Basic Mechanical Functions

Mechanical Function:• The role that any part plays inside an object is

defined as its ‘mechanical function’.

• Four simple mechanical functions are– Guidance– Linking– Lubricating– Sealing

Guidance:Guidance:

Guidance and the links between prevent certain motions that would negatively affect the way the machine works.

Guidance is the function of a part that directs another part along a specific path.Guidance dictates whether the motion is either rotational (wheel and axle) or translational (sliding drawer)

Motion:

An object, totally independent from any other object has 6 degrees of motion freedom, - translation along 3 axis, and rotation around the same three axis.

Guidance:Guidance:

2 translations and 2 rotations around 3 different axis result in 12 different potential motions.

Lubrication:Lubrication:• Lubrication is the function of a substance that reduces

friction.

• Lubrication can be done by liquids (oil), semi-liquids (grease) or solids (graphite)

Lubrication:Lubrication:

Choosing materials that facilitate motion reduces frictionFor example: choosing nylon or teflon

Shape of an object can also reduce friction. For example – bearings and rollers

Sealing:Sealing:

• A seal is a part whose function is to prevent a fluid (liquid or gas) from escaping its container.

• A seal between 2 parts may be obtained by a simple contact between them, but more often by the insertion of a compressible (squishy) material.

• See “Links- Types” and “Links- Characteristics”PowerPoint presentations

Basic Mechanical FunctionsLinking function:Linking function: