KEVOS® MAKEOS · Power Transmission

Tapered Land Thrust Bearing Design (Pad Layout, Film Factor, Friction, Oil Flow Required and Passed)

For a tapered land thrust bearing carrying a heavy axial load, what pad layout and unit load result, what film-thickness factor do I take to the handbook chart, how much friction power does it lose, how much oil does it need for my temperature rise and does its film pass that much?

Tapered land thrust bearing design by the handbook procedure: outside diameter D2 = √(4W ÷ (π Kg p) + D1²), radial pad width a = (D2 − D1) ÷ 2, pitch-line circumference B = π(D1 + D2) ÷ 2, approximate pads B ÷ (a + s), pad length b = (B − i s) ÷ i, unit load p = W ÷ (i a b), pitch-line velocity U = B N ÷ 12, leakage factor YL = b ÷ (1 + π² b² ÷ 12 a²), film-thickness factor K = 5.75 × 10⁶ p ÷ (U YL Z) for reading the film thickness from the chart, friction power Pf = 8.79 × 10⁻¹³ i a b J U² Z with J from the chart, oil flow required Q = 42.4 Pf ÷ (c Δt), shape factor YS = 8 a b ÷ (D2² − D1²) and film flow QF = 8.9 × 10⁻⁴ i δ2 D2³ N YG YS² ÷ (D2 − D1) with the oil-flow factor YG from the chart.

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How this tool works

Inputs, units and where to find them

InputUnitTypical source
Axial loadNAxial (thrust) load on the bearing.
Inside diameter D1mmInside diameter of the thrust face, set by the shaft and its clearance.
Outside diameter chosen D2mmOutside diameter you choose, near the diameter required.
Design unit load pkPaUnit load used to find the outside diameter; the handbook gives 200 psi (1379 kPa) normal and 500 psi (3447 kPa) maximum for tapered land bearings.
Fraction of circumference occupied by pads KgFraction of the circumference occupied by pads; 0.8 or 0.9.
Oil groove width smmWidth of each oil groove between pads.
Number of pads chosenpadsNumber of pads, the even number nearest the approximate number shown.
Speed NrpmShaft speed.
Taper at the outside diameter δ2 (Table 2)mmTaper depth at the outside diameter from the handbook’s Table 2 for the pad size.
Oil
Oil viscosity at outlet temperaturecPOil viscosity in centipoises at the outlet temperature (inlet plus the allowed rise).
Oil densitykg/m³Density of the oil.
Oil specific heatkJ/(kg·K)Specific heat of the oil.
Oil temperature rise allowed°COil temperature rise you allow; the handbook gives 50 °F (27.8 °C) as an acceptable maximum.
Read from the handbook charts
Minimum film thickness h (Fig. 9, from K and the tapers)mmMinimum film thickness read from the handbook’s Fig. 9 using the factor K shown and the tapers; about 0.001 in for small and 0.002 in for large or fast bearings.
Power-loss coefficient J (Fig. 10, from h)Power-loss coefficient read from the handbook’s Fig. 10 at the film thickness.
Oil-flow factor YG (Fig. 11, from YS and D1/D2)Oil-flow factor read from the handbook’s Fig. 11 using the shape factor YS and D1/D2 shown.
Least film thickness you acceptmmLeast minimum film thickness you accept; the handbook suggests about 0.001 in (0.025 mm) for small bearings and 0.002 in (0.051 mm) for larger and high-speed bearings.

What each input means

Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.

