In the machining industry, we all know the importance of mechanical gear in equipment operations. From moving your industrial machinery to amplifying speed, gears are the top choice of manufacturers.
According to the Businesswire Report, the global market for Gears and drives is estimated to reach a market size of US$176.6 Billion by 2026. The swift increase in the market value is due to the high-efficiency and variable speed features.
There is no single type of gear; gears are classified into different types. Based on their specifications, shapes, and designs, these types have their own dimensions, applications, perks and drawbacks. This article will comprehensively cover all these topics for you.
In this guide, you will also learn about the parameters you must consider while choosing gear for your application. So, without any further delay, let’s jump straight to it.
What Are Gears?
Gears are mechanical machine parts with a set of teeth all around their body structure, which employs in pairs to transfer power between two machining components. They are rotating devices used for speed or rotary change in the equipment.
The pairs of gears always operate in sync by meshing their teeth to transmit energy and prevent slippage during operation. When the driver gear rotates, it turns the driven gear in the same direction to influence the turning force.
Usually, gears are of different sizes slotted together to cause rotation. Small circular gears provide faster rotation with less force. On the hand, the big circular gear generates slow rotations with high force.
Gears have broad applications, from a clock to heavy industrial equipment. But before we understand some of the basic types of gears, let’s discuss their advantages and disadvantages.
Advantages and Disadvantages of Gears
You must analyze the benefits and downsides of gears if you are planning to buy gears shortly. Some of the benefits and downsides of mechanical gears are as follows;
Advantages:
- Gears have high efficiency, thus, aiding in lifting heavy loads.
- Gear devices are compact in size.
- They focus on transmitting high torque and accuracy.
- Gear prevents slippage; hence, it provides the required velocity.
- It is a durable element that does not demand frequent changes.
- With a low maintenance rate, they only need routine checkups and lubrication.
Disadvantages:
- Gear does not offer flexibility.
- Gear may end up damaging machinery due to excessive load on the meshing tooth.
- They cause noise and vibration during heavy-load operations.
- Gears fail to transmit power over large distances.
- They require appropriate lubrication to maintain performance.
Different Types of Gears
Here is the list of the most widely used gear drivers in the used in industry;
1. Spur Gear
One of the most common types of gear in machining equipment is a spur gear. They are frequently called parallel gears because of the teeth’ configuration. In this type, teeth are placed parallel to the shaft.
You can mate spur gears with either an internal gear (having teeth inwards towards the center) or a gear rack and pinion (a straight rod with tooth meshing with a small gear).
They have simple construction allowing easier manufacturing processes. They are ideal for controlling the speed, power, and torque rate of the device.
2. Helical Gear
The structure of the helical gear is quite similar to the spur gear. However, instead of straight-edged teeth, they have winding teeth. The teeth are twisted around the circumference of the cylindrical body. The teeth are at a 45° helix angle in this specific type.
They transmit power via two types of axial configurations; parallel and right-angled.
With a larger contact ratio, helical gear is ideal for carrying high loads. A report by Technavio suggests helical gears are capable of holding larger loads than other types of gears. These gears provide consistent velocity, power, and torque value to meet the higher industrial requirements.
3. Bevel Gear
This type of gear is cone-shaped, with teeth cut at the right angle (90 degrees). They are different from regular gears because they transmit energy between two shafts that are non-parallel. These are employed to modify the axis of rotation or control speed.
Bevel gears are compact in size with easier placement. They can provide faster and more accurate output. However, they are more expensive than parallel and spur gear.
4. Worm Gear
In this type, the worm is referred to as a cylindrical gear matted with a worm wheel. The worm rotates against the wheel and transmits energy between two non-parallel non-intersecting shafts.
Worm gears have screw-shaped and angled teeth configurations. The rotates in one direction and produces less friction. Thus, providing low vibrations and smooth rotations.
They are ideal speed reducers due to the presence of sliding contact. Also, worm gears are unsuitable for high-scale power applications.
5. Rack and Pinion Gear
If you have seen rack and pinion gear, you must have noticed they come in pairs. A cylindrical gear and a flat bar with teeth on the surface typically make a rack and pinion system. Rack and pinion gears are used to convert the rotational motion into linear movement.
They either have straight or curved teeth depending on the type of the meshing gear. However, they have several downsides, such as high friction, stress and limited application range.
6. Miter Gears
The structure of miter gear is similar to regular bevel gear, but they transmit power between two perpendicular and intersecting shafts. In this type, the shafts are placed at a 90-degree angle and provide a 1:1 gear ratio.
