Top Things You Need To Know About Gears And Its Key Components

Gears are one of the key ingredients of mechanical and electromechanical transmissions. Gears are included in a variety of different motion control devices too.

In today’s article, we will talk about the key elements regarding the design of gears for your projects. We are also going to focus on their terminology, formulas and different aspects of gear design that will prevent you from making any mistakes while performing a gear calculation.

Amongst a multitude of applications, geared transmission has the responsibility of transferring the right torque served by a motor. Geared transmission is the strongest and most reliable transmission system.

The reason for geared transmission to be the strongest is its efficiency to deliver power. Gear transmission limits energy loss which ultimately results in a much lower amount of friction between surfaces.

In today’s article, we’re going to talk about all things related to gear. We’re going to talk about the gears used in. After that, we’ll move on to gear terminology, formulas related to gear and end with reasons behind gear failing.

With that being said, Let’s begin! 

Types Of Gear Used In The Industry Today

The industry itself is quite diverse when it comes to the types of gear. But the majority of the industry uses 3 kinds of gears. They are:

  1. The first kind is the gear that operates on parallel shafts while being mounted on a pinion. Example: Epicycloidal gears, helical gears, and spur gears.
  2. The ones that operate on transmission and have perpendicular shafts. Gears that depend on the worm screw for torque transmission is a good example of this.
  3. Bevel gears that transfer motion on converging belts rotationally.

Before opting for gear in your industrial project, you need to know how each type of gear functions. In parallel to this, it’s critical to know how the flanks of the pinion’s tooth and the gear engage while designing a smooth rotational transmission that maintains constant angular speed.

It’s important to know the in and out of gears before doing gear calculation. To tackle this complex process, you need to read more about terminology regarding gears. 

Gears terminology

  • Gear ratio:  Gear ratio indicates the relation of two meshed gears through their rotational speed. Among the two meshed gears, one expels pressure on the other. The ratio results through the diameter difference of both gears. This enacts a rotational speed difference between shafts. So, with keeping that in mind, the gear ratio is calculated by the number of teeth on the gear divided by the number of teeth on its pinion. 
  • Pitch diameter: Pitch diameter can be found on the center distance of gears operating and the number of teeth
  •  Base pitch: the Base pitch is the pitch measured where the involute starts, at the base circle. The base pitch has 6 different components. They are:
    • Center distance: Centre distance equals the sum of the gears pitch diameter and pinion pitch diameter. Divided by 2.
    • Circular pitch: Circular pitch is the round distance between the two points of a gears tooth. Both of the gears need to have the same pitch circle to engage with each other. 
    • Diametral pitch (module): Diametral pitch is the standard measure of gear teeth. The number of teeth per inch of the diameter is defined as a diametral pitch. Diametral pitch is reduced by increasing the size of gear teeth. Diametral pitch ranges between 1 and 25.
    • Mounting distance (D): Mounting distance is the midpoint of the shaft gear and the angle intersects the line of the pitch and the reference point of the gear. To ensure proper mounting and usage of toothed components, you’ll need to heed the mounting distance.
    • Pressure angle (angle of obliquity):  Pressure angle is the slope at the diametral pitch of a gears tooth. Shaft of the gear is parallel to the tooth if the angle of pressure is at 0. This creates a spur gear.
    • Helix angle: Helix angle is the longitudinal inclination angle of the gear tooth. Shaft of the gear is parallel to the tooth whenever the helix angle is at 0 degrees. This is similar to that of the spur gear.

It’s essential to know these concepts for proper gear calculation. Now that we’ve talked about the fundamentals, we can now talk about the key elements of different types of gears.

Now it’s time to remember the gears that are of the highest quality. And to know the highest quality, you’ll need to know the key elements in addition to their teeth and size

Key Elements Of Design Calculation

  • Number of teeth (Z): Number of teeth is an important value in gear design and calculation.
  • Pitch diameter (Dp):. Pitch diameter is another key aspect of the gear. It’s also the starting point of transmission calculation. Pitch diameters value is related to the gear’s module and number of teeth (Z)
  • Module (M): Module indicates a group of gears. Gear and tooth sizes are based on module value.
  • Outside Diameter (De): Outside diameter is the distance measured between the peaks of two teeth that are opposed. The value of Outside Diameter depends on (Z), (M) and the pitch angle. 
  • Pitch (P):  Pitch is the distance between the midpoint of two consecutive teeth measured on the pitch circle. If we divide pitch diameter by (Z) then we’ll receive (P)                   
  • Face angle (Beta):. Face angle is the angle that is measured from the outside of the gear to the pitch angle. This angle relies on pitch angle and (Z).
  • Root angle (Gama): Root angle is the value based on face angles specified in tables.
  • Pitch angle (Alpha): Pitch angle is used to design gear on which (DP) can be found. Pitch angles value is related to gear ratio. 
  • Mounting distance (D): Mounting distance is the midpoint of the shaft gear and the angle intersects the line of the pitch and the reference point of the gear. To ensure proper mounting and usage of toothed components, you’ll need to heed the mounting distance.

Formulas Related To Gear

Main formulas used in gear calculation.

Reasons behind gears failing

  • Not enough resistance to tackle force or bending, this causes teeth to fail.
  • Inadequate load ratio amongst 2 or more pairs of teeth can be caused by manufacturing errors. 
  • Problems can occur due to vibration. Whenever the base pitch and pinion is separated from the base pitch of gears, excessive noise and vibration occur. Consequently reducing the service life of the gear.


Gears are a key element in your industrial workflow. And to form a good system of mechanical transmission there is no alternative to learning everything about gears.

We’ve talked about everything related to gear from terminology to cautions. All you need to do now is implement this knowledge into your workflow. And, you should be good to go.

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