2. Gear Design Calculations
Power generated by bullocks, P is 650 W
Rpm generated is 2.
Rpm of the pulley is = 145/35*94/22*110/31*2 = 125 rev/min
Let us call the driving gear as pinion and the driven gear as gear.
1st Meshing
Assumed face width of pinion = 45mm
Assumed face width of gear = 50mm
Torque on the pinion shaft, T = P*60/(2*3.14*2) = 3103.5Nm
Transmitted load, Wt is T/(pitch dia / 2) = 10700 N
Pitch line velocity, V = (2*3.14*2/60)*(.58/2) = 0.06 m/s
Kv = 0.977
J(pinion) = 0.46, J(gear) = 0.41
σbp = 211.33 Mpa, σbg = 213.7 Mpa
Kr is taken as 0.85 (90% reliability)
Designing for 10 years of life, Kl = 1.01
For E=207 Gpa, v=0.28, Cp = 189 (MPa)0.5
ρp = 0.1, ρg = 0.023, I = 0.03.
σc = 894 MPa.
CL = 0.9988, CR = 0.85,
We choose A3 AGMA class steel for the material, which has
Sfb
’ = 325MPa, Sfc
’ = 930MPa
Sfb = 1.01*325/0.85 = 386 MPa, Sfc = 0.9988*930/0.85 = 1092 MPa.
Nb(pinion) = (386/211) = 1.8, Nb(gear) = (386/213) = 1.8
Nc(pinion-gear) = (1092/894)^2 = 1.49
All FOS are greater than 1, the design is safe and we can proceed further.
Let us call the driving gear as pinion and the driven gear as gear.
Rpm of the pinion is 2*(145/35) = 8.3 rev/min.
2nd Meshing
Assumed face width of pinion = 40mm
Assumed face width of gear = 40mm
Torque on the pinion shaft, T = P*60/(2*3.14*8.3) = 747Nm
Transmitted load, Wt is T/(pitch dia / 2) = 6364 N
Pitch line velocity, V = (2*3.14*8.3/60)*(.235/2) = 0.102 m/s
Kv = 0.97
J(pinion) = 0.4, J(gear) = 0.35
σbp = 262 Mpa, σbg = 299 Mpa
Kr is taken as 0.85 (90% reliability)
Designing for 10 years of life, Kl = 0.99
ρp = 0.04, ρg = 0.0096, I = 0.03.
σc = 1134 MPa.
CL = 0.966, CR = 0.85,
We choose A4 AGMA class steel for the material, which has
Sfb
’ = 360MPa, Sfc
’ = 1100MPa
Sfb = 0.99*360/0.85 = 419 MPa, Sfc = 0.966*1100/0.85 = 1242 MPa.
Nb(pinion) = (419/262) = 1.6, Nb(gear) = (419/299.9) = 1.39
Nc(pinion-gear) = (1242/1134)^2 = 1.2
All FOS are greater than 1, the design is safe and we can proceed further.
3. Let us call the driving gear as pinion and the driven gear as gear.
Rpm of the pinion is 2*(145/35)*(94/22) = 35.4 rev/min.
3rd Meshing
Assumed face width of pinion = 24mm
Assumed face width of gear = 24mm
Torque on the pinion shaft, T = P*60/(2*3.14*35.4) = 175.34Nm
Transmitted load, Wt is T/(pitch dia / 2) = 1594 N
Pitch line velocity, V = (2*3.14*35.4/60)*(0.22/2) = 0.4 m/s
Kv = 0.94
J(pinion) = 0.45, J(gear) = 0.39
σbp = 125.61 Mpa, σbg = 144.9 Mpa
Kr is taken as 0.85 (90% reliability)
Designing for 10 years of life, Kl = 0.966
ρp = 0.037, ρg = 0.011, I = 0.036.
σc = 714 MPa.
CL = 0.935, CR = 0.85,
We choose A2 AGMA class steel for the material, which has
Sfb
’ = 280MPa, Sfc
’ = 790MPa
Sfb = 0.966*280/0.85 = 318 MPa, Sfc = 0.935*790/0.85 = 869 MPa.
Nb(pinion) = (318/125) = 2.5, Nb(gear) = (318/144) = 2.2
Nc(pinion-gear) = (869/714)^2 = 1.48
All FOS are greater than 1, the design is safe.
