Car top carrier with quick release clamping device

A cargo carrying case for rooftop mounting on a motor vehicle having a pair of crossbars, comprising

• a box having a floor,
• at least one clamp device mounted under the floor of the box, the clamp device having an open position configured for receiving a crossbar, and a closed position configured for firmly grasping the crossbar, and
• at least one lever structure mounted inside the box, the lever structure being moveable between a first position and a second position, the lever structure being connected to the clamp device so that movement of the lever structure from the first position to the second position causes the clamp device to move from the open position to the closed position, thereby securing the box on the crossbar, wherein the clamp device includes a jaw structure having a stationary upper portion and a pivoting bottom portion that moves toward the upper portion when the lever structure is moved from the first position to the second position.