Understanding different gear types

Gears can be classified based on the way their axes are positioned. Though gears are broadly classified into types like spur gear, helical gear, bevel gear etc, there are many other types and sub-types of gears based on gear design patterns. For the purpose of this article, let us focus on six major gear types.

Types of gears

Spur gears

Spur gears are noted for their cylindrical pitch surface. They mesh correctly only if fitted parallel to the shaft, and they have no thrust load. Spur gears are easy to produce and highly accurate. Hence, this gear type is used the most widely in the industry.

Bevel Gear

Bevel gears work to transmit force between shafts that interact at one point. They are conical in shape with teeth along the cone. Bevel gears come in various other types such as straight gears, helical gears, spiral gears, angular gears, hypoid gears, miter gears, crown gears, and zerol gears. The greatest advantage of bevel gear design is that it is possible to change the angle of the gear. Bevel gears are generally used in 90 degrees, but that angle could be changed according to requirements.

Helical gears

Helical gears are cylindrical in shape and have widening tooth lines. They are quieter and more capable than spur gears at transmitting higher loads. Helical gears create thrust force, which mandates using thrust bearings along with this hear type.
Helical gear design includes twists towards the right or the left in the teeth line. Thus, gears of opposite hand must be used to make the meshing more effective.

Rack and pinion

A gear rack is used to convert circular motion into linear motion. This involves a circular gear rotating on a linear gear (a rack) This mechanism can be used for gears with straight teeth as well as helical teeth. Gear racks are also quieter to operate and can transmit higher loads. The tooth pitch and the size of the pinion of a gear rack determines the amount of force it can transmit.

Worm gear

A worm gear is an arrangement of gears such that a gear in the form of a screw meshes with a worm wheel. Together, this arrangement is called worm gear. Worms and worm wheels come in different shapes. For example, the hour-glass gear design of worm wheels can increase the contact ratio. However, producing such gears is challenging. There is a greater chance of friction with this type of gear design as the worm and the worm wheel slide against each other. This is typically resolved by using a hard material for the worm and a softer material for the wheel. The friction factor also reduces the efficiency of this gear type.

Internal gear

Internal gears have an atypical gear design. Their teeth are situated on the inside of the cylinder and they work in pair with external gears. Involute and trochoid interference as well as issues with trimming limit teeth differences between internal and external gears. Both internal and external gears rotate in the same direction when they mesh, whereas tow external gears will rotate in opposite direction when meshing. Internal gears do not reverse the direction of the output shaft.


Gear design and gear size are two major factors to be considered when selecting a good gear. Thus, close attention must be paid to design and inspection of gears. CalibroMeasure works to bring more accuracy and efficiency to gear inspection by automating multiple aspects of gears inspection process. We bring proven expertise in building machines that can inspect multiple aspects of multiple gears at a time.

To know more about how we could work with you to deliver better gears faster to the market, drop us an email at sales@calibromeasure.in or give us a call at +918975767905/+919822032062

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CalibroMeasure Equipments P. Ltd. with its highly experienced team designs & manufactures automated dimensional inspection solutions for precision gears & transmission shafts for final as well as in process inspection.


Addrees: G-39/7/2, MIDC, Waluj Aurangabad, Maharashtra, India

Mail: connect@calibromeasure.com

Phone: +918975767905, +919822032062