A drive ram for use with a medical fluid injector may include a central, longitudinal reference axis. First and second gripper members may be pivotally interconnected with a plunger engaging end of the drive ram. Each of the first and second gripper members may be pivotable about a common pivot axis that intersects the reference axis. Each of the gripper members may further include a first end that is remote from the common pivot axis. In some embodiments, the first and second gripper members may be pivotable between a first position and a second position. In the first position, the first ends of the gripper members may be spaced apart by a first distance, while in the second position, they may be spaced apart by a second distance that is greater than the first distance.