Gears are used to transmit motion or power from one shaft to another. There are several types of gears classified by their relative position of axes, velocity, type of gearing, and position of teeth. The main types discussed are spur gears, which have parallel teeth and axis and are used to transmit power between parallel shafts, helical gears which have teeth cut at an angle for smoother operation, rack and pinion gears which convert rotational to linear motion, bevel gears which change the direction of rotation by 90 degrees, and worm gears which transfer motion between non-parallel shafts. Spur gear terminology includes features like the top land, bottom land, face, flank, addendum, dedendum, space width

1. Gears
• PRESENTED BY:
Mohammed Tayeeb

2. Contents
• Gears
• Classification Of Gears
• Types Of Gears
• Spur Gear Terminolgy

3. Gears
Gears are used To Transmit a motion or power
from one shaft to another.

4. Classification Of Gears
 According to the relative position of Axes.
1. Parallel Axes
2. Inersecting Axes
3. Non Parallel and Non intersecting Axes
 According to the velocity of gear.
1. Low Velocity 2. Medium Velocity 3. High Velocity
 According to the type of gearing
1. Internal Gearing 2. External Gearing

5.  According to the posoition of teeth on the gear surface
1. Straight
2. Inclined
3. Curved

6. Types Of Gears
1. Spur Gear
2. Helical Gear
3. Rack and Pinion
4. Bevel Gear
5. Worm Gears

7. 1. Spur Gear
 Teeth is parallel to axis of rotation.
 Transmit power from one shaft to
another parallel shaft.
 Used in Electric screwdriver,
oscillating sprinkler, windup alarm
clock, washing machine and clothes
dryer.

8. 2. Helical Gear
 The teeth on helical gears are cut at an angle to the face
of the gear
 This gradual engagement makes helical gears operate
much more smoothly and quietly than spur gears
 One interesting thing about helical gears is that if the
angles of the gear teeth are correct, they can be mounted
on perpendicular shafts, adjusting the rotation angle by
90 degrees

9. 3. Rack and Pinion
• Rack and pinion gears are used to convert rotation
(From the pinion) into linear motion (of the rack)
• A perfect example of this is the steering system on many
cars

10. 4. Bevel Gear
• Bevel gears are useful when the direction of a shaft's
rotation needs to be changed
• They are usually mounted on shafts that are 90 degrees
apart, but can be designed to work at other angles as well
• The teeth on bevel gears can be straight, spiral or hypoid
• It is Used in locomotives, marine applications, automobiles,
printing presses, cooling towers, power plants, steel plants,
railway track inspection machines, etc.

11. 5. Worm Gears
Worm gear sets – consists of a helical gear and a power
screw (worm), used to transfer motion between non-
parallel and non-intersecting shafts.

12. Spur Gear Terminolgy

13. Top land- It is the surface of the top of the tooth.
Bottom land- The surface of the bottom of the tooth.
Face- Tooth surface between the pitch circle and the top land.
Flank- Tooth surface between the pitch circle & the bottom land.
Addendum- It is the radial height of the tooth above the pitch
circle.
Dedendum- It is the radial depth of the tooth below the pitch
circle.
Space width- It is the width of the tooth space along the pitch
circle.

14. Face width- The length of the tooth parallel to the gear axis.
Tooth thickness- It is the thickness at the tooth measured along the
pitch circle.
Backlash-It is the difference between the tooth space and the tooth
thickness

15. Construction