Miter gears are cost-effective and durable. They do not alter the speed of the device while transmitting power. These gears are ideal for applications requiring constant torque.
7. Screw Gears
It is commonly known as crossed helical gear because it consists of two gears. One gear cut at a helical while the other cut opposite the helical shape. They are positioned at 45 degrees to the gear axis, making a screw-like shape.
Screw gears work on the mechanism of screw mating and show screw movement. They employ the same-hand configuration instead of right-hand or left-hand pairing. Screw gears are less expensive but provide accurate transmission. Thus, they are ideal for speed reduction purposes.
These gears are used for tuning musical instruments and automotive equipment. However, screw gears are not suitable for high torque and power transmission.
8. Internal Gears
It is a type of gear with teeth on the internal diameter of the cylindrical surface. These gears usually mate with spur gear for power transmission.
If you mesh two external gears together, the final rotation comes in the opposite direction. However, if you are meshing a pair of Internal and external gear, the direction of rotation will be the same.
When the difference ratio in the number of teeth between the internal gear and pinion is less than 17, it causes interference. They are ideal for applications where high strength and small dimensions are requisite.
Application of Different Types of Gears
Gears have a wide range of applications in different industries because of their efficiency, precision, lower voice level, and durability. They are employed in all machining sectors to transmit torque, change direction, and increase/decrease the speed of the driven component.
1. Aircrafts
In the aerospace industry, mechanical gears are widely used for different applications in aircraft. Gears are employed in the engine of the aircraft to generate high-speed rotational power to propel the aircraft forward.
Gears are also employed in the landing gear system of the aircraft to ensure safe takeoff and landing. The global aircraft landing gear market is expected to rise from $10.79 billion in 2021 to $22.90 billion in 2028.
Moreover, a variety of gears are used to manage aircraft movement during flight.
2. Automobiles
Do you know that the automotive industry is the largest consumer of gear, with over 40% of the total market share?
A combination of gears is used for lifting heavy car parts and driving conveyors. In automobiles, the mechanical gears are responsible for transferring the power from the engine to the automobile’s wheels.
Also, they are employed in the steering and braking system for directional control and safety.
3. Clocks
If you have seen mechanical clocks, you must have seen a pair of gear in them. You must wonder why gears are used in clocks. Basically, they move the clock’s hands with consistency. As they are attached to the moving springs of the clocks, they provide accurate timekeeping.
Mechanical gears regulate the speed of the clock with a consistent gear ratio. Therefore, it is crucial to use standard quality gears for mechanical gears.
4. Marine Systems
Gears are a significant part of marine systems and are used for different applications, such as power transmission in the propulsion system, steering system, and lifting loads. The gear works similarly to the aircraft in the propulsion system. The mechanical gears transmit energy and produce thrust to move the vessel forward.
In the marine system, gears are used for transmitting energy to the winches, cranes, and anchor windlasses for lifting purposes. They are also responsible for controlling the vessel’s direction accurately. Gears in the marine system ensure reliable performance in harsh conditions.
5. Material Handling Equipment
Mechanical gears are used for moving, lifting, carrying, or transporting machining materials. Heavy equipment such as cranes, pallet jacks, and trucks employ different gears to generate multiple gear ratios, allowing the equipment to move heavy loads efficiently.
The gears enable the engine to operate smoothly and precisely to improve productivity at the warehouse.
6. Measuring Instrumentation
Gears play an imperative role in measuring equipment due to their high precision and accuracy. In measuring instrumentations, mechanical gears are designed to transform rotational movement into linear movement. They are utilized for amplification or reduction of speed and torsion.
Different gear measuring instrumentation such as vernier calipers, micrometer calipers, and gear tooth vernier calipers precisely measure varying dimensions by converting circular motion into straight-line motion.
7. Power Plants
Power plants are the primary industry that uses gears for high and error-free production. There are various types of gear which you can use for generating power in different power plants.
Gas turbines, fuel handling systems, and thermal/hydropower electricity power plants use gears to provide rotational power to generate electricity.
8. Pumps
Gears designed for pumps cover a wide range of pumping applications. The meshing gears in the pumps enable an expanding volume on the inlet side which creates a vacuum used for pulling liquids such as oil, viscous fluids, and chemicals.
In the pump, the viscous liquid is trapped between the two gear tooth cavities and rotational motion, which forces the liquid to the outlet side. Gear pumps are widely used in hydraulic power and pipeline injections.
