ANTIJACKKNIFING SYSTEM

• US 3,618,983 A
• Filed: 12/10/1969
• Issued: 11/09/1971
• Est. Priority Date: 12/10/1969
• Status: Expired due to Term

• Current Assignee: Harry D. Forse
• Original Assignee: Harry D. Forse
• Inventors: Forse, Harry D.
• Primary Examiner(s): Friaglia, Leo
• Application Number:
  US04/883,826
• Time in Patent Office: 699 Days
• Field of Search: 280/432 303/3,21CF,18 188/3
• US Class Current: 280/432
• CPC Class Codes: B62D 13/00 Steering specially adapted for trailers combined traction and steering hitches B60D
• CPC Class Codes: B62D 53/0878 the fifth wheel coupling incorporating braking or restraining means

Abstract

An antijackknifing system for a tractor-semitrailer combination. In one embodiment, a first fluid cylinder is provided having a piston with fluid on opposite sides thereof, the piston being linearly actuated in opposite directions, respectively, by turning movement of the steerable front wheels of the tractor in opposite directions from the center position. A second fluid cylinder is provided having a piston therein with fluid on opposite sides thereof, the piston being linearly actuated in opposite directions from a neutral position, respectively, by pivotal turning movement of the semitrailer with respect to the tractor in opposite directions from its centered position. A third fluid cylinder is provided having a piston with fluid on opposite sides thereof. A first conduit connects the three cylinders on one side of the respective pistons thereby providing a first closed fluid system, and a second conduit connects the three cylinders on the opposite sides of the respective pistons thereby providing a second closed fluid system so that movement of the piston of one of the first and second cylinders away from its neutral position without corresponding coordinated movement of the piston of the other of the first and second cylinders causes movement of the piston of the third cylinder away from its neutral position to accommodate fluid displaced by movement of the piston of the one cylinder. The piston of the third cylinder is coupled to increase the braking force exerted by the trailer brakes and simultaneously to decrease the braking force exerted by the tractor brakes in response to movement of the piston of the third cylinder away from its neutral position in either direction thereby to assist the driver in restoring a normal coordinated relationship between the position of the front wheels of the tractor and the pivotal position of the semitrailer with respect to the tractor.

Claims

1. In combination with a wheeled tractor vehicle having selectively actuable wheel brakes and steerable front wheels, a wheeled seMitrailer vehicle having selectively actuable wheel brakes, means for pivotally coupling said semitrailer to said tractor, and means for normally selectively applying said tractor and semitrailer brakes;

an antijackknifing system comprising;

means for sensing the absence of a normal coordinated relationship between the steered position of said front wheels and the pivotal position of said semitrailer with respect to said tractor, said normal relationship occurring when said tractor and semitrailer are normally traveling a highway; and

means for modifying the braking effort applied by at least one of said tractor and semitrailer brakes in response to said sensing means thereby to assist the driver in restoring said normal relationship.

2. The system of claim 1 wherein said modifying means increases the braking effort applied by said trailer brakes in response to said sensing means.

3. The system of claim 1 wherein said modifying means decreases the braking effort applied by said tractor brakes in response to said sensing means.

4. The system of claim 3 wherein said modifying means further simultaneously increases the braking effort applied by said trailer brakes in response to said sensing means.

5. The system of claim 1 wherein said sensing means includes first means for sensing turning movement of said front wheels in either direction, second means for sensing pivotal turning movement of said semitrailer with respect to said tractor in either direction, and third means coupled to both of said first and second means and responsive thereto for sensing an uncoordinated turning movement of said front wheels with respect to said semitrailer.

6. The system of claim 5 wherein said first means includes at least a first fluid cylinder having fluid and a piston therein and means for linearly actuating said piston in response to said turning movement of said front wheels;

said second means including at least a second fluid cylinder having fluid and a piston therein and means for linearly actuating said piston in response to said turning movement of said semitrailer;

said third means including at least a third fluid cylinder having fluid and a piston therein, and fluid conduit means for coupling said first, second and third cylinders in a closed fluid system whereby movement of said piston of one of said first and second cylinders in the absence of corresponding coordinated movement of said piston of the other of said first and second cylinders causes movement of said piston of said third cylinder thereby to accommodate the fluid displaced by movement of said piston of said one cylinder;

said modifying means being coupled to said piston of said third cylinder and actuated thereby in response to movement thereof.

7. The system of claim 6 wherein said piston of said third cylinder is in a neutral position in response to said normal relationship, said piston of said third cylinder being moved toward one end thereof in response to uncoordinated turning movement of said semitrailer with respect to said front wheels in one direction, and toward the other end thereof in response to uncoordinated turning movement in the opposite direction, said modifying means being actuated in response to movement of said piston of said third cylinder in either direction away from said neutral position.

