Drives - Gear Drive, Types of Gear, Spur, Helical, Bewel, Worm, Rack and Pinion

GEAR DRIVE

A gear is rotating machine element having cut teeth which mesh with another toothe parts in order to transmit the power.

Types of Gear

• Spur Gear

• Helical Gear

• Herringbone Gear

• Bevel Gear

• Worm Gear

• Rack and Pinion

• Internal and External Gear

• Face Gear

• Sprcokets Gears

Parallel and co-planer shafts connected by gears are called spur gears.
Spur gears have straight teeth and are parallel to the axis of the wheel.
The advantages of spur gears are their simplicity in design, economy of manufacture and maintenance, and absence of end thrust
Spur gears are known as slow speed gears.
Spur gears are the most common type of gears.

Helical Gear

Helical gears have their teeth inclined to the axis of the shafts in the form of a helix.
Helical gears can take higher loads than similarly sized spur gears. The motion of helical gears is smoother and quieter than the motion of spur gears.
The angle of the helix on both the gear must be same in magnitude but opposite in direction, i.e., a right hand pinion meshes with a left hand gear.
These gears are usually considered as high speed gears.

Herringbone Gear

Herringbone gears resemble two helical gears that have been placed side by side.
A disadvantage of the herringbone gear is that it cannot be cut by simple gear hobbing machines.
Herringbone is usually referred to as Double helical gear but the fact is that Herringbone is type of double gear with two helical gears joined together correctly of opposite helix and they don't have any clearance between them, whereas in double helical gear there is a groove between the two helical gear given for tool run out for manufacturing.

Bevel/Miter Gear Spiral Bevel Gears

In these Spiral Bevel gears, the teeth are oblique. Spiral Bevel gears are quieter and can take up more load as compared to straight bevel gears. Zero Bevel Gears
Zero Bevel gears are similar to straight bevel gears, but their teeth are curved lengthwise. These curved teeth of zero bevel gears are arranged in a manner that the effective spiral angle is zero. Intersecting but coplanar shafts connected by gears are called bevel gears. Straight bevel gears can be used on shafts at any angle, but right angle is the most common.

Worm Gear

Worm gears are used to transmit power at 90° and where high reductions are required. • In worm gears, one gear has screw threads. Due to this, worm gears are quiet, vibration free and give a smooth output.
Worm gears and worm gear shafts are almost invariably at right angles.

Rack and Pinion

A rack is a toothed bar or rod that can be thought of as a sector gear with an infinitely large radius of curvature. Pinion can be considered as a spur gear.
Torque can be converted to linear force by meshing a rack with a pinion: the pinion turns; the rack moves in a straight line.
Such a mechanism is used in automobiles to convert the rotation of the steeing wheel into the left-to-right motion of the tie rod(s).

Internal gear

Internal gears have teeth cut on the inside of cylinders or cones and are paired with external gears. The main use of internal gears are for planetary gear drives and gear type shaft couplings.
There are limitations in the number of teeth differences between internal and external gears due to involute interference, trochoid interference and trimming problems.
The rotational directions of the internal and external gears in mesh are the same while they are opposite when two external gears are in mesh.

Face gear

There are three distinct gear types in angle drives. The most commonly used are bevel and worm drives. Face gear drives are the third alternative.
It is possible to cut gear teeth on the face of a gear wheel. Also, gear teeth can be cut on the inside of a gear ring an example of which is shown in the top figure below. Internal gears have better load carrying capacity than external spur gears. They are safer in use because the teeth are guarded.
Manly its of two types 1) Internal face gear 2) External face gear

Sprocket gear

A sprocket gear is wheel provided with teeth or cog that mesh with a chain track or other perforated or intended material.
It is distinguished from a gear in that sprockets are not meshed directly and differs from a pulley in that sprockets have teeth and pulleys are smooth.

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