The bevel gears are used for transmitting power at a constant velocity ratio between two shafts whose axes intersect at a certain angle. They are usually mounted on shafts that are 90 degrees apart, but can be designed to work at other angles as well.The teeth bearing surface of the gear, or surface pitch, is conically shaped or tapered.A good example is seen as the main mechanism for a hand drill. As the handle of the drill is turned in a vertical direction, the bevel gears change the rotation of the chuck to a horizontal rotation.The normal gear ratio range for straight bevel gears is 3:2 to 5:1.

The bevel gears may be classified into the following types, depending upon the angles between the shafts and the pitch surfaces.

**1. Mitre gears :**

When equal bevel gears (having equal teeth and equal pitch angles) connect two shafts whose axes intersect at right angle, then they are known as "mitre gears". Miter gears are bevel gears manufactured in a 1:1 ratio, with the same number of teeth on mating gears and with perpendicular axes.

**2. Angular bevel gears :**

When the bevel gears connect two shafts whose axes intersect at an angle other than a right angle, then they are known as "angular bevel gears".

**3. Crown bevel gears :**

When the bevel gears connect two shafts whose axes intersect at an angle greater than a right angle and one of the bevel gears has a pitch angle of 90o, then it is known as a "crown gear".

**4. Internal bevel gears :**

When the teeth on the bevel gear are out on the inside of the pitch cone, then they are known as

"internal bevel gears".

"internal bevel gears".

**Advantages of Bevel Gears :-**

Operate on shafts intersecting at an angle, usually the angle is 90°(but not always).

**Disadvantages of Bevel Gears :-**

- Generally low gear ratios.
- The shaft bearings must support the load.
- Require complex and precise installation.

**Applications :-**

- Marine
- Automobiles
- Printing presses
- Cooling Towers
- Power Plants
- Steel Plants
- Railway Track Inpection Machines ect.