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### Step Thrust Plate Bearing Design Equation and Calculator

**Machine Design Applications
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**Bearing Engineering and Design**

**Step Thrust Plate Bearing Design Equation and Calculator**:

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Flat Thrust Plate Bearing Design Formulas and Calculator

Step Thrust Plate Bearing

Preview: **Step Thrust Plate Bearing Design Calculator**

Thrust Bearing Typical Loads |
||

Surface |
LoadsLbs/in ^{2} |
Max LoadsLbs/in ^{2} |

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:

D_{2} = ( ( 4 W ) / ( ( π K_{g} p ) + D_{1}^{2} )^{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) ( D_{2} + D_{1} )

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 a^{2} U^{2} Z ) / h

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

b_{2} = ( 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

b_{2} = 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

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