8. The system of claim 7 wherein said modifying means includes first auxiliary means for selectively decreasing the braking effort applied by said tractor brakes, second auxiliary means for selectively increasing the braking effort applied by said trailer brakes, and actuator means coupled to said piston of said third cylinder for actuating said first and second auxiliary means.

9. The system of claim 8 wherein said tractor and semitrailer brakes are air actuated, said first auxiliary means comprising a first valve for bleeding air from said tractor brakes, said second auxiliary means comprising a second valve for increasing the air pressure applied to said trailer brakes, said actuator means Comprising a pilot valve coupled to said first and second valves for actuating the same.

10. The system of claim 5 wherein said first means includes a first pair of first and second fluid cylinders each having fluid and a piston therein, means for coupling said pistons of said first and second cylinders for simultaneous movement, and means for linearly simultaneously actuating said pistons of said first and second cylinders in response to said turning movement of said front wheels;

said second means including a second pair of third and fourth fluid cylinders each having fluid and a piston therein, means for coupling said pistons of said third and fourth cylinders for simultaneous movement, and means for linearly simultaneously actuating said pistons of said third and fourth cylinders in response to said turning movement of said semitrailer;

said third means including a third pair of fifth and sixth cylinders each having fluid and a piston therein, and first fluid conduit means for coupling said first, third and fifth cylinders in a first closed fluid system and second fluid conduit means for coupling said second, fourth and sixth cylinders in a second closed fluid system whereby movement of the pistons of one of said first and second pairs of cylinders in the absence of corresponding coordinated movement of the pistons of the other of said first and second pairs of cylinders causes movement of the pistons of said third pair of cylinders thereby to accommodate the fluid respectively displaced by movement of the pistons of said one pair of cylinders, said modifying means being coupled to the piston of at least one of said third pair of cylinders and actuated thereby in response to movement thereof.

11. The system of claim 10 wherein said fifth and sixth cylinders respectively have spring means therein for urging the respective pistons in a direction to discharge fluid therefrom.

12. The system of claim 11 wherein said modifying means includes first auxiliary means for selectively decreasing the braking effort applied by said tractor brakes, second auxiliary means for selectively increasing the braking effort applied by said trailer brakes, said pistons of said third pair of cylinders respectively having a neutral position in response to said normal relationship, one of said third pair of cylinders being of the free piston type, and actuator means coupled to said piston of the other of said third pair of cylinders and to said first and second auxiliary means for actuating the same in response to movement of said last-named piston in either direction away from its neutral position.

13. The system of claim 11 wherein said modifying means includes first auxiliary means for selectively decreasing the braking effort applied by said tractor brakes, second auxiliary means for selectively increasing the braking effort applied by said trailer brakes, said pistons of said third pair of cylinders respectively having a neutral position in response to said normal relationship, said piston of said fifth cylinder being moved toward one end thereof against the force exerted by the respective spring means in response to uncoordinated turning movement of said semitrailer with respect to said front wheels in one direction, said piston of said sixth cylinder being moved toward one end thereof against the force exerted by the respective spring means in response to uncoordinated turning movement in the opposite direction, first actuator means coupled to said piston of said fifth cylinder and to said first and second auxiliary means for actuating the same in response to said uncoordinated turning movement in said one direction, and second actuator means coupled to said piston of said sixth cylinder and to said first and second auxiliary means for actuating the same in response to said uncoordinated turning movement in said opposite direction.

14. The system of claim 5 wherein said first means includes a first fluid cylinder having a piston therein with fluid respectively on the opposite sides thereof and means for linearly actuating said piston in response to said turning movement of said front wheels;

said second means including a second fluid cylinder having a piston therein with fluid respectively on the opposite sides thereof and means for linearly actuating said piston in response to said turning movement of said semitrailer;

said third means including a third fluid cylinder having a piston therein with fluid respectively on opposite sides thereof, and first fluid conduit means for coupling said first, second and third cylinders on one side of the respective pistons in a first closed fluid system and second fluid conduit means for coupling said first, second and third cylinders on the other side of the respective pistons in a second closed fluid system whereby movement of said piston of one of said first and second cylinders in the absence of corresponding coordinated movement of said piston of the other of said first and second cylinders causes movement of said piston of said third cylinder thereby to accommodate the fluid displaced by movement of said piston of said one cylinder;

said modifying means being coupled to said piston of said third cylinder and actuated thereby in response to movement thereof.

15. The system of claim 1 further comprising means for selectively enabling and disabling said antijackknifing system.

16. The system of claim 15 wherein said last-named means includes speed responsive means for enabling said antijackknifing system in response to a predetermined speed of said trailer and semitrailer.