GEARS|JSS 2|BASIC TECHNOLOGY| THIRD TERM
THIRD TERM
Week 8
Topic: GEARS
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Definition
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Types of gear
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Uses of gear / gear ratio
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Function of lubricants in gear
By the end of the lesson, Students should be able to:
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Explain the meaning of gear
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Differentiate the types of gear
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Demonstrate the uses of the various types of gear
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Determine gear ratio
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Outline the functions of lubricants in gear
GEARS
Definition
Gears are mechanical components with teeth that mesh with the teeth of another gear to transmit torque and rotational motion. They are used to change the direction, speed, or torque of mechanical energy.
Types of Gear
Spur Gears: These are the most common type, with straight teeth parallel to the gear’s axis. They are used in applications requiring speed reduction and torque increase.
Helical Gears: These gears have teeth cut at an angle to the gear’s axis, which allows for smoother and quieter operation compared to spur gears. They are used in applications requiring high speeds and loads.
Bevel Gears: These gears have teeth cut on an angular surface and are used to transmit motion between intersecting shafts, usually at a right angle.
Worm Gears: Consisting of a worm (a screw) and a worm wheel (a gear), these gears are used to achieve high torque reduction with a compact design.
Rack and Pinion: This system converts rotational motion into linear motion. The pinion is a small gear that moves along a flat, toothed component (the rack).
Planetary Gears: Consist of a central sun gear, planet gears, and a ring gear. They are used in applications requiring high torque and compact design, such as in automatic transmissions.
USES OF GEAR / GEAR RATIO
Speed Reduction and Torque Increase: Gears can reduce the speed of a motor while increasing the torque. The gear ratio, defined as the ratio of the number of teeth on the driving gear to the number of teeth on the driven gear, determines the amount of speed reduction and torque increase.
Direction Change: Gears can change the direction of motion. For example, bevel gears can change the direction of a shaft’s rotation by 90 degrees.
Mechanical Advantage: Gears can provide a mechanical advantage, making it easier to move heavy loads.
Synchronization: Gears are used in clocks, watches, and other timing devices to synchronize motion.
FUNCTION OF LUBRICANTS IN GEAR
Lubricants play a crucial role in the performance and longevity of gears. Their primary functions include:
Reducing Friction: Lubricants minimize the friction between the gear teeth, leading to smoother operation and reduced wear.
Cooling: By dissipating heat generated from the friction and movement of the gears, lubricants help in maintaining an optimal temperature.
Protecting Against Corrosion: Lubricants form a protective film on the surface of gears, preventing rust and corrosion.
Cleaning: They help in cleaning the gear surfaces by carrying away debris and contaminants.
Reducing Wear and Tear: By forming a film between the contacting surfaces of the gears, lubricants reduce direct metal-to-metal contact, thereby minimizing wear and tear.
