Exploded Diagram of the Ancient Bronze Crossbow Trigger Mechanism

Rear Sight
original: zhaomen (照門), literally "shining gate." This is the rear sight used to align the eye with the front sight and the target.

The Hook
The darkened area indicates the bronze barb within the hook and the stop-arm fork opening. When joined, the mechanism moves with divine fluidly, like a winch original: qulu (屈鹿), literally "bent deer," a technical term for a mechanical crank or winding device..
original: gou (鉤). In crossbow terminology, this is often called the "nut" or "tooth"—the component that catches and holds the string under tension.

The Housing
original: xia (匣). The bronze casing or "trigger box" that holds all the internal components in place within the wooden stock.

Trigger Lever
original: boji (撥機). The actual lever pulled by the finger to initiate the shot.

Intermediate Sear
This fork opening fits onto the axle pin above the hook; move this forward and backward to toggle the release.
original: dianji (墊機). A secondary internal lever that reduces the weight of the trigger pull, allowing a heavy draw-weight to be released with minimal finger pressure.

Axle Pins
original: jian (鍵). The bronze bolts or pins that act as pivot points for the internal moving parts.