Year 4 - Design and technology
Bell crank and lazy-tong linkages
Levers and linkages: interactive books
Study Hub
Study Guides
This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit develops pupils' knowledge of mechanisms through levers and linkages. They will apply this knowledge by exploring mechanisms and incorporating them into an interactive book with a user-centred focus.
Lesson Summary
You will learn to make bell crank and lazy-tong linkages.
Key Notes
- A bell crank linkage moves levers at angles from each other.
- A lazy-tong linkage is made of levers which lengthen or shorten when one end is pushed or pulled.
Vocabulary To Learn
- linkage: A mechanism connecting levers together.
- input: The motion used to start a mechanism.
- output: The motion created by the input.
- loose pivot: A free moving point that connects two levers together.
- fixed pivot: A point that connects a lever to one place.
Common Mistakes To Avoid
- It doesn't matter where you place the pivots on a lazy-tong linkage.
3 Quick Questions (With Answers)
1. Explain the lesson in two key points.
A bell crank linkage moves levers at angles from each other. A lazy-tong linkage is made of levers which lengthen or shorten when one end is pushed or pulled.
2. What does this key word mean in this lesson? 'linkage'
A mechanism connecting levers together.
3. Correct this common mistake.
Mistake: It doesn't matter where you place the pivots on a lazy-tong linkage. Correction: Where the pivots are placed is very important on a lazy-tong linkage. If they are not placed correctly, the mechanism will not function correctly.
More Lessons In This Unit
Browse all guides in the Year 4 Design and technology guide library.