2 Automotive Drivetrains Connect/disconnect engines power to the drive wheel(s) allow for different speed ratios provide for reverse power control for.

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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

Purpose:

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Automotive Drivetrains

•Transmission•Axle assembly •Transaxle (fwd)•Drive Shaft(s)•related components

Components:

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Automotive Drivetrains

•The turning effort of the crankshaft

•measured in foot-pounds•maximum torque is produced

within a narrow RPM range (torque curve)

Engine torque:

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Engine Torque

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Automotive Drivetrains

= work performed at the rate at which it is being done

= torque X RPM / 5252

Horsepower

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Engine Horsepower

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Automotive Drivetrains

•Used to apply torque to other rotating parts of the drivetrain

•used to multiply torque in automobiles

Gears

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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)

Gear Types

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Automotive DrivetrainsSpur gear

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Automotive DrivetrainsHelical Gear

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Automotive DrivetrainsStraight Bevel Gearset

Gears must be perpendicular to each other

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Automotive DrivetrainsSpiral Bevel vs. Hypoid

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Automotive DrivetrainsPlanetary Gear

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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

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

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Automotive DrivetrainsGears Continued:

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Automotive DrivetrainsGears continued:

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Automotive Drivetrains

As torque is multiplied power remains unchanged

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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

Gear Ratios:

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Automotive Drivetrains

= a reduction in the driven gears speed

= an increase in the driven gears torque

Gear Reduction

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Automotive Drivetrains

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Automotive DrivetrainsIf the DRIVING gear in the previous example is producing 250 ft.-lb. of

torque how much torque is the DRIVEN gear producing?

4 X 250 = 1000 ft.-lb. torque

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Automotive Drivetrains

Bearings•Used to attach a shaft to a

common component AND allow for movement or rotation

•friction reduction

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Automotive Drivetrains

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

• ball bearing - balls used for friction reduction

• roller bearing

• tapered roller

Bearing Types

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Bushing (simplest type) also called a plain type

bearing

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Ball Bearing

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Roller Bearing

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Needle Roller Bearing

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Tapered Roller Bearing

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Automotive Drivetrains

•radial or journal bearing

•thrust bearing

Bearing Usage

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Automotive Drivetrains

•Bearing preload - the amount of torque- load on a bearing–measured with a torque wrench

Bearing Measurements

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Automotive Drivetrains

CLUTCH

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?