Patent ID: 8052402
Filing Date: 2011-11-08
Classification: F04B

Abstract:
1. A hand operated pump for generating negative and positive air pressure, said pump comprising: a pump body including a pump cylinder; a piston mounted for reciprocation in the pump cylinder; a piston rod connected to the piston and extending rearward from the piston in the pump cylinder; an actuator operatively connected to the piston rod for moving the piston in the pump cylinder through a power stroke, the piston thereafter being movable through a return stroke prior to another power stroke; a selector valve in the pump body communicating with the pump cylinder and moveable between a positive-pressure position and a negative-pressure position; and an outlet in the pump body communicating with the selector valve for applying said negative and positive air pressure to a device in response to operation of the actuator; the selector valve communicating with a front chamber in front of the piston and a rear chamber behind the piston such that operation of the actuator to move the piston through said power stroke when the selector valve is in the negative-pressure position causes the pump to generate negative pressure at said outlet, and operation of the actuator to move the piston through said power stroke when the selector valve is in the positive-pressure position causes the pump to generate positive pressure at said outlet; wherein movement of the piston through said return stroke when the selector valve is in the negative-pressure position does not cause the pump to generate negative pressure at said outlet.