Land Transportation cont.

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Land Transportationcont.
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Transmitting Power

• Drive System A system used to transfer the
  motion of the engines crankshaft into the power
  that moves the vehicle. Sometimes called power
  train.
• First Job is to multiply the amount of torque the
  engine produces.

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Transmission Systems

• The device that provides the multiplying,
  dividing, or reversing of mechanical power and
  torque coming from the engine.
• Use two kinds of gears
• Spur Gears
• Helical Gears

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Manual Transmission

• Totally controlled by the operator
• In a typical 5 speed transmission gears can be
  aligned in 6 ways (5 forward, 1 reverse), each
  with a different gear ratio
• A gear ratio changes the amount of torque. First
  gear typically 31, which means for every 3 times
  the input shaft spins the output shaft spins
  once. Fourth gear is typically 11, which means
  both input and output are spinning at the same
  speed.

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Manual Transmission

• A clutch is used to disconnect the engine from
  the transmission
• Allows operator to start the vehicle smoothly,
  shift gears, and disengage the engine from the
  drive train, allowing the motor to continue to run

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Automatic Transmission

• Not dependant on the operator
• Uses a torque converter instead of a clutch
• It is a type of fluid coupler, uses fluid to
  transmit power
• Automatic transmissions can produce unlimited
  numbers of gear ratios due to the use of
  planetary gears.

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Driveshaft and Axles

• Transmission connected to either a transaxle or
  driveshaft.
• Power is then sent from the transaxle or
  driveshaft to the differential
• Differential - Takes rotational power from one
  source and transfers it to two axles. Also allows
  wheels to spin at different speeds to make
  turning easier

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Control System

• Braking Systems
• Hydraulic Breaking System - A braking system that
  links a master cylinder to a brake pedal and to
  one or two brake cylinders at each wheel.
• When operator depresses the brake pedal, the
  master cylinder sends pressure via hydraulic
  fluid to each brake cylinder.

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Kinds of Braking systems

• Drum Brakes - Two brake shoes are shaped to fit
  the inside of the brake drum and expand to create
  friction when the brake pedal is pressed.

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• Disc Brakes - A steel disc called a rotor is
  mounted to the wheel assembly so it spins freely.
  The brake caliper straddles the disc and squeezes
  against both sides when the brake pedal is
  depressed.

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Power Brakes

• Brake system adds a vacuum control valve between
  the brake pedal and master cylinder.
• The vacuum helps exert force on the master
  cylinder and allows the driver to use less foot
  pressure.

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Antilock Braking System

• Computer Controlled Braking system. Uses sensors
  at each wheel to monitor the speed the wheels are
  turning.
• System used only when tires are spinning at
  different speeds. (Loss of traction during
  braking)
• Controller sends pulses to the other wheel to
  help maintain the same speed, and help maintain
  control of the vehicle.

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Pneumatic Brakes(Air Brakes)

• Uses compressed air to activate the master
  cylinder.
• The system can be computer controlled to provide
  a specific amount of pressure for each situation.
  
• Tractor trailers and trains use air brakes
  because they can be adjusted to the account for
  the weight of the cargo there carrying.