Patent attributes
A lock includes a cylinder, a cylinder plug and a locking pin assembly. The cylinder plug is rotatably mounted in the cylinder and has a dummy keyhole and a cylinder plug keyhole defined completely through the cylinder plug. The locking pin assembly has multiple locking pins that are slidably partially held in the cylinder plug keyhole. A two step method to open the lock with a key with serrations initially inserts the key serrations into and presses the key serrations completely through the dummy keyhole. Then the serrations are rotated, aligned with and pulled back into the cylinder plug keyhole. Conventional displacement of the locking pins allows the cylinder plug to be rotated, which opens the lock. Pressing the key completely through the lock removes any foreign objects such as toothpicks, chewing gun or pieces of paper and allows the lock to be opened.