Powder-actuated fastener-driving tool

A power-actuated fastener-driving tool of the type comprising:

• (a) a housing having a first opening therein;
• (b) a barrel and cylinder assembly disposed in said first opening and adapted for reciprocal movement in said housing, said barrel and cylinder assembly comprising (1) a hollow barrel, and (2) a hollow cylinder member detachably secured to said barrel and having first and second longitudinally extending grooves, said barrel being secured to said cylinder member so that the two members act as a single unit;
• (c) a piston assembly slidably disposed within said barrel and cylinder assembly;
• (d) a cylinder stop assembly comprising projecting means normally extending into said first groove in said cylinder member so as to limit the longitudinal and rotational travel of said barrel and cylinder assembly realtive to said housing;
• (e) a breech block assembly mounted in a second opening in said housing that communicates with said first opening, said breech block assembly comprising a breech block having a central chamber, a bore, guide means in said block for slidably receiving a strip of powder-filled cartridges, and detent means for releasably holding said strip in said breech block;
• (f) a firing pin housing mounted in said second opening in said housing in back of said breech block, a hole in said firing pin housing extending parallel to said barrel and intersecting said central chamber, a firing pin mounted in said hole, and spring means yieldably restraining said firing pin so as keep it out of said central chamber until a suitable force is applied to said firing pin;
• (g) a firing mechanism comprising a firing actuator, a firing actuator support slidably mounted in a support chamber in said housing and slidably supporting said actuator, said support chamber comprising an end wall separating said support chamber from said firing pin housing, first spring means biasing said actuator toward said end wall, second spring means biasing said actuator for movement toward said end wall relative to said firing actuator support, latch means for locking said actuator to said firing actuator support, spring means normally biasing said latch means into locking relation with said actuator, and a push rod attached to said support means, said push rod extending through an opening in said end wall and said breech block bore and contacting said cylinder so that movement of said barrel and cylinder assembly in a rearward direction within said housing will cause said push rod to move said support means in a rearward direction so that said firing actuator will be capable of applying a force to the rear of said firing pin if said latch means is then released to unlock said actuator;
• (h) trigger means for releasing said latch means, said trigger means comprising (1) a trigger movably mounted to said housing, said trigger having a front section for operator engagement, a rear section formed with a first round depression, and a middle section integrally connecting said front section and said rear section, said middle section being bifurcated so as to allow said strip of cartridges to pass therethrough, (2) a pivot pin mounted to said housing, (3) a lever movably mounted to said pivot pin and adapted for movement toward and away from said firing mechanism, said lever having a second round depression, (4) a dowel pin mounted to said housing, (5) a torsion spring coupled to said lever and said dowel pin and adapted to urge said lever away from said firing mechanism, and (6) a trigger push rod releasably engaged with and extending between said trigger and said lever, said trigger push rod constituting a rod with rounded ends seated in said first and second depressions and retained there by the force exerted by said torsion spring on said lever, whereby when said trigger is pulled said lever will (a) engage and release said latch means if said actuator support is held back by said cylinder, whereby to cause said firing actuator to propel said firing pin forward to fire a powder-filled cartridge disposed in line with said cylinder member, or (b) engage and be blocked by said actuator support if said actuator support is forward against said end wall;
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• (i) a cartridge advance mechanism comprising a cam, a pawl and a spring, said cartridge advance mechanism being adapted to advance a strip of powder-filled cartridges along said guide means in said breech block so as to position a cartridge in firing position adjacent said cylinder and said firing pin as said cylinder and barrel assembly is reciprocated.