| 摘要 |
<p>A novel trigger mechanism for a crossbow is disclosed, in which a relatively large mechanical advantage is employed to obtain reduced trigger pressures in comparison with trigger pressures in the prior art. The mechanism has two main components, namely a trigger and a catch, pivotally mounted in a case which is in turn mounted in the crossbow stock. The trigger has a trigger arm extending downwardly from the trigger pivot point and out of the case, and a sear arm extending forwardly and having a rearward-facing sear surface. The catch is installed with its pivot point slightly above the plane of a bowstring entry area in the case, and thus slightly above the plane of the bowstring. The catch has a bowstring-retaining hook portion extending forwardly from the catch pivot point, and a catch arm extending downwardly from the catch pivot point and terminating in a forward-facing sear surface, which is engaged by the sear surface of the trigger sear arm when the crossbow is armed. By virtue of a relatively high mechanical advantage in the catch, of about 4.5 to 1, combined with the mechanical advantage in the trigger and with lubrication and/or polishing of the sear surfaces, low trigger pressure is achieved. The trigger pressure is augmented by means of a spring installed between a portion of the case and the trigger.</p> |