What this means: Axial load
Illustration: Axial loadA block with an arrow pushing on it; the arrow is the force Axial load.WExample: 311376 NAxial load
What it is
Axial (thrust) load carried by the thrust bearing.
Units and format
Enter a number in N: newtons. The form accepts 0.000001 N to 100000000 N. Required: the tool does not calculate until every input is valid.
Example
The form opens with 311376 N as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
Raises the unit load and the diameter required.
Get it right
Include hydraulic, gear and impeller thrust at the worst running condition.
What this means: Inside diameter D1
Illustration: Inside diameter D1A circle with a line straight through its centre from edge to edge, marking the diameter Inside diameter D1.D_1measured acrossthe centreExample: 177.8 mmInside diameter D1
What it is
Inside diameter of the thrust face.
Units and format
Enter a number in mm: millimetres. The form accepts 0.000001 mm to 5000 mm. Required: the tool does not calculate until every input is valid.
Example
The form opens with 177.8 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
A larger bore needs a larger outside diameter for the same area.
Get it right
Set by the shaft diameter plus running clearance.
What this means: Outside diameter chosen D2
Illustration: Outside diameter chosen D2A circle with a line straight through its centre from edge to edge, marking the diameter Outside diameter chosen D2.D_2measured acrossthe centreExample: 431.8 mmOutside diameter chosen D2
What it is
Outside diameter of the thrust face or pads.
Units and format
Enter a number in mm: millimetres. The form accepts 0.000001 mm to 5000 mm. Required: the tool does not calculate until every input is valid.
Example
The form opens with 431.8 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
Sets the pad width and pitch circumference.
Get it right
Round the diameter required to a convenient size, or use the largest that fits.
What this means: Design unit load p
Illustration: Design unit load pA pressure gauge whose needle moves with Design unit load p; the needle follows the value you type.pExample: 2757.9 kPaDesign unit load p
What it is
Unit load used to find the outside diameter of the tapered land bearing.
Units and format
Enter a number in kPa: kilopascals. The form accepts 0.000001 kPa to 20000 kPa. Required: the tool does not calculate until every input is valid.
Example
The form opens with 2757.9 kPa as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
A lower design load needs a larger outside diameter.
Get it right
About 1379 kPa (200 psi) normal and 3447 kPa (500 psi) maximum.
What this means: Fraction of circumference occupied by pads Kg
Illustration: Fraction of circumference occupied by pads KgTwo wheels of different sizes linked together; Fraction of circumference occupied by pads Kg compares one with the other.K_gExample: 0.9Fraction of circumference occupied by pads Kg
What it is
Fraction of the pitch circumference occupied by pads rather than grooves.
Units and format
Enter a plain number with no unit. The form accepts 0.000001 to 1. Required: the tool does not calculate until every input is valid.
Example
The form opens with 0.9 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
A smaller fraction needs a larger outside diameter.
Get it right
Usually 0.8; 0.8 or 0.9 for tapered land bearings.
What this means: Oil groove width s
Illustration: Oil groove width sA bar with a dimension line and arrows from one end to the other, marking the length Oil groove width s.sExample: 12.7 mmOil groove width s
What it is
Width of each oil groove between the pads.
Units and format
Enter a number in mm: millimetres. The form accepts 0.000001 mm to 200 mm. Required: the tool does not calculate until every input is valid.
Example
The form opens with 12.7 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
Wider grooves shorten the pads.
Get it right
The handbook example uses 0.5 in (12.7 mm) on a large bearing.
What this means: Number of pads chosen
Illustration: Number of pads chosenA row of identical items being counted; Number of pads chosen is how many there are.iExample: 6 padsNumber of pads chosen
What it is
Number of pads around the thrust face.
Units and format
Enter a number in pads: pads. The form accepts 2 pads to 100 pads. Use a whole number. Required: the tool does not calculate until every input is valid.
Example
The form opens with 6 pads as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
Sets the pad length and the unit load.
Get it right
Take the even number nearest the estimate shown.
What this means: Speed N
Illustration: Speed NA turning disc with a marker; Speed N is how many full turns it makes in each minute.turns of the shaftper minuteNExample: 3600 rpmSpeed N
What it is
Rotational speed of the shaft.
Units and format
Enter a number in rpm: revolutions per minute. The form accepts 0.000001 rpm to 100000 rpm. Required: the tool does not calculate until every input is valid.
Example
The form opens with 3600 rpm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
Sets the pitch-line velocity, friction and film.
Get it right
Use the running speed at full thrust load.
What this means: Taper at the outside diameter δ2 (Table 2)
Illustration: Taper at the outside diameter δ2 (Table 2)A surface with a step cut into it and a dimension from the original surface down to the bottom of the step, marking Taper at the outside diameter δ2 (Table 2).δ_2original surfaceExample: 0.127 mmTaper at the outside diameter δ2 (Table 2)
What it is
Depth of the taper at the outside diameter of the pad, from the handbook table.
Units and format
Enter a number in mm: millimetres. The form accepts 0.000001 mm to 5 mm. Required: the tool does not calculate until every input is valid.
Example
The form opens with 0.127 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
The film flow rises in proportion.
Get it right
Interpolate in Table 2 for the pad size a × b.

