A Bevel Gear is a type of gear with teeth that are cut on conical surfaces rather than cylindrical surfaces. These gears have intersecting axes and are used to transmit power and motion between shafts that are not parallel to each other. Bevel gears are commonly used when a change in the direction of rotation or the angle of transmission is required.

The primary function of bevel gears is to transmit rotational motion and torque between non-parallel shafts. The teeth on bevel gears are shaped in such a way that they mesh together smoothly and efficiently, allowing for the transfer of power. The specific functions of bevel gears include:

1. Change in Direction: Bevel gears are often used to change the direction of rotation between two intersecting shafts. They can transmit motion at various angles, such as 90 degrees or any other required angle.

2. Angle Transmission: Bevel gears are capable of transmitting power and torque between shafts that are inclined to each other at different angles. They are commonly used in applications where the input and output shafts are not parallel, such as in differential gears.

3. Torque Distribution: Bevel gears can distribute torque between multiple shafts. By using a combination of bevel gears in a gear train, power can be transmitted and distributed to different output shafts.

4. Speed Adjustment: By using different-sized bevel gears, the rotational speed can be adjusted between input and output shafts. Larger bevel gears can drive smaller bevel gears, resulting in speed variation.

Bevel gears are needed in various engineering applications, including:

1. Automotive Industry: Bevel gears are widely used in automotive applications, particularly in the differential gears of vehicles. They enable the smooth transfer of power from the engine to the wheels while allowing for different wheel speeds during turns.

2. Industrial Machinery: Bevel gears find extensive use in industrial machinery, including power tools, printing presses, and milling machines. They are utilized for transferring power and motion between non-parallel shafts in these systems.

3. Aerospace and Defense: Bevel gears are employed in aerospace and defense applications, such as helicopter transmissions, aircraft landing gear systems, and missile guidance systems. They enable efficient power transmission and directional changes in these critical systems.

4. Marine Industry: Bevel gears are utilized in marine propulsion systems, ship steering mechanisms, and thrusters. They provide the necessary torque and angle transmission for marine vessels.

5. Power Generation: Bevel gears are used in power generation equipment like wind turbines and hydroelectric systems. They help in changing the direction of motion and transmitting power between different components.

6. Robotics: Bevel gears are commonly used in robotic systems where the motion needs to be transmitted between non-parallel shafts. They provide flexibility and versatility in robotic joint mechanisms.

Bevel gears are crucial in applications that require the transmission of power and motion between non-parallel shafts. Their ability to change direction, transmit torque at different angles, and adjust speeds makes them essential in various engineering systems.