A traditional nail puller has two sharp jaws which can be hit into the wood to reach nails which are difficult to remove. The jaws penetrate the wood and grip underneath the nail head, around the shaft of the nail.
The base heel on the jaws then works as a lever to close the jaws around the nail. The more force applied on the pivot point, the tighter it should grip the nail.
The nail puller is leveraged over, on the pivot point and the nail is pulled out by the gripping jaws. As soon as the tension on the pivot point is loosened, the jaws will open again and release the nail.
