# Compound machines: what they are, composition and examples

Human development has enabled great inventions, which have meant great benefit and improved quality of life.

What was unthinkable centuries ago today can be achieved with the push of a button, and that is that electronics have been one of mankind’s greatest inventions.

Washing machines, computers, cars … there are countless devices that we use in our daily life on which we have become dependent and, on the other hand, we have no idea how they work at all. All these devices are what we call complex machines, which in turn are made with so-called simple machines.

In this article, we’ll cover what these types of machines are, going back to their components and giving some examples to see it more clearly.

## What are composite machines?

Compound machines are those mechanical devices which have been formed from two or more simpler machines which are connected in series. Being connected in this way, when one of these parts of the composite machine is activated, the others work in a coordinated way, being able to together offer a function that individually could not.

Compound machines have evolved with the development of technology. The first were mechanical, but with the discovery of electricity they were made of electricity and mixed.

Almost any type of device with a more or less complex mechanism is a composite machine. Whether it’s from something as small as a wristwatch can be like an aerospace spaceship. In addition, the degree of complexity can be very variable, being an example of this cart, which consists of only two levers.

Whenever composite machines are used, their parts are subjected to friction which generates wear over time. For this reason, these types of machines require certain care such as proper lubrication and being sent to a mechanic in case they do not work properly.

## Composition of composite machines

Compound machines work in stages; through which different types of operators work so that the function for which the mechanism has been developed can be given. There are two types of these operators:

### mechanical operators

These are the elements that allow the operation of the machine by turning the force into motion. Their set is what is called a mechanism, being the main operators of this type the wheel, axles and gears.

The wheel is a circular part that rotates around an axis. By itself, it is considered a simple machine, being one of the most important inventions of mankind, thanks to the fact that it has been used in countless more complex machines.

The axles are bars which connect the wheels and the pulleys and allow the free movement of the latter but protected by a support.

Finally, gears are mechanical operators made up of two circular toothed parts, the larger of which is called the crown and the smaller the pinion. It transmits the circular motion by means of the movement and contact of the toothed wheels.

### energy operators

These types of operators are responsible for storing energy or power and transforming it into another type so that the device can activate and perform its function. Examples of these are springs, batteries, batteries and motors.

Electric batteries have been manufactured in many shapes and sizes and allow energy to be accumulated which is stored for later use.

Motors are devices that transform energy into another type, so that the machine can use it and perform its function. There are electric, steam and fuel motors.

## Simple machines

Simple machines were widely studied during the Renaissance. At that time, the classification of this type of machine consisted of 6 types:

• inclined plane
• falca
• police
• turn
• the sink
• screw

Over time, and thanks to technological progress, new machines of this type have been developed which, in turn, they made it possible to develop more sophisticated complex machines with specialized functions that people of antiquity could hardly imagine.

## Examples of complex machines

Here are several examples of composite machines which have all the typical characteristics of these products.

### 1. Bike

This vehicle is a clear example of what a composite machine is. It is propelled by the force exerted with the feet on the pedal, causing the wheels attached to the frame to rotate and allow movement.

### 2. Crane

It is a machine that allows heavy items to move up and down or the movement can be complicated. Loads are lifted by being placed on a hook that is at the end of a rope or chain.

This machine was one of the great creations of mankind, as it facilitated the construction of large buildings and its origins date back to ancient Greece.

### 3. Cat in the car

It is used to lift objects that have a lot of weight, such as a car or very heavy furniture. It works with a lever and can be mechanical or hydraulic.

### 4. Pany

It is a metal mechanism that is incorporated in the doors and drawers, which consists of a part that prevents their opening.

By incorporating the element that deactivates it, either a key, or in the latest versions a fingerprint, the lock is unlocked and allows access to the interior of the house or to the contents of the drawer.

### 5. Can opener

It is a device used to open metal cans.

### 6. Car

Vehicle in which, when the key is inserted in the ignition, the engine is activated which allows the axles holding the wheels to the bottom of the car to move and thus allow displacement.

Also called a cassette tape recorder, this device which today can be seen as reminiscent of the music of the eighties works by playing the recordings which contained the cassettes.

### 8. Turbine

These are machines through which a fluid passes continuously and this gives kinetic energy to the turbine through the vanes endorsed on it. Thus, the turbine spins, functioning as a motor. Its basic element is the wheel.

### 9. Tractor

It is a self-propelled vehicle used to drag or push trailers. They can be used in different sectors: agriculture, nautical, construction, earthworks …

Thanks to its creation, it significantly reduced the workforce as well as increased production, being one of the main elements of the agricultural revolution.

### 10. Washing machine

It is an electromechanical device, Which can be both domestic and industrial, which is used to clean clothes.

In its central part it has a drum with holes which, when the washing machine is activated, turns over when water mixed with detergent enters.

The drum moves thanks to the action of an electric motor which is transmitted in traction by pulleys.

Some more modern models have improved the washing experience by drying clothes during the process of removing waste from fabrics.

#### Bibliographical references:

• Beck, R. (1999). History of the world: models of interaction. Evanston, Illinois: McDougal Littell.
• Strizhak, V .; Igor P .; Toivo P. (2004). Developments in the design, use and strength calculations of threads and threaded joints. HMM2004 International Symposium on the History of Machines and Mechanisms. Kluwer Academic Editors.