A Brief Table of Different Types of Mechanical Gears
| Type of Gear | Specifications | Applications |
| Spur Gear | Widely used gear type.Provides high precision and efficiency. Straight teeth cut with cylindrical body.Do not provide axial thrust.Produce vibration and noise during meshing. | Washing machines Construction Equipment Conveyors Clocks |
| Helical Gear | Have twisted teeth with a circular body. Provide less friction and sliding. Available in right and left-hand designs.They provide quiet and smooth operations. Create axial thrust force. | Compressors Blowers Water pumps Automobile Industry |
| Worm Gear | Cylindrical bodyConsists of a worm screw and worm wheel.Provide high torque value and efficiency.Have complicated teeth design.Have a self-locking feature. | Elevators Rolling mills Small conveyors Lifts and hoists |
| Bevel Gear | Cone-shaped gear body with cut teeth.Intersecting shaft configuration, typically 90 degrees.Complex manufacturing due to angled teeth.Its types include; straight, spiral, and zerol. Provides axial thrust and quieter operations. | Automobiles Power plants Watering and cooling systems Locomotives |
| Rack and Pinion Gear | Pair gears consist of cylindrical gear and gear rack. Produce high friction level and stress.Can withstand heavy loads and stress. | Light weighted cars Steering wheel Material handling equipment |
Basic Parameters for Gear Design
Consider these parameters for gear design before you select the gear for your application;
1. Gear Shape
As you must have seen gears in circular shape. But gears are also available in different forms. For example;
- Conical shape
- Triangular shape
- Square shape
- Elliptical shape
Circular or cylindrical gears have uniform and constant speed and output torque. However, non-circular gears provide irregular speed and torque rating. Therefore, it is necessary to understand the working mechanism and output of circular and non-circular gears for accurate selection.
2. Module
The basic unit the ISO provides for measuring gear teeth is called a module. It describes the size of the teeth or the distance between center and contact point of teeth and gear. It is a primary parameter to consider because only the same type of module gear mesh together.
Module is a ratio that is calculated by dividing the pitch diameter by a number of teeth. Mathematically you can find the module with this formula;
Pitch diameter of gear / Number of teeth = Module
m = d / z
To find the pitch, use the formula;
Circle circumference/ Number of teeth
p = πd / z
3. Gear Axes Configuration
There are three basic types of gear axes configuration; parallel axes, intersecting axes, and non-parallel axes.
- Parallel Axes: In this configuration, gear shafts are parallel to each other.
- Intersecting Axes: Gear shafts intersect each other at a point in this configuration.
- Non-parallel/ Non-intersecting Axes: Unlike the other two configurations, axes are neither parallel nor intersecting in this type.
4. Pressure Angle
Pressure angle is a angle formed between the pitch line of gear and tooth profile. It is important to find the pressure angle because it impacts the efficiency and strength of the tooth.
The most commonly used pressure angle is 20 degrees; however, you will also find angles of 14.5 and 17.5 in some cases.
To find the pressure angle (α) of the gear, you use the following formula;
α = arccos [(C – T)/ (P * π)]
- P stands for pitch
- C stands for circular pitch
- T stands for the thickness of the tooth
- Arccos stands for the inverse cosine function
- π is equal to approx. 3.14.
5. Number of Teeth
A number of teeth are essential to determine gears’ speed, gear ratio, and load-carrying capacity. The number of teeth is crucial for calculating the gear ratio (the rate of input and output gear).
Use the mathematical formula below to calculate the gear ratio;
Number of teeth (input)/ Number of teeth (output)
6. Twist Direction
The direction in which the tooth twists around the cylindrical body refers to the twist direction of the gear. Helical gears have two types of twist directions; right-hand and left-hand twist directions.
In the right-hand helical gear, teeth wrap around in a clockwise direction. However, teeth wrap around in an anti-clockwise direction in the left-hand helical gear.
7. Torsion Angle
The angle of inclination through which a gear rotates around its rotational axis. It is an angle through which the driven gear rotates relative to the driving gear while transmitting torque. As the torsion angle increases, it increases the axial direction.
Make sure the torsion angle is below 25 degrees to prevent failure and wear.
Related Guide: What is Machinability and How Is It Measured?
The Ways to Use Gears in Mechanical Design Situations
Do you know that gears are used for creating different automated functions? Some of ways to use gears are as follows;
- To create a grasping mechanism with gears, you can use two spur gears of the same size. It will reverse the driven gear with the driver gear.
- You can utilize missing teeth gears to create intermitted motion mechanism to control the rotating shaft.
- If your application requires motion transmission in one direction, use a one-way clutch in the gear speed reducer.
