Gears are mechanical devices used to transfer rotational energy, motion, and torque between different shafts and axes. Gears are usually toothed wheels which drive one another in a chain with circular motion.
Theory Explained
Figure 1: Gear Diagram
In a conventional gear system, the gear that makes the other gear spin is called the driver gear, while the gear being spun or activated is called the driven gear. The driver gear makes the driven gear move as the teeth on both gears mesh with each other, thus when the teeth are pushed against each other, the driven gear will spin.
It is important to note that the direction of spin for the driven gear and driver gear will always be opposite. For example, if the driver gear spins anticlockwise, the driven gear will spin clockwise. However, if the direction of both gears are the same and if there is a gear in between, the gear in the middle is considered to be the idler gear.
Figure 2: Gears spinning in opposite directions
As shown in the diagram, gears can vary in sizes and the number of teeth on each gear, which is important in determining the gear ratio of the gear setup, as well as the general torque and angular velocity produced. The gear ratio is simply a quotient/ratio between the number of teeth on two different gears. For example, if a gear G₁ has 10 teeth and the other gear G₂ has 20 teeth, the gear ratio of G₁ and G₂ is: G₁/G₂ = 10/20 = 0.5. This means that G₂ will rotate twice as fast as G₁.
The size of the gears is important in determining the torque and angular velocity produced. For example, when a larger gear with more teeth drives a smaller gear, the smaller gear rotates faster but with less torque, where torque is the force exerted from the circular motion (product of tangential force and radius of the circle). Therefore, torque will be directly proportional to the angular velocity, where the angular velocity is inversely proportional to the number of teeth. It is therefore useful to calculate the angular velocity and torque with the given teeth ratio.
Applications
Gears are used in many applications. For simpler systems such as bikes, gears are used for bikers to adjust the speed going uphill or downhill. More sophisticated gear systems are usually found in automobiles, industrial equipment, and robotics.
In the automotive industry, gears are used in car transmissions to allow drivers to adjust the speed and torque. Bevel gear systems in differentials also allow wheels to rotate at different speeds, especially when the vehicle is turning. In terms of steering, rack and pinion gears are most used in steering mechanisms to convert rotational motion (angular velocity) into linear motion (linear velocity). This can also be calculated through the equation ω = rv, where the angular velocity ω is a product of the radius and the linear velocity.
Figure 3: Car Gears
In the robotics sector, gears are used to allow robots to move with precision, as well as allowing robots to be in the accurate or its intended position.
Figure 4: Gears on Robots
In more everyday objects such as printers and cameras, gears are also particularly useful. Gears in cameras help to adjust the focus of the lens, while the gears in printers allow for the paper to be transferred within the printer to improve efficiency.
Impact and Significance
Gears are widely used due to its high versatility and high reliability. Its ability to modify torque and angular velocity is an important characteristic to controlling different systems accurately.
Gears can also be modified to infinitely many configurations to maximize an optimal output, therefore many users can use gears to their own likings.
Fun Facts
Gears were invented in the 3rd Century BC.
The biggest gear in the world is the Hoffman Engineering’s Shipment with a diameter of 13.2m and weighing 73.5 tons.
Gears are usually made out of plastics and metals.
Works Cited
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Karim Nice and Hall-Geisler, K. (2023). How Gears Work. [online] HowStuffWorks. Available at: https://science.howstuffworks.com/transport/engines-equipment/gear.htm.
Knowledge Platform (2019). Gears and the Principles of Gear Systems. [online] www.youtube.com. Available at: https://www.youtube.com/watch?v=BKjo8Usp21k [Accessed 4 Jan. 2022].
Printeraction (2021). Redirecting. [online] Google.com. Available at: https://www.google.com/url?q=https://www.instructables.com/Basic-Gear-Mechanisms/&sa=D&source=docs&ust=1722912375691149&usg=AOvVaw14j6L3tzjNyrRQbfHBFUGY.
Seimitsu.in. (2022). Gears for Robotic Application. [online] Available at: https://www.seimitsu.in/Blog-on-Gears-For-Robotics.html [Accessed 6 Aug. 2024].
uk.rs-online.com. (2023). Spur Gears - A Complete Guide. [online] Available at: https://uk.rs-online.com/web/content/discovery/ideas-and-advice/spur-gears-guide.
www.driverseducationusa.com. (n.d.). Vehicle Gears. [online] Available at: https://www.driverseducationusa.com/resources/vehicle-gears/.
Zacharias, D. (2019). How does a gear work? [online] igusblogs. Available at: https://blog.igus.eu/knowledge-base/how-a-gear-works/.
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