Oil

What this means: Oil viscosity at outlet temperature
Illustration: Oil viscosity at outlet temperatureFluid layers between a fixed and a moving plate, sliding past each other; Oil viscosity at outlet temperature is the fluid’s resistance to that flow.ZExample: 18 cPOil viscosity at outlet temperature
What it is
Viscosity of the oil in centipoises at the outlet temperature.
Units and format
Enter a number in cP: cP. The form accepts 0.000001 cP to 10000 cP. Required: the tool does not calculate until every input is valid.
Example
The form opens with 18 cP as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
Higher viscosity lowers the factor K and raises friction.
Get it right
Inlet temperature plus the allowed rise, from the oil’s viscosity chart.
What this means: Oil density
Illustration: Oil densityA cube of material: density Oil density is its mass divided by the volume it fills.massvolumeρExample: 880 kg/m³Oil density
What it is
Density of the lubricating oil.
Units and format
Enter a number in kg/m³: kilograms per cubic metre. The form accepts 0.000001 kg/m³ to 2000 kg/m³. Required: the tool does not calculate until every input is valid.
Example
The form opens with 880 kg/m³ as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
With the specific heat, sets the heat the oil carries per litre.
Get it right
About 850 to 900 kg/m³ for mineral oils.
What this means: Oil specific heat
Illustration: Oil specific heatHeat flowing from a hot side to a cold side through a wall or into a material; Oil specific heat sets how much heat moves or is stored.hotcoldc_pExample: 1.9953 kJ/(kg·K)Oil specific heat
What it is
Specific heat of the lubricating oil.
Units and format
Enter a number in kJ/(kg·K): kilojoules per kilogram per kelvin. The form accepts 0.000001 kJ/(kg·K) to 10 kJ/(kg·K). Required: the tool does not calculate until every input is valid.
Example
The form opens with 1.9953 kJ/(kg·K) as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
A higher specific heat lowers the temperature rise or the flow needed.
Get it right
About 1.9 to 2.0 kJ/(kg·K) for mineral oils.
What this means: Oil temperature rise allowed
Illustration: Oil temperature rise allowedA thermometer whose level rises with Oil temperature rise allowed; the level follows the value you type.ΔtExample: 27.778 °COil temperature rise allowed
What it is
Temperature rise of the oil through the bearing you allow.
Units and format
Enter a number in °C: degrees Celsius. The form accepts 0.000001 °C to 100 °C. Required: the tool does not calculate until every input is valid.
Example
The form opens with 27.778 °C as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
A smaller rise needs more oil flow.
Get it right
The handbook gives 27.8 °C (50 °F) as an acceptable maximum.

Read from the handbook charts

What this means: Minimum film thickness h (Fig. 9, from K and th…
Illustration: Minimum film thickness h (Fig. 9, from K and the tapers)The cross-section of a plate or wall with a dimension across its thickness, marking Minimum film thickness h (Fig. 9, from K and the tapers).hsection through the materialExample: 0.05588 mmMinimum film thickness h (Fig. 9, from K and…
What it is
Minimum film thickness read from the handbook chart at the factor K and the tapers.
Units and format
Enter a number in mm: millimetres. The form accepts 0.000001 mm to 5 mm. Required: the tool does not calculate until every input is valid.
Example
The form opens with 0.05588 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
Used for the power-loss coefficient and the film check.
Get it right
K is shown in the results; enter the chart with it and your taper values.
What this means: Power-loss coefficient J (Fig. 10, from h)
Illustration: Power-loss coefficient J (Fig. 10, from h)Two bars: a base value and the same value multiplied by Power-loss coefficient J (Fig. 10, from h), the factor.base valuewith factorJExample: 260Power-loss coefficient J (Fig. 10, from h)
What it is
Power-loss coefficient read from the handbook chart at the film thickness.
Units and format
Enter a plain number with no unit. The form accepts 0.000001 to 10000. Required: the tool does not calculate until every input is valid.
Example
The form opens with 260 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
Friction power rises in proportion.
Get it right
Enter Fig. 10 with the film thickness h.
What this means: Oil-flow factor YG (Fig. 11, from YS and D1/D2)
Illustration: Oil-flow factor YG (Fig. 11, from YS and D1/D2)Two bars: a base value and the same value multiplied by Oil-flow factor YG (Fig. 11, from YS and D1/D2), the factor.base valuewith factorY_GExample: 0.61Oil-flow factor YG (Fig. 11, from YS and D1/D…
What it is
Oil-flow factor read from the handbook chart at the shape factor and diameter ratio.
Units and format
Enter a plain number with no unit. The form accepts 0.000001 to 5. Required: the tool does not calculate until every input is valid.
Example
The form opens with 0.61 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
The film flow rises in proportion.
Get it right
YS and D1/D2 are shown in the results.
What this means: Least film thickness you accept
Illustration: Least film thickness you acceptThe cross-section of a plate or wall with a dimension across its thickness, marking Least film thickness you accept.h_accsection through the materialExample: 0.0254 mmLeast film thickness you accept
What it is
Least minimum film thickness you accept for this bearing.
Units and format
Enter a number in mm: millimetres. The form accepts 0.000001 mm to 5 mm. Required: the tool does not calculate until every input is valid.
Example
The form opens with 0.0254 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
Effect on the result
Flags the design when the film read is thinner.
Get it right
About 0.025 mm (0.001 in) for small and 0.051 mm (0.002 in) for large or high-speed bearings.

