Abstract: A syringe for giving medical injections which has an internal mechanism for retracting the needle into the syringe after the injection has been given and locking the needle and plunger inside the barrel of the syringe to reduce the risk of accidental needle pricks. In one embodiment the needle is manually retracted by pulling back on the plunger and in the other embodiment the needle is propelled by a compressed spring into a hollow chamber within the plunger.

Abstract: This invention provides an improved injection molding apparatus which includes a check valve assembly mounted at the forward end of a feedscrew, the valve assembly being characterized by forward and rearward valve seat surfaces which co-act in a first position to allow a plasticized polymeric material to enter and flow through the valve into an injection chamber and which co-act in a second position to stop any additional material from entering the valve assembly. The second valve position is effected by a feedscrew injection stroke which generates a backpressure to close the valve, the backpressure moving a check ring of the valve assembly into a position to block entry into the valve. The valve seat surfaces are coated with a bonded metal, metal alloy, or ceramic material which effectively increases the abrasion resistance of the valve seat surfaces and thus also increases the wear service life of the check valve assembly. Other wear surfaces of the valve assembly may also be coated for abrasion resistance.

Abstract: This invention provides a fastening system comprised of at least two pieces to be fastened together, the pieces exhibiting planar characteristics and each piece is characterized by having at least one slotted through bore in the material comprising the piece and, a fastener having a stem portion and orthogonally oriented cross bar portions at each of its ends to define an I-shaped configuration, the fastener interconnecting the pieces together in planar face-to-face orientation by having one of its cross bar portions passed through the slotted bore in one of the pieces and having the other cross bar portion passed through the slotted bore in the other of the pieces such that the stem portion is in a seated engagement within the bores of the pieces.

Abstract: This invention provides various configurations of spacers for use in plastic block constructions to prevent relative lateral side-to-side movement between adjacent blocks of the construction when they are connected together with interlockable tab extensions. The spacers are mounted within joint spaces between adjacent blocks of the construction and are in contacting operative engagement with the interlocked tabs to prohibit any relative lateral movement out of alignment between the blocks in the direction towards or away from the frontal or rearward planar faces of the blocks and to retain the blocks aligned in a common plane.

Abstract: A chain saw safety switch mounted in combination with a chain braking mechanism such that, when chain braking is initiated, both the chain motion about a chain guide bar and motor operation are automatically stopped. The safety switch according to one embodiment of the invention is mounted to the safety guard of the chain braking mechanism in a position such that it may be rendered operable by either a selective action of the saw operator or by the operator's reaction response to a hazardous operating condition. In either case, the safety switch effects short-circuiting of the motor ignition to stop all motor operation while at the same instant, the safety guard effects stoppage of the cutting chain motion about the chain guide bar. Alternatively, the safety switch is mounted in conjunction with the movable safety guard such that short-circuiting of the motor ignition is effected through the chain braking mechanism.