Linkages

Linkages

A linkage is a system of connected rods and levers that are used to transmit motion and force. Linkages may be used to:

• change the direction of motion and force
• change the size of the output motion compared to the size of the input motion
• create parallel motion
• change one type of motion into another type of motion.

The linkage above illustrates how the direction of motion and force may be changed.
The diagram above illustrates how a linkage may be used to: change the direction of motion and force change the size of the output motion compared to the size of the input motion change the size of the output force compared to the size of the input force
The diagram above illustrates how a linkage may be used to create a parallel motion.
The diagram above illustrates a pantograph linkage. A pantograph is used to copy and rescale shapes and drawings.
The diagram above illustrates how a linkage is used in a crank and slider mechanism and how rotary motion is converted into reciprocating motion.
Parallel motion linkage used in a parallel arm fret saw.
Linkages connected to two bell crank levers create a near vertical reciprocating sawing action.

Linkages found in a sewing machine.

The photograph above shows various linkages and levers in a typical sewing machine. Also visible in the photograph is a belt and pulley drive, nylon bevel gears, retaining springs and lubricating grease.