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© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois.

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Presentation on theme: "© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois."— Presentation transcript:

1 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois by Russell Krick

2 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

3 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Cylinder block construction  Piston construction  Piston ring construction  Piston pin construction  Connecting rod construction  Crankshaft construction  Engine bearing construction  Rear main bearing oil seal construction  Select-fit parts  Balancer shafts

4 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Engine Bottom End Includes the block, crankshaft, connecting rods, and piston assemblies

5 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Engine cylinder blocks are normally made of cast iron or aluminum  Cast iron is very heavy and strong  Aluminum is relatively light and dissipates heat well

6 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cylinder Block Cylinders may be integral parts of the block or formed by pressed-in liners

7 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cylinder Sleeves  Metal, pipe-shaped inserts that fit into the cylinder block  act as cylinder walls  Cast iron sleeves are commonly used in aluminum cylinder blocks  Sleeves can also be installed to repair badly damaged cylinder walls in cast iron blocks

8 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cylinder Sleeves  There are two basic types of sleeves:  dry sleeves  wet sleeves

9 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Dry Sleeve  Presses into a cylinder that has been bored oversize  Made from relatively thin material  Not exposed to engine coolant  The outer surface touches the walls of the cylinder block

10 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Wet Sleeve  Exposed to the engine coolant  Thicker construction than a dry sleeve  Designed to withstand combustion pressure and heat without the added support of the cylinder block

11 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Dry sleeveWet sleeve Sleeve Installations

12 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Sleeve Installations Aluminum cylinder block with pressed-in, cast iron wet sleeves

13 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Line Boring  Machining operation that cuts a series of holes through the block for the crankshaft or camshaft bearings  Holes must be in perfect alignment for the crankshaft or camshaft to turn freely

14 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Two- and Four-Bolt Mains  Two-bolt main block  uses two cap screws to secure each main bearing cap to the block  Four-bolt main block  uses four cap screws to hold each main cap  used on high-performance engines  with extra bolts, the block can withstand more crankshaft downward pressure

15 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Crossbolted Block  Has extra cap screws going in through the sides of the block and main caps for added strength  Often used on high-performance engines

16 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Block Girdle  Also called a main bearing bedplate  Large one-piece cap that fits over the entire bottom of the block  All the main caps are formed as one piece to increase strength and block stiffness

17 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Pistons are normally cast or forged from an aluminum alloy  Cast pistons  relatively soft, used in slow-speed, low- performance engines  Forged pistons  used in fuel-injected, turbocharged, and diesel engines

18 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Piston This piston is for a diesel engine and has a groove that allows an oil spray to help cool the piston

19 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Piston Dimensions

20 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cam-Ground Piston  Slightly out-of-round when viewed from the top  Machined a few thousandths of an inch larger in diameter perpendicular to the piston pin centerline  compensates for different rates of expansion due to differences in metal wall thickness

21 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cam-Ground Piston

22 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cam-Grind Theory  As the piston is heated, the thicker area around the pin boss causes the piston to expand more parallel to the piston pin  The piston becomes round when hot  A cam-ground piston maintains the correct piston-to-cylinder clearance when cold and at operating temperature

23 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Piston Taper  Used to maintain the correct piston-to- cylinder clearance  The top of the piston is machined slightly smaller than the bottom  Since the piston head gets hotter than the skirt, it expands more  The piston is almost equal in size at the top and bottom at operating temperature

24 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Piston Taper

25 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Refers to the contour of the piston head  Piston head is shaped to match and work with the shape of the combustion chamber  Piston may have a flat top or a domed head Piston Shape

26 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Piston Shape This is a piston for a diesel engine having a direct injection nozzle

27 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Slipper Skirt  Produced when the portions of the piston skirt below the piston pin ends are removed  Provides clearance between the piston and the crankshaft counterweights  Piston can slide farther down in the cylinder without hitting the crankshaft

28 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Slipper Skirt Piston

29 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Variable Compression Piston  A two-piece design controlled by engine oil pressure  The piston head fits over and slides on the main body of the piston  Engine oil pressure is fed between the two halves to form a hydraulic cushion

30 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Variable Compression Piston  With normal driving, oil pressure extends the top of the piston for maximum compression ratio and power  When engine speed increases, combustion pressure pushes the head down to lower the compression ratio  prevents engine knocking and pinging

31 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Automotive pistons normally use three rings:  two compression rings  one oil ring

32 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Compression Rings  Prevent pressure leakage into the crankcase  Wipe some of the oil from the cylinder walls  Usually made of cast iron  An outer layer of chrome or other metal may be used to increase wear resistance

33 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Compression Rings

34 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Keep crankcase oil out of the combustion chambers  Available in two basic designs:  rail-spacer type (three piece)  one-piece type Oil Rings

35 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Oil Rings A.Rail-spacer ring (most common) B.One-piece ring made from cast iron

36 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Piston Ring Dimensions

37 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Piston Ring Gap  Distance between the ends of the ring when installed in the cylinder  Allows the ring to be installed on the piston and to “spring” outward in its cylinder  Allows the ring to conform to any variation in the cylinder diameter due to wear

38 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Piston Ring Gap Most piston rings use a butt joint

39 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Piston Ring Coatings  Soft ring coatings  porous metal, such as iron  help the ring wear in quickly  the outer surface will wear away rapidly so the ring conforms to the shape of the cylinder  Hard ring coatings  chrome or moly  increase ring life and reduce friction  used in new or freshly machined cylinders

