| 摘要 |
834,835. Trigger mechanisms STERLING ENGINEERING CO. Ltd. April 2, 1958 [April 30, 1957], No. 13729/57. Class 119 A trigger mechanism in which a change-fire device determines the operating position of a sear 5 capable of longitudinal movement in respect of a trigger 2, including disconnection therefrom due to an interposed spring 8, has a second spring 10 mounted independently of the trigger to assist the first spring in moving the sear consequent on release of the trigger. The sear 5 has an elongated hole 7 to house its pivot and a step 4 engaging a step 3 on the trigger. The spring 8 has a plunger 9 which contacts perpendicularly a flat on the trigger. The change-fire device can be rotated to any of three positions and retained there by a spring 16; an abutment 14 being brought opposite to a face 17, a recess 19, or a face 18 of the sear corresponding respectively to "safe", "semi-automatic" and "automatic". Depending on the position of the abutment 14 the sear is either locked with its tip 20 in a bent in the bolt; or the sear is unaffected by it, and is pushed back by the spring 8, to disengage the step 4 from the step 3 on the trigger; or the sear is held to retain the steps 3 and 4 continually in contact. The second spring is on a rod 11, pivoted to the sear at 12 and to the frame at 13. It reinforces the spring 8, which is inadequate alone to re-engage the tip 20 in the bent at "semi-automatic". To avoid transferring impact between the bolt and sear to the trigger at "automatic" the steps 3 and 4 are made to lie below a line 23 joining the pivots 6 and 22 of the trigger and sear.
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