INDUSTRIAL RAILROAD SYSTEMS
Radio Remote Control 1402
General Description 1402
System Functions 1404
Basic Commands 1404
Direction Commands 1404
Throttle Commands 1404
Locomotive Independent Brake Commands 1404
Emergency Stop Commands 1404
Coast Command 1404
Sand Command 1404
Additional Functions and Commands 1404
Principles of Operation 1404
Command Transmission 1404
Coding Principles 1405
Encoder and Transmitter 1405
Receiver and Decoder 1405
Safety of Operation 1406
Automatic Train Operation 1407
Train Detection and Commands 1407
Train Commands 1408
System Operation 1408
Single-Track Operation 1410
Manual Control 1410
Additional Console Functions 1410
Train Equipment 1410
The term “industrial railroad” covers a wide variety of installations. In general, it applies to the use of railroad equipment by an industry on its own property for special transportation and material handling purposes. Large-scale activities, such as steel mills and open-pit mines, may utilize miles of track, dozens of locomotives and hundreds of cars. Smaller installations may involve a few hundred feet of track, a single locomotive and only a few cars. Locomotives and cars may be similar to equipment used by mainline railroads, or may be of special design related to the material transported and functions required.
Regardless of size or function, it is necessary that an industrial railroad operate safely and efficiently. Railroad signaling principles and apparatus can be applied to achieve these objectives. In some cases, these applications are similar to those for mainline operation. Thus switch machines, switch circuit controllers, color-light signals, and crossing warning signals for in-plant roadways are used just as in ordinary railroad operations. Similarly, car retarders with radar speed detectors are used to regulate the speed of cars rolling from industrial car dumpers so that dumping can proceed at maximum rate while cars roll to empty-car tracks at speeds which hold coupling impacts to acceptable levels.
In other cases, the requirements of an industrial railroad may be quite different. For example, a switch circuit controller may be linked to a warehouse door so that an associated signal displays the proceed aspect for the door area only when the door is fully open.
Two systems developed by GRS are of particular importance to industrial railroads: radio remote control of locomotives for switching-type operations; and automatic train operation for transporting tonnage loads over appreciable distances without the need for train crews.
RADIO REMOTE CONTROL
GRS radio remote control of locomotives permits locomotives to be started, accelerated, braked, stopped, reversed, (plus many other functions) at any point within line of sight or at distances up to 2000 feet from the control point. Control may be from fixed locations or from man-carried portable control units. Fixed transmitters are suitable when operations are concentrated in the vicinity of the control point and do not require the operator to do
around cars being switched. Portable transmitters are useful for operations
over spread-out areas and when work is required on or about the cars being
handled. Operating principles are similar for both fixed and portable control
Since portable control has great flexibility of application, it is appropriate to focus attention on portable operation. With portable remote control, regardless of locomotive position in the train, an operator can at all times ride the leading end of the train where he can clearly see conditions ahead. He can alight to throw switches, couple and uncouple cars, or to work anywhere along the train without the need for using hand signals, with their potential for being obscured or misread. For heavy operations, such as loading and dumping, he can be off the train at a location which provides visibility so that he can accurately spot cars, but which is safely distant from any hazards.
The GRS radio remote control system has capacity for control of up to 64 locomotives operating in the same area; each responds only to its assigned transmitter. A maximum of 16 functions can be controlled per locomotive in a 64-locomotive system. With 32 locomotives, 18 functions can be provided.
As many as 64 transmitters at an installation may operate on the same frequency, minimizing the need for multiple-channel licensing. Same- frequency operation with individual locomotive control is made possible by a unique GRS timesharing feature, discussed later. At the time of publication, typical frequencies used are 72, 75 and 154 mHz for portable operation, with channels between 155 to 167 mHz and at 452 mHz for fixed stations. System operation is not a function of carrier frequency and can be provided on other channels should frequency allocations change.
A functional block diagram of the equipment to control one locomotive is shown in Figure 1401. The portable control equipment (send unit) is carried by the operator, and the locomotive equipment (receive unit) is mounted in a convenient place on the locomotive. Electronic circuits use solid-state components throughout, and relays on the locomotive are quick-detachable for ease of maintenance.
