The reason is a unique bronze gate wedge that's shaped like a block instead of round like all other gates.
原因在于这种独特的青铜闸阀楔板形状上如同方形阻断闸门，而不象其它类型的闸阀。
2
Meanwhile, the wedge-shaped design of the fixture block can play the role of self-locking, and thus causing the moving and static contacts to be steadily contacted.
同时，卡块的楔形设计能起到自锁的作用，使动静触头能够稳定接触。
3
The bottom of the disc is made of knife-shaped gate with a cut off function of the medium. When gate is closed, oblique plane of gate valve encounters wedgeblock of gate to achieve sealing effect.