Related Resources: calculators

Step Thrust Plate Bearing Design Equation and Calculator

Machine Design Applications
Bearing Engineering and Design

Step Thrust Plate Bearing Design Equation and Calculator:

Related:

Flat Thrust Plate Bearing Design Formulas and Calculator

Step Thrust Plate Bearing

Preview: Step Thrust Plate Bearing Design Calculator

Thrust Bearing Typical Loads
Surface	Loads Lbs/in2	Max Loads Lbs/in2
Parallel surface	< 75	< 150
Step Surface	200	500
Tapered Land Surface	200	500
Tilting Pad Surface	200	500

Reproduced with permission from Wilcock and Booser, Bearing Design and Applications, McGraw-Hill Book Co., Copyright © 1957.

---

General Design Parameters: Recommended optimum proportions, a = b, b2 = 1.2b1, and e = 0.7h.

---

External diameter formula:

D₂ = ( ( 4 W ) / ( ( π K_g p ) + D₁² )^1/2

Where:

W = applied load, pounds
K_g = fraction of circumference occupied by pads; usually, 0.8
p = bearing unit load, psi

---

Radial pad width, given in inches

a = (1/2) ( D₂ + D₁ )

---

Number of bearing pads, i. Assume that the oil groove width, s = 0.062 inch is minimum

i = B / ( a + s ) = nearest even number

i as the nearest even number to that calculated.

---

Length of bearing pad given in inches

b = B / i - s

---

Pitch line velocity, given in fpm

U = ( B N ) / 12

where, N - rpm

---

Film thickness, given in inches

h = [ ( 2.09 x 10^-9 i a ³ U Z ) / W ]^0.5

---

Depth of step, given in inches

e = 0.7 h

---

Friction power loss, given in HP

P_f = ( 7.35 x 10^-13 i a² U² Z ) / h

---

Pad step length, distance is on the pitch line, from the leading edge of the pad to the step. Given in inches.

b₂ = ( 1.2 b ) / 2.2

---

Hydrodynamic oil flow, given in gpm

Q = 6.65 x 10^-4 i a h U

---

Temperature rise, given in degrees F

Δt = ( 42.4 P_f ) / ( c Q )

Should temperature rise to be excessive, this is an indication that the flow is insufficient

Notation:

a = radial width of pad, inches
b = circumferential length of pad at pitch line, inches
b₂ = pad step length
B = circumference of pitch circle, inches
c = specific heat of oil, Btu/gal/°F
D = diameter, inches
e = depth of step, inch
f = coefficient of friction
g = depth of 45° chamfer, inches
h = film thickness, inch
i = number of pads
J = power loss coefficient
K = film thickness factor
K_g = fraction of circumference occupied by the pads; usually, 0.8
l = length of chamfer, inches
M = horsepower per square inch
N = revolutions per minute
O = operating number
p = bearing unit load, psi
p_s = oil-supply pressure, psi
P_f = friction horsepower
Q = total flow, gpm
Q_c = required flow per chamfer, gpm
Q^o_c = uncorrected required flow per chamfer, gpm
Q_F = film flow, gpm
s = oil-groove width
∆t = temperature rise, °F
U = velocity, feet per minute
V = effective width-to-length ratio for one pad
W = applied load, pounds
Y_g = oil-flow factor
Y_l = leakage factor
Y_S = shape factor
Z = viscosity, centipoises
α = dimensionless film-thickness factor
δ = taper
ξ = kinetic energy correction factor

References:

• Machinery's Handbook, 29th Edition
• Understanding Journal Bearings, Malcolm E. Leader, P.E. Applied Machinery Dynamics Co.
• Theory and Practice of Lubrication for Engineers by Dudley D. Fuller, Wiley and Sons, 1984, ISBN 0- 471-04703-1
• Bearing Design and Application by Donald F. Wilcock and E. Richard Booser, McGraw Hill, 1957, 195, LC number 56-9641