Breech Block Lock (positive Or Impositive) Patents (Class 89/180)
  • Patent number: 9574835
    Abstract: A firearm, in particular handgun, has a barrel mechanism with a barrel and a chamber, a closing mechanism with a slide and also a cylinder-piston mechanism for gas pressure-operated closure delay. The cylinder-piston mechanism has a hollow cylinder with a hollow cylinder wall. A channel is formed between the barrel mechanism and the cylinder-piston mechanism. The hollow cylinder wall is fitted with at least one reinforcing element. The firearm may be produced by the following process steps: introduction of a first portion of the bore into the basic body up to the recess; introduction of a second portion of the bore up to the hollow cylinder; drilling of the channel, wherein the drill is conducted through the bore; and introduction of the reinforcing element into the recess, wherein the bore is closed in a gas-tight manner.
    Type: Grant
    Filed: March 2, 2015
    Date of Patent: February 21, 2017
    Assignee: Umarex GmbH & Co. KG
    Inventors: Eyck Pflaumer, Martin Wonisch, Thomas Scheunert
  • Publication number: 20140260944
    Abstract: A bolt assembly for a machine gun according to an exemplary aspect of the present disclosure includes, among other things, a lock interface insert configured to be insertable into a bolt. The lock interface insert includes a main body defining a first engagement surface and a second engagement surface. At least one of the first and second engagement surfaces is configured to selectively engage a portion of a breech lock.
    Type: Application
    Filed: March 15, 2013
    Publication date: September 18, 2014
    Inventor: Christ Stratis Gryparis
  • Patent number: 8713833
    Abstract: Disclosed is a bolt assembly that may include several lands that extend along the forward end of the bolt assembly that occupy only about 1 percent to about 12 percent of the surface area of the forward end. Also disclosed is a bolt carrier that defines a cam path that includes an increased unlock dwell time of approximately twice the unlock dwell time provided by a cam path shaped like a standard M-16 cam path. Also disclosed is a bolt carrier that includes a protrusion at a forward end of the bolt carrier with a bore that extends through the protrusion and the bolt carrier at a substantially constant bore diameter, where the protrusion is sized to be received in the barrel extension extends approximately one hundred thousandths of an inch from the end of the bolt carrier.
    Type: Grant
    Filed: October 14, 2013
    Date of Patent: May 6, 2014
    Inventor: Karl R. Lewis
  • Patent number: 8459165
    Abstract: Breech guides for use with breech assemblies and firearms including such breech guides are disclosed. An example breech guide for use with a breech assembly of a firearm includes a support element positioned within the breech assembly and a control element on the support element, the control element is adapted to control a cartridge-feeder mechanism of the firearm. The example breech guide includes a guide element on the support element. The guide element is adapted to guide the breech assembly relative to guide rails of the firearm. The support element extends along an axis of symmetry substantially perpendicular to a bore axis. The control element and the guide element being substantially coaxially positioned relative to the axis of symmetry.
    Type: Grant
    Filed: January 24, 2012
    Date of Patent: June 11, 2013
    Assignee: Heckler & Koch GmbH
    Inventors: Stefan Doll, Martin Stussak
  • Patent number: 8276302
    Abstract: A firearm has a frame, a slide mounted to the frame, a trigger, a hammer-type firing mechanism including a hammer, and a manual slide and hammer lock safety mechanism (“manual safety”) including a detent spring biased rotatable tab mounted to the frame that blocks the slide from reciprocating and the hammer from rotating relative to the frame if the tab is actuated in an “on” position. The manual safety completely disables the firearm even if the trigger is actuated, thereby rendering the firearm safer.
    Type: Grant
    Filed: December 30, 2009
    Date of Patent: October 2, 2012
    Assignee: Smith & Wesson Corp.
    Inventor: Gary Zukowski
  • Patent number: 8272312
    Abstract: The invention relates to a breech for a repeating rifle with a breech guide, a locking chamber arranged in the breech guide, and a locking sleeve that is arranged concentrically about a rear part of the locking chamber and that has several locking elements that can be moved by an expansion device between an inner unlocked position and an outer locked position for engaging in a locking groove of a barrel. The expansion device has, according to the invention, a support sleeve that can move in the axial direction between the rear of the locking chamber and the locking sleeve.
