What is a Bearing?

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Bearings, Gaskets and Seals

• What is a Bearing?
• Component used to reduce friction between
  rotating parts in a machine.
• Types of bearings
• Plain bearing
• Ball bearing
• Angular ball bearing
• Roller bearing

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Bearings, Gaskets and Seals

• Plain bearings are the simplest
• Cylindrical sleeve used to support a rotating
  shaft
• Shaft slides on the surface of the plain bearing
• Film of lubricant forms between shaft and plain
  bearing while shaft rotates

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Bearings, Gaskets and Seals

• 3 types of Plain bearings
• Sleeve Bearing
• Flange Sleeve Bearing
• Thrust Plain Bearing

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Bearings, Gaskets and Seals

• Bearing choice dependent upon the load.
• 2 types of load
• Radial Loads that are perpendicular to the
  shaft
• Axial loads that are parallel to the shaft

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Bearings, Gaskets and Seals

• Bearing Choice
• Sleeve Bearing - Radial Loads
• Thrust Bearing - Axial Loads
• Flange Sleeve Bearing - Combination of both
• Lubrication is key
• Lubricate through a hole on the outside of the
  sleeve bearing
• Permanent lubrication from porous metal
  impregnated with oil.
• Sometimes grooves machined on the sleeves to
  provide lubricant path.

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Bearings, Gaskets and Seals

• Ball Bearings
• Type of Antifriction Bearing
• Friction reduced due to rolling motion rather
  than sliding motion in plain bearings

Balls roll on a raceway (Not shown at left)
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Bearings, Gaskets and Seals

• 5 types of Ball Bearings
• Radial Open
• Open to the environment
• Radial Shielded
• Protected from the environment
• Radial Sealed
• Seal retains lubricant
• Prevents relubrication

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Bearings, Gaskets and Seals

• Angular Ball Bearing
• Same principle as radial
• Shoulders designed for a combined
• radial and axial loads.
• Most common in pumps/compressors
• Thrust Ball Bearing
• 2 flat washers and a cage
• Balls positioned between the washers
• Axial load applications

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Bearings, Gaskets and Seals

• Roller Bearings
• Another type of Antifriction Bearing
• Friction reduced due to rolling motion rather
  than sliding motion in plain bearings
• Use rollers instead of balls
• Rollers have greater contact area than balls
• Higher load capacity than ball bearings of same
  size
• More contact area more friction
• Used for heavy duty moderate speed application
• Car axles common use

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Bearings, Gaskets and Seals

• 3 types of Roller Bearings
• Tapered Roller Bearing
• Inner outer cones (rings), rollers,
• cage
• Rings can separate to assist assembly
• High radial and axial loads
• Radial Needle Bearings
• Support high load in limited space
• No raceway
• Rollers make direct contact with
• the shaft.

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Bearings, Gaskets and Seals

• Thrust Needle Bearing
• Perform same as thrust ball
• bearings.
• Capable of higher loads

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Bearings, Gaskets and Seals

• Gaskets Seals
• Used to prevent leaks and contamination
• 2 categories
• Static seals
• Dynamic seals
• Static Seals
• Gaskets - Used when there is no movement between
  the mating surfaces
• Dynamic Seals
• Mechanical Seals used to seal moving surfaces

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Bearings, Gaskets and Seals

• Gaskets
• Prevent fluid leakage
• Block out dirt and contaminants
• Deform under pressure to seal
• small irregular surfaces
• Material cork, metals, fibers,
• Teflon, rubber.
• Material choice depends on pressure, temperature
  and chemical properties of the medium
• Identified by the thickness of the material in
  fraction of an inch.

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Bearings, Gaskets and Seals

• O-Rings
• Prevent fluid leakage between
• mating parts
• Operation O-Ring deforms when
• it is subject to a squeeze between
• 2 surfaces
• Flattens whens comes in contact with the surfaces
  to be sealed
• Excessive squeeze wears
• O-Ring out too quickly
• Insufficient squeeze leakage
• Buna-N, Teflon, Silicone,
• ethylene propylene,
• polyurethane

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Bearings, Gaskets and Seals

• Mechanical Seals
• Used in pumps to prevent leakage
• Prevents fluid from leaking from
• the fluid side to dry side
• 4 components
• Holder
• Spring
• Seal Head
• Seat
• Dynamic seal
• Seals by the rotation of the seal head
• on the seat
• Flat faces held together by the spring and fluid
  pressure