Abstract: A fastener driving tool that includes a lifter subassembly for moving the driver from a driven position to a ready position. In one embodiment, the lifter is mounted to a movable pivot arm, and if the driver is mispositioned at the beginning of a lifting phase, the lifter can displace a small distance to allow the lifter to move over the driver's protrusions, thereby allowing the lifting phase to continue without causing a jam. A retainer (or “cam follower”) is positioned along a rounded cam profile surface of at least one lifter disk to prevent the lifter from displacing during later portions of the lifting phase, or during a transition phase. The lifter includes at least two rotating disks with extending pins to engage driver protrusions. One of the lifter disks can have gear teeth on its perimeter, instead of a cam profile surface.

Abstract: A portable linear fastener driving tool is provided that drive staples, nails, or other linearly driven fasteners. The tool uses a gas spring principle, in which a cylinder filled with compressed gas is used to quickly force a piston through a driving stroke movement, while a driver also drives a fastener into a workpiece. The piston/driver is then moved back to its starting position by use of a rotary-to-linear lifter, and the piston again compresses the gas above the piston, thereby preparing the tool for another driving stroke. The driver has protrusions along its edges that contact the lifter, which lifts the driver during a return stroke. A pivotable latch is controlled to move into either an interfering position or a non-interfering position with respect to the driver protrusions, and acts as a safety device, by preventing the driver from making a full driving stroke at an improper time.