    Type: Grant
    Filed: June 8, 2009
    Date of Patent: September 25, 2012
    Assignee: Blaser Finanzholding GmbH
    Inventors: Mathias Kneppler, Meinrad Zeh, Hans-Peter Schwärzler, Jürgen Rothärmel, Christian Scherpf
  • Patent number: 8117957
    Abstract: A breech device of a hand firearm comprises a firearm casing, a trigger mechanism, a carrier slidably arranged within the firearm casing, and a breech block engaging the carrier and having a firing pin. The breech device further includes a tensioning element slidably engaged with the carrier and coupled to at least one follower pin engaging the firing pin and slidably engaged with the breech block. The tensioning element includes a projecting part having a forward-directed nose adapted to engage a stop detent on the trigger mechanism. The breech device further includes a tensioning pin slidably engaged with the carrier and the breech block.
    Type: Grant
    Filed: July 24, 2009
    Date of Patent: February 21, 2012
    Inventor: Vladimir Loganchuk
  • Publication number: 20110239852
    Abstract: Semiautomatic or fully automatic firearm, in particular in the form of a rifle or a pistol, containing a barrel whose rear barrel end is in the form of a cartridge chamber into which a projectile can in each case be inserted from the rear; a breech body which is arranged in a breech guide between the cartridge chamber and a rear wall such that it can move in the longitudinal direction between an open position, which releases the cartridge chamber in order to load a projectile, and a closed position which closes the cartridge chamber, wherein, in the closed position, the breech body closes the cartridge chamber at the rear and is used as an opposing bearing for the cartridge case; characterized in that at least one permanent magnet is provided such that, at least in the closed position and in the positions close to the closed position, its magnetic field forces the breech body to the closed position, such that the magnetic force of the at least one permanent magnet simulates a higher mass of the breech body, w
    Type: Application
    Filed: December 18, 2008
    Publication date: October 6, 2011
    Inventor: Gerhard KIRSTEIN
  • Patent number: 7950177
    Abstract: A bolt action firearm includes a bolt assembly with a bolt body having an outer surface defining a longitudinal guide channel extending along a length of the bolt body from a rearward end to a forward end. A receiver defines a central longitudinally extending bore for accommodating the bolt body. A bolt guide is configured to be coupled to the receiver. The bolt guide includes a projection configured for traveling in the guide channel when moving the bolt body in the receiver so as to ensure that the bolt body is at a predetermined correct angular orientation within the receiver.
    Type: Grant
    Filed: December 30, 2008
    Date of Patent: May 31, 2011
    Assignee: Thompson/Center Arms Company, Inc.
    Inventors: Mark C. Laney, Matthew Zglobicki
  • Patent number: 7886470
    Abstract: A method of assembling a firearm is provided. The method includes providing a bolt assembly that includes a bolt carrier that includes a cammed slot and a first passage, a bolt member slidably coupled to the bolt carrier and positioned within the first passage, the bolt member includes at least one aperture and a second passage, a piston member slidably coupled to the bolt member and positioned within the second passage, the piston member includes an elongated slot and a third passage, wherein the elongated slot includes a first length, and a cam pin slidably coupled to at least one of the bolt carrier, the bolt member and the piston member, the cam pin includes a fourth passage; and coupling the bolt assembly within a cavity of the firearm such that the bolt assembly is slidably coupled to an upper receiver of the firearm.
    Type: Grant
    Filed: March 28, 2008
    Date of Patent: February 15, 2011
    Inventor: Gerald J. Doiron
  • Publication number: 20100300278
    Abstract: A firearm with an improved breech bolt assembly comprises a barrel (12), a breech bolt assembly (18, 21), a body (14) equipped on opposite sides with ports (15) for the ejection of a cartridge case, in addition to a magazine (17), wherein the breech bolt assembly, which is moveable with respect to the body (14) comprises a breech bolt-holder slide (21), a breech bolt (18) equipped with a rotating locking head (25), cam guide rails (26, 27) of the relative movement between the breech bolt (18) and slide (21), and also stopping means (28, 29) of the relative movement comprising a control pin (28) which can be moved vertically with respect to a first control seat (29), charged by a recoil spring (30) applied between the slide (21) and the pin (28), said pin (28) having a cocking handle (23), or reloading lever, rotatingly applied thereto, for the manual moving of the breech bolt assembly (10).
