Mechanisms Flashcards
Advantage to the clutch coupling method
Allows the user to connect or disconnect the drive to control the speed.
Disadvantage to the clutch coupling method
More expensive due to greater number of parts
Will require regular maintenance because it will wear.
Functions of bearings
. Supports load while allowing something to rotate
. Reduces friction due to less contact area, which reduces the wearing away of the shaft
What are belt/chain drives used for?
As an alternative to a simple gear train, which would have a low efficiency due to friction.
How do you make the pulleys rotate in opposite directions with a belt drive?
Cross the belt between the two pulleys
Advantages of belt drives
Cheap and easy to replace. Require little maintenance because they do not need lubrication.
Absorb shock loads by slipping
How do you keep a belt drive tensioned?
Use a spring-loaded jockey pulley
Why would a toothed belt drive be used?
When slippage of the belt would not be wanted, if it would damage mechanisms.
Why would a chain drive be used?
For transmitting large forces, where there can be no slippage allowed.
What is used instead of a pulley for a chain drive?
Sprocket (toothed wheel)
What is used instead of a pulley for a chain drive?
Sprocket (toothed wheel)
Advantages of chain drives
. Very strong, won’t slip
Disadvantages of chain drives
. Must be oiled regularly
. More expensive than belt drives
. Noiser than belt drives
What are Cams and followers used for?
. To change input rotary motion into output oscillating or reciprocating motion.
. Often used to control valves
What is the distance from the highest and the lowest point on the cam profile called?
Stroke
