What are Machine Elements?

The smallest mechanical parts in a machine, these elements work as a sum of their parts. An example of a mechanical element is a bearing. It is made up of parts such as rings, balls and seals but it would not function as a bearing if it was split up into these individual parts.

We can see an example of how mechanical engineering has evolved by looking at the average car. A typical motor vehicle has around 30,000 machine elements, from larger parts down to small screws. When all of these elements work together, the car works as it is designed to.

Below we will look at the most common machine elements and what they are used for.

Types of machine elements

* Bearings: these common machine elements eliminate friction between two moving parts. They come in various shapes and sizes and allow rotating machinery such as motors and sliding doors to function
* Shafts: long and cylindrical, shafts are used to transfer mechanical power and torque between two components. These elements are used in vehicle axles, motors, clocks and watches
* Keys: used in machine design, keys connect shafts to rotating elements to transfer torque. Keys are important components in motors, gear drives, pulleys and marine propellers
* Couplings: these mechanical components connect two rotating in-line shafts to transmit power. A coupling can be rigid or flexible depending on requirement. Couplings are used in generators, paddle steamers, and automotive steering linkages
* Fasteners: these components can be screws, nuts, bolts, rivets, split pins or circlips. They are one of the most used mechanical elements and work to protect machinery against high pressures, vibration and excessive force.
* Gears: these elements feature toothed wheels to transfer power and rotation between two shafts. They act as levers to either increase or decrease angular velocity while decreasing or increasing torque. Gears are used in vehicle gearboxes and appliances such as blenders and washing machines.

Machine elements can be categorised into two main types: general-purpose and special purpose.

General-purpose machine elements

These elements act as the building blocks of machinery and include parts such as chains, keys, bearings, belts, shafts and fasteners such as nuts and bolts. These are called general-purpose as they usually perform the same function, wherever they are.

While they are general-purpose, their size and shape can differ as these specifications are outlined by international standards. One example of differing standards is hex bolts: they can be manufactured to 18 different standards. This makes machine elements simple to replace as they are easily available and usable in different machines.

Special-purpose machine elements

Special-purpose machine elements are the opposite to general-purpose in that they have a specific use that can be customised for certain needs.

An example of special-purpose mechanical elements are ship engines. They vary in design and can include between 6 and 14 cylinders. No two engines are created the same, as every component is redesigned. Some of the machine elements that differ between engines are exhaust valve, cylinder head, piston and piston rings, crankshaft and the connecting rod.

For the full range of machine elements, consult the Elesa catalogue.