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Summaries · Grade 7 Technology › Drawing conventions, fitness for purpose and rescue systems
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Drawing conventions, fitness for purpose and rescue systems

Line types and scale on technical drawings, fitness for purpose, and hydraulic rescue systems. Read one part at a time and tap “I know this”. Then test yourself in the quiz.

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Drawing conventions

Thick and dark: outlinesThin and faint: construction linesDashes: hidden edgeLong and short dashes: centre line60Dimension line with arrows and the size
Every line on a technical drawing has its own meaning.
  • A working drawing is accurate, with all the measurements.
  • Oblique projection: depth lines at 45°. One-point perspective: depth lines meet at one point on the horizon.
  • A freehand sketch gets ideas down quickly. Always acknowledge your sources when you investigate.
Hydraulic rescue tools help after an accident.
Hydraulic rescue tools help after an accident.
Tap when you could tell someone without looking.

Designing a rescue crane

  • Design process in order: investigate, design, make, evaluate, communicate.
  • Model crane: a crank winds a string over a pulley. The most important specification: it must not tip over when loaded.
  • A counterweight balances the load. A bulb in the electromagnet circuit shows when the magnet is on.
  • Evaluate: does the model meet all the specifications? Communicate with neat drawings, notes and the model.
Small syringe: you push far,with little forceLarge syringe: moves less far,but with much more forcewater or oil
Push the small syringe: the large one moves less, but with more force. With air it feels spongy.
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Remember this and test yourself

Remember this: your summary
  • Outlines: thick and dark. Construction lines: thin and faint. Hidden edge: dashes.
  • Centre of a circle or hole: a thin line of long and short dashes (chain line).
  • Scale 1 : 10 and 5 cm on the drawing = 50 cm in reality.
  • Fit for purpose: it does the job; cost effective: people can afford it.
  • The Jaws of Life is hydraulic: oil cannot be squashed, so it passes on big forces.

Write these points in your book. Read them again the night before the test.

Memory trick

Thick = there (visible). Dashes = hidden behind. Long-short = centre.

Flash cards · Tap to turn over

Important words

First say what the word means, then turn the card over.

Test yourself · Part 2

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