US Patent 7444749 rotary knife

A rotary knife apparatus has first and second protecting strips placed on both sides of a joint end of a blade of the rotary knife, and two protecting strips placed on the same base tube as a rotating point. A bi-fork braking component is used to control its opening. A toggle control component is placed on one end of the bi-fork braking component that faces the direction of a grip, and the end faces a joint end has a first and second acting fork. The first and second acting forks are connected to the first and second protecting strips so that the toggle control component can be moved back and forth to drive the two protecting strips close and separate.