Double linkage triggering system used for crossbow

1. A double linkage triggering system used on a crossbow, characterized in that, said triggering system includes a main body, which is composed of a trigger unit and a shooting unit, wherein the trigger unit and shooting unit are separately mounted to the crossbow;

the trigger unit comprises:

a bracket body, a trigger block, a hammer, a trigger power-adjusting bolt, a triggering mechanism and a trigger-safety device;

the hammer is hinge connected to the bracket body and the triggering mechanism is configured to rotate the hammer from a starting position to a firing position;

the trigger block is hinge connected to the bracket body and each end of the trigger block is respectively limited by the hammer and the trigger power-adjusting bolt;

the triggering mechanism and trigger power-adjusting bolt are located in the bracket body;

the trigger-safety device includes a rotating block and a shifting block;

the rotating block is connected with the shifting block by a bolt and is hinge connected to the bracket body, wherein, the rotating block is counterbalanced to the hammer, and,

the shifting block is arranged outside of the bracket body;

the shooting unit comprises:

a sight stand, a guide device, a pressure plate, a rotary latch, a roof plate, a latching plate, a returning device, and an anti-empty shooting mechanism;

the returning device is inserted into the roof plate and is counterbalanced to the latching plate, and furthermore,

the roof plate is hinge connected to the latching plate and a positioning groove is formed on a front end of the latching plate, wherein the triggering mechanism is configured to move the hammer of the separately mounted trigger unit to pivot the latching plate of the separately mounted shooting unit;

both of the sight stand and the rotary latch are hinge connected to the roof plate, wherein the rotary latch is located at an interior of the sight stand and two contacting surfaces are formed between the rotary latch and the roof plate at an angle of 120° to 160° and any angle therebetween; and

the guide device and the pressure plate are further provided on the sight stand.

2. A double linkage triggering system used on a crossbow according to claim 1 , characterized in that, said triggering system further includes the anti-empty shooting mechanism, further comprising an arrow placing device, a stopblock and a positioning spring;

an arrow slot is formed on the front end of an upper surface of the arrow placing device;

a sliding groove is located on a middle section of the arrow placing device;

a mounting block and a positioning pin are located on a distal end of the arrow placing device;

the positioning pin is surrounded by the positioning spring and is contacted with the roof plate;

the mounting block is inserted into the roof plate;

the stopblock, with a side face having a fixing groove and a lower surface configured by both a wedge-shaped sliding surface and a horizontal fixing surface, is hinge connected to the rotary latch.

3. A double linkage triggering system used on a crossbow according to claim 1 , characterized in that, the triggering mechanism includes a triggering pin and a triggering spring, wherein the triggering pin is surrounded by the triggering spring.

4. A double linkage triggering system used on a crossbow according to claim 2 , the returning device consists of a returning pin and a returning spring, wherein the returning pin is surrounded by the returning spring.

5. The double linkage triggering system of claim 1 , further comprising a shooting unit that is separate from the trigger unit.