Gear 1 Flashcards
What are the main functions of gears?
Transmit power or motion, provide high transmission efficiency, rugged and durable.
How are gears classified based on shaft orientation?
Parallel shafts: spur/helical; Intersecting shafts: bevel; Non-parallel/non-intersecting: worm/hypoid.
What are the advantages of helical gears over spur gears?
Smoother, quieter meshing; handles higher loads; but generates axial thrust.
What is the function of herringbone gears?
Cancel axial thrust in helical gears, smoother transmission at high speed.
What is the pitch circle of a gear?
Theoretical circle used for gear calculations; tangent to meshing gear’s pitch circles.
Define module (m) in gear terminology.
m = d/N; ratio of pitch diameter to number of teeth (in mm); standardised.
What is circular pitch (p) and how is it related to module?
p = π·m; distance between corresponding points on adjacent teeth measured along pitch circle.
What is the tooth thickness on the pitch circle?
t = p/2 = π·m/2
What are addendum and dedendum?
Addendum = m; Dedendum = 1.25m; radial distances from pitch circle to top/bottom of tooth.
Define clearance, whole depth and working depth in gears.
Clearance = 0.25m, Whole depth = 2.25m, Working depth = 2.0m.
What is conjugate action?
Tooth profiles that maintain constant angular velocity ratio during meshing.
What is the pressure angle (ϕ) and typical values used?
Angle between line of action and tangent to pitch circles; typical: 20°, 14.5°.
What is an involute gear profile?
Curve traced by a point on a taut string unwinding from a circle; ensures conjugate action.
What is the gear ratio (Z) in terms of teeth?
Z = Ng/Np = dg/dp = ωp/ωg
What are necessary conditions for proper gear meshing?
Equal module and pressure angle: m1 = m2 and ϕ1 = ϕ2.
How is centre distance (C) between gears calculated?
C = 0.5·m·(N1 + N2)
What is the minimum number of teeth for standard gears (ϕ = 20°)?
18 teeth.
Why is gear tooth system useful?
Ensures interchangeability of gears with same module and pressure angle.
What are key parameters to define a spur gear?
Module (m), number of teeth (N), pressure angle (ϕ).
What are common gear types between parallel shafts?
Spur, helical, internal gears.
