Sperrklinken-Mechanismus für chirurgische Instrumente

Releasable ratchet mechanism for medical instruments such as endoscopic instruments are disclosed. The ratchet (412) mechanism includes: a leaf spring (400) with a locking barb which is located on a handle (85) of the medical instrument; a ratchet (499) on a lever arm (75) of the medical instrument which lever arm (75) is pivotally engaged to the handle (85); and a latch (440) on the handle (85) of the medical isntrument. The latch (440) on the handle (85) engages and resiliently deforms the leaf spring (400) to cause engagement of the locking barb (412) in a groove (418) of the ratchet (499) when the latch (440) is in a first position. When in a second position, the latch (440) releases the locking barb (412) from the ratchet groove (418). Preferably, the locking barb (412) has an extending edge surface on an axis which is substantially parallel to the pivoting axis (80) of the handle (85) and lever arm (75), and the teeth (419) of the ratchet (499) have extending edge surfaces on axes substantially parallel to the extending edge surface of the locking barb (412). Also, preferably, the edge surfaces of said teeth (419) of the ratchet (499) are located along an arc (D) of a cylinder having the handle/lever arm pivot axis (80) as its center line.