2 Automotive Drivetrains Connect/disconnect engines power to the drive wheel(s) allow for different...
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Transcript of 2 Automotive Drivetrains Connect/disconnect engines power to the drive wheel(s) allow for different...
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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?