    Type: Application
    Filed: October 3, 2008
    Publication date: December 2, 2010
    Applicant: FABBRICA D'ARMI PIETRO BERETTA S.p.A.
    Inventor: Ulrich ZEDROSSER
  • Publication number: 20100186581
    Abstract: A method and apparatus providing an action system for a semi-automatic shotgun including a receiver having an ejection port for expelling an empty cartridge of a fired projectile. The action system includes a bolt attached to a bolt carrier, wherein the bolt and the bolt carrier are movable within the receiver and substantially parallel to a longitudinal axis. A surface is attached to at least the bolt carrier or the receiver, and a roller is positioned rearward of the ejection port and proximate the surface, wherein a resistance is provided to rearward movement of at least the bolt or bolt carrier.
    Type: Application
    Filed: August 17, 2006
    Publication date: July 29, 2010
    Inventors: Jeffrey Hajjar, Warren Stockton
  • Publication number: 20090308240
    Abstract: The invention relates to a breech for a repeating rifle with a breech guide, a locking chamber arranged in the breech guide, and a locking sleeve that is arranged concentrically about a rear part of the locking chamber and that has several locking elements that can be moved by an expansion device between an inner unlocked position and an outer locked position for engaging in a locking groove of a barrel. The expansion device has, according to the invention, a support sleeve that can move in the axial direction between the rear of the locking chamber and the locking sleeve.
    Type: Application
    Filed: June 8, 2009
    Publication date: December 17, 2009
    Applicant: BLASER FINANZHOLDING GMBH
    Inventors: Mathias KNEPPLER, Meinrad ZEH, Hans-Peter SCHWÄRZLER, Jürgen ROTHÄRMEL, Christian SCHERPF
  • Patent number: 7568422
    Abstract: A semiautomatic rifle has a housing defining a housing axis and containing a bolt assembly that reciprocates along the housing axis. The bolt assembly has a bolt carrier and a bolt, which reciprocates axially with respect to the carrier. A barrel is connected to the housing, and has a rear portion having a locking chamber that removably receives part of the bolt. An arm element interconnects the bolt carrier and the bolt, and operates to extend the bolt in response to rearward movement of the bolt carrier within the housing. The arm may be pivotally connected to the bolt carrier. The bolt may include a rod external of the bolt carrier, having a rear end contacting the arm, and a forward end contacting the rear of the barrel.
    Type: Grant
    Filed: September 28, 2006
    Date of Patent: August 4, 2009
    Inventor: Christopher Gene Barrett
  • Patent number: 7526990
    Abstract: A contact safety device between two mechanical parts mobile which respect to one another to guarantee the internal kinematics, by the release or activation of control means, wherein said device incorporates a safety unit connected to one of said two mechanical parts enclosing a probe activated by one of said two mechanical part and amplifying means constituted by an amplifying lever activated by said probe and an immobilizing lock activated by said amplifying lever meshed on said control means so as to transform a rectilinear micro-movement into a circular movement of large magnitude.
    Type: Grant
    Filed: November 14, 2006
    Date of Patent: May 5, 2009
    Assignee: CTA International
    Inventors: Michel Lenoble, Michel Baubois
  • Patent number: 7299737
    Abstract: A method and apparatus providing an action system for a firearm. The action system includes a primary roller-lock mechanism located rearward of an ejection port. The primary roller-lock mechanism includes a bolt and a first primary roller caged within the bolt. A bolt carrier ramp is attached to a bolt carrier. A barrel extension ramp is attached to a barrel extension. The first primary roller, bolt carrier ramp, and barrel extension ramp cooperate to effectively delay movement of the bolt and bolt carrier in response to firing of the firearm.
    Type: Grant
    Filed: December 3, 2004
    Date of Patent: November 27, 2007
    Assignee: Snake River Machine, Inc.
    Inventors: Jeffrey Hajjar, Warren Stockton
  • Patent number: 7287456
    Abstract: A breech system for a firearm exhibits a breech which can be locked in its movement in the barrel block by at least one locking element, which is pressed against the rear end of the barrel by means of a breech spring surrounding the rigid barrel of the weapon, the barrel being enclosed with the exception of the front and rear apertures, whereby the breech spring is supported at the rear section of the barrel and at least one link element subjected to tension connects the front end of the breech spring and the breech. In order to guarantee precise function and in a manner which is safe for the user, by means of a simple arrangement which is reproducible in manufacture, a purely mechanical delay element is inserted in the link between the breech (10) and the breech spring (9).
