How Do Bevel Gears Works ?

Gears are a crucial part of many motors and machines. Gears help increase torque output by providing gear reduction and they adjust the direction of rotation like the shaft to the rear wheels of automotive vehicles.Here in these Article we will learn about Bevel Gear Mechanism.

Bevel Gears are used when the power of one shaft must be transmitted at a different angle to another shaft.The most common example of bevel gears at work is an automobile differential.The drive shaft of the motor must transfer its power at a right angle to the axle of the wheels.The bevel Gears have the same diameter and number of teeth, so they will each turn at the same rate.

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. Straight Bevel Gears :

Straight bevel gears, with a conical pitch surface and straight, tapering teeth are mounted on shafts that are perpendicular to each other and also in the same plane.

3. Spiral Bevel Gears :

Spiral bevel gears, which have curved teeth seated at an angle that allows for gradual tooth contact, similar to helical gears, are mounted on shafts that are perpendicular to each other and also in the same plane

4. Hypoid Bevel Gears :

Hypoid bevel gears, which are related to spiral bevel gears, but the mating gears axes do not intersect. Hypoid Bevels have a hyperbolic pitch surfaces, rather than conical surfaces.

Advantages of Bevel Gears :-

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

Disadvantages of Bevel Gears :-

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

Applications :-
Due to their ability to change the direction of force and the operating angle of the machinery, bevel gears are used in many diverse applications such as
  1. Locomotives 
  2. Marine 
  3. Automobiles
  4. Printing presses
  5. Cooling Towers
  6. Power Plants
  7. Steel Plants
  8. Railway Track Inspection Machines ect.

One of the most common uses is in the hand drill, where bevel gears change the vertical rotation of the hand into the horizontal rotation of the drill. Another well-known use is in differential drives of motor vehicles, where bevel gears enable the transmission of power to two axles spinning at different speeds, such as those on a cornering automobile.
Helicopter engines utilize bevel gears to redirect the shaft of the engine to the vertical turn of the rotors. These gears are also used in the functioning of mechanical garage doors.

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