In accordance with a principle which is becoming more and more widespread, a revolver crane comprises a shaft pivotally mounted to the frame of the revolver and capable of swinging parallel to the axis of the barrel between a closed position in which the axis of the cylinder lies in the plane of symmetry of the revolver, and an open position in which he chambers of said cylinder are disengaged for loading or ejecting ammunition.
The invention relates more particularly to the problem of retaining the crane when it is no longer in the closed position, with such retention being necessary to prevent the crane together with the cylinder it carries from escaping forwardly by virtue of the crane shaft sliding in the associated housing provided in the frame of the revolver.
Numerous solutions have already been proposed for solving this problem, and typical retaining devices for performing this function are recalled briefly below.
The most traditional solution used for retaining the crane axially consists in machining a circular groove in the vicinity of the free end of the crane shaft, with an add-on member then being provided to penetrate into the groove and retain the crane without preventing it from pivoting.
The retaining member is frequently a transversely disposed dog point screw, with the end of this stop screw engaging in the circular groove, thereby providing a crane-retaining function.
This solution turns out to be not very satisfactory since the retaining screw can become loose; in addition it constitutes a visible part and a considerable amount of machining still needs to be done.
In a variant, the stop screw is replaced by a tab moveable transversely to the axis of the crane, said tab being mounted to rock or to slide, and being subjected to tab action of a spring for keeping it in position. Such a system is illustrated, for example, in French patent number 2 487 062. This naturally suffers from the same drawbacks as the preceding system.
In other revolvers, a removeable trigger guard assembly is provided including a portion of the trigger mechanism. In this case, the tenon of the trigger guard is used for acting as the retaining member with the end of said tenon engaging in a circular groove (of trapezoidal cross-section) machined near the free end of the crane shaft.
This solution suffers from major drawbacks, of which the most important is the complication involved with the operation of dismantling the crane, since the trigger guard must necessarily also be dismantled.
Proposals have also been made for revolvers having barrels with threaded ends and surrounded by respective sleeves (for a revolver having interchangeable barrels with associated sleeves), whereby the rear portion of each sleeve is extended downwardly: this serves to define a thrust face such that there is always a portion thereof making contact with the front face of the crane. This system suffers from the drawback of requiring a special sleeve with a rear face that must be machined to within close tolerances. In addition, whenever the crane needs to be dismantled, it is naturally necessary to remove the sleeve first.
Other prior systems may also be mentioned to complete the state of the art.
U.S. Pat. No. 2 958 151 describes a revolver whose crane is removeable sideways by pushing in a stud acting as a pivot pin for the crane. U.S. Pat. No. 975 685 describes a rotary stopper mounted at the rear of the barrel and coaxially thereabout, with one of the two angular positions of said stopper allowing the crane shaft to be released. U.S. Pat. No. 678 274 describes a revolver in which the crane shaft is prevented from rotating, with the crane being retained longitudinally by the head of a screw mounted at the end of said shaft.
Finally, mention may also be made of prior art systems in which there is no stopper associated with the crane, as illustrated by U.S. Pat. No. 1 518 027.
The object of the invention is to provide a crane retaining device which is more effective than the prior art devices described above, which is simpler in structure and cheaper to obtain, and which allows the crane to be dismantled easily without interfering with the axis of the cylinder being accurately positioned when the crane is in the closed position.