Automotive Drivetrains Connect/disconnect engines power to the drive wheel(s) allow for different speed ratios provide for reverse power control for safe turning torque multiplication 2 Purpose:

Automotive Drivetrains Transmission Axle assembly Transaxle (fwd) Drive Shaft(s) related components 3 Components:

Automotive Drivetrains The turning effort of the crankshaft measured in pounds per foot maximum torque is produced within a narrow RPM range (torque curve) 4 Engine torque:

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Engine Torque 6

Automotive Drivetrains = work performed at the rate at which it is being done = torque X RPM / Horsepower

Engine Horsepower 8

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Automotive Drivetrains Used to apply torque to other rotating parts of the drivetrain used to multiply torque in automobiles 10 Gears

Automotive Drivetrains Spur gear (most basic) Helical gear (helix = form a curve) Herringbone gear = 1 gear w/2 helical gears w/teeth angles reversed Bevel gear - cone w/top cutoff hypoid gear - similar to above planetary gear(set) 11 Gear Types

Automotive Drivetrains 12 Spur gear

Automotive Drivetrains 13 Helical Gear

Automotive Drivetrains 14 Straight Bevel Gearset Gears must be perpendicular to each other

Automotive Drivetrains 15 Spiral Bevel vs. Hypoid

Worm Gear 16

Automotive Drivetrains 17 Planetary Gear

Automotive Drivetrains Backlash - the clearance between two meshed gears – measured with a dial indicator end play - axial or end-to-end movement of a gear – also measured with a dial indicator 18 Gear Measurements

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Torque Multiplication Torque is calculated by multiplying force X distance OR the center of the shaft times (X) the point where the force is exerted 20

Automotive Drivetrains 21 Gears Continued:

Automotive Drivetrains 22 Gears continued:

Automotive Drivetrains As torque is multiplied power remains unchanged 23

Automotive Drivetrains The mathematical relationship of one gear to another expresses the amount of torque multiplication between two gears ratio = # of teeth of DRIVEN gear / # of teeth of drive gear - OR - ratio = outside diameter of DRIVEN gear/ O.D. of drive gear 24 Gear Ratios:

Gear Ratio 25

Automotive Drivetrains = a reduction in the driven gears speed = an increase in the driven gears torque 26 Gear Reduction

Automotive Drivetrains 27

Automotive Drivetrains If the DRIVING gear in the previous example is producing 250 ft.-lb. of torque how much torque is the DRIVEN gear producing? 28 4 X 250 = 1000 ft.-lb. torque

Automotive Drivetrains Bearings 29 Used to attach a shaft to a common component AND allow for movement or rotation friction reduction

Automotive Drivetrains Bushing (simplest type) also called a plain type bearing ball bearing - balls used for friction reduction roller bearing tapered roller 30 Bearing Types

Bushing (simplest type) also called a plain type bearing 31

Ball Bearing 32

Roller Bearing 33

Needle Roller Bearing 34

Tapered Roller Bearing 35

Automotive Drivetrains radial or journal bearing thrust bearing 36 Bearing Usage

Automotive Drivetrains Bearing preload - the amount of torque- load on a bearing – measured with a torque wrench 37 Bearing Measurements

Automotive Drivetrains CLUTCH 38 The engine produces torque Torque is transferred to the drive wheels through a series of gears and shafts How do we disconnect engine power from the drive wheels?