Key Applications and Functions of Different Gears
To answer the question, what is a gear? We can say that a gear is a kind of machine element which has teeth cut around a cylindrical or cone-shaped surface with equal spacing? They are used to transmit rotations and forces from the driving shaft to the driven shaft when a pair of these elements have meshed. There are different types of gear. They have a different basis of classification. The history of gears is old and is mentioned by Archimedes to be in use in ancient Greece in B.C.
Classification of Gears and their Application
All types of gears are given in the classification chart below.
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Gears can be classified as parallel shaft gears, intersecting shaft gears and non-intersecting non-parallel shaft gears depending on the position of their axes.
Some important gears are given in detail below.
Internal gear
Screw gear
Worm gear
Bevel gear
Spiral bevel gear
Spur gear
Mitre gear
Gear rack
Helical gear
Each type of gear is discussed in brief below:
Internal Gear
These gears have teeth cut on the inside part of cones and cylinders and are used to pair with external gears. These are used in shaft couplings which are of gear types and planetary gear drives. Due to trimming problems and interference such as trochoid and involute, there lies one disadvantage with this gear, which is an unequal number of internal and external gears.
Screw Gear
Screw gears or sometimes called crossed helical gears are helical gears used in motion transmission between non-intersecting shafts. In parallel shafts, the helical gears used have the same helix angle but in opposite directions. It consists of the same hand helical gears at an angle of 45 degrees on the non-intersecting and non-parallel shafts. It is used for small power transmission.
Worm Gear
It consists of two elements, a screw-shaped cut on the shaft called a worm and the other one is a mating gear called a worm wheel. These two together on a non-intersecting shaft form worm gear. material is used for worm and a soft one for worm wheels as it is necessary to reduce friction due to sliding contact of surfaces. They can have a cylindrical shape and also an hourglass type which increases the contact ratio but reduces the production.
Mitre Gear
These are basic bevel gears with a speed ratio of 1. The direction of power transmission is changed by them without changing speed. They can be both straight and spiral. With spiral mitre gear thrust bearing is also used as it produces thrust force in the axial direction. Mitre gears with shaft angles other than 90° are called angular mitre gears.
Bevel Gear
These have a cone shape at their pitch surface and teeth are cut along the cone. They transmit force between two shafts that intersect at a point. Various kinds of bevel gears are helical bevel gears, spiral bevel gears, straight bevel gears, mitre gears, angular bevel gears, zero gears, hypoid gears and crowns bevel gears.
Spiral Bevel Gear
Bevel gears with curved tooth lines are called spiral bevel gears. They are superior to straight bevel gears in efficiency, strength, vibration and noise due to higher contact ratio but are difficult to produce. Since teeth are curved, it produces thrust force in the axial direction. These gears with zero twisting angles are called zerol bevel gears.
Spur Gear
Spur gears are included in the parallel shaft gear group. They are cylindrical gears having tooth lines straight and parallel to the shaft. Cylindrical gears are gears with cylindrical pitch surfaces. In meshing pairs, the larger one is called gear and the smaller one is pinion. They achieve high accuracy and are relatively easy to produce.
Gear Rack
A gear rack consists of same sized and shaped teeth cut at equal distances along a flat surface or a straight rod. It is a cylindrical gear having a radius of pitch infinity. It converts rotational motion into linear motion by meshing with a cylindrical gear pinion. Straight tooth racks and helical tooth racks are its broader classification.
Helical Gear
These gears can transmit high loads. They are very quiet and are cylindrical gear with winding tooth lines. Its two subdivisions are left-hand twist and right-hand twist.
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Different Types and Applications of Gears
Since gears are an essential part of many devices, tools and vehicles they have a wide range of applications. Everywhere different types of gears are used as per the requirement. Thus applications of gears are given below as per the types of gears.
Fun Facts about Types of Gears and Their Applications:
Studying gear can become tiresome after a point in time. To get you out of this boredom Vedantu has brought some facts about gear:
The first gear was made of wood. They were applied in watermills and windmills.
Metal gears were used for the first time in the clocks.
Gears used in cars are known as helical.
Some gears are not circular in shape. Some of them are conical and square.
The largest gear in the world weighs 73.5 tons and is 13.2 m in diameter.
Roller coasters cannot work without gears
An insect named Issus has gears in its hind legs which allows the legs to function together in synchronized motion when the insect jumps. This is an example of natural gear.
