What does a crank and slider mechanism do?

A crank and slider converts rotary motion into reciprocating motion, or reciprocating motion into rotary. A connecting rod links the rotating crank to a slider in a guide.

A crank and slider has a crank radius of 40 mm. What is the stroke of the slider?

The slider moves through a stroke of 80 mm. The stroke equals twice the crank radius, and 2 × 40 = 80 mm.

What is a cam and follower?

A cam is a shaped plate or cylinder that rotates and pushes a follower. The follower rises and falls, turning rotary motion into reciprocating or oscillating motion.

CCEA A-Level Technology and Design 8900

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Mechanical and Pneumatic ComponentsOption B

Topic overview Open and closed loop mechanical and pneumatic control Safe working with compressed air and mechanisms Levers, linkages and moments Gear types and gear trains Pulleys, belts, chains and shaft fixings Cams, cranks and converting motion Compressed air supply and pneumatic valves Cylinders, shuttle valves, restrictors and reservoirs Pneumatic circuits for logic, timing and speed control

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Mechanical and Pneumatic Components

Cams, cranks and converting motion

3 things to know
AS 1 Paper 2

Overview

Linear, rotary, oscillating and reciprocating motion, crank and slider, pear, heart, snail, eccentric and plate cams, rise, fall and dwell, and followers.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Describe the four types of motion.

Key term

Define rise, fall and dwell for a cam.

Key term

Give an example of reciprocating motion and an example of oscillating motion.

Questions from this subtopic

Each one with the model answer underneath.

1
Describe the four types of motion.
Model answer
Linear motion is movement in a straight line in one direction. Rotary motion is movement round in a circle. An oscillating motion swings back and forth in an arc. A reciprocating motion moves back and forth in a straight line.
2
Give an example of reciprocating motion and an example of oscillating motion.
Model answer
A sewing machine needle and an engine piston both reciprocate. A pendulum and a windscreen wiper both oscillate.
3
What does a crank and slider mechanism do?
Model answer
A crank and slider converts rotary motion into reciprocating motion, or reciprocating motion into rotary. A connecting rod links the rotating crank to a slider in a guide.
4
A crank and slider has a crank radius of 40 mm. What is the stroke of the slider?
Model answer
The slider moves through a stroke of 80 mm. The stroke equals twice the crank radius, and 2 × 40 = 80 mm.
5
What is a cam and follower?
Model answer
A cam is a shaped plate or cylinder that rotates and pushes a follower. The follower rises and falls, turning rotary motion into reciprocating or oscillating motion.
6
Define rise, fall and dwell for a cam.
Model answer
Rise is the part of a turn in which the follower moves up, and fall is the part in which it moves down. Dwell is the part in which the follower stays still while the cam turns.

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