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The Design and Application of Spur Gears

July 29, 2021

The Design and Application of Spur Gears

Spur gears are arguably the most widely used and simplest type of gear there is. This is primarily because they are very easy to manufacture and can be used for a wide range of various applications. By design, they are cylindrical with straight teeth that are parallel to the shafts. Their teeth have an involute profile. This tooth design enables the gear to produce radial forces but not axial forces. One of the main disadvantages of this particular profile is the high generation of noise and stress. As such, spur gears are commonly used for applications involving lower speed even if they can be utilized at any speed.



In terms of materials, spur gears are usually made from different metals such as brass or steel.



For certain applications, they can be made from plastics as well like nylon or polycarbonate. While plastic gears are less noisy, they are not as durable and strong metals. One major advantage of a spur gear compared to other types is its high transmission efficiency because it does not experience high losses caused by slippage. In fact, bigger reduction ratios can further be achieved if several of these gears are used in a series called a gear train.


There are two different types of spur gears - internal and external gears. The internal gears have teeth that are cut on the inside part of the cylinder. They are more compact than their external counterparts. This is because the shafts are positioned very close together. They are commonly used for planetary gear drives. On the other hand, external spur gears have teeth that are cut on the outside surface of the cylinder. They meshed together and rotated in opposite directions and they sit inside the internal gear.


Overall, spur gears are perfect for speed reduction and torque multiplication applications, such as in the case of crushing machines. Even while they are less desired for passenger automobiles, they are also often utilized in trains and aircraft engines. They truly are a versatile gear.