    Type: Grant
    Filed: July 26, 2005
    Date of Patent: October 30, 2007
    Inventor: Peter Spielberger
  • Patent number: 7047864
    Abstract: Firearm(s) with a breech lock are disclosed. One such firearm includes a first pivoting lever which, when actuated, releases the breech lock and a second lever, which when actuated also releases the breech lock. The first and second levers are located on opposite sides of the weapon.
    Type: Grant
    Filed: June 7, 2004
    Date of Patent: May 23, 2006
    Assignee: Heckler & Koch GmbH
    Inventors: Gerd Spinner, Helmut Weldle
  • Patent number: 6910404
    Abstract: A carrier assembly for a gun comprises a gun bolt carrier disposed to reciprocate axially with respect to the central axis of the gun, and a gun bolt disposed to reciprocate axially within the carrier. The gun bolt has a locking groove therein. The assembly also comprises a bolt locking mechanism extending through a portion of the bolt carrier to selectively engage the locking groove and thereby prevent the bolt from moving with respect to the carrier. The assembly further comprises a generally axial groove in a non-reciprocating portion of the gun that engages and selectively rotates the rotatable bolt locking mechanism to selectively lock the bolt to the carrier.
    Type: Grant
    Filed: May 13, 2003
    Date of Patent: June 28, 2005
    Assignee: General Dynamics Armament and Technical Products, Inc.
    Inventors: Peter C. Wolff, Peter A. Bates
  • Patent number: 6907814
    Abstract: Firearm(s) with a breech lock are disclosed. One such firearm includes a first pivoting lever which, when actuated, releases the breech lock and a second lever, which when actuated also releases the breech lock. The first and second levers are located on opposite sides of the weapon.
    Type: Grant
    Filed: August 23, 2002
    Date of Patent: June 21, 2005
    Assignee: Heckler & Koch, GmbH
    Inventors: Gerd Spinner, Helmut Weldle
  • Patent number: 6810613
    Abstract: This invention concerns a supplementary safety device in the form of a false cartridge to be inserted into the chamber of a light firearm barrel, including a radially expandable portion controlled by a lock operated by a specific key for locking/unlocking it in the barrel in which it is housed, so it may be removed only voluntarily.
    Type: Grant
    Filed: May 10, 2002
    Date of Patent: November 2, 2004
    Assignee: Fabbrica D'Armi Pietro Beretta S.p.A.
    Inventor: Ugo Gussalli Beretta
  • Patent number: 6708437
    Abstract: An apparatus for loading a cartridge into a cartridge chamber of a firearm is provided. The apparatus includes a barrel, and a bolt assembly mounted for movement from a rear position to a forward position to advance a cartridge into the cartridge chamber. The bolt assembly includes a center axis which is not in coaxial alignment with the center axis of the barrel when the bolt assembly is in the rear position. The bolt assembly further includes a bolt head defining a percussion recess. The percussion recess is dimensioned to receive a proximal end of the cartridge with clearance to permit transverse movement of the proximal end of the cartridge relative to the percussion base. The firearm also includes a locking piece adjacent the cartridge chamber for centering the bolt head as the bolt assembly moves from the rear position toward the forward position such that the center axis of the bolt assembly is substantially coaxially aligned with the center axis of the barrel.
    Type: Grant
    Filed: August 28, 2001
    Date of Patent: March 23, 2004
    Assignee: Heckler & Koch, GmbH
    Inventor: Johannes Murello
  • Publication number: 20040035286
    Abstract: Firearm(s) with a breech lock are disclosed. One such firearm includes a first pivoting lever which, when actuated, releases the breech lock and a second lever, which when actuated also releases the breech lock. The first and second levers are located on opposite sides of the weapon.
    Type: Application
    Filed: August 23, 2002
    Publication date: February 26, 2004
    Inventors: Gerd Spinner, Helmut Weldle
  • Patent number: 6622609
    Abstract: Disclosed is a breech mechanism with a non-rotating breechblock that is suitable for use with repeating firearms. The present invention is composed of relatively few moving parts, and each of the parts is itself simple, yet together they become an elegant solution to the problem providing a repeating firearm which minimizes damage the ballistic characteristics of the bullet as the bullet is inserted into the chamber of the firearm. The present invention, then, provides a repeating firearm substantially with the accuracy of a single shot manual loading firearm with a non-rotating breechblock.
