Vacuum pump

A vacuum pump comprising:

• a pump body that includes an elastic sleeve;
• a valve stem;
• a valve pin that is surrounded by the valve stem with an end of the valve pin snap fitted to the valve stem;
• a piston that surrounds the valve pin and that is located inside of the pump body and sealed against the pump body;
• a plug with an inner body that is located within the pump body, an outer body that is located outside the pump body with the valve stem located inside of the plug, and a stepped groove that is located between the inner body and the outer body and has a diameter larger than the inner body and the outer body;
• a ring that surrounds the pump body and the plug;
• a head cap that surrounds the valve stem and that is configured to move within a cavity of the ring;
• and
• a spring disposed between the valve stem and the stepped groove of the plug at a position radially outward of the valve stem, wherein:
• an inner surface the pump body is snapped-fit and sealed against an outer surface of the inner body of plug,
• an inner diameter of the outer body of the plug is larger than an inner diameter of the inner body of the plug,
• the valve stem includes an inner cavity from which the piston is located and an upper cavity,
• the upper cavity is a groove that is open toward the pump body,
• an upper end of the spring is placed in the upper cavity and a lower end of the spring is placed against the stepped groove and the ring, and
• when the head cap is moved within the cavity of the ring, the head cap is configured to move the valve pin within the pump body via the valve stem.