Linkages and Cams (Junior Cert Applied Technology): Revision Notes

Linkages and Cams

Linkages and cams are key parts in learning about mechanisms in Applied Technology. They help move motion and energy, making machines work.

Definitions

• Linkages: These systems are made of connected parts, like levers, to move and change motion and force efficiently. They can create complex movements by joining many parts, such as car windscreen wipers.
• Cams: Cams turn rotary motion into straight-line motion and are used in engines and systems needing exact movement. They push a follower on a track, driven by a spinning camshaft.

How Linkages Form Mechanisms

Linkages create mechanisms by joining levers at pivot points, which let them rotate and move motion and force. This helps transfer motion in a machine effectively, useful in different types of machinery.

Types of Linkages

1. Reverse Motion Linkage:
   Note

   Diagram: This shows reverse motion linkage where input motion is reversed at the output.

   • These systems change motion's direction and are important in tight spaces needing a direction change.
   • Example: Used in scissor lifts and drawer sliders.

1. Bell Crank Lever:
   Note

   Diagram: This shows the bell crank lever with the pivot point and movement in a pedal bin.

   • This lever redirects motion, usually at a 90-degree angle, to let forces move around obstacles.
   • Example: Used in bicycle brakes to change direction for braking force.

Operation of Cams

Cams turn rotary into straight-line motion using shapes like discs or hearts to guide the follower's movement. This is vital for timing movements in machines, like engine valves opening and closing.

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Linkages and cams are crucial for efficient mechanical systems, greatly aiding in design and function improvements.