1) Description of Internal Spur Gear

Spur gears are the most fundamental and common type of gear. Their teeth feature a straight-line profile, with the tooth line (the intersection of the tooth surface and the pitch cylinder) running parallel to the gear's axis. They form the starting point and foundation for gear transmission design.

2) Working Principle

Two spur gears transmit motion and power through the meshing of their tooth profiles. When a pair of teeth begins to engage, they make simultaneous contact across the entire tooth width and roll purely along the line of contact. Their transmission ratio is constant, equal to the reciprocal of the number of teeth on each gear.

3) Characteristics of Internal Spur Gear

• Simple tooth profile: The tooth form is an involute curve, with the tooth line being a straight line parallel to the axis.
• Easy to manufacture: The machining process is well-established, resulting in relatively low production costs.
• No axial force: No axial component force is generated during transmission, allowing for simplified bearing design.

4) Advantages of Internal Spur Gear

• Simple design and manufacture with low cost.
• High transmission efficiency.
• No axial force, simplifying support structures.

5) Application

Suitable for low-speed, light-load applications or situations where noise levels are not a primary concern, such as:

• Shift gears in manual transmissions
• Simple machinery including clocks, toys, etc.
• Agricultural implements and small-scale reduction gearboxes