Cams, Eccentrics, and Rachets

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Forging new generations of engineers
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CAMS, Eccentrics, and Ratchets
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CAMS ARE MECHANICAL DEVICES THAT CHANGE ROTARY
MOTION TO LINEAR MOTION

• CAM ROTARY MOTION

LEVER LINEAR MOTION
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CAM Followers and Linkages Transfer the Linear
Motion of the CAM Lobe to the place where it is
used
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CAM Lobe Parts
Toe
Flank
Ramp
Base Circle
Heel
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CAM Lobe Lift
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CAM Displacement Graph

• AS ECCENTRIC CAM ROTATES ONE REVOLUTION OR 360
  DEGREES THE MOVEMENT OF THE FOLLOWER IS SHOWN BY
  THE LINE ON THE GRAPH. AT 180 DEGREES THE
  FOLLOWER IS AT ITS MAXIMUN HEIGHT.

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Basic CAM Shapes
Circle
Heart
Acceleration
Pear
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Flat Plate CAM With Roller Follower
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Groove Box and Grooved Flat Plate Cam
Groove Box CAM
Grooved Flat Plate CAM
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CYNDRICAL CAM and FACE CAM

• Both provide a rocking motion

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Peripheral CAMS

• Peripheral cams are the most widely used form of
  an eccentric cam
• In the peripheral cam, a follower rides on the
  outside edge of the cam
• The high spot on the cam is called the lobe
• The low spot is called the dwell
• Cams can also move the follower at different
  levels

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Eccentric and Strap

• The eccentric is inside a device called an
  eccentric strap
• The eccentric is used where heavy loads are
  moved
• The strap is connected to a link or rod which in
  turn is fastened to a pivot on an object which
  moves linearly

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Cloverleaf and Swash plate CAM

• Cam Variations
• Cloverleaf
• drives the follower bar in both directions
• Swash plate
• provides rocking motion

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Different Style of a Swash Plate CAM
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Types of CAM Followers

• POINT SLIDING ROLLER ANGLE

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Using CAMS
3 Port pneumatic valve is opened and closed
Rotating CAM Controls the operation of a car
distributor
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Using CAMS In Gas Engines
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Small Engine CAM
Engine CAMS

• Car Engine Cams

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Eccentric CAMS
Concentric Circle
Eccentric Circle
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Fuel Pump Design Using An Eccentric CAM
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Connecting Rods

• Sometimes called coupling rods these are used to
  transfer energy from one moving part to another,
  without using gears or axles
• Used to synchronize the movement of parts, to
  convert rotary motion to oscillating movement

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Ratchet Wheel And Pawl
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Types Of Ratchets and Pawls
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Ratchet Wheel and Pawl Used To Arrest Motion
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Fishing Reel Uses a Ratchet Wheel and Pawl
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Hand Crank Winch Using a Ratchet and Pawl
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Come Along Uses A Ratchet Wheel and Pawl
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Answer The Following

• What is a CAM?
• What Does a CAM Do?
• Name 5 Different Types Of CAMs.
• What is a Follower?
• Name 4 Types of Followers.
• What is a Ratchet?
• What is a Pawl?
• What is a Ratchet and Pawl used for?
• What is an Eccentric?