Pumps: Cycle pump

• They are used to inflate bicycle tires

The internal structure of a cycle pump

• Air is compressed in cylinder A by the piston
• The piston is fitted with a leather or rubber washer
• This gives an air-tight fit when there is compression in cylinder A
• When the piston is pushed inwards
• The air in A is force through the rubber valve into the rubber tube
• This valve prevents air from escaping
• When the piston is moved outwards the valve prevents air already in the rubber tube from escaping
• There is a hole at the top of the cylinder
• This allows air to enter into the pump cylinder
• The cycle is repeated when the piston is pushed inwards
• Since the hole is near the top end air can no longer escape through it when its is being compressed

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