40 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Piston pins are normally made of case- hardened steel, which increases the wear resistance  A hollow piston pin is machined and polished to a very precise finish

41 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Piston Pins  Piston pins are held in the piston by one of two means:  snap rings (full-floating piston pin)  press-fit

42 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Full-Floating Piston Pin Secured by snap rings Free to rotate in both the rod and piston

43 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Press-Fit Piston Pin Forced tightly into the connecting rod’s small end and free to rotate in the piston pin hole

44 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Piston Pin Offset  Locates the piston pin hole slightly to one side of the piston centerline  Helps quiet the piston during use  The piston pin hole is moved toward the piston’s major thrust surface  the thrust surface is the surface of the piston that is pushed tightly against the cylinder wall during the power stroke

45 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Piston Assembly The piston notch indicates the front of the piston

46 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only This piston has a full-floating piston pin Piston Assembly

47 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Most connecting rods are made of steel  Connecting rods normally have an I-beam shape for a high strength-to- weight ratio

48 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Oil spurt holes  provide added lubrication for the piston pin, cylinder walls, and other parts  Drilled rod  allows oil to enter the clearance between the pin and bushing Connecting Rod Features

49 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Connecting Rod Features A. Oil spurt holes B. Drilled rod

50 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Connecting Rod Numbers Ensure that each connecting rod is in the proper location and that the rod cap is installed on the corresponding rod body correctly

51 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Broken-Surface Rod  The rod is scribed and broken off when manufactured  Produces a rough, irregular mating surface between the rod and cap  Done to help lock the rod and cap into alignment

52 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Powdered Metal Forging  Forms the rough shape of the part out of metal powder before final shaping in a powerful forge  Helps control the shape and weight while reducing machining

53 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Machined Block Forging  Involves initial turning in a lathe to bring the blank of metal to size before forming it in a drop forge  Helps eliminate flashing  flashing is a small blip of rough metal produced when the two halves of the forge come together to “smash” the metal into shape

54 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Engine crankshafts are usually made of cast iron or forged steel  Forged steel crankshafts are needed for heavy-duty applications  turbocharged engines  diesel engines

55 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Crankshaft Oil Passages

56 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Crankshaft Oil Flow  Oil enters the crankshaft at the main bearings and passes through holes in the main bearing journals  Oil then flows through passages in the crankshaft and out to the connecting rod bearings

57 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  There are three basic types of engine bearings:  crankshaft main bearings  connecting rod bearings  camshaft bearings

58 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Engine Bearings

59 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Bearing Construction Steel is used for the body. Alloys are plated over the backing to form the bearing surface.

60 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Bearing Crush  Used to help prevent the bearing from spinning inside its bore  The bearing is made slightly larger than the bearing bore  When the rod or main cap is tightened, the bearing ends press against each other, locking the bearing in place

61 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Bearing Crush

62 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Bearing Spread  Used on split-type engine bearings to hold the bearing in place during assembly  The distance across the parting line of the bearing is wider than the bearing bore  bearing spread causes the bearing insert to stick in its bore when pushed into place

63 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Standard Bearing  Has the original dimensions specified for a new, unworn, or unmachined crankshaft  May have the abbreviation “STD” stamped on its back

64 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Undersize Bearing  Used on a crankshaft journal that has been machined to a smaller diameter  Available in undersizes of 0.010", 0.020", 0.030" and sometimes 0.040"  Undersize is normally stamped on the back of the bearing

65 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Undersize Bearing This bearing is for a journal that has been machined " undersize

66 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Bearing Positioning B. LugC. Dowel A. Spread

67 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Bearing Oil Holes and Grooves  Holes allow oil to flow through the block and into the clearance between the bearing and the journal  Grooves provide a channel so oil can completely encircle the bearing before flowing over and out of it

68 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Bearing Oil Holes and Grooves

69 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Main Thrust Bearing and Washers  Main thrust bearing  limits crankshaft end play  thrust flanges are formed on the main bearing sides, almost touching the thrust surfaces machined on the crankshaft  Thrust washers  used instead of a thrust bearing to limit crank end play

70 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Main Thrust Bearing and Washers

71 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Thrust Washers Washers slide into place between the crankshaft and block

72 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only The rear main bearing oil seal prevents oil leakage around the back of the crankshaft

73 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Rear Main Bearing Oil Seal  There are several different types of seals  These types include:  two-piece neoprene  one-piece neoprene  wick or rope seal

74 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Has a lip to trap oil and another lip that keeps dust and dirt out of the engine Two-Piece Neoprene Seal

75 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Two-Piece Neoprene Seal The seal fits into a groove cut into the block and rear main cap

76 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only One-Piece Neoprene Seal The seal fits around the rear flange on the crankshaft

77 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Wick Rear Oil Seal  Woven rope filled with graphite  One piece of the rope seal fits into a groove in the block  Another piece fits in a groove in the main cap  Not as common on modern vehicles as one- and two-piece neoprene seals

78 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Parts that are selected and installed in a certain position to improve the fit or clearance between parts  pistons are commonly selected to fit precisely into their cylinders  Because of select-fit parts, it is important that you reinstall parts in their original locations

79 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Used in some engines to cancel the vibrating forces produced by crankshaft, piston, and rod movement  Usually found on 4- and 6-cylinder engines  Usually, a chain is used to turn the shafts at twice crankshaft rpm

80 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Balancer Shafts Shafts are supported on bearings and lubricated by pressurized oil


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