Belts, Fasteners, & Hoses

1. Belts, Fasteners, & Hoses This unit: Introduction to Automotive Belts, Fasteners, & Hoses. Review pertinent information. Wrap up and quiz!

2. Overview After this presentation you should be able to: List the different types of belts used on automobiles. Understand how these belts transmit power and when they should be replaced. List and discuss the way that screw threads are described. Explain how bolt heads are marked to indicate their strength. Discuss six types of screw and bolt heads and the tools used with them. Describe four ways that nuts and bolts can be prevented from loosening. Discuss snap rings and their uses. Explain the purposes of keys and splines. Describe thread inserts and how they are installed. List the different types of hoses found in automobiles. Understand how these hoses operate and when they should be replaced.

3. Belts: Introduction We have three different types of automotive belts. They are: 1. The V - Belt 2. The Serpentine Belt 3. The Timing Belt

4. Belts: Power Transmission Belts are the cheapest utility for power transmission between shafts that may not be parallel. Power transmission is achieved by specially designed belts and pulleys. The demands on a belt drive transmission system are large and this has led to many variations on the theme. They run smoothly and with little noise, and cushion motor and bearings against load changes, albeit with less strength than gears or chains. However, improvements in belt engineering allow use of belts in systems that only formerly allowed chains or gears.

5. Belts: The V- Belt V belts are an early solution that solved the slippage and alignment problem. It is now the basic belt for power for the transmission. They provide the best array of traction, speed of movement, load of the bearings, and longer service life. The "V" shape of the belt tracks in a mating groove in the pulley (or sheave), with the result that the belt cannot slip off. The belt also tends to wedge into the groove as the load increases — the greater the load, the greater the wedging action — improving torque transmission and making the v-belt an effective solution, needing less width and tension than flat belts.

7. Belts: The Serpentine Belt A serpentine belt is a single, continuous belt used to drive multiple peripheral devices in an automotive engine, such as an alternator, power steering pump, water pump, A/C compressor, air pump, etc. The belt may also be guided by an idle pulley and/or belt tensioner. It is more efficient than the older multiple belt system. Higher tension reduces slip, which increases belt life and mechanical efficiency. Reduced slip can allow the use of lower-ratio pulleys; this reduces the load on the engine, increasing gas mileage and available power. With multiple belt systems, if a single belt breaks, such as the alternator belt, the driver may not realize that there is a problem before the engine becomes damaged. A serpentine belt also is much easier to maintain and replace, since there is no need to remove multiple belts in order to replace one of them.

9. Belts: The Timing Belt A timing belt, timing chain or cam belt is a part of an internal combustion engine that controls the timing of the engine's valves. Some engines use timing gears. The term "timing belt" is also used for the more general case of any flat belt with integral teeth. Such belts are used for power transmission or to interchange rotary motion and linear motion, where either high loads or maintaining a specific drive ratio are important.

11. Belts: When To Replace Most belt are made of rubber reinforced with nylon. Over time, heat, or oil breaks down the rubber leaving cracks in the rubber and glazing. These cracks can lead to belt failure.

12. Belts: When To Replace • Serpentine belts are made of higher quality materials and often don’t show traditional signs of wear • Check these belts with a special wear gauge that fits into the groove (if the top of the gauge is under the top, replace)

15. Fasteners: Introduction Fasteners are the parts that hold the automobile together. Examples are screws, nuts and bolts, studs, rivets, snap rings, and cotter pins. Most types of fasteners can be removed so that the assembly can be taken apart. There are also permanent ways to fasten things together, such as welding (joining similar metals) and soldering (joining two metals by applying a metal filler). For example the car body is made by welding metal parts and panels together.

16. Fasteners External Threads (Male Threads) • Bolts, Studs, Screws Internal Threads (Female Threads) • Nuts, Threaded holes

17. Fasteners Imperial Threaded Fasteners • UNC – Unified National Coarse. • UNF – Unified National Fine.

18. Fasteners Fine Threaded Fasteners • Stronger Thread • Less likely to come loose • Slow to assemble • Easier to ruin the thread (cross thread) Imperial threaded fasteners come in inch increments. ½”, 5/16”, 3/8”, 7/16” …

19. Fasteners 5/16” UNC X 1 ½” Bolt Diameter 1 ½” Long Coarse

20. Fasteners 5/16” - 13 X 1 ½” Bolt Total Length 13 Threads/inch Major Diameter

21. Fasteners Bolt Grading (Strength) Grade 8 Grade 5 Grade 2 Add 2 to the number of lines

22. Fasteners Metric Threaded Fasteners • ISO Metric – International Organization for Standardization • Most new vehicles have metric fasteners • M6, M7, M8, M10, M12, M14 … M8 X 25 X 1 8mm Metric Pitch (threads are 1mm apart) 25mm long

