Patent ID: 8721600

Claim:
A gun for dispensing bone cement from a cartridge, said gun including: a casing, said casing having a front end; a cradle attached to said casing so as to be located forward of the front end of said casing, said cradle shaped to receive a cartridge containing bone cement; a drive rod mounted to said casing so as to extend forward of said casing, said drive rod having a forward end shaped to act against a piston integral with the cartridge and said drive rod being moveably mounted to said casing so that the forward end of said drive rod can abut and push the piston away from said casing; a linkage assembly, said linkage assembly including: a trigger pivotally mounted to said casing; a first link separate from said trigger, said first link having opposed first and second ends, the first end being pivotally mounted to said trigger, wherein said first link moves upon the pivoting of said trigger; and a second link separate from said trigger and said first link, said second link being pivotally mounted to said casing and being connected to the second end of said first link so that the movement of said first link pivots said second link; a drive rod advancement assembly disposed in said casing adjacent said drive rod, said drive rod advancement assembly being located adjacent said second link so as to be actuated upon the pivotal movement of said second link, said drive rod advancement assembly configured to, upon actuation of said drive rod advancement assembly, engage said drive rod so as to advance said drive rod against the piston integral with the cartridge held by said cradle; a third link separate from said trigger, said first link, and said second link, said third link linking the movement of said linkage assembly to said drive rod so that the movement of said linkage assembly is transferred through said third link to said drive rod so that said drive rod advances at a higher speed than when said second link actuates said drive rod assembly, said third link having: an engaged position in which said third link connects said linkage assembly to said drive rod so that the pivoting of said trigger results in the advancement of said drive rod and; a disengaged position in which said third link does not connect said linkage assembly to said drive rod so that the pivoting of said trigger does not result in said third link advancing said drive rod so that the actuation of said drive rod advancement assembly by the pivotal movement of said second link results in said drive rod advancement assembly advancing said drive rod; and a control member that moves said third link between the engaged and disengaged positions.