An Introduction to Mechanisms

1 Homework Tasks

1. Cam Profiles

  • Name the following cam profiles and explain how it controls the movement of the follower.

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2. Pulley Calculations

For each of the problems below - draw a diagram of the pulleys described and then calculate the answer.

  • a) A driver pulley has a diameter of 150mm and rotates with a speed of 30rpm. Calculate the speed of a driven pulley with a diameter of 50mm.
  • b) A driver pulley has a diameter of 70mm and rotates with a speed of 200rpm. Calculate the speed of a driven pulley with a diameter of 350mm.
  • c) A driver pulley has a diameter of 100mm and rotates with a speed of 60rpm. Calculate the required diameter of a driven pulley if we want it to rotate at 150rpm.
  • d) We have a driver pulley with a diameter of 80mm. And a driven pulley with a diameter of 40mm. What speed will the driver pulley need if the driven pulley must rotate at a speed of 90rpm?
  • e) A driven pulley has a diameter of 10mm and must rotate at a speed of 200rpm. What diameter will the driver pulley need if it can only rotate at 50rpm?

3. DC Motors

Define the following DC motor terms:

  • a) Magnetic field
  • b) Armature
  • c) Commutator
  • d) Brushes

4. Glues

Describe the main uses for the following glues:

  • a) PVA glue
  • b) Epoxy Resin Glue
  • c) Super Glue
  • d) Spray glues
  • e) Clear model glue

5. C.A.D. usage

Answer the following questions:

  • a) What is the meaning of the term C.A.D?
  • b) How does making a 3D model of a product help a design team develop the product?
  • c) Do you thing there is no need to use an expensive piece of equipment such as a laser cutter to make a model? Explain your answer.

6. Mechanism Design

A local florist has asked you to design a model to be placed next to the checkout. The mechanism (shown Below) is nearly complete but a simple mechanism needs adding. The mechanism must make the characters arm move up and down in a fairly smooth movement.

  • a) Complete the drawing by adding the mechanism.
  • b) Explain how it works?

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