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Summary. Description Selection characteristics Advantages/Disadvantages Applications. Sleeve Bearings. Plain Bearings Journal Bearings Bushings. Sleeve Bearing. Description:. Bearing used to constrain, guide, or reduce friction in rotary applications.

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Summary

Summary

  • Description

  • Selection characteristics

  • Advantages/Disadvantages

  • Applications


Sleeve bearings

Sleeve Bearings

Plain Bearings

Journal Bearings

Bushings


Sleeve bearing

Sleeve Bearing


Description

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.


Selection characteristics

Inner Diameter

Outer Diameter

Length

Material

Type of Lubrication

Tolerances

PV rating

Selection Characteristics


Press fit and shaft clearance considerations

Press Fit and Shaft Clearance Considerations


Sleeve bearing materials

Sleeve Bearing Materials

Relative softness (to absorb foreign particles), reasonable strength, machinability (to maintain tolerances), lubricity, temperature and corrosion resistance, and in some cases, porosity (to absorb lubricant).

A bearing element should be less than one-third as hard as the material running against it in order to provide embedability of abrasive particles.


Materials

Whitemetal - usually used as a lining bonded to bronze, steel or cast iron.

Copper Based alloys - most common alloys are copper 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.

Materials


Materials cont d

Materials (cont’d)

  • Ptfe - suitable in very light applications

  • Sintered bronze - Sintered bronze is a porous material which can be impregnated with oil, graphite or Ptfe. Not suitable for heavily loaded applications but useful where lubrication is inconvenient.

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


Types of lubrication

Types of Lubrication

  • Hydrostatic

  • Hydrodynamic

  • Boundary Lubrication

  • Dry Bearings


Hydrodynamic lubrication

Hydrodynamic Lubrication


Pv rating

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 as shown 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


Design considerations

Design Considerations

  • Plain bearings should be kept as short as possible. (Length/diameter ratio of 0.75 - 1.5)

  • Two well-spaced short bearings are better than one long one.

  • Dry bearings of the impregnated sintered bronze type are available in stock sizes and these should be used if possible.


Advantages of sleeve bearings over roller bearings

Advantages of Sleeve Bearings over Roller Bearings

  • Won’t 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)


Other advantages

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


Typical applications

Typical Applications

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

  • Marine Industry: thrust bearings of ship driveshafts

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

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


Available sizes

Available Sizes


Interesting application

Interesting Application

Space Shuttle Transport Vehicle:

  • wheels turn on bronze sleeve bearings


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