Pocket Knife - Lock-blade Knives

Knives with locking blades, often referred to as lock-blade knives or clasp knives, have a locking mechanism that locks the blade into its fully opened position. This lock must be released in a distinct action before the knife can be folded. The lock-blade knife improves safety by preventing accidental blade closure while cutting. It is this locking blade feature that differentiates the lock-blade knife from either the peasant knife or the slipjoint spring-back knife.

Lock-blade knives have been dated to the 15th century. In Spain, one early lock-blade design was the Andalusian clasp knife popularly referred to as the navaja. Opinel knives use a twist lock, consisting of a metal ferrule or barrel ring that is rotated to lock the blade either open or closed. In the late 20th century lock-blade pocket knives were popularized and marketed on a wider scale. Companies such as Buck Knives, Camillus, Case, and Gerber, created a wide range of products with locks of various types. The most popular form, the lockback knife, was popularized by Buck Knives in the 1960s, so much that the eponymous term "buck knife" was used to refer to lockback knives that were not manufactured by Buck.

The lockback's blade locking mechanism is a refinement of the slipjoint design; both utilize a strong backspring located along the back of the knife. However, the lockback design incorporates a hook or lug on the backspring, which snaps into a corresponding notch on the blade's heel when the blade is fully opened, locking the blade into position. Closing the blade requires the user releasing the blade to apply pressure to the bar spring located towards the rear of the knife handle to disengage the hook from the notch and thus release the blade.

The Walker Linerlock and the framelock came to prominence in the 1980s. In both designs the liner inside the knife is spring-loaded to engage the rear of the blade when open and thus hold it in place. In the case of the framelock, the liner is the handle, itself. The Swiss Army knife product range has adopted dual linerlocks on their 111 mm models. Some models feature additional "positive" locks, which essentially ensure that the blade cannot close accidentally. CRKT has patented an "Auto-LAWKS" device, which features a second sliding switch on the hilt. It can operate as any liner-lock knife if so desired, but if the user slides the second control up after opening, it places a wedge between the liner-lock and the frame, preventing the lock from disengaging until the second device is disabled.