Portable send units are available in singlepiece and two-piece designs. The single-piece unit, Figure 1402, worn at the waist on a belt, includes electronic circuitry plus switches and pushbuttons used for locomotive control. The two-
PORTABLE CONTROL EQUIPMENT
— — 1 ANTENNA
BATTERY I SUPPLY .j I
— — — 1 — — —
TO LOCOMOTIVE I
CONTROLS BRAKES I RELAYS
THROTTLE ETC. I
Figure 1401. Block diagram, radio remote control system.
design, Figure 1403, locates the control functions in a smaller, lighter waist
unit, with electronic functions in a separate back pack.
Send units are powered by plug-in nickel- cadmium storage batteries with capacity for an eight-hour shift. Extra batteries are carried on the locomotive and charged during operation, so that fresh batteries are readily available to the operator.
Mating of a send unit with a specific locomotive is accomplished by the send unit encoder and receive unit decoder indicated in Figure 1401. Quickly inserted paired plugs, one for the encoder the other for the decoder, establish a specific address for the locomotive and the unique code for calling that address in the associated control unit.
Posture switches in the portable send unit provide safety assurance by monitoring the operator’s body position. Should his position vary from upright for more than a reasonable time, indicating a possible fall or collapse, transmission is cut off. Unless transmission resumes within a preset time, the locomotive stops.
Figure 1403. Two-piece operator-carried send unit.
The basic system controls six locomotive functions by means of eleven commands.
Basic System Functions
Sand Apply momentarily (1)
Forward and reverse direction commands establish direction and are accepted only while the locomotive is stationary. Once established, direction is maintained through intervening starts and stops until a superseding direction command is received.
Each throttle command moves the throttle one notch, advance or retard as commanded, with eight notches beyond idle available. Repeated operation of the command lever on the control unit thus moves the throttle up or down to a desired notch. Throttle operation may be interlocked with brake operation. For example, a call for braking can automatically return the throttle to idle, and a throttle advance command can call for brake release. The throttle automatically goes to idle when certain commands, such as coast, are received. Return to idle also occurs automatically in the event of abnormal conditions, such as loss of communication or inadequate air pressure in the locomotive main reservoir.
Locomotive Independent Brake Commands
If the locomotive is not moving, the brake- apply command causes full application of the locomotive’s brakes. With the locomotive moving, brake application pressure on the independent brake (up to a preset maximum) depends on the length of time the command switch is held in the apply position. Conversely, pressure decreases progressively with the time the command switch is held in the release position. Brakes are applied automatically if communication fails or if maui reservoir pressure is not maintained at a required minimum level. In addition to basic commands for locomotive independent brakes, it is standard practice, where applicable to operations, to include commands for control of automatic brakes, as described later.
Emergency Stop Commands
The emergency stop initiate command requires only momentray operation of the command lever. The result is rapid buildup of brake pressure to a higher than normal level. Emergency braking is released by operation of the emergency stop command lever to release position.
The coast command is activated by operation of a pushbutton. In response, the throttle returns to idle and all brakes are released.
The sand command applies sand to the rails in the direction of travel while the command pushbutton is depressed.
Additional Functions and Commands
In addition to commands for the preceding basic functions, GRS radio remote control can provide seven additional commands. These may be allocated to a variety of functions.
For example, straight air brake control can be implemented with two commands. A three-position switch (spring return to center) controls graduated straight air brake application when operated to one position, and graduated release in the other position.
Automatic service brake control also can be implemented with two commands. A three-position switch (spring return to center) when operated repeatedly to the apply position results in incremental reductions of brake pipe pressure up to a full service reduction of 25 psi. Operating the switch to the release position releases the brakes. Release is complete, not graduated.
Typical additional functions which may be provided, subject to command capacity, are:
Momentary engine brake release Headlight
Engine shutdown Bell
Pin puller Horn
Principles Of Operation
Locomotive addresses and commands are transmitted via 100-ms pulses of frequency-modulated radio carrier. Pulses are repeated at random intervals at an average rate of once a second. Each carries complete address and command information. Between pulses the carrier is off.
