Air compression pump

An air compression pump comprising:

• a pump head;
• a pumping device fluidly connected with the pump head, wherein the pumping device includes a first cylinder, a second cylinder and a plunger, wherein the first cylinder has a first end connected with the pump head and a second end coupled to a first piston, wherein the first cylinder is inserted in the second cylinder, wherein the second cylinder is movably coupled to the first cylinder such that the first piston moves in the second cylinder in response to movement of the second cylinder with respect to the first cylinder, wherein the second cylinder includes a first end cap and a second end cap respectively coupled to two ends thereof, wherein the first cylinder is inserted through the first end cap, wherein the plunger is inserted in and movably coupled to the first cylinder and has a first end coupled to a second piston and a second end connected with the second end cap, wherein the second piston moves in the first cylinder in response to the movement of the plunger with respect to the first cylinder, and wherein the plunger is inserted through the first piston;
• and
• a relief valve fluidly connected with and received by the pump head, wherein the relief valve defines a relief hole which is fluidly communicable with the first cylinder, wherein the relief valve includes a valve body selectively closing the relief hole, and wherein the valve body is movable to an open position to relieve pressure in the air compression pump by allowing pressurized air to flow out of the air compression pump through the relief hole.