    Type: Grant
    Filed: November 20, 2002
    Date of Patent: September 23, 2003
    Assignee: Spearfire Ltd.
    Inventor: Shai Barkan
  • Patent number: 5854440
    Abstract: A shoulder-launched multi-purpose assault weapon having a modified spotting ifle with a top-mounted electrically fired rocket launcher tube is provided. The spotting rifle forms the base structure of the weapon and all weapon controls are located on the rifle. The rifle has several dual-function mechanisms which perform the combined functions of assembly and safing, bolt-locking back and cartridge ejecting, simultaneous adjustment of both open and optical sights, firing, selectively, of both the spotting round and the electrically fired rocket round. The combination of these dual-firing mechanisms provides a lighter weight, better-balanced and smaller weapon. The reduction in parts count improves reliability and lowers cost. Other improved features include an adjustable spotting rifle barrel used to match the boresight of the rocket tube and an improved locking mechanism. A dual function trigger assembly operated two sears from a single trigger.
    Type: Grant
    Filed: June 20, 1996
    Date of Patent: December 29, 1998
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Michael M. Canaday, Fred W. Watson, Jr.
  • Patent number: 5710389
    Abstract: A breech bolt and lock assembly for a gas-operated firearm is provided. The ssembly is contained within a bolt housing which in turn contains a bolt operating spring and a two-part bolt mechanism. The two-part bolt has a cylindrical outer bolt which encloses the inner bolt and firing pin. A second spring operates the firing pin. During firing, the inertia of the firing pin and inner bolt prevents the sudden rearward movement of the discharging cartridge. There is no other locking of the breech, however, the weight of the inner bolt and pin assembly may be changed to accommodate different propellant loads.
    Type: Grant
    Filed: August 14, 1995
    Date of Patent: January 20, 1998
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Michael Canaday
  • Patent number: 5259137
    Abstract: The breech mechanism for a firearm is provided with a breech housing, a locking head connected to the barrel and having a radially inwardly directed conical locking shoulder oriented rearwardly of a cartridge carrier, and a substantially cylindrical breech block movable relative to the breech housing in a direction toward and away from the barrel. A locking sleeve concentrically surrounding the breech block and axially slidable relative thereto to a limited degree, is divided at its front end by a plurality of longitudinal slots into a plurality of spring tongues and carries at the free, front end of each spring tongue a locking element formed in one piece therewith and in the form of an annular segment. Each locking element has a radially outwardly directed cone segment bearing on the locking shoulder in a locking position and having on its front end a radially inwardly directed cone segment with which it bears on a spreading cone arranged in the vicinity of the front end of the breech block.
    Type: Grant
    Filed: August 3, 1992
    Date of Patent: November 9, 1993
    Assignee: Horst Blaser Jagdwaffenfabrik
    Inventors: Gerhard Blenk, Meinrad Zeh
  • Patent number: 5164534
    Abstract: A secondary recoil absorption mechanism absorbs some of the recoil energy associated with the firing of the firearm. The secondary recoil absorption mechanism includes a roller mounted on the breech block to engage a ramp element pivotally mounted on the frame of the firearm. The ramp element includes a rounded corner against which the roller abuts. The ramp element is connected to a cocking lever by a roller mounted in a guide groove defined on a cocking lever. The cocking lever is moved manually to move the ramp rounded corner out of the path of movement of the breech block mounted roller and to move the breech block into a cocked position held behind a sear. The guide groove includes a plurality of sections.
    Type: Grant
    Filed: February 19, 1992
    Date of Patent: November 17, 1992
    Inventor: John L. Royster
  • Patent number: 4977815
    Abstract: An automatic machine pistol is provided, which is not subject to fouling, which is compact and light while incorporating a pneumatic recoil buffer, which resists muzzle climb, and which can be accessed and cleaned without disassembly. The machine pistol is comprised of a reciprocating bolt within a housing of the pistol. The reciprocating bolt is carried within the housing on four rails by eight roller bearings. No sliding contact is made between the bolt and any other portion of the pistol. A portion of the high pressure gas from the barrel is bled through a bleed hole in the barrel block or barrel into a gas port tube which is telescopically inserted into the bolt. The gas port tube delivers the portion of the discharge gas in a forward direction in opposition to the motion on recoil. An upwardly directed nozzle is communicated to the receiving bore within the bolt.
