Fluid-pressure and analogous brake systems – Locks
Reexamination Certificate
1999-12-02
2002-01-15
Rodriguez, Pam (Department: 3613)
Fluid-pressure and analogous brake systems
Locks
C303S123000, C180S287000
Reexamination Certificate
active
06338534
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
The present invention principally relates to theft prevention systems for trailers, particularly those used in a over-the-road tractor-trailer vehicle combination commonly referred to as an “18-wheeler”. These trailers are almost universally provided with pneumatic braking systems which include a parking/emergency brake with brake shoes or other braking elements urged to the braking position by spring means in the absence of pneumatic pressure supplied to the braking system.
In this common arrangement, a parked trailer, being disconnected from the tractor vehicle with its source of air pressure will have its parking/emergency brakes (hereinafter simply “parking brakes”) urged to fill braking position preventing the trailer from rolling or being moved. However, the commonly provided system can be moved by any standard tractor vehicle having the usual air hose and electrical connections for a trailer. Once the alien tractor is connected with its air hoses to the trailer and the trailer braking system is pressurized, the parking brakes air pressure causes the spring forces to be overcome so that the parking brakes are no longer applied.
Numerous expedients have been employed to prevent or deter theft of a parked trailer, including systems which require some action in addition to connecting air pressure to the pneumatic brake system to release the parking brakes. Some of the theft deterrent systems incorporate a solenoid valve in the appropriate air line between the tractor and the trailer rear wheels and have a key lock switch or other device required to energize the solenoid. The valve will open when the key switch is closed to allow air pressure from the tractor to release the brakes on the wheels of the trailer (as it would if the valve were not present). These prior systems typically drew current for the solenoid from the electrical cable providing power to the trailer lights, and thus some portion of the conductors of that cable needed to be connected and energized, but this in itself was not an anti-theft feature since this would occur in the course of normal procedure by the truck driver.
Systems as described above are shown, for example, in U.S. Pat. No. 4,793,661 and U.S. Pat. No. 4,712,422 to Dougald, G. Munro. In these patents, the theft of the trailer is deterred by operation of a solenoid valve by a key operated switch on the trailer. Rather than being a key switch, the switch may take the form of a keyboard module switch operable only by a person in possession of the required key code. Note that the key-operated switch is on the trailer, and only standard equipment connections from a tractor are required so that an alien tractor can take the trailer if the operator is in possession of a key or a key code. U.S. Pat. No. 4,691,801 to Yale Mann and Pekka Sarssi describes a vehicle protection device which, in addition to a fuel valve block and other features, also has a parking brake lock for trailer brakes; all of these are operated by a portable infra-red transmitter (rather than the key operated switch or keyboard module switch of the Munro patents). U.S. Pat. No. 5,378,929 to Yitzchak Mor and Daniel Yuranyi describes a somewhat more complicated system of valves and alarms than those discussed above whereby the system can be manually activated using a hand-held remote control transmitter and receiver (or a hard-wired switch) located somewhere in the trailer.
U.S. Pat. No. 4,621,874 to Jan Gustafsson is a vehicle theft preventing device for brakes operated with compressed air having a particular valve system and which requires the operation of a code lock on the trailer to release the brakes by pressing the correct code to adjust a valve to release the brakes. U.S. Pat. No. 3,735,834 to Daniel A. St. Onge describes a brake locking system with a key operated mechanism on the trailer required to close a normally open relay by use of a proper key; the valves of the system cannot be operated to admit air pressure to release spring force applying the brakes without such a proper key even though air pressure and EMF (through an electric cable) are connected to the vehicle.
Other patents relevant to the background of the invention and to the state of the art are U.S. Pat. No. 4,519,653 to Paul B. Smith and U.S. Pat. No. 4,881,388 to Ronald Pruim.
In addition to use of key-operated switches, numeric keypads for entry of key codes, or combination switches that may be used to generate a locking or unlocking signal in a vehicle security device, there are other security applications in which unauthorized operation is controlled by provision of a card reader which identifies an ID card of an operator seeking to operate the device. Such apparatus for management of the operation of a centrifuge is shown In U.S. Pat. No. 5,871,435 to Satoshi Numata, et al. Portions of such apparatus may be employed in an ID card reader version of Applicant's invention. As evidencing the state of the art relevant to the enablement of Applicant's disclosure, the Numata et al. patent and the other relevant patents above are to be considered incorporated by reference here.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to a theft prevention system for tractor-trailer transport vehicles. In particular, such trailers usually employ an air brake system using two air lines where one parking air line controls the trailer's parking/emergency brakes and another system air line controls the regular operating brakes. Air supplied by an air pressure supply means at the tractor controls both brake systems. In accordance with DOT specifications, the emergency brakes should set automatically when the trailer is parked and/or the air supply is disconnected. A major problem as mentioned above is that the thieves, if not otherwise deterred, can steal an entire parked trailer by coupling a tractor to the trailer, releasing the parking brakes in the customary manner, and driving away with the trailer in tow.
While previous anti-theft systems have provided locking means for parked trailers which prevented the release of parking brakes, the present invention has advantages and special features which primarily relate to a regimen of preventing alien tractors not belonging to a trucking company from releasing the parking brake in a trailer belonging to a trucking company equipped with the system of the present invention. The receiver and solenoid valve of the present invention are responsive only to a special transmitter installed in an authorized tractor. Thus, only authorized tractors can couple to and successfully deactivate the parking brakes. Although a wireless transmitter in a tractor may be utilized to transmit the signal to release the parking brakes, it is preferred that a signal be transmitted over existing conductors in the electric cable connected to the trailer for controlling and powering the lighting of the trailer. Numerous types of signaling may be employed including DC, AC, audio frequency and radio frequency transmission. The coding of the signal required by the receiver to actuate the solenoid valve to release the emergency brakes can be as complex as desired to prevent would-be thieves from sending a false signal not originating from an authorized tractor to release the trailer brakes. In a preferred embodiment, the electrical and pneumatic components of the system are configured so that continued receipt of the parking brake release signal is not required as long as air pressure to the trailer is maintained above a minimum value and the electrical power to the lighting system or theft prevention system are not interrupted.
Another optional feature of the system requires that the driver of the truck have a key, key code, or key card to activate the transmitter rather than to simply flip a switch in the tractor cab. This gives additional security that upon gaining access to the tractor cab, one cannot release t
Gray Clark W.
Kee Dan B.
Head Johnson & Kachigian
Rodriguez Pam
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