Abstract: A rooftop drag reducing device includes a lower base portion fixedly mounted to the roof of a truck for semi-trailers. An upper portion of the drag reducing device is selectively movable relative to the base portion between a fully extended operating position, and a fully retracted storage position. In the fully retracted position, the upper portion is received within the lower portion such that at least part of the top surface of the lower portion is above the top surface of the upper portion. The design in accordance with the present invention increases the overall stability of the drag reducing device in both the extended and retracted positions, provides enhanced protection for the upper portion in its retracted position fully received within the lower portion, provides greater clearance than is possible with known drag reduction devices, and increases the maximum elevation within the cab or sleeper compartment of the vehicle to which the drag reduction device is mounted.

Abstract: A roof top drag reducing device includes a lower base portion mounted to or formed integrally with the roof of a truck for semi-trailers. An upper portion of the drag reducing device is selectively movably mounted relative to the lower base portion between a first elevated operative position atop the lower base and a second non-operative retracted position generally forward of and below the lower base portion. The top portion of the drag reducing device will be in its elevated operative position when a trailer is attached to the truck and reduction of air resistance over the trailer is desired. The top portion of the drag reducing device will be in its forward non-operative position, when, for example, several cabs are being towed and transported together from one location to another. If the lower base portion is formed integrally with the roof of the truck, the lower base portion can form the ceiling of a sleeper compartment or area of the truck to significantly increase the height of the sleeper area.

Abstract: The rooftop drag reducing device comprises a top and a bottom and may be mounted to the cab of trucks for semi-trailers at the factory. The device may then be conveniently collapsed with the top fitting inside the bottom when multiple trucks are shipped with the second and third truck, for example, having their front wheels mounted to the fifth wheel of the truck in front of them. Since the drag reducing device has had its height reduced it will pass under low bridges.The device is initially integrally molded in one piece and cut into the top and bottom portions along a oblique cut line step. The top may be left connected to the bottom at the front to form a living hinge. Alternatively, a piano hinge may be used to connect the top and bottom portions at the front thereof. Bolts along the sides are used to hold the top in its upright position. These bolts pass through stepped side flanges which strengthen the device.The rear of the top is closed to form a rigid box-like structure to resist sway.