in a gripper mechanism for devices for handling objects in the form of sheets or plates , simple and easy operability of the gripper claws of pivoting gripper arms into the open position for adjustment purposes , test purposes and the like is achieved in that a manual operating element made of plastic is connected in the gripper claw operating drive between an operating lever which is mounted on the relevant gripper arm such that it can pivot , and a coupling linkage which is connected to one of the gripper claws which can pivot , and this manual operating element can pivot on the operating shaft of the gripper claw operating drive in such a manner that the claw can be caused to open easily while the machine is at rest , without any risk of injuries .