Conclusion:
The topic of gears forms an essential part of mechanics and a lot of questions are asked from this topic in various examinations including engineering exams in higher standards. The above write-up covers the topic of Types of Gears Their Applications in great detail. It starts with the definition of gear and goes on to cover topics like its types, classification, applications, etc. After reading this write-up you will be in a position to understand the basics of the chapter and also well prepared to grasp advanced concepts related to the topic.
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FAQs on Types of Gears: Complete Guide for Students
1. What is a gear and what is its primary function in a machine?
A gear is a rotating mechanical part with cut teeth that mesh with another toothed part to transmit torque and motion. Its primary function is to alter the speed, torque, and direction of a power source. Gears are fundamental components in countless machines, from simple clocks to complex vehicle transmissions.
2. How are gears classified based on their shaft alignment?
Gears are broadly classified into three main categories based on the orientation of the shafts they connect:
Parallel Shafts: Gears like Spur and Helical gears are used when the input and output shafts are parallel.
Intersecting Shafts: Bevel gears are used to transmit motion between shafts whose axes intersect, often at a 90-degree angle.
Non-Parallel, Non-Intersecting Shafts: Worm gears and Screw gears are used for shafts that are in different planes and do not intersect.
3. What is the difference between a spur gear and a helical gear?
The primary difference lies in the design of their teeth. Spur gears have straight teeth that are parallel to the gear's axis, leading to high-impact stress and noise. In contrast, helical gears have teeth cut at an angle, allowing for a more gradual and smoother engagement. This design makes helical gears quieter and capable of carrying heavier loads than spur gears of the same size.
4. What is the working principle behind a gear system?
A gear system works on the principle of mechanical advantage, achieved by transmitting motion through interlocking teeth. When a smaller gear (pinion) drives a larger gear, it results in a decrease in speed but an increase in torque. Conversely, when a larger gear drives a smaller one, it increases the speed while decreasing the torque. The transfer of power is governed by the law of gearing, which ensures a constant velocity ratio between the gears.
5. How does a gear train increase or decrease speed and torque?
A gear train modifies speed and torque based on the gear ratio, which is the ratio of the number of teeth on the driven gear to the driver gear.
To decrease speed (and increase torque): The driving gear must have fewer teeth than the driven gear. This is called a reduction drive.
To increase speed (and decrease torque): The driving gear must have more teeth than the driven gear. This is known as an overdrive.
This inverse relationship between speed and torque is a fundamental aspect of mechanical power transmission.
6. What are bevel gears and where are they typically used?
Bevel gears are cone-shaped gears used to transmit power between two shafts that intersect at an angle, most commonly 90 degrees. Their teeth can be straight or spiral. Due to their ability to change the direction of rotation, they are widely used in applications like vehicle differentials, hand drills, and various industrial machinery where a right-angle drive is required.
7. Which type of gear is used to transmit power between non-parallel and non-intersecting shafts?
For shafts that are not parallel and do not intersect (also known as skew shafts), a worm gear system is typically used. This system consists of a worm (which resembles a screw) and a worm wheel (a gear). The worm's screw-like action on the wheel allows for smooth power transmission and very high gear ratios in a compact space.
8. Why are worm gears often used in applications requiring high torque reduction and no back-driving?
Worm gears are preferred for these applications due to two unique properties. First, they can achieve very high gear ratios in a single step (e.g., 50:1 or more), making them ideal for significant torque multiplication. Second, most worm gears are inherently self-locking. This means the wheel cannot drive the worm, preventing the load from back-driving the power source, which is a critical safety feature in applications like lifts, hoists, and conveyor belts.
9. What are some common real-world examples of different gear types in action?
Different gear types are used in everyday objects and complex machines:
Spur Gears: Found in washing machines, clocks, and screwdrivers.
Helical Gears: Used in automobile transmissions for their smooth and quiet operation.
Bevel Gears: Essential in car differentials to allow wheels to turn at different speeds.
Rack and Pinion: Used in vehicle steering systems to convert the steering wheel's rotation into linear motion.
Worm Gears: Found in guitar tuning mechanisms and elevators for their self-locking property.
10. How is the gear ratio calculated, and what does it signify?
The gear ratio is a crucial value that signifies the change in speed or torque between the input and output shafts. It can be calculated in two primary ways:
Gear Ratio = (Number of teeth on Driven Gear) / (Number of teeth on Driver Gear)
Alternatively, it is the inverse of the speed ratio:
Gear Ratio = (Speed of Driver Gear) / (Speed of Driven Gear)
A gear ratio greater than 1 means a reduction in speed and an increase in torque, while a ratio less than 1 indicates an increase in speed and a reduction in torque.
