How Pumps Work

A useful piece of equipment for bike owners is a bike pump. It comes in very handy when you encounter a punctured tyre and as it requires no electricity to work it, a bike pump can be used wherever you are, so it doesn’t matter if you find the flat tyre when you’re stuck in the middle of nowhere as you can soon solve the problem with a manual bike pump. By hooking the pump to the tyre valve stem, you can quickly inflate the tyre with just a few manual pumps of the piston pump handle. But how you ever wondered how pumps work? I’ll be discussing exactly how pumps work, focussing on bikes and air mattresses.

 

Before I can explain how a basic bike pump works, it’s useful for you to understand the various parts of the pump. Typically, a bike pump is a narrow, vertical, cylindrical device. A hose is hooked to an outlet valve at the bottom of the tower. At the opposite end of the hose is a nozzle that you attach to the tyre valve when using the pump. Inside the pump’s tower is a piston that moves up and down during the inflation process. The top of the piston is attached to a handle which you pull up and push down in order to inflate the tyre so you can ride your bicycle once more.

 

The basic principle of a bike pump is as follows: the handle is pushed up and down, moving the piston up and down in turn. The bottom end of the piston forces the air down and into the air valve which leads to the hose. The air moves down the hose and into the tyre where it inflates.

 

There are five stages to inflating bike tyres with a manual pump. Here’s how the process happens in more detail.

 

1.      Piston rises

As you pull the handle of the pump upwards, the piston rises, drawing air into the body of the pump.

 

2.      Air enters chamber

As the air enters the chamber, the pressure causes the inlet valve to open.

 

3.      Piston lowers

As you push the handle of the pump downwards, the piston lowers which compresses the air and closes the inlet valve.

 

4.      Outlet opens

The pressure in the air chamber builds up and increases which forces the outlet valve to open and the air to rush through.

 

5.      Air inflates tyre

The air enters the tyre through the hose and inflates it.

  

A similar process happens with air beds when inflated with a manual pump. Usually this is in the form of a foot pump and you create air pressure by pushing down on the pump with your foot and releasing again, in a constant motion until the air bed is fully inflated and firm to the touch. There is usually a stopped which you can insert into the hole where the pump was fitted in order to keep the air inside the mattress. When you no longer need to use the mattress, simply pull out the stopper and press down on the mattress to release the air and deflate the mattress.

 

I mentioned earlier that bike pumps are useful for getting you out of a sticky deflated tyre situation. But what happens when the bike pump is broken? Here’s how to fix a broken bicycle pump.

 

1.      Check for leaks

Hold your finger against the valve fitting at the end of the hose and manually operate the pump once or twice. You’ll know if the hose or fittings are faulty as air will hiss out at the valve fitting, the base of the pump, or through the hose itself.

 

2.      Cracked or broken hoses

If the hose is cracked or broken it should be replaced with a new one. Hoses have to withstand high pressure so patching it up generally won’t solve the problem.

 

3.      Leaking pump heads

Repair a leaking pump head by unscrewing the nut and replacing the seal. If the head is leaking at the connection to the hose, replace the connector with an adjustable hose clamp.