Grade speed control and method for railway freight vehicle

A grade speed control method for a railway freight train having a locomotive and at least one articulated rail car having an ECP brake control system including a fluid pressure activated brake cylinder device and a graduated release valve, the method comprising:

• a. monitoring actual train velocity;
• b. selecting a target train velocity;
• c. detecting a velocity difference between the target velocity and the actual velocity;
• d. calculating a prevailing acceleration of the train;
• e. calculating a target acceleration;
• f. deriving a brake cylinder pressure adjustment to achieve the target acceleration;
• and
• g. implementing said brake cylinder adjustment to cause the prevailing acceleration to generally correspond to the target acceleration to bring the actual velocity to the target velocity.

A grade speed control method for a railway freight train having a locomotive and at least one articulated rail car having an electro-pneumatic (ECP) brake control system including a fluid pressure activated brake cylinder device and a graduated release valve, the method comprising:

• a. monitoring actual train velocity;
• b. selecting a target train velocity;
• c. detecting a velocity difference between the target velocity and the actual velocity;
• d. adjusting brake cylinder pressure on said at least one articulated rail car responsive to said velocity difference to cause the actual velocity to generally correspond to the target velocity;
• e. determining whether the velocity difference exceeds a predetermined amount;
• f. determining whether the prevailing acceleration is positive or negative;
• g. deriving a first brake cylinder pressure adjustment based upon a higher level of desired braking force;
• h. deriving a second brake cylinder pressure adjustment based upon a lower level of desired braking force;
• i. implementing said first brake cylinder pressure adjustment responsive to at least one of the velocity difference exceeding the predetermined amount and the prevailing acceleration being positive;
• and
• j. implementing said second brake cylinder pressure adjustment responsive to at least one of the velocity difference being less than the predetermined amount and the prevailing acceleration being negative.

A grade speed control method for a railway freight train having a locomotive and at least one articulated rail car having an electro-pneumatic (ECP) brake control system including a fluid pressure activated brake cylinder device and a graduated release valve, the method comprising:

• a. monitoring actual train velocity;
• b. selecting a target train velocity;
• c. detecting a velocity difference between the target velocity and the actual velocity;
• d. adjusting brake cylinder pressure on said at least one articulated rail car responsive to said velocity difference to cause the actual velocity to generally correspond to the target velocity;
• e. detecting whether a brake cylinder pressure adjustment would result in a brake cylinder pressure exceeding one-half of a full service brake cylinder pressure;
• and
• f. providing a warning responsive to said detecting a brate cylinder pressure exceeding one-half of a full service brake cylinder pressure.

A grade speed control method for a railway freight train having a locomotive and at least one articulated rail car having an electro-pneumatic (ECP) brake control system including a fluid pressure activated brake cylinder device and a graduated release valve, the method comprising:

• a. monitoring actual train velocity;
• b. selecting a target train velocity;
• c. detecting a velocity difference between the target velocity and the actual velocity;
• d. adjusting brake cylinder pressure on said at least one articulated rail car responsive to said velocity difference to cause the actual velocity to generally correspond to the target velocity;
• e. detecting whether a brake cylinder pressure adjustment would result in a reduction of brake cylinder pressure by more than a predetermined amount;
• and
• f. substituting a predetermined maximum brake cylinder pressure reduction responsive to said detecting a reduction of brake cylinder pressure by more than a predetermined amount.

A grade speed control method for a railway freight train having a locomotive, multiple unpowered rail cars, an electropneumatic brake control system having graduated brake capability and including fluid pressure activated brake cylinders on each of said multiple unpowered rail cars, the method comprising:

• a. selecting a target train velocity for negotiating a down grade;
• b. monitoring actual train velocity on said down grade;
• c. detecting a velocity difference between the target velocity and the actual velocity;
• and
• d. adjusting brake cylinder pressure to vary friction retardation on said multiple unpowered rail cars responsive to said velocity difference to cause the actual velocity to generally correspond to the target velocity.

An apparatus on a railway freight train for controlling the speed of the train on a down grade, said freight train having a locomotive, multiple unpowered rail cars, an electropneumatic brake control system having graduated brake capability and including fluid pressure activated brake cylinders on each of said multiple unpowered rail cars, the apparatus comprising:

• a. train engineer controls for selecting and inputting a target train velocity for negotiating a down grade;
• b. train speed sensors to monitor actual train velocity on said down grade;
• c. a grade speed controller receiving input from said train engineer controls and said train speed sensors, said grade speed controller operatively associated with said electropneumatic brake control system on said multiple unpowered rail cars for controlling pressure in said fluid pressure activated brake cylinders;
• d. said grade speed controller comparing said target velocity and said actual velocity to detect a velocity difference therebetween;
• and
• e. said grade speed controller adjusting brake cylinder pressure to vary friction retardation on said multiple unpowered rail cars responsive to detecting a velocity difference to cause said actual velocity to generally correspond to said target velocity.