The Emhart high security locking system was patented in 1978 and uses rotating pins to achieve an interlocking action between the driver (top) and key(lower) pins. The key’s cuts are on angles, similar to that of Medeco’s keys (the exception being Medeco’s keys are skewed at 15 degrees, while Emhart’s are 20 degrees) Below is an Emhart key.

 The interlocking action is accomplished by having a protrusion on the driver pin that locks into a notch on the key pin. When the key is inserted, the keys pins are lifted until they reach the shear line, and at the same time, the pin stacks rotate until the notch in the key pins and the protrusion on the driver pin are parallel to the face of the lock. Once the rotation has been achieved, the driver and key pins are allowed to separate. The protrusion on the driver pin slides into the unique, ribbed plug. Since the plug is ribbed, and the driver pins stay in the plug while the key is being turned, this lock cannot be opened by shimming, and a plug follower cannot be used during disassembly. The springs and pin stacks must be extracted from the top of the lock first, and then the plug may slide out. Below is a picture of the pin stacks and key from an Emhart lock.

Below is a photo of the Emhart plug and pins with the key in the lock.

The Emhart lock is protected against drilling and picking. I have never heard of an Emhart lock being picked, and I have not seen a decoder or opening tool for this lock. This lock, if picked, also presents a problem when relocking the lock. For the pin stacks to reconnect, all of the pins must be held to their proper elevation and rotation during the turning of the plug. If the lock is picked, one must devise a way to keep the pins at their proper elevation and rotation. If the pins are not held in place during the picking, the lock may not function, and the entry will not be surreptitious.