The short pulse width gives inherently low probability that pulses from multiple send units will coincide to cause interference, even though they transmit on a common frequency. This protec Function
Forward, reverse, neutral (3)
Advance, retard (2)
Apply, release (2)
Initiate, release (2)
Throttle idle plus brakes
is augmented by the random pulse repetition rate. Should pulse coincidence
occur for one burst, the probability that succeeding pulses will coincide is
extremely low. Figure 1404 illustrates how randomized pulse repetition provides
effective multiplexing of send units operating on the same carrier frequency.
Additional protection against inter-set interference is obtained from the capture-effect characteristic of the FM receiver, which essentially eliminates a weaker signal when a moderately stronger signal is present. Note that the occurrence of interference from whatever source does not constitute a hazard, since the system rejects garbled or unreadable messages and stops the locomotive.
The carrier pulse is modulated simultaneously by a number of tones which make up a code for the locomotive addressed and the functions commanded.
Either of two tones may be transmitted in each of ten code channels. Depending on the number of controlled locomotives, five or six channels are used for the address code, and four for command codes. A pulse is valid only when each channel carries one (but not more than one) legitimate tone. Invalid pulses are rejected.
Encoder and Transmitter
In the send unit, Figure 1405, insertion of the
address code plug selects the six address tones.
The function switches and pushbuttons on the
FIRST PULSE IS
unit act through a diode matrix to select the four tones for the command
channels. The resulting 10 tones are applied to the modulator of the
transmitter. The random pulse generator controls the transmitter by keying
energy to it for 100-ms pulses at random intervals averaging one second.
Operating energy for all functions is obtained from the battery through the
Receiver and Decoder
and decoder functions are identified in Figure 1406. The frequency-modulated
transmit pulses are received, the address and command tones extracted, and the
tones amplified. The amplified tones are fed to address and command tone
detectors. The address detectors are connected to the logic circuitry through
the address code plug, which relates address coding to that established by the
paired plug in the transmitter.
The A and B outputs for each command channel are fed to an exclusive OR gate, which outputs if one and only one input is present. OR output is also directed to an AND gate which receives address inputs through the code plug. The AND gate outputs only if (1) correct address tones are present (2) incorrect address tones are absent, and (3) only one command tone is present in each command channel. With these conditions met, the AND relay is energized and commands are passed along to interface amplifiers for driving locomotive application relays. Additional security is provided by interlocking the relay circuits so that improper
& COMMAND TONES
TRANSMISSIONS OCCUR ONCE EACH SECOND AT RANDOM
EXCEPT WHEN NEW COMMAND IS INITIATED.
MUST RECEIVE PULSE WITHIN THREE SECONDS
TO CONTINUE OPERATION
Figure 1404. Principle of random transmissions.
(two relays in the same channel simultaneously operated or released) cause a
Safety Of Operation
As in all GRS control systems related to train operation, safety is a paramount consideration. With radio remote control, safety is assured by the closed circuit concept: the locomotive must continue to receive a proper signal at periodic intervals to avoid an enforced stop.
on the position of the direction control switch, the send unit automatically
transmits the forward, reverse, or neutral directional command as a keep-alive
If either the send unit or the receive unit fails, periodic reception of the direction command ceases and the locomotive stops automatically. Automatic stop also occurs if the locomotive moves out of range of the send unit, or if the safety posture switch opens, thus interrupting transmission.
An additional safety feature is achieved by transmission of commands on a priority basis. One
Figure 1405. Send unit encoder and transmitter.
Figure 1406. Locomotive receiver and decoder logic.
only one command is transmitted at a time. If more than one command switch or
pushbutton should be operated simultaneously, only the more restrictive of the
functions called for is transmitted.
AUTOMATIC TRAIN OPERATION
Materials handling is a major cost element in many industries. Where the material consists of substantial tonnage of heavy, bulky substances such as ores and minerals, rail transport offers advantages of load capacity, ruggedness and ability to cover long distances. GRS systems for automatic train operation enable an industry to obtain the benefits of rail transport of material with minimum manpower.
