Gear Transmission Professional Knowledge

1. Definition of Gear Transmission

2. Core Functions

1. Transmit motion and power: Transmit the rotary motion of one shaft (driving shaft/input shaft) to another shaft (driven shaft/output shaft).
2. Change rotational speed: Realize speed increase or reduction through the combination of gears with different numbers of teeth.
3. Change torque: The output torque increases when the rotational speed decreases, and vice versa.
4. Change motion direction: For example, bevel gears can realize the direction change of vertical transmission.

3. Transmission Characteristics

3.1 Advantages

• Constant transmission ratio
• High transmission efficiency
• Compact structure and strong load-bearing capacity
• Long service life and reliable operation

3.2 Disadvantages

• High manufacturing and installation cost
• No overload protection function
• Vibration and noise during operation
• Not suitable for long-distance transmission
• Regular lubrication and maintenance required

4. Main Classification of Gears

4.1 Classified by the relative position of the axes of two gears

• Parallel-axis gears
• Intersecting-axis gears
• Cross-axis gears

4.2 Classified by tooth profile curve

• Involute gears: The most commonly used type, with simple manufacturing, insensitivity to the error of installation center distance and stable transmission.
• Cycloidal gears: Good wear resistance, mostly used in special occasions such as clocks, flowmeters and so on.
• Circular arc gears: High contact strength, applied in heavy-duty industrial gear boxes.

4.3 Other common types

• Rack and pinion: Convert rotary motion into linear motion, or vice versa.
• Internal gear: Teeth are distributed on the inner surface of the circular ring, used in compact planetary gear mechanisms and other structures.
• Planetary gear: Composed of a sun gear, multiple planet gears, a ring gear and a planet carrier, with compact structure and large transmission ratio.

5. General Core Parameters of Gears