Sleeve Bearings

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Summary

Description

Selection characteristics

Advantages/Disadvantages

Applications


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Sleeve Bearings

Plain Bearings

Journal BearingsBushings


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Sleeve Bearing


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Description:

Bearing used to constrain, guide, or

reduce friction in rotary applications.

Work by means of sliding action as

opposed to the rolling action used by

ball, roller and needle bearings.

Proper lubrication is required to reduce

wear and friction.


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Selection Characteristics

Inner Diameter

Outer Diameter

Length

Material

Type of Lubrication Tolerances

PV rating


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Press Fit and Shaft Clearance

Considerations


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Sleeve Bearing Materials

Relative softness (to absorb foreign particles),

reasonable strength, machinability (to maintain

tolerances), lubricity, temperature andcorrosion resistance, and in some cases, porosity

(to absorb lubricant).

A bearing element should be less than one-third as

hardas the material running against it in order to

provide embedability of abrasive particles.


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Materials

Whitemetal - usually used as a lining bonded to

bronze, steel or cast iron.

Copper Based alloys - most common alloys arecopper tin, copper lead, phosphor bronze: harder

and stronger than whitemetal: can be used un-

backed as a solid bearing.

Aluminium based alloys - running properties not

as good as copper based alloys but cheaper.


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Materials (contd)

Ptfe - suitable in very light applications

Sintered bronze - Sintered bronze is a

porous material which can be impregnatedwith oil, graphite or Ptfe. Not suitable forheavily loaded applications but usefulwhere lubrication is inconvenient.

Nylon - similar to Ptfe but slightly harder:used only in very light applications.


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Types of Lubrication

Hydrostatic

Hydrodynamic

Boundary Lubrication

Dry Bearings


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Hydrodynamic Lubrication


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PV Rating

P - Bearing Pressure (psi)

V - velocity in feet per minute of the wear surface

PV is then obtained by multiplying P x V asshown in the following example:

3/4" shaft @ 341 RPM, 90 lb. total load, bearing length 1".

V = .262 x RPM x shaft diameter, or .262 x 341 x .750 = 67 sfpm.

P = total load projected area (area = .750 x 1.0 = .75 in.), or 90 lbs.

.75 = 120 psi.

PV = 120 psi x 67 sfpm = 8040 PV


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Design Considerations

Plain bearings should be kept as short aspossible. (Length/diameter ratio of 0.75 -

1.5) Two well-spaced short bearings are better

than one long one.

Dry bearings of the impregnated sinteredbronze type are available in stock sizes andthese should be used if possible.


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Advantages of Sleeve Bearings

over Roller Bearings

Wont fail from fatigue

Require less space in radial direction

Good damping ability

Lower noise level

Less severe alignment requirements

Lower cost

Lower Friction (hydrodynamic)

(Norton, 654-655)


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Other Advantages

Good capacity to absorb shock loading

Accept oscillating motion

Load is distributed over larger area

Operate efficiently over a wider range of PV

values than any other type (up to 3,000,000+

with the proper lubrication) Load-carrying capability of bronze oil lubricated

sleeve bearings increase with rpm


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Typical Applications

Automotive Industry: transmission shafts, links,pins, crankshafts and camshafts

Marine Industry: thrust bearings of shipdriveshafts

Bike Industry: rear suspension linkages,suspension forks, brake arms, shifters

Ideal for oscillating, intermittent-motion or less-than 360-degree rotation


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Available Sizes


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Interesting Application

Space Shuttle Transport Vehicle:

wheels turn on bronze sleeve bearings

Documents

Sleeve Bearings