23. Fasteners Metric Imperial • Black/Silver in colour • Gold, red, green, yellow, etc. • Lines on the head • Numbers on the head • UNC, UNF • ISO metric • Standard tools (inch) • Metric tools (mm) • In millimeters • In inches

24. Nuts Hex Nut – Most common on automobiles. Castle Nut – locks with a cotter pin Wing Nut – No tool required Locking Nut – Nylon Patch (center, top) Lug Nut – Taper face to help center the wheel Speed Nut – Push-on (mostly screws)

26. Washers Flat Washer – Distributes pressure over a wider surface area. Lock Washer - Prevents the fastener from loosening. Used at high vibration places. Bites into the material and the fastener.

28. Screws Machine Screws – no nut required ( usually less then ¼” Passes through one piece and threads into other. Sheet Metal Screws(self tapping) – makes its own hole/threads Set Screw – (allen wrench/no head) Used for aligning/securing pullies on the shaft.

29. Fasteners Basic Rules • Use correct length and thread. • Start threads by hand (no tool). • Install all bolts before final tightening any one on a single part. • Tighten all installed fasteners before leaving or leave a note • NOT TIGHT! • Tighten evenly to a correct torque specification • and in proper sequence.

30. Fasteners Tightening Wheels Tightening multiple bolts

31. Fasteners Roll-pins/Spring-pins aligns + locking devices driven into a hole to Lock a pulley or a spline.

33. Automotive Fasteners: Antiseize Compound When a steel bolt is turned into an aluminum part such as a cylinder head or block, the bolt threads should first be coated with an antiseize compound. The prevents corrosion, seizing, galling, and pitting. With out such a compound, the steel bolt tends to lock, or seize, in the aluminum threads. Then, when the bolt is removed, the aluminum threads will be seriously damaged. But if the bolt was coated with antiseize compound, the bolt may be removed without damaging the aluminum threads.

34. Automotive Fasteners: Thread Inserts Damaged or worn threads in a cylinder block, cylinder head or other part can often be repaired with a thread insert. In the installation of one type of thread insert, first the old threads are drilled out. Next the hole is tapped with the special tap that comes with the repair package. Then the thread insert is screwed into the tapped hole to bring the hole back to its original thread size. Now, lets take a look!

36. Automotive Fasteners: Snap Rings There are two types of snap rings – external & internal. External snap rings are used on shafts to prevent gears or collars from sliding on the shaft. Internal snap rings are used in housings to keep shafts or other parts in position. Some snap rings have holes which make it easier to install and remove them. Some snap rings have tangs instead of holes.

39. Automotive Fasteners: Keys and Splines Keys and splines lock gears, pulleys, and hubs to shafts so that they rotate with the shaft. The wedge – shaped key fits into slots (keyways) in the shaft and hub. Splines are external and internal teeth cut in both the shaft and the installed part. This is the same as having a number of keys. The shaft and installed part must turn together. In many machines, the splines fit loosely so that the installed part is free to slide along the shaft but still must turn with the shaft. Splines may be straight or curved.

42. Automotive Fasteners: Rivets Rivets are metal pins used to fasten parts together. One end of the rivet has a head. After a rivet is in place, a driver, or hammer – and – rivet set, is used to form a head on the other end of the rivet.

44. Automotive Fasteners: Blind Rivets/Pop Rivets Blind rivets can be installed in blind holes. These are holes where the end of the rivet cannot be reached to form a head. The image on the next slide shows how to install a blind rivet.

47. Automotive Fasteners: Gaskets A gasket is a thin layer of soft material such as paper, cork, rubber, or synthetic material. It is placed between two flat surfaces to make a tight seal. An example is the gasket between the cylinder head and cylinder block. When the gasket is squeezed by tightening the fasteners, the soft material fills any small irregularities in the mating surfaces. This prevents any leakage of fluid, vacuum, or pressure through the joint. Sometimes the gasket is used as a shim to take up space. Many different types of gaskets are used in the automobile, particularly in the engine. In the engine, they seal joints between the oil pan, manifolds, and water pump and the cylinder head and block.

50. Automotive Fasteners: Formed – In – Place Gaskets These gaskets are formed by a bead of plastic gasket or sealant material. This material can be used instead of preformed gaskets in many places in the automobile. It is used under valve covers, thermostat housings, water pumps, and differential covers. When you use a tube of the gasket material, follow the instructions on the tube.