Gear

Question 1

Name type of gear

Answer 1

Parallel gear - spur gear, helix gear, rack and pinion
Intersecting gear - bevel gear
Non- intersecting/non parallel - worm gear

Question 2

Common terminology

Answer 2

Addendum
Dedendum
Circular pitch
Diametric pitch
Interfence and contact ratio
Gear ratio

Question 3

Circular pitch eq

Answer 3

P = pi d/ N

Question 4

Diametral pictch (P)

Answer 4

P = N/d

Question 5

Interference eq, ra

Answer 5

ra = √( rb² + c²sin²@)

rb - base circle radius

Question 6

Contact ratio CR

Answer 6

CR = ( √(rap² - rbp²) + √(rag² - rbg²) - c sin @) / pb

pb = (π dp)/N
r - radius
a - addendum
b - base circle

Question 7

Gear ratio

Answer 7

Wp/wg = np/ng = -dg/dp = Np/Ng

W and n = rotating spd rpm/rad s

Question 8

Force on gear

Answer 8

Ft = tan force
Fr = seperating force
F = resultant force = ft/ cos @
Fr = ft tan @

Question 9

Power and torque

Answer 9

P = Ft x V/ 33000

P = ft x V
T = ft x r
Ft = 2T/d

Question 10

Pitchline velocity

Answer 10

V = πdn/12

V=πdn/60000

Question 11

Basic lewis equation

Answer 11

Stress = (Ft p)/bY

b = face width
Y = lewis factor (graph)

Question 12

Modified lewis equation

Answer 12

Stress = ((p ft)/(b J)) x Kv x Ko x Km

J = spur gear geo factor

Question 13

Bending endurance strength

Answer 13

Sn = Sn’ CL Cg Cs Kr Kt Kms

Sn’ = 1/2 su or 1/4 BHN

Question 14

Gear surface error

Answer 14

Abrasion (foreign material , scoring ( heat cuz. Welding/tearing) , pitting (fatigue)

Question 15

Surface fatigue stress

Answer 15

Stress = Cp √ ( ( Ft/b dp I) kv ko km)

I = (sin @ cos @)/2 . (R/R+1)
R = dg/dp
Cp = elas coeff
L= geo factor
Dp = diameter of pinion

Question 16

Hert strength

Answer 16

Sh = Sfe Cli Cr (all given)