to the gears and between the driven and driving gears.
The size of the idler gear, in this case, can be chosen only based on the amount of space that has to be saved, as it will not impact the driving gear’s rotational speed.
Such a system may also be established when space constraints make it impracticable or impossible to use bigger driving and driven gears.
The idler can accomplish the same tasks as a belt or chain stretched between the drive and drive gears in this manner.
What Is The Use Of Idler Gear
The use of idler gear depends on the application. For example, in the manual transmission vehicle, the reverse idler in a manual transmission allows the shaft to power the forward gears and also to drive the gear that shifts the automobile into reverse.
The transmission’s other gears are in direct contact with the counter gear, transferring power to the axle that drives the wheels and propels the car forward.
On many machines, the input shaft and output shaft should rotate in the same direction.
However, if the mechanism is made up of an even number of gear wheels, the direction of rotation of the output shaft is different from that of the input shaft.
To solve this problem, an idler gear is added between two wheels to modify the output shaft’s rotation direction.
Another important point is that the idler gear helps the engine principle.
What Is The Difference Between Idler Gear And Spur Gear
Spur gears transmit power in the same plane when the two shafts (drive and driven) are parallel.
The teeth of spur gears are parallel to the axis of the axle.
Therefore, when it meshes with another spur gear, it transmits power on a parallel shaft. They are the most common gears with applications in automotive, transportation systems, gear pumps and motors, speed reducers, etc.
Therefore, the spur gear affects the torque and the speed of the gear train.
But the idler gear is only positioned in between 2 gears to assist the gears to rotate in different directions, yet not affect the surface speed of the input shaft and the output shaft.
Even when calculating the input and output gear ratio, the idler gear does not impact the calculation because it will not affect the gear ratio regardless of the size.
Do Idler Gears Have Torque
The answer is no. The idler gear does not have torque. However, it transfers torque from one end to the other.
In gear drive, you can transfer torque without affecting the rotation; therefore, you need an idler gear to make it possible.
Ordinarily, when two gears mate, it is impossible to rotate in the same direction, and to maintain the rotation but transfer only the torque, an idler gear can be used.
However, an idler gear does not add or reduce the torque transferred to it; Instead, it transfers to the output shaft the same speed and torque as it received from the input shaft.
So, an idler gear does not have a torque; it only transfers what is supplied to it.
What Is Another Name For An Idler Gear
Just as some of us have more than one name, no wonder you may be asked about your middle name while filling out a form.
Similarly, an idler gear has other names that some people use to refer to.
For example, an idler gear can also be called an intermediate gear. The reason behind such a name is that the idler gear is usually found in between two gears. It doesn’t work alone. Therefore, the name intermediate is fitting.
Another name used for idler gear is reverse gear idler. The reason for this name is that it may only need an idler gear to change the direction of the motion.
By engaging the idler gear, the direction flow has been reversed; for this reason, an idler gear is also called a reversed gear.
Why Is Idler Gear Made Of Hard Material
The idler is made of hard material due to the nature of its role. If you know idler gear, you will understand that the material is harder than the other gears.
That is because idler gear has the additional role of tensioning the belt or chain. It is, therefore, subjected to tension, force, tear and wear.
The manufacturer used harder material to make idler gear to cope with such a hard role.
Another point to consider is that the idler gear is bi-dimensional.
Other gears are one-directional, but the idler gear goes in both directions, which will no doubt cause tear and wear quicker than other gears. For that reason, the manufacturer decided to make it harder than other gears.
For instance, input gear will used to the directional force to which it is subjected, but when it is twisted to and fro it will make it wear.
What Are The Parts Of Idler Gear
The parts of the idler gear depend on the application. Below, let us mention some parts of the idler gear.
1. Ball bearings: Ball bearings are composed of rolling spheres separated by two “tracks” or bearing rings, which serve to reduce the contact surface and friction on the moving planes.
2. Bushings: A hollow and cylindrical piece inserted into a hole to reduce its internal diameter.
3. Nuts: Sometimes, a nut can lock the idler gear to prevent it from pulling out.
4. O-ring: Depending on the application, some idler gear uses an o-ring to prevent oil leakages.
5. Washers: A washer may be placed on the idler gear before the nut.
6. Springs: if the idler is used as a clutch, spring will be in it.
7. Clutches: Some idler gear has a clutch that helps it change the motion’s direction.
What Is The Idler In A Car
The idler gear is very useful in a car. In a car engine, the idler gear is placed between the camshaft and the crankshaft for the two shafts to maintain a similar direction. Therefore, if the crankshaft is rotating clockwise, the idler gear makes it possible for the camshaft to rotate clockwise.
Another application of idler gear in the car is in the manual transmission.
For example, the idler gear is used in the reversing mechanism of cars powered by an internal combustion engine.
The reverse idler in a manual transmission allows the shaft to power the forward gears and drive the gear that shifts the vehicle into reverse.
How Many Teeth Should An Idler Gear Have
An idler’s size and teeth number is irrelevant because an idler does not affect the 2 gear ratio, which is in between the input and output gear.
In calculating the sequence and the ratio of the gear assembly, the ratio depends only on the two other gears without considering an intermediate gear, an idler gear.
The idler gear changes the direction of the final gear, so whether small size or big size, the idler gear role never changes, and the number of teeth does not change anything.
Now, let’s talk about the surface speed.
You should know that the input shaft’s surface speed is transferred to the idler gear, and the idler gear transfers the exact surface speed to the output shaft.
That is done regardless of the size of the intermediate gear, whether big or small.
Therefore, the idler gear does not affect the transfer of the surface speed from the input shaft to the output gear unless there is a problem along the line, such as spillage.
Conclusion
An idler gear is a gear that changes the direction of a motion without influencing the speed and the torque of the gear drive.
It transfers motion from the input shaft to the output shaft.
Remember that the idler gear does not affect the speed and the torque, regardless of size.
The number of the teeth of the idler gear is not relevant because it does not affect the output.
In cars, the idler gear is used in engine timing and the transmission system, especially the manual transmission.
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