Vehicle suspension control system and method

1. A method for a vehicle having a plurality of axles and a lift mechanism configured to dynamically transfer weight from a first axle to a second axle, the method comprising:

responding to an operating condition by adjusting the lift mechanism to provide a determined amount of lift; and

in response to vehicle braking, reducing the determined amount of lift, wherein the determined amount of lift is limited when a tractive effort of the vehicle is above a first threshold.

2. The method of claim 1 , wherein the determined amount of lift is further limited based on a speed of the vehicle when the speed is above a second threshold.

3. The method of claim 2 , wherein the first threshold is lowered as the speed increases above the second threshold.

4. The method of claim 1 , further comprising identifying a position of the vehicle within a map based on the tractive effort and speed, the map defining a plurality of operating areas that limit an operation of the lift mechanism based on the tractive effort and the speed.

5. The method of claim 4 , wherein each operating area limits the operation of the lift mechanism to at least one of a plurality of predetermined states, the plurality of predetermined states including increasing provided lift, decreasing provided lift, and holding provided lift.

6. The method of claim 5 , wherein each operating area further limits the operation of the lift mechanism to at least one of a plurality of predetermined lift options, including holding the lift mechanism to continue providing a current lift amount, starting the vehicle with lift, running the vehicle with lift, and providing lift when a potential vehicle stall is detected.

7. The method of claim 6 , further comprising limiting the operation of the lift mechanism to provide no lift when a predetermined critical speed is exceeded.

8. The method of claim 6 , further comprising further limiting the operation of the lift mechanism based on at least one of vehicle stall risk, vehicle slip, vehicle penalty, infrastructure conditions, and conditions external to the vehicle.

9. The method of claim 8 , wherein vehicle penalty is based on at least one of lift mechanism component stress, wheel slip, fuel level, and lift mechanism actuator forces.

10. A method for a vehicle having a plurality of axles and a lift mechanism configured to dynamically transfer weight from one axle to another, the method comprising:

responding to an operating condition by adjusting the lift mechanism to provide a determined amount of lift; and

determining a vehicle penalty based on at least one of track condition, wheel diameter, lift mechanism component stress, locomotive component stress, wheel slip, infrastructure limits, and fuel level; and

limiting the determined amount of lift based on the determined vehicle penalty, wherein the determined amount of lift is one or more of the following:

a) the determined amount of lift is limited to a smaller amount of lift when a track is dry than when the track is wet,

b) the determined amount of lift is limited such that a weight on an axle does not exceed a predetermined maximum weight for the axle or drop below a predetermined minimum weight for the axle, or

c) the determined amount of lift is limited based on an amount of weight shifted from one truck to another truck.

11. A method for a vehicle having a plurality of axles and a lift mechanism configured to dynamically transfer weight from one axle to another, the method comprising:

responding to an operating condition by adjusting the lift mechanism to provide a determined amount of lift; and

determining a vehicle penalty based on at least one of track condition, wheel diameter, lift mechanism component stress, locomotive component stress, wheel slip, infrastructure limits, and fuel level; and

limiting the determined amount of lift based on the determined vehicle penalty, wherein infrastructure limits include a maximum weight for a region of a track and the determined amount of lift is limited such that a total weight of the vehicle positioned in the region does not exceed the maximum weight for the region.

12. A method for a vehicle having a plurality of axles and a lift mechanism configured to dynamically transfer weight from one axle to another, the method comprising:

responding to an operating condition by adjusting the lift mechanism to provide a determined amount of lift; and

determining a vehicle penalty based on at least one of track condition, wheel diameter, lift mechanism component stress, locomotive component stress, wheel slip, infrastructure limits, and fuel level; and

limiting the determined amount of lift based on the determined vehicle penalty, wherein the operating condition includes one or more of:

a) detecting a change in state of at least one of tractive effort, vehicle speed, track condition, fuel level, stall risk, axle weight, and infrastructure limits; or

b) a change in a position from one operational area of a map to another operational area of the map, the map providing a plurality of operational areas based on vehicle speed and tractive effort.

13. A vehicle system, comprising:

a truck with a plurality of axles, a lift mechanism configured to dynamically transfer weight from one axle to another, and two dump valves configured to reduce air pressure in a pneumatic line of the lift mechanism; and

a control system with a computer readable storage medium and instructions for,

responding to an operating condition by performing a lift operation, wherein the lift mechanism is adjusted to provide a determined amount of lift;

responding to a dump condition by performing a dump operation, the dump operation taking priority over performing the lift operation.

14. The vehicle system of claim 13 , wherein the dump condition comprises an emergency condition and the dump operation is performed by opening both dump valves.

15. The vehicle system of claim 14 , wherein the emergency condition comprises at least one of detection of unpowered axle wheel slide or negative creep, prediction of unpowered axle wheel slide or negative creep, and application of emergency air or friction brakes.

16. The vehicle system of claim 13 , wherein the dump condition comprises vehicle braking and the dump operation is performed by opening at least one dump valve.