Type of Gear Transmissions:
1. Spur Gear,
3.Herring bone Gear,
5.Rack and pinion,
6.Worm and worm wheel.
1. SPUR GEARS:Spur Gears in any transmission system are employed for changing the speed, the torque and are fixed on shafts either rigidly or with sliding traverse.
2. HELICAL GEARS:
Helical Gears can be used for transmitting motion between parallel shafts as between perpendicular shafts. Helical gears used for transmission at an angle are called SPIRAL GEARS.
Advantages of Helical Gears:
•Noiseless motion even at higher speeds.
•Smooth transmission of small gears with fewer teeth, at large transmission ratio ( up to 15:1)
These gears must be rigidly installed on the shaft. These gears result in an axial force in one direction depending upon the direction of rotation and are used for transmitting small power.
3. HERRING-BONE GEAR:
HERRING-BONE Gears are pairs of Helical Gears. These gears are used for large power transmission.
Advantages of Herring-bone Gears in addition to Helical Gears:
•No Axial Force. It is balanced axially in both direction of rotation.
•Large power transmission can be done at impact loads having frequent starts (inching).
These gears also must be rigidly installed on the shaft.
4. BEVEL GEAR:
Bevel Gear transmission is employed for transmitting motion from one direction to the other at any angle. In general 90° transmission is used mostly.
5. WORM & WORM WHEEL:
Worm and worm wheel gives a large single stage speed reduction in perpendicular direction. Such transmission gives lower efficiency of transmission due to increased frictional losses. For a noiseless motion, worm 1 is usually made of medium carbon / alloy steel and the worm wheel 2 of bronze (or in some cast iron).
6. RACK & PINION:
The rotary motion of pinion 1 (small gear) is transformed into linear motion of the rack 2. For transmitting large power worm & worm rack transmission is employed.
These gears are used separately or with combinations as per the requirement of the transmission.