US Patent 7249417 Pocketknife with a safety lock

A pocketknife has a handle, a blade, a safety lock and a spring. The handle has a blade seat, a cover, a cavity, a slide slot, a passage and a pivot slot. The blade is mounted pivotally in the cavity and has a proximal end, two opposite edge and two wheels. The wheels are attached respectively to the edges of the blade, and one wheel has an engaging element. The safety lock is mounted slidably in the handle and has a slide and a latch. The slide is mounted slidably in the slide slot. The latch engages detachably the engaging element in the locking wheel on the blade. The spring is mounted in the slide slot in the handle and presses the safety lock so that the latch on the slide engages the engaging element to securely hold the blade when the blade is open or closed.