Automatic train operation systems are individually designed to the specific needs of the industry served. A typical system is illustrated by an automatic railroad which transports iron ore.
In this installation, ore trains propelled by electric locomotives are loaded at loading pockets, proceed over approximately six miles of railroad, are dumped at a crusher plant, and return empty to the loading end for reloading. Train operation is completely automatic; no train crews are carried. Traffic movements are sequenced and expedited on the basis of designed-in system logic.
Trains operate as units. Cars and locomotives remain coupled unless separated for maintenance. To eliminate turn around at terminals, locomotives pull loaded trains and push returning empties. Loading and dumping are continuous. To maintain material flow, typically seven automatic trains operate simultaneously.
Train separation and route integrity are main- trained by block system and interlocking installations. Trains normally approach-clear their routes, but a cTc system is also provided to permit operator intervention. Control of train propulsion and brake systems utilizes principles employed in train control, cab signal, and rapid transit systems. Apparatus and circuitry used for such systems are described in detail elsewhere in this publication. Attention in this section will be concentrated therefore on those features of automatic train operation which are distinctive.
Train Detection And Commands
High-frequency track circuits are used both for train detection and for transmission of commands
trains; coupling to the track is by WEE-Z bonds. Bonds are triple-tuned. Thus,
a WEE-Z bond can simultaneously transmit two distinct carrier frequencies
(detection track circuit feed, train command) and receive a third carrier
(detection track circuit receive). Carrier for train commands is picked up
inductively aboard trains via receiver coils carried on the train over the
The command carrier is on-off coded at various rates to specify train performance. Detection carriers are transmitted during the “off” intervals of command codes. Detection circuits are not rate sensitive, but do require that the detection carrier be coded before it can be accepted. Six carrier frequencies and 11 code rates are used as shown in Figure 1407. In line with electronic practice, code rates in this application are identified by their frequency equivalents in Hz, i.e. cycles per second, rather than pulses per minute.
Track carrier frequencies fl, f2, f3, f5, and f6 are used for occupancy detection and are not picked up by the train. Train command carrier frequency f4 is not recognized by wayside circuits, but is picked up by the train to control its operation. Although detection and command functions occur concurrently, only one carrier frequency is present on the track at any instant, alternating between track and train frequency at the existing code rate.
Since the same train command carrier frequency is used throughout the system, multiple command carriers from different WEE-Z bonds could be present in a track section at the same time if all command transmitters operated continuously. To avoid this, the f4 transmitters are. normally off. When a train enters a detection track circuit it releases the track relay, which turns on the f4 transmitter for that block, transmitting the appropriate command to the train. When the train moves on to the next track circuit, the next track relay releases, turning on the next f4 transmitter and turning off the prior transmitter.
At some locations, such as switches, insulated joints may be required to confine detection energy to defined areas. If required, command codes are transmitted to trains in such areas via insulated wire loops installed adjacent to the rails and energized with the command carrier. The train receivers pick up the carrier by inductive coupling with the loop instead of the rail. The loop wires are transposed at intervals to cancel coupling of the command carrier from the loop to the rails. Since trains do not shunt the loop, it is necessary to assure that system operation will not permit a second train to be in a position over a loop where it could pick up commands intended for another train.
TRACK CARRIER FREQUENCIES
Figure 1407. Track carrier frequencies and command codes used by automatic railroad for ore transport.
The 11 command codes provide for the wide variety of functions necessary for efficient ore handling. The 1.25-Hz, 1.7-Hz, and 2.3-Hz codes establish respectively, 30-, 15- and 7.5-mph speed limits for trains en route between terminal areas.
