Today's Mechanisms Mini Test

1. Which is the stroke of the cam? a,b,c or d?

2. a) Name this mechanism: Worm and wheel

b) Label part A: worm
c) Label part B: wheel

3. Other than the mechanism above, name a mechanism which allows rotation in one direction only, and draw the schematic diagram of it.

              Ratchet and Pawl

4. a) Calculate the Velocity Ratio of this mechanical system.

       VR = B/A x D/C

             = 10/1 x 24/12

             = 10 x 2

             = 20


b) Calculate the output speed if A is turning at 60 rev/s
           VR = input motion/output motion

           20  = 60/output

      output = 60/20

                 = 3 rev/s

5. Draw and label two mechanisms which are rotary to reciprocating motion.
 Crank and slider

 Cam and Follower

6. State how to calculate the Velocity Ratio of a pulley.

Count the number of ropes (not including the effort rope)

or use the equation VR = distance moved by input/distance moved by output.