Automatic locomotive speed control

A method for automatically controlling the speed of a consist of locomotives having a lead engine and a plurality of trailing engines, where each engine has a predetermined, efficient high throttle position and a desired low throttle position, and where the trailing engines for control purposes are numerically designated in sequence beginning with the first trailing engine immediately behind the lead engine, said method comprising the steps of:

• selecting a desired operating speed for the consist;
• generating a cutout control signal in said lead engine and transmitting the control signal to the trailing engines in serial order;
• providing said control signal with a characteristic that changes as the actual speed of the consist rises above and falls below said desired operating speed;
• modifying said characteristic of the control signal as it is transmitted from the first trailing engine to successive trailing engines, in a manner such that the control signal at each trailing engine in succession represents a predetermined speed increase;
• and
• decoding said control signal at each trailing engine and setting the throttle thereof at either the high position to put the engine on line or the low position to cut it out, whereby engines are successively throttled back from the rear of the consist and returned on line from the front to maintain the consist at said desired operating speed.

Apparatus for automatically controlling the speed of a consist of locomotives having a lead engine and a plurality of trailing engines, where each engine has a predetermined, efficient high throttle position and a desired low throttle position, said apparatus comprising:

• a plurality of control units for respective lead and trailing engines for controlling the throttles of the trailing engines,
• each of said units having means for sensing the speed of the consist, operator-activated means for selecting a desired operating speed for the consist, and means responsive to activation thereof for generating a cutout control signal having a characteristic that changes as the actual speed of the consist deviates from said desired operating speed,
• each of said units further having a pair of lines interconnected at a junction point and adapted for connection to corresponding trainline wires extending from said lines to the short and long hood trainline connectors respectively of the locomotive, an output lead connecting said control signal generating means with said junction point for transmitting said control signal thereto, and a decoder connected with said junction point and responsive to said control signal characteristic for setting the respective engine throttle at either the high position to put the engine on line or the low position to cut it out,
• each unit having means for rendering said control signal generating means operable when the unit is in the lead engine, whereby such lead unit is capable of generating said control signal and transmitting the same to the junction point therein for transmission to units in trailing engines, and means isolating said output lead from said junction point to prevent control signal conduction along said output lead away from said junction point,
• each unit being provided with means for disabling the decoder thereof when the unit is in the lead engine, whereby locomotives equipped with said control units may be employed as lead or trailing engines and the control units will respond without being especially set up for a lead unit or trailing unit function.