A clamping device includes a rotatable element disposed between a jaw and a jaw support. The rotatable element has a slanting surface, interfacing a roller, and thus is configured to push the jaw toward an opposite jaw of the clamping device when rolling in a clamping direction. An auto lock mechanism is included in the clamping device, which can secure the rotating element for keeping the jaws separated. The auto lock mechanism can be activated or deactivated when the jaws are separated at a maximum or near maximum separation.