| 摘要 |
A gun sight positioning mechanism (22) disclosed includes a parallelogram linkage for moving a gun sight positioning shaft angularly with a trunnion shaft (32) on which a gun is supported and has a slip clutch (44) that connects the linkage to one of the shafts so that the sight can be aimed downwardly at the target area while the gun remains aimed upwardly along the projectile path. Preferably, the slip clutch connects the linkage to the gun sight positioning shaft and includes a stop (56) that allows the sight to be aimed upwardly back into alignment with the gun after viewing the impact. First and second links (46,52) of the linkage are respectively connected to the trunnion and sight positioning shafts and interconnected by a connecting link (54) whose length is adjustable to insure the proper angular movement of each shaft with the other. A mount of the slip clutch has a flanged end secured to the sight positioning shaft and a distal end on which a handle (58) is secured to provide the pivoting of the sight shaft independently of the gun. A spring washer of the clutch biases a brake member thereof against the second link which is thereby engaged with the flanged end of the mount to provide the slip clutch action.
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