Considerations When Designing and Selecting Gears
Now, you must understand that all gears are not suitable for all applications. There are particular considerations that you must keep in view when finding the perfect fit for you. Let’s discuss them;
1. Operational and Environmental Conditions
The most critical factor to consider for gear’s reliable performance and longevity is operational and environmental conditions. Working conditions such as friction, vibration, and unbearable load impact the performance of gears. Environmental conditions affecting the performance of gears are humidity, excessive heat, and sanitation.
2. Dimensional Restrictions
Gear dimensions are limited for restricted space applications because, typically, gears mesh at the center of shafts for power transmission.
However, some restricted space application demand adjustments to fit the gear within the machine dimension. In such cases, the teeth profile is adjusted according to the application.
Therefore, it is recommended to consider this factor if you are designing gear for limited-space applications.
3. Transmission Requirements
You must understand that gears are not only specified for power transmission. They also perform other functions such as; directional change, amplifying speed, reducing speed.
Therefore, it is advisable to consider gear type, design and axes configuration before selecting a gear. Determine if the specific type fulfils your transmission requirements or not.
Mathematically gear ratio is equal to;
Gear ratio= Output/ Input
If you want to find the output torque, use the formula;
T (Output)= T Input x Gear Ratio (Output/ Input)
Similarly, if you want to calculate the output speed of the gear, follow the expression;
Speed (Output)= Speed Input x Gear Ratio (Output/ Input)
4. Design Standards
Gears are not standardized by any general industrial standards. Generally, they are manufactured either according to the manufacturer’s specifications or a particular design specification without following any basic design standards.
However, in some countries have their own industrial standards for gears. These countries are America, Japan, and Germany.
5. Costs
If you are looking for customized gear, the cost is something that you must consider in the first place. The gear material, surface treatments, lubrication type/method, and precision level all add to the final cost.
Therefore, consider investing in standard gear available at reasonable prices because custom gears cost increases when manufacturing, maintenance, and after-care are kept in the calculation.
Why is It Difficult to Obtain Needed Gear?
You might encounter many limitations and errors while finding the right replacement or desired gear for your machinery. Some are as follows;
1. There is No Standard for the Gear Itself
If you are finding gear with specific requirements, you may fail because there of a lack of universal standards. There is no industry standard in terms of size, diameter, manufacturing material, surface roughness, etc.
2. There is a Diversity of Gear Specifications
If you belong to a professional machining industry, you must be aware of the diverse specifications of gears in the market. Despite torsion angle, tooth pitch, and the number of teeth specifications, there are other factors you must consider to find compatible gears and replacements.
Research suggests that heat treatment and surface hardness significantly impact gear performance. Factors such as bore size, treatments, and rigidity must be standardized to reduce the difficulty of finding gear replacements.
3. Cannot Obtain the Desired Gears
If your gear is worn out, it is extremely daunting to find the desired gears because the drawing of gears and parts lists is usually not mentioned in the manual. Moreover, sometimes, it isn’t easy to contact the manufacturer and obtain the required gear.
Therefore, finding the needed gear is quite challenging.
4. When Only One Gear is Needed, the Production Cost is High
Finding a replacement for small gear production, such as 1 or 2 gears, is difficult because production and repair costs are relatively high. Mechanical gears are cost-effective when mass production is needed; however, the same design will cost much higher in terms of single replacement.
5. Possibility of Using Standard Gears
To resolve the above issues, it is recommended to utilize standardized gear if they match your machinery requirements. You can use standardized gears, usually mass-produced by the gear manufacturers.
Using standard gear reduce the hectic task of designing gear, spending high cost on replacement, and finding reliable contractors.
How to Produce Gears
There are different methods manufacturers use to produce gears. All gear manufacturing processes have distinct set advantages and specifications. Some of the standard gear-making methods are;
- Gear Machining (commonest)
- Forging
- Blanking
- Powder Metallurgy
- Extruding
- Casting
- Hot rolling
Want more information about casting processes?
Read out: 11 Types of Casting Processes Used in Manufacturing
Kemal – Gear Machining Services
Now you must understand the basic types, specifications, and applications to determine which gear would be the right fit for you. However, if you are still trying to figure out where to get your highly precise gear manufactured, your search is over!
Kemal is a top-priority company that provides precise and accurate gear machining services. We offer 100% customized gear machining services with guaranteed accuracy and precision. We have qualified machinists who ensure top-notch product development and durability.
Besides gear machining services, we provide CNC, Mold manufacturing, and injection molding services.
For a free quote and additional information, contact us. Our customer support is available around the clock for assistance.
