Continuously shooting pneumatic grease gun structure

Continuously shooting pneumatic grease gun structure comprising:

• an air chamber housing including a body section defining therein an elongated air chamber, an inlet passage formed on the body section for communicating one end of the air chamber with outer side of the air chamber housing, an outlet passage formed on the body section for communicating another end of the air chamber with the outer side of the air chamber housing, a push hole extending to outer side of the air chamber housing through a section of the body section corresponding to the other end of the air chamber;
• a piston disposed in the air chamber, the piston being reciprocally axially movable within the air chamber between a start position and an end position, whereby when in the end position, the piston permits the air in the air chamber to pass through the piston and escape through the outlet passage to outer side of the air chamber housing;
• a grease push rod coaxially fitted in the push hole and synchronously movable along with the piston;
• and
• a restoring spring compressed between the other end of the air chamber and a face of the piston opposite to the other end, the restoring spring serving to provide resilient force to keep the piston in the start position, said pneumatic grease gun structure being characterized in that the pneumatic grease gun structure further comprising:
• a controlling valve disposed on the body section and movable between an open position and a close position, whereby when in the close position, the controlling valve blocks the inlet passage to hinder external high pressure air from entering the air chamber, while when in the open position, the controlling valve unblocks the inlet passage, permitting external high pressure air to pass through the inlet passage into the air chamber;
• and
• a shift air passage formed in the body section for such conducting the air in the air chamber as to move the controlling valve from the open position to the close the position, when the piston is positioned in the start position, the controlling valve being positioned in the open position.