Spur Gear

Design of Spur Gear

• Spur gears are used to transmit motion between two parallel axes shafts.
• They are the simplest of all the gears and easiest in production.
• The teeth of spur gears are cut along the periphery and parallel to the axis of gear.

Design of Spur Gear

• The various modes of gear tooth failures are classified in two basic categories.
• To avoid gear tooth failure, the gear designer should have a sufficient knowledge of possible causes of gear tooth failure and corresponding remedies.
• • Bending failure or breakage of tooth
  • Wear failure or surface destruction

Beam strength of Gear design (Sb)

From Lewis equation

Sb=σb . b . mY

Where, σb = bending stress developed due to load Pt

∵ σb= Se = σut/3

b = face width (10 m – 12 m)

Pt = tangential tooth load

module, m=D/T

Y – Lewis from factor (tooth geometry factor)
for pressure angle α = 20°