The 3.0-Hz ‘reverse ends” code relates to the arrangement by which locomotives pull trains in one direction and push in the other. When the locomotive is pulling, it is at the leading end of the train and picks up train commands through its own receivers. When it is pushing, however, it is at the trailing end. Command carrier, which feeds toward the train, is thus shunted out before it reaches the locomotive. Each train therefore includes a “tail car” as the end car. The tail car is equipped with receivers which are connected by a trainline cable to the locomotive. Transfer relays on the locomotive, actuated by the control system, reverse the connection to locomotive or tail car receivers when the reverse ends command is received.
The 3.9-Hz “stop” command causes train propulsion to be cut off and the brake system to respond as required for a normal stop. The stop command is transmitted when operation requires a train to be halted for routine purposes. After a
stop, a train will start up again when a code authorizing train movement is
Note that the stop command is not required to stop the train in case of malfunction. Unless a valid code (including stop) is present at all times, an irreversible emergency stop occurs. The train cannot then move until the condition which caused the emergency stop has been corrected and an authorized person boards the train to reset the train system manually.
The remaining low-speed commands, used to direct train movements in the terminal areas, specify both train speed and direction. These commands are picked up at the end of the train required by local operating conditions. With precisely controlled 2-mph and inching speed available in both directions, train speed and car spotting are “fine tuned” for loading and dumping requirements.
The automatic railroad is a two-track line running north-south. At the north end, ore is loaded into cars by gravity as trains move slowly under loading pockets. At the south end, car dumpers tip the car bodies to dump contents into ore crushers. Figure 1408 shows the track plan. Overall system
7.5 MPH NB
MEDIUM INCH SB
2 MPH NB
HIGH INCH SB
2 MPH SB
WHEN SIDING IS UNOCCUPIED
CAN A TRAIN BE RUN INTO THIS
SIDING ON A.T.O.
• MINE EN:
LOADING — — — ‘“ ,738 — — —
— SOUTHBOUND TRAIN
WHERE SHOWN, TRAINS MAY BE STOPPED AND
— NORTHBOUND TRAINJ HELD (PLUS IN DUMPER AND LOAD POCKETS)
4 — EQUIPPED FOR A.T.O. SB
_______ — EQUIPPED FOR A.T.O. NB
4 b- — EQUIPPED FOR A.T.O. SB AND NB SB—
NORMALLY USED SOUTHWARD
NB— NORMALLY USED NORTHWARD
Figure 1408. Simplified track plan, automatic railroad for ore transport. (approx. 6 miles).
is centered in a supervisory control console, Figure 1409, located in the
crusher building, which permits selection of the variety of operating modes
which the system can provide. The console is also used for local functions
associated with the dumper. Secondary control panels at the loaders, Figure
1410, provide control of trains during loading operations. Loading is manually
controlled. Dumping is normally automatic, but can be manually controlled.
Referring to Figure 1408, after the last car is dumped at the crusher, the train automatically moves south, locomotive leading. When the tail car clears, switch 4 reverses and the train stops. Control is now transferred from the locomotive to the tail car. With switch 4 reversed and the track ahead checked for occupancy, a proceed command is transmitted to the train, which then starts its return trip northward.
empty trains normally use tracks 1A, 1B, and southbound loaded trains tracks
2B. However, the system also permits double-direction running over a substantial portion of the trackage, as shown on Figure 1408. Selection of direction mode is made by pushbutton on the supervisory control console.
Assuming double-track operation, the empty train proceeds northward at speeds commanded by the system appropriate to track and traffic conditions. As the train approaches crossover 20, the system logic selects in order of priority, depending on availability, loader 4, loader 3, loader 2, or loader 4 siding as the train’s destination, If there is no preceding empty train routed to the selected loader, nor any conflicting train movements in the area, the train proceeds to this destination. Otherwise the train is stopped at crossover 20 and held until it can proceed to the designated loading pocket.
Figure 1409. Supervisory control console, automatic railroad for ore transport. Includes dumper control functions.
empty train enters the loading area at 7.5 mph. When the locomotive (at the
trailing end of the train) is about 190 feet from the loading conveyor, speed
automatically reduces to 2 mph, and the train stops entirely when the
locomotive is about 90 feet from the conveyor.
