Automatic brake verification system

1. A method of testing a braking device in a drivetrain of a vehicle which includes at least one tractive element coupled to an electric traction motor, the method comprising:

(a) prompting a driver to apply the braking device;

(b) subsequent to the prompt, applying the braking device to the tractive element;

(c) using an electronic controller, causing the traction motor to apply a predetermined force to the tractive element; and

(d) using the controller, monitoring the tractive element for movement while the force is being applied.

2. The method of claim 1 wherein:

(a) the predetermined force is of a magnitude that should not cause movement of the tractive element when the braking device is applied, if the braking device is operating properly; and

(b) the braking device is declared to be operating properly if the tractive element does not move during the test.

3. The method of claim 1 further comprising using the controller to apply the braking device before applying the predetermined force to the tractive element.

4. The method of claim 1 further comprising using the controller to confirm that the braking device is applied before applying the predetermined force to the tractive element.

5. The method of claim 1 wherein the braking device is a friction service brake.

6. The method of claim 1 wherein the braking device is a friction parking brake.

7. The method of claim 1 further comprising displaying the results of the test to the driver.

8. The method of claim 1 further comprising storing at least one parameter representative of the test for later retrieval.

9. The method of claim 1 further comprising:

(e) initially setting the predetermined force at a magnitude that will not cause movement of the tractive element when the braking device is applied;

(f) increasing the force until movement of the tractive element occurs; and

(g) recording the magnitude of the force which causes movement of the tractive element.

10. The method of claim 9 further comprising:

(h) after step (g), modulating the force applied to the tractive element so as to drive the tractive element at a substantially constant speed; and

(i) recording the force required to drive the tractive element at the substantially constant speed.

11. A system for testing a braking device in a drivetrain of a vehicle, comprising:

(a) a prime mover coupled to a power source;

(b) at least one electric traction motor electrically coupled to the power source, the traction motor coupled to at least one tractive element;

(c) at least one braking device arranged to act on the tractive element; and

(d) an electronic controller operably connected to the traction motor, the controller configured to:

(i) prompt a driver to apply the braking device before applying the predetermined force to the tractive element;

(ii) subsequent to the prompt, cause the traction motor to apply a predetermined force to the tractive element while the braking device is applied to the tractive element; and

(iii) monitor the tractive element for movement while the force is being applied.

12. The system of claim 11 wherein:

(a) the predetermined force is of a magnitude that should not cause movement of the tractive element when the braking device is applied, if the braking device is operating properly; and

(b) the controller is programmed to declare the braking device to be operating properly if the tractive element does not move during the test.

13. The system of claim 11 wherein the controller is further programmed to apply the braking device before applying the predetermined force to the tractive element.

14. The system of claim 11 wherein the controller is further programmed to confirm that the braking device is applied before applying the predetermined force to the tractive element.

15. The system of claim 11 wherein the controller is further programmed to display the results of the test to the driver.

16. The system of claim 11 wherein the controller is further programmed to store at least one parameter representative of the test for later retrieval.

17. The system of claim 11 wherein the controller is programmed to:

(iv) initially set the predetermined force at a magnitude that will not cause motion of the tractive element when the braking device is applied;

(v) increase the force until movement of the tractive element occurs; and

(vi) record the magnitude of the force which causes movement of the tractive element.

18. The system of claim 17 wherein the controller is further programmed to:

(vii) after step (vi), modulate the force applied to the tractive element as to drive the tractive element at a substantially constant speed; and

(viii) record the force required to drive the tractive element at the substantially constant speed.