Patent ID: 6135733
Filing Date: 2000-10-24
Classification: F04B

Abstract:
A manual air pump comprising:a cylinder comprising a first chamber and including a first end and a second end,a head provided to the second end of the cylinder, the head including an outlet passage communicated with the first chamber for supplying air to an object to be inflated,a piston assembly including:a first piston rod having a first end with a first piston slidably received in the first chamber and a second end, the first piston separating the first chamber into a first chamber section adjacent to the head and a second chamber section distal to the head, the first piston rod defining a second chamber therein,a second piston rod having a first end with a second piston slidably received in the second chamber and a second end, the second piston separating the second chamber into a third chamber section adjacent to the first piston and a fourth chamber section distal to the first piston, anda handle secured to the second end of the second piston rod to move therewith,means for supplying ambient air into one of the second chamber section and the fourth chamber section during an outward stroke of the handle away from the head,means for releasably engaging the handle with the first piston rod;means for communicating the third chamber section with the outlet passage when the first piston rod is retained in the second end of the first chamber;whereby reciprocating movement of the handle causes high volume/low pressure inflation when the engaging means engage the handle with the first piston rod to allow joint sliding movement of the first piston rod and the second piston rod, and reciprocating movement of the handle causes low volume/high pressure inflation when the handle is disengaged from the first piston rod and the first piston rod is retained in the second end of the first chamber.