Glue dispensing gun

A glue dispensing gun comprising:

• a barrel for receiving a glue container having a rear end cover, said barrel provided at a rear end with a receiving slot which is comprised of a front stop edge and a rear stop edge;
• a center rod having a front end which is located in the rear end of said barrel via said receiving slot and is provided with an advancing piece in contact with the rear end cover of the glue container, said center rod being comprised of a compression spring and a pushing piece, said compression spring and said pushing piece being fitted over said center rod, said center rod being further comprised of a recover spring and a retaining piece, said recovery spring and said retaining piece being fitted over said center rod;
• an eccentric transmission member mounted in said receiving slot of said barrel such that said eccentric transmission member is corresponding in location to said recovery spring and said retaining piece of said center rod;
• and
• a hand grip having a trigger, said trigger comprised of a connection rod fastened thereto such that a top end of said connection rod is fastened to said eccentric transmission member whereby said trigger controls a forward motion and a backward motion of said center rod in conjunction with said eccentric transmission member;
• wherein said eccentric transmission member is comprised of a guide block, a bearing fitted over said guide block, and a push block fastened to said guide block such that one end of said push block is rested against said pushing piece of said center rod, said guide block being fastened to the top end of said connection rod of said trigger and provided eccentrically with a pivoting hole, said guide block being pivoted to said receiving slot by a pivot which is received in said pivoting hole of said guide block, said guide block being actuated by said trigger to turn eccentrically such that said push block turns along with said guide block so as to push said pushing piece of said center rod to swivel slantingly to bring about the forward motion of said center rod, said bearing being rested against by a lower end of said retaining piece of said center rod, with said retaining piece of said center rod being confined by said front stop edge and said rear stop edge of said receiving slot whereby said pushing piece of said center rod is not pushed by said push block of said eccentric transmission member and is positioned vertically in relation to said center rod at such time when said trigger is not activated, said retaining piece being confined by said front stop edge and said rear stop edge of said receiving slot such that said retaining piece is positioned vertically in relation to said center rod, thereby enabling said center rod to move backward whereby said eccentric transmission member is actuated by said trigger such that a lower end of said retaining piece of said center rod is no longer in contact with said bearing, and such that an upper end of said retaining piece of said center rod is urged by said recovery spring of said center rod, thereby causing said retaining piece to tilt to prevent said center rod from moving backward at the time when said center rod is moving forward.