Cams and Followers

• What is the purpose of a cam in a mechanical system?

  To change rotary motion (input) into reciprocating motion (output).
• What are the two main parts of a cam mechanism?

  The cam profile (shaped part) and the follower.
• What is the cam profile?

  The shaped edge of the cam that controls the movement of the follower.
• What is the follower?

  The part that moves up and down by sliding or rolling on the edge of the rotating cam.
• What type of motion does the cam provide?

  Rotary motion (input motion)
• What type of motion does the follower provide?

  Reciprocating motion (output motion)
• In which direction does a cam usually rotate in diagrams?

  Anticlockwise
• Where are cams and followers commonly found?

  In machines and toys
• What happens to the follower as the cam rotates?

  The follower rises and falls depending on the cam's shape.
• What does an off-centre cam shaft do?

  It makes the cam rotate unevenly, causing the follower to move up and down.
• What type of motion does a circular (eccentric) cam produce?

  Smooth, continuous motion.
• Where are circular cams commonly used?

  In steam engines.
• What is the motion of a pear cam like?

  The follower stays still for half the cycle, then rises and falls.
• Where are pear cams commonly used?

  In car engine shafts.
• What is special about a heart cam?

  It allows the follower to rise and fall with a uniform speed.
• What is a knife followers pros/cons?

  It has a sharp edge and gives a strong push, but wears out quickly due to small contact area.
• What is a flat follower?

  A follower with a flat face that exerts less push than other types. Used in car engines to open/close valves.
• What is a roller follower?

  A follower with a rolling contact that reduces wear and friction. Used in large gas/oil engines and aircraft engines.
• What type of follower has a sharp knife edge?

  The knife Follower
• Why are knife followers rarely used?

  Because they wear away quickly due to their small contact area.
• What is the shape of a flat follower?

  The end is flat and perfectly faced.
• Where are flat followers commonly used?

  In car engines to open and close inlet and exhaust valves.
• How does the force exerted by a flat follower compare to other types?

  It exerts less push than knife or roller followers.
• What is the key benefit of a roller follower?

  It reduces wear and friction due to its rolling motion.
• Where are roller followers commonly found?

  In large stationary gas or oil engines and aircraft engines.
• What is the ‘stroke’ in a cam follower system?

  The total distance moved by the follower.
• What does ‘fall’ mean in cam follower motion?

  The follower moving downwards.
• What does ‘rise’ mean in cam follower motion?

  The follower moving upwards.
• What is ‘dwell’ in cam follower motion?

  When the follower stays stationary (not moving up or down) for a period of time.
• What causes the dwell period in a cam system?

  The distance between the centre of the shaft and the edge of the cam remains constant during that time.
• What three key parts must every lever have?

  An effort, a load, and a fulcrum (pivot).
• What is a lever?

  A beam that can rotate about a fixed point called the fulcrum or pivot.
• What happens when effort is applied to one end of a lever?

  It causes the load to move at the other end.
• How can you lift a heavy load with less effort using a lever?

  Move the fulcrum closer to the load.
• How are the three classes of levers defined?

  By the positions of the effort, load, and fulcrum (pivot) along the lever.
• In a Class 1 lever, where is the fulcrum?

  In the middle, with the effort on one side and the load on the other.
• What are some examples of Class 1 levers?

  Seesaw, crowbar, scissors, claw hammer, tin snips, weight scales.
• In a Class 2 lever, where is the load located?

  In the middle, between the fulcrum and the effort.
• What are some examples of Class 2 levers?

  Wheelbarrow, bottle openers, nutcrackers, foot pumps.
• In a Class 3 lever, where is the effort located?

  In the middle, between the pivot and the load.