The approach indicator light on the loader operator’s panel comes on when the route to the loader is lined up, and goes out when the train stops in the loading area. The loader operator then inches the train further northward by pressing the TO LOADER pushbutton until the ore car immediately next to the locomotive is in loading position.
The train then reverses, and is loaded while moving southward leaving the loader. This movement, at inching speed, is initiated by turning the loader panel STOP/LOAD switch to LOAD. Inching speed is adjustable by a panel control to match ore delivery rate by the conveyor. With the last car loaded, the STOP/LOAD switch is turned to STOP, and the train stops. The TO SYSTEM button is then pushed. The system responds by establishing a route and, assuming track occupancy conditions
Figure 1410. Loader control panel, automatic railroad for ore transport.
the train automatically departs on the southward run to the crusher over tracks
If the crusher is unoccupied, the loaded train proceeds to and stops at a point approximately 60 feet outside the crusher building. If the crusher is occupied, the train first stops approximately 1400 feet from the building, then advances to the
60-foot position when the last car of the preceding train enters the crusher building.
To direct the train into the dumping operation, the crusher operator pushes the ACCEPT TRAIN pushbutton on his console. Assuming related conditions are in order, including crusher building doors open and pit blocking doors correctly positioned, the train advances into the building and stops with the first set of cars spotted for dumping. Overruns or underruns in spotting are adjusted automatically. Cars may be dumped singly or in pairs. Dumping is automatic, with the sequence spot-dump-spot continuing until unloading is complete. When all cars have been dumped, the train proceeds to the tail track south of switch 4, ready to return northward for reloading.
The system is designed so that tracks 1A, 1B, 2A, 28 may be taken out of service one at a time by a simple pushbutton control on the supervisory console. Ore hauling continues with double-direction running on the remaining track adjacent to the out-of-service section. The system automatically positions power switches for routing trains onto and off the single-track section, and transmits command codes in the direction appropriate to train direction. Empty trains and loaded trains pass on the section of double track remaining in service.
Train priority for use of the single-track section is determined by one of two system programs selected by pushbutton on the control console. One program sets up first-come first-served priority, the second program mandates alternation of northbound and southbound train movement.
While normal en route train operation is fully automatic, the control console enables the crusher operator to exercise supervision equivalent to that of a cTc operator. By means of pushbuttons he can direct train movements, position switches, release electric switch locks, and call maintainers at field locations.
In typical cTc systems, crews operate trains according to information conveyed by signal indications. With no crew on board trains, the auto-
system eliminates the need for signal indications. Instead of controlling
signal aspects, the system feeds command codes to the track to control trains
Additional Console Functions
The supervisory console also provides continuous indication of system status. Indicator lamps on the track diagram show track occupancy and train progress. Other lamps indicate switch position and locking. In addition, information is provided on traffic direction established on tracks, power on/off status at field locations, occurrence of control and indication cycles, and status of loading pockets.
Each locomotive carries electronic equipment for reception, amplification, and decoding of command codes. Throttle, brake, and direction selection functions are regulated by the electronic system via output relays and appropriate actuators of the locomotive controls involved.
Train speed is determined from the outputs of axle-driven frequency generators which also provide input to FR overspeed governors described in Section 700, “Train Control.” The system detects any difference between authorized speed and actual speed and controls throttle and brake systems to eliminate the difference. The FR governor protects against overspeed. Motion detector circuitry, also fed from the axle generators, verifies that trains begin moving within a preset period after receipt of a proceed command. Failure of a train to respond indicates a system problem and results in an emergency brake application that requires on-board reset before brakes can be released.
A control and indication panel, Figure 1411, is mounted on the locomotive equipment cabinet for the control systems. Pushbuttons on the panel permit selection of automatic or on-board control of the locomotive. Manual control is used for locomotive hostling and for maintenance purposes. Check lights on the locomotive panel show locomotive system status. Command lights indicate the command code being received. A group of fault indicator lights serves to identify and store information on the system area responsible in the event an on-board problem causes an emergency stop. These provide valuable trouble-shooting information for maintenance personnel, who subsequently board the locomotive to correct the condition giving rise to the stop.
