Tuesday, 28 August 2012

The SIMPLE bicycle pump

There are so many items we use in our daily lives. But, do we know how these items work? It will amaze you when you learn how much of thought is gone in to making these important, yet simple articles. In this post I wanted to look at the working of a simple bicycle pump.

Here is the layout of a bicycle pump: 

Created by Namita Anil Kumar
It consists of 7 basic parts:
  1. Body - The outside of the pump.
  2. Compression Chamber - The area where the air is stored and undergoes compression.
  3. Hose - Connects the compression chamber to the tyre valve.
  4. Piston - Compresses the air.
  5. Inlet Valve - A one way valve valve that allows air to flow into the compression chamber.
  6. Outlet Valve - A one way valve that allows the air from the compression chamber to flow through the hose.
  7. Handle


The functions of each part will be evident by looking at the mechanism of the pump.
  • Consider a pump with its piston is at the lowest position. At this position the space with in the body above the piston is filled with air from outside the body. At this point both the valves are closed. The hose is attached to the tyre valve. In the first step, the user pulls the handle up. When the hose is connected to the tyre the air present in the tyre occupies the the space in the hose. But the air in the hose doesn't enter the compression chamber due to the outlet valve.

    • Piston rises & Air enters: 
    When the user puls the handle upwards the piston rises. When the piston rises the inlet valve opens and the air from the area on top of the piston is pushed into the compression chamber. The air flows through the inlet valve. The inlet valve does not allow the air to flow back out of the compression chamber. During this process the outlet valve remains closed.

    • Piston lowers: 
    When the user pushes the handle downwards the piston lowers. When the piston lowers the air in the compression chamber gets compressed. During this process the inlet valve is closed. And the outlet valve is remains closed till a particular extent. While the piston is lowered fresh air is sucked into the area above the piston from outside the body of the pump.

    • Outlet valve opens & Tyre inflates:
    When the piston is lowered the pressure of the air in compression chamber increases due to compression. When the pressure of the air in the chamber exceeds the pressure of the air in the hose (ai that was previously present in the tyre), the outlet valve opens. Then the compressed air enters through the outlet valve and the hose, into the tyre. 

    Then the process repeats itself. On further pulling and pushing of the handle the tyre finally inflates.

    This is the working of a basic bicycle pump. Certain pumps can be fitted with a pressure gauge.

    Pumps vary upon the types of valves that are used. None the less the working principle is the same as mentioned above i.e. they all open when the pressure exceeds a particular level.

    *all the images have been created by myself, Namita Anil Kumar.

    So now that you know how a pump works, I hope you acknowledge its technology the next time you use your pump (assuming you ride a bicycle). Happy riding!

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