Method and formulas

  1. D2 = √(4W ÷ (π Kg p) + D1²); a = (D2 − D1) ÷ 2; B = π(D1 + D2) ÷ 2; approximate pads B ÷ (a + s); b = (B − i s) ÷ i; p = W ÷ (i a b); U = B N ÷ 12.
  2. YL = b ÷ (1 + π² b² ÷ 12 a²); K = 5.75 × 10⁶ p ÷ (U YL Z).
  3. Pf = 8.79 × 10⁻¹³ i a b J U² Z hp; Q = 42.4 Pf ÷ (c Δt) gpm.
  4. YS = 8 a b ÷ (D2² − D1²); QF = 8.9 × 10⁻⁴ i δ2 D2³ N YG YS² ÷ (D2 − D1) gpm; chamfers or more taper are needed when QF is less than Q.
  5. Inputs are converted to inches, pounds and °F for the handbook constants; results are shown in SI with the inch values.
  6. Example: 6 pads 127 × 146.89 mm carry 2,781.8 kPa; the bearing loses 68.076 kW and needs 83.729 L/min against 101.31 L/min passed by the film.

Limitations

  • Film thickness h, the power-loss coefficient J and the oil-flow factor YG come from the handbook’s charts; read them at the K, h, YS and D1/D2 shown.
  • The tapers come from the handbook’s Table 2 for the pad size; the taper usually covers 80 % of the pad length.
  • Tapered land bearings need good alignment as their size increases.
  • Example values are illustrations. Replace them with values for your actual task.

Typical uses

  • Design a tapered land thrust bearing for a turbine, compressor or pump
  • Check whether the film passes enough oil or chamfers are needed
  • Estimate friction loss and oil flow for the lubrication system

Who it is for

  • Machine designers
  • Pump, compressor and turbine engineers
  • Students

What you get

  • Outside diameter required
  • Pad width, pitch circumference, approximate pads and pad length
  • Unit load and pitch-line velocity
  • Leakage factor YL and film-thickness factor K
  • Friction power and oil flow required
  • Shape factor YS and the film flow passed

Interpreting the result

  • If the film passes less oil than the heat needs, increase the taper or add feed chamfers.
  • A higher viscosity or speed raises the film thickness but also the friction loss.

References

  • Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2339, 2347–2352. Topic reference; no source tables or recommended settings are reproduced.

Learn the Concepts Behind This Tool

These KEVOS® Library readings explain the method this tool uses, with worked examples.

  • Useful alongside · KEVOS® original book

    Thrust bearings

    In Plain Bearings by the Numbers

    What it covers: Check a thrust face's area, unit load, sliding speed and PV, estimate its friction heat and oil flow with the KEVOS® thrust tools, and see why tapered lands and tilting pads carry load.

KEVOS® tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.

Open the Tapered Land Thrust Bearing Design (Pad Layout, Film Factor, Friction, Oil Flow Required and Passed) calculator

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