Mechanical boolean steering

1. A steering system for a vehicle adapted to travel on a track or a guideway, the vehicle having at least one steerable wheel connected to an axle pivotably supported by a support frame, the steering system comprising:

a drive shaft having a rotational axis along its length;

a first substantially semicircular gear element provided on the drive shaft and adapted to engage a first rack;

a second substantially semicircular gear element provided on the drive shaft and adapted to engage a second rack,

wherein the first and second substantially semicircular gear elements are offset along the rotational axis of the drive shaft and are located about a common end of the drive shaft such that:

the first substantially semicircular gear element engages the first rack when the drive shaft is rotated in a first direction;

the second substantially semicircular gear element engages the second rack when the drive shaft is rotated in a second direction, the second direction being opposite to the first direction; and

both first and second substantially semicircular gear elements engage the first and the second rack, respectively, when the drive shaft is in a neutral position.

2. The steering system of claim 1 , wherein, with rotation of the drive shaft in the first direction, the first substantially semicircular gear element actuates the first rack in a linear motion.

3. The steering system of claim 1 , wherein, with rotation of the drive shaft in the second direction, the second substantially semicircular gear element actuates the second rack in a linear motion.

4. The steering system of claim 1 , wherein, with rotation of the drive shaft in the first direction from the neutral position, the second substantially semicircular gear element is disengaged from the second rack.

5. The steering system of claim 1 , wherein, with rotation of the drive shaft in the second direction from the neutral position, the first substantially semicircular gear element is disengaged from the first rack.

6. The steering system of claim 1 , wherein the first substantially semicircular gear element is connected to a first portion of the drive shaft by at least one first connection member.

7. The steering system of claim 1 , wherein the second substantially semicircular gear element is connected to a second portion of the drive shaft by at least one second connection member.

8. The steering system of claim 1 , wherein the first substantially semicircular gear element is offset from the second substantially semicircular gear element circumferentially about a circumference of the drive shaft.

9. The steering system of claim 7 , wherein the first substantially semicircular gear element is offset from the second substantially semicircular gear element by 180° about the circumference of the drive shaft.

10. The steering system of claim 7 , wherein a part of the first substantially semicircular gear element overlaps a part of the second substantially semicircular gear element.

11. The steering system of claim 7 , wherein the first substantially semicircular gear element is connected to the second substantially semicircular gear element at an overlapping portion of the first and second substantially semicircular gear elements.

12. The steering system of claim 1 , wherein the first substantially semicircular gear element has a plurality of first teeth that engages a plurality of corresponding teeth on the first rack and wherein the second substantially semicircular gear element has a plurality of second teeth that engages a plurality of corresponding teeth on the second rack.

13. The steering system of claim 12 , wherein the plurality of first and second teeth on the first and second substantially semicircular gear elements, respectively, and the plurality of corresponding teeth on the first and second racks, respectively, are linear gear teeth.

14. The steering system of claim 8 , wherein the plurality of first and second teeth on the first and second substantially semicircular gear elements, respectively, and the plurality of corresponding teeth on the first and second racks, respectively, are helical gear teeth.

15. The steering system of claim 8 , wherein the plurality of first and second teeth on the first and second substantially semicircular gear elements, respectively, and the plurality of corresponding teeth on the first and second racks, respectively, have the same gear pitch.

16. The steering system of claim 8 , wherein the plurality of first teeth on the first substantially semicircular gear element and the plurality of corresponding teeth on the first rack have a different gear pitch compared to the plurality of second teeth on the second substantially semicircular gear element and the plurality of corresponding teeth on the second rack.

17. A method of steering or maintaining a travel path of a vehicle adapted to travel on a track or a guideway, the vehicle having at least one steerable wheel connected to an axle pivotably supported by a support frame, the method comprising the steps of:

maintaining a vehicle steering system in a neutral position to maintain the travel path of the vehicle in a straight line;

engaging the vehicle steering system in a first direction to cause the vehicle to turn in a direction corresponding to the first direction; and

engaging the vehicle steering system in a second direction to cause the vehicle to turn in a direction corresponding to the second direction,

wherein the vehicle steering system comprises:

a drive shaft having a rotational axis along its length;

a first substantially semicircular gear element provided on the drive shaft and adapted to engage a first rack; and

a second substantially semicircular gear element provided on the drive shaft and adapted to engage a second rack,

wherein the first and second substantially semicircular gear elements are offset along the rotational axis of the drive shaft and are located about a common end of the drive shaft such that:

the first substantially semicircular gear element engages the first rack when the drive shaft is rotated in a first direction;

the second substantially semicircular gear element engages the second rack when the drive shaft is rotated in a second direction, the second direction being opposite to the first direction; and

both first and second substantially semicircular gear elements engage the first and the second rack, respectively, when the drive shaft is in a neutral position.

18. The method of claim 17 , wherein rotation of the drive shaft in the first direction to engage the first substantially semicircular gear element with the first rack causes the first rack to move in a linear motion and wherein rotation of the drive shaft in the second direction to engage the second substantially semicircular gear element with the second rack causes the second rack to move in a linear motion.

19. The method of claim 17 , wherein rotation of the drive shaft in the first direction causes the second substantially semicircular gear element to disengage from the second rack, and wherein rotation of the drive shaft in the second direction causes the first substantially semicircular gear element to disengage from the first rack.

20. A vehicle adapted to travel on a track or a guideway, the vehicle comprising:

at least one steerable tire connected to an axle pivotably supported by a support frame;

a steering system for steering the vehicle;

a steering wheel operatively connected to a drive shaft of the steering system; and

at least one wheel operatively connected to the steering system, wherein the steering system further comprises:

a first substantially semicircular gear element adapted to engage a first rack; and

a second substantially semicircular gear element adapted to engage a second rack,

wherein the first and the second substantially semicircular gear elements are offset along the rotational axis of the drive shaft and are located about a common end of the drive shaft such that:

the first substantially semicircular gear element engages the first rack when the drive shaft is rotated in a first direction to steer the first wheel in the first direction;

the second substantially semicircular gear element engages the second rack when the drive shaft is rotated in a second direction to steer the second wheel in the second direction, the second direction being opposite to the first direction; and

both the first and the second substantially semicircular gear elements engage the first and the second rack, respectively, when the drive shaft is in a neutral position to maintain the first and second wheels in a neutral position.