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Automotive Bearings and Sealants

This article discusses the purpose of bearings, different types of automotive bearings, types of lubricants used in light vehicles, and the types, construction, and uses of gaskets and seals in the automotive industry.

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Automotive Bearings and Sealants

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  1. Automotive Bearings and Sealants

  2. Objectives • Explain purpose of bearings • Identify different types, construction, and uses of automotive bearings • List types of lubricant used in a light vehicle • Explain different types, construction, and uses of gaskets

  3. Objectives • Explain types and uses of chemical automotive sealants • Explain different types, construction, and uses of seals

  4. Objectives • Explain the purpose of the various gaskets used to seal an engine. • Identify the major gasket types and their uses. • Explain general gasket installation procedures. • Describe the methods used to seal the timing cover and rear main bearing.

  5. Bearings and Bushings • Bearings are used when two components move against or with each other • Bearing Loads • Usually computed by weight and movement of load

  6. Bearings and Bushings • Bearing Loads • Weight determines size, placement, and type of bearing to be used • Thrust load looks at direction and amount of force against the weight

  7. Bearings and Bushings • Bearing Journals and Races • Machined areas on a shaft • Provide a smooth finish to protect bearing • Usually hardened to withstand loads

  8. Bearings and Bushings • Races • Serve same purpose as the journal • Normally included with replacement bearing • Assembled as part of bearing or can be loose

  9. Bearings and Bushings • Bearing Inserts • Also known as “plain bearings” • Used in engine as rod or main bearings • Fitted into a mounting component • Two pieces are needed to make one complete bearing

  10. Bearings and Bushings • Roller Bearings • Support radial loads and small amount of thrust • Typical roller bearing is fairly small and has several rollers trapped in a cage

  11. Bearings and Bushings • Roller Bearings • Cage holds bearings in a circle and maintains equal spacing • Straight or tapered • Needle bearings are also roller bearings • May or may not be held in a cage

  12. Bearings and Bushings • Ball Bearings • Similar to a roller bearing • Highly machined steel balls versus rollers • Support axial and radial loads well • Sometimes two rows of balls are present to improve load support

  13. Bearings and Bushings • Bushings • Thin steel tubing cut to specific lengths • Coated with copper • Does not support axial loads • Limits radial movement of a shaft • Cannot be used in high-thrust or high-radial load areas

  14. Inspecting and Repacking a Wheel Bearing • Bearing failure is indicated by a noise from bearing area • Bearing failure causes two types of damage • Spalling • Brinelling

  15. Inspecting and Repacking a Wheel Bearing • Dry bearings can weld themselves to the race or the component

  16. Inspecting and Repacking a Wheel Bearing • Remove suspected bearing and clean it thoroughly • Dry bearing with compressed air • Do not allow rollers or cage to spin

  17. Inspecting and Repacking a Wheel Bearing • Inspect each ball or roller for damage • Inspect case and race for damage • Any sign of damage warrants replacing bearing

  18. Inspecting and Repacking a Wheel Bearing • Repacking the Bearing • Each roller or ball must be greased before installation • Several types of repacking tools are available including compressed-air-powered

  19. Inspecting and Repacking a Wheel Bearing • Repacking the Bearing • Bearing must be clean and dry before repacking • Ensure grease extends up through bearing when complete

  20. Lubricants • Grease is used on roller and ball bearing components • Grease must be matched to component and its usage • Grease can be multipurpose • Always consult service manual

  21. Bearing Construction (Friction reducers) • Friction Bearing- Two smooth surfaces sliding against each other • Antifriction bearing- utilizes balls or rollers between moving parts

  22. Antifriction bearings

  23. Bearing Clearances • Bearings must be tight enough to resist pounding but lose enough for oil to enter • .002” • .05mm

  24. Oil Seals • Oil is retained in the engine from • Gaskets- cork or rubber • Sealants-RTV-Room temperature vulcanizing • Oil seals

  25. Gasket Classifications • Hard gaskets • Made of steel, copper, or a composite of metal and fiber • Soft gaskets • Made of cork, rubber, or paper • Silicone gasket material • Three different types • Sealants • Usually in liquid form

  26. Gaskets

  27. Common Engine Gaskets • Head gaskets • Have the most demanding job. • Manifold gaskets • Are intake, exhaust, or combination. • Valve cover gaskets • Must seal between different metals or materials. • Oil pan gaskets • Seal between the block and pan.

  28. Engine Gaskets and Seals

  29. Gaskets • Retain lubricants or to seal a chamber • Head Gasket • Seals extremely high pressure of the combustion chamber • Most head gaskets are a composite material • Verify correct part for application

  30. Gaskets • Intake and Exhaust • Must be designed to work in extreme heat • Must be able to work between two different metals

  31. Gaskets • Other Gaskets • Made from cork, synthetic rubber, neoprene, paper, and chemical-based • Use the right gasket for the job at hand

  32. Types of Sealants • Aerobic sealants • Cure only when exposed to oxygen (air). • Are commonly used to form gaskets. • Anaerobic sealants • Cure only in the absence of oxygen (air). • Are used for thread sealant.

  33. Chemical Sealants • Chemical sealers • Gasket sealer • Room temperature vulcanizing (RTV) sealer • RTV cannot be used in high heat and high pressure applications

  34. Chemical Sealants • Cannot be used on fuel system components • RTV color denotes application and temperature ranges

  35. Seals • Used between moving components and their housings to retain liquids • Withstand high pressure and high temperatures • Lip seals are most common type • Some have garter spring to hold seal tight to surface

  36. Seals • O-rings • Rubber ring fits into a groove on moving or stationary component • Extends beyond groove and pressed against second component

  37. Seals • Boots • Used primarily to protect rather than seal • Most common is CV joint boot

  38. Oil Seal Designs • Fiber-packing type • Two-piece lip type • One-piece radial type

  39. Oil Seal Designs (Cont’d)

  40. Sealants

  41. Oil Seals

  42. Summary • Sealants include gaskets, chemicals, or seals • Bearings must support axial and radial loads • Gaskets used between stationary parts • Seals used between moving parts • O-rings are special purpose seals

  43. Summary • Gaskets serve as sealers, spacers, wear indicators, and vibration dampers. • General recommendations for installing gaskets include the following: • Never reuse old ones. • Clean all mating surfaces. • Use sealants properly.

  44. Summary (Cont’d) • Head gaskets on today’s bi-metal engines have a demanding job. • General-purpose sealers aid in gasket sealing without upsetting the performance of the gasket. • Oil seals keep oil and other fluids from escaping around a rotating shaft.

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