Patent ID: 8267297

Claim:
A driving mechanism for use in a fastener driving tool, said driving mechanism comprising: (a) a hollow cylinder comprising a cylindrical wall and having a movable piston therewithin, said hollow cylinder having a first end and a second, opposite end, said hollow cylinder containing a displacement volume created by a stroke of said piston; (b) a guide body that is substantially adjacent to the second end of said cylinder, said guide body having a receiving end, an exit end, and a passageway therebetween, said receiving end being proximal to said second end of the cylinder, said guide body being configured to receive a fastener that is to be driven from said exit end; (c) a driver member that is in mechanical communication with said piston at a third end of said driver member, said driver member having a fourth, opposite end that is sized and shaped to push said fastener from said exit end of the guide body, wherein said passageway of the guide body allows said driver member to pass therethrough toward said exit end during a driving stroke and toward said receiving end during a return stroke, said driver member, when at a driven position, protruding toward said exit end of the guide body after said piston moves toward the second end of said cylinder, and said driver member, when at a ready position, being withdrawn into said guide body after said piston moves toward the first end of said cylinder; (d) a main storage chamber that substantially surrounds at least a portion of said cylinder and always is in fluidic communication with said displacement volume of the cylinder, wherein said main storage chamber and said displacement volume are charged with a pressurized gas during all portions of an operating cycle, with no gas replenishment system on-board said tool; and (e) a lifter member that, under first predetermined conditions, moves said driver member from its driven position toward its ready position; wherein said cylinder and piston act as a gas spring, under second predetermined conditions, to move said driver member from its ready position toward its driven position, using said pressurized gas of both said main storage chamber and said displacement volume acting on said piston, while said driver member's fourth end contacts said fastener and moves the fastener from said exit end of said guide body.