Gears are fundamental mechanical components used to transmit motion and force between machine parts. Their primary function is to change the speed, torque, and direction of a power source.
Understanding gears and gear ratios is essential for anyone involved in mechanical design, engineering, or physics.
What is the purpose of gears in a machine?
Spur Gears
Used for parallel shafts, they are simple and efficient but can be noisy at high speeds.
Used to:
Reverse direction of rotation
Change force or speed of rotation, when using different size gears.
Spur Gear
Bevel Gears
Conical gears used to transmit motion between intersecting shafts, often at a 90-degree angle.
Used to:
change angle of rotation, usually 90 degrees
What type of gear has teeth that are cut on an angle to the face of the gear?
Helical Gears
Have angled teeth, offering smoother and quieter operation, suitable for high-speed applications.
Which type of gear is known for its quiet operation and high efficiency?
Worm Gear
A worm gear is a type of gear that consists of a screw-like gear called a worm that meshes with a toothed gear called a worm wheel. It is commonly used in applications where a high gear ratio is required, such as in elevators, conveyor systems, and heavy machinery.
Applications
Very high gear ratios for a high level of torque
Which type of gear is often used in conveyor systems?
Gear Ratio
The gear ratio is the relationship between the number of teeth on two meshing gears. It determines how the rotational speed and torque are modified between the driving gear (input) and the driven gear (output).
Gear Ratio=Number of Teeth on Driving GearNumber of Teeth on Driven Gear
Or expressed as a ratio:
Gear Ratio = Output Teeth : Input Teeth
30 output : 10 input = 3:1
3:1 means that the output gear will have 3 times the torque but 1/3 of the speed.
In a gear system, the gear ratio is the ratio of the number of teeth on the driving gear to the number of teeth on the .
What is the gear ratio of a gear system with 20 teeth on the input gear and 40 teeth on the output gear?
Example Gear Ratio
If a driving gear with 10 teeth meshes with a driven gear with 20 teeth, the gear ratio is 2:1.
This means the driven gear rotates once for every two rotations of the driving gear. Consequently, the torque is doubled, but the speed is halved.
What is the gear ratio if the input gear has 12 teeth and the output gear has 4 teeth?
