classification of gears

CLASSIFICATION OF GEARS

 The gears may be classified as follows:

1.ACCORDING TO THE POSITION OF AXES OF THE SHAFT:

• parallel
• intersecting
• non-intersecting and non-parallel 

i)Parallel

  The two parallel and co-planar shafts are connected by  spur gears.They have teeth parallel to the axis of rotation and  are used to transmit motion from one shaft to another parallel shaft

If the teeth are inclined to axis then such type of gear is known as helical gear.The double helical gears are known as herringbone gear.

ii)Intersecting shaft.

INTERSECTING SHAFTS

    The two intersecting ,but co planar shafts connected by gears known as bevel gears.they have teeth formed on conical surface.

BEVEL GEAR

iii).Non intersecting and non parallel

     The two non intersecting and non-planar i.e. non-coplanar  shafts are connected by skew bevel gear or spiral gear.this type gearing has line contact ,the rotation of which about the axes generates the pitch surfaces known as hyperboloids.

2.ACCORDING TO THE PERIPHERAL VELOCITY OF THE GEARS :

• Low velocity
• Medium velocity
• High velocity

The gears having velocity less than 3 m/s are termed as low velocity.The gears having velocity between 3 and 15 m/s are known as medium velocity gears.If the velocity of gear is more than 15 m/s then these are called high speed gears.

3.ACCORDING TO THE TYPE OF GEARING:

• External gearing 
• Internal gearing
• Rack and Pinion

In external gearing .the gears of two shafts mesh externally with each other.The larger of two wheels is known as spur wheel and smaller wheel is known as pinion.In an external gearing ,the motion of the two wheels is always unlike .

In internal gearing the gears of two shafts mesh internally with each other.The larger of two wheels is known as annular wheel and smaller wheel is known as pinion.In an internal gearing ,the motion of two wheels is always   like.

INTERNAL GEARING

In some cases ,the gear of shaft meshes externally and internally with the gears  in straight line.such type of gear is known as rack and pinon.It is used to convert linear motion into rotary motion and vice versa.

4.ACCORDING TO THE POSITION OF TEETH ON GEAR SURFACE:

• Straight gears-spur gear
• Inclined gears-helical gear
• curved gears-spiral gear