To transmit motion between two shafts. or a shaft and a slide.
Sliding motion between Gears tooth surfaces.
Omega = Angular Velocity (rad/s)
Omega1*Radius1 = Omega2*Radius2
Practical limit for Velocity Ratio...
for Spur Gears = 6
for Helical Gears = 10
for higher ratios, two or more Gear Pairs are used.
Spur Gears - since Line Contact,
- Sudden application of load,
- high impact stresses,
- excessive noise at high speeds.
Helical Gears - starts with a point contact and extends along a diagonal line across the teeth - low impact stresses, reduction in noise.
Spur Rack (infinite diameter), Pinion, Gear
External Gear, Internal Gear
External Pinion, External Gear => One rotates in CW, One rotates in CCW
External Pinion, Internal Gear => Both rotate in same direction