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Tilting Pad Thrust Plate Bearing Design Equation and Calculator
Machine Design Applications
Bearing Engineering and Design
Tilting Pad Thrust Plate Bearing Design Equation and Calculator:
Each bearing section is wedge shaped, as shown at the right below, for the purposes of design calculation, it is considered to be a rectangle with a length b equal to the circumferential length along the pitch line of the section being considered and a width a equal to the difference in the external and internal radii,
Related:
 Flat Thrust Plate Bearing Design Formulas and Calculator
 Tapered Land Thrust Plate Bearing Design Formulas and Calculator
Tilting Pad Thrust Plate Bearing
Preview: Tapered Land Thrust Plate Bearing Design Calculator
Thrust Bearing Typical Loads


Surface

Loads
Lbs/in^{2} 
Max Loads
Lbs/in^{2} 
Parallel surface

< 75

< 150

Step Surface

200

500

Tapered Land Surface 
200 
500 
Tilting Pad Surface

200

500

Table p
Reproduced with permission from Wilcock and Booser, Bearing Design and Applications, McGrawHill Book Co., Copyright © 1957.
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 = unit load, see Table p
Radial pad width , given in inches
a = (1/2) ( D_{2}  D_{1} )
Pitch line circumference , given in inches
B = π (D_{1} + D_{2} ) / 2
Number of bearing pads, estimated
i = ( B K_{g} ) / a = nearest even number
i as the nearest even number to that calculated.
Length of bearing pad given in inches
b = ( B K_{g} ) / i
Operating number
O = ( 1.45 x 10^{7} Z_{2} U ) / ( 5 p b z)
Where, Z_{2} = viscosity of oil at outlet temperature (inlet temperature assumed temperatur rise through the bearing).
Reproduced with permission from Wilcock and Booser, Bearing Design and Applications, McGrawHill Book Co., Copyright © 1957.
Minimum film thickness given in mils inches  h_{min} = α b
α = dimensionless film thickness is found from Film Thickness Factor Chart
In general, this value should be 0.001 inch for small bearings and 0.002 inch for larger and highspeed bearings.
Coefficient of friction, f found from Coefficient of Friction Chart
Friction power loss (HP), derived from table using film thickness h
P_{f} = ( f W U ) / 33,000
Actual oil flow, given in gpm
Q = 0.0591 α i a b U
Δt = ( 0.0217 f p ) / ( α c )
Where:
c = specific heat of oil in Btu/gal/°F
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} = oilsupply 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 = oilgroove width
∆t = temperature rise, °F
U = velocity, feet per minute
V = effective widthtolength ratio for one pad
W = applied load, pounds
Y_{g} = oilflow factor
Y_{l} = leakage factor
Y_{S} = shape factor
Z = viscosity, centipoises
α = dimensionless filmthickness 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 471047031
 Bearing Design and Application by Donald F. Wilcock and E. Richard Booser, McGraw Hill, 1957, 195, LC number 569641
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