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Automotive Belts

Automotive Belts. Chapter 22. Objectives. Explain the differences between V-belts, V-ribbed belts, and timing belts Inspect and evaluate the condition of all types of belts Correctly remove and replace all types of belts. Introduction.

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Automotive Belts

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  1. Automotive Belts Chapter 22

  2. Objectives • Explain the differences between V-belts, V-ribbed belts, and timing belts • Inspect and evaluate the condition of all types of belts • Correctly remove and replace all types of belts

  3. Introduction • Accessories are usually driven with a belt from the crankshaft • Pumps and air-conditioning compressors driven by V-belt or V-ribbed serpentine belt • On some engines, the camshaft is also driven by a timing belt

  4. Belt Material • Belts are strong and flexible with tensile cords • Overcord material on top of belt • Undercord supports the cord and transfers load to pulleys • Tensile cords prevent the belt from sagging in the middle • Some belts are made of neoprene or chloropene • Oil-resistant, artificial rubber

  5. V-Belt • More surface area contact than the same width flat belt • Must be the correct size • V-belt cords • Strength: determined by tensile cord placement • High cordline belts are stronger • Require more material to manufacture • Center cord belts are cheaper • Do not last as long • Some use dual belts to drive accessories

  6. V-Ribbed Belts • Ribbed on one side • Thinness of the belt makes it more flexible • Usually the ribbed side matches the pulley grooves of accessories • Flat side goes against a spring-loaded tensioning roller

  7. Serpentine Belt Drive • Serpentine belt drive systems • Belt follows a snake-like path • One belt operates all accessories • Easier to install than V-belts • Take up less space • Transmit power more efficiently • Last longer

  8. Stretch Belts • Do not require a belt tensioner • Used to drive the air-conditioning compressor from the crankshaft pulley

  9. Timing Belts • On some overhead cam engines, a timing belt drives the camshaft • Quieter than a timing chain • Do not require lubrication • More efficient • Resist stretching • Timing belts • Have very strong fiberglass cordline and rubber-impregnated molded teeth

  10. Drive Belt Service • Considerations • Replace at reasonable intervals • Keep them strong and dependable • Change them before they fail • Failed water pump drive belt can cause engine failure • Failures rise significantly after four years of use

  11. Belt Inspection and Adjustment • Serpentine belt fails • Cooling system, electrical systems, and power steering cease • Inspecting belts • Cracking • Pulley grooves for oil, rust, or wear • Belt alignment • Misalignment: parallel and angular

  12. Replacing Belts • Considerations • Disconnect the battery • Be sure the new belt is the right size • Use string in the pulley groove to estimate the size • Belt sizes change in ½ inch increments • V-ribbed pulley grooves • Count the number of grooves on a pulley being replaced

  13. Belt Tension • Important for long belt life • Belts stretch slightly in the first few minutes of operation • If overtightened, parts can be overloaded • Slipping belt can result in several problems

  14. Belt Tension (cont'd.) • Spring-loaded tensioner inspection • Inspect turning for resistance • Check tensioner arm for looseness • Spring-loaded tensioner internal damper • Acts like a brake on the tensioner arm • Minimizes pulsations on the belt drive system • V-ribbed belt replacement • Make a sketch before removal

  15. Belt Tension (cont'd.) • V-belt tension • Set new V-belt tension to 15 pounds higher than recommended • Recheck and adjust • V-ribbed belt tension • Use a click-type tension gauge

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