    Type: Grant
    Filed: May 5, 1989
    Date of Patent: December 18, 1990
    Inventor: Mark L. Stephens
  • Patent number: 4579037
    Abstract: A machine pistol with means for retarding blowback of the slide assembly. The device has both right hand and left hand stocks to enable the weapon to be fired from a comfortable visual sighting position at eye level with the wrist axes perpendicular to one another. The slide assembly includes a bolt that carries the firing pin, extractor and ejector and that reciprocates relative to the receiver and barrel, and a tubular cylindrical muzzle sleeve removably connected to the forward end of the bolt and that fits coaxially around the barrel. A coaxial helical spring fits between the barrel and muzzle sleeve to urge the muzzle sleeve (and bolt) to the forward firing position wherein the forward end of the muzzle sleeve extends outwardly beyond the end of the barrel.
    Type: Grant
    Filed: February 13, 1984
    Date of Patent: April 1, 1986
    Assignee: Weapon Technology Systems R & D, Ltd.
    Inventor: Richard R. Gillum
  • Patent number: 4227439
    Abstract: Anti-bounce apparatus for an automatic cannon reciprocating bolt assembly which includes a bolt, a bolt carrier and bolt mounted locking lugs, comprises means defining engagement surfaces contoured for enabling the forward moving carrier to cam the lugs into bolt locking relationship with a cannon breech at increasing velocity, without bouncing, carrier energy loss being thereby minimized and firing of a chambered shell by a carrier mounted firing pin being assured. Further comprising the anti-bounce apparatus is a plurality of inertially actuated locking collets connected to the bolt carrier for causing, responsive to impact of the carrier with the breech at the instant of firing, frictional locking between the carrier and portions of the cannon fixed to the breech, rearward bouncing of the carrier relative to the locking lugs, with consequent premature or erratic bolt unlocking, being thereby prevented.
    Type: Grant
    Filed: March 27, 1979
    Date of Patent: October 14, 1980
    Assignee: Ares, Inc.
    Inventor: Richard R. Gillum
  • Patent number: 4066000
    Abstract: An automatic weapon incorporating a retarded blow back, a cartridge and bolt centering assembly, light weight and minimum component construction, simplicity in disassembly, easily detachable barrel, unique belted ammunition feed system, disposable ammunition box, a guide buffering assembly, muzzle brake, remote firing capability, front sight charging system and a bulkhead recoil absorbing arrangement.
    Type: Grant
    Filed: April 25, 1974
    Date of Patent: January 3, 1978
    Assignee: Brunswick Corporation
    Inventor: Charles Edward Rostocil
  • Patent number: 4024793
    Abstract: A clamp and wedge attachment to fixed and moving components frictionally ages the components which become disengageable upon application of overriding forces. The wedge has an enlarged detachable loading end which fits between two tines of the clamp which acts as flexure springs. This structure eliminates the slide bounce problem encountered in adapting the M39, 20MM Automatic Revolver Cannon to a constant recoil mode of operation.
    Type: Grant
    Filed: October 8, 1975
    Date of Patent: May 24, 1977
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Edward R. Larrison, Ray O. Reade
  • Patent number: 3990346
    Abstract: An improved gas locked firearm using expanding gases to force a bullet through a barrel in which a portion of said gases are diverted through a gas port communicating with a gas locking chamber adjacent said barrel which chamber is formed between said barrel and an extension arm of the bolt or breech block extending forward therefrom a distance along the rear portion of the barrel and forming an elongated gas chamber between a shoulder on the rear of the barrel and a plate extending from said breech block extension in a manner to trap the expanding gases between said barrel shoulder and said plate to lock the breech block in a forward position while gas pressure exists in the barrel and provided with additional gas ports in the breech block extension and plate to vent remaining gases as the firearm action cycles.
    Type: Grant
    Filed: February 18, 1975
    Date of Patent: November 9, 1976
    Inventor: Robert M. Irwin