Levers and linkages in products | Design and technology

Starter quiz

Which of these linkages work in the same way?
- bell crank
- parallel ✓
- push pull ✓
- reverse motion
How many pivot points are there on a bell crank linkage?
- 2 - one loose and one fixed
- 3 - two loose and one fixed ✓
- 3 - two fixed and one loose
- 4 - two fixed and two loose
What do we call the effort needed to start movement in a mechanism?
- 'input' ✓
What does 'opposite direction' mean?
- a similar direction
- the same direction
- the wrong direction
- the reverse direction ✓
A 90 degree angle is also known as a...
- fixed angle
- right angle ✓
- left angle
- quarter angle
Match the linkage to the description.
- Lazy-tong
  
  ⇔
  
  Lengthens and shortens when it is pushed or pulled. ✓
- Bell crank
  
  ⇔
  
  Has levers that move at right angles to each other. ✓
- Parallel
  
  ⇔
  
  Has two pairs of levers that move in the same way. ✓
- Reverse motion
  
  ⇔
  
  Creates an output opposite to the input. ✓
- Push Pull
  
  ⇔
  
  Creates an output in the same direction as the input. ✓

Exit quiz

What does the word 'purpose' mean?
- A mechanism
- A product
- A job or function ✓
What is a product?
- A simple mechanism
- An item to be used ✓
- A movement
- The way something is made
Why are flaps used in books aimed at young children?
- Easy to use ✓
- Complicated to make
- Strong ✓
- Lots of levers
Which of these linkages creates an output in the opposite direction to the input?
- reverse motion ✓
- bell crank
- push pull
Think about interactive books and match these words to the meaning.
- Linkage
  
  ⇔
  
  How an interactive piece will move ✓
- User
  
  ⇔
  
  The person using the book ✓
- Purpose
  
  ⇔
  
  What the book is designed to do (eg, entertain, educate) ✓
- Product
  
  ⇔
  
  The book itself ✓
- Material
  
  ⇔
  
  What the book is made from ✓
Why aren't lazy-tong linkages used in interactive books?
- All interactive books are aimed at very young children.
- Other simpler linkages make the same movement. ✓
- It is too complicated. ✓
- It looks good.

Worksheet

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Lesson Details

Key learning points

Interactive books have a variety of linkages inside them.
Linkages are chosen to carry out a purpose in a product.
Analysis of existing book designs can help develop new designs.

Common misconception

All linkages can be found in interactive books.

Not all linkages are suitable for use in an interactive book. Those that are used are chosen because they are the simplest, most functional option for the intended purpose.

Keywords

Product - an item designed to be used
Purpose - an intended function or result
Input - the motion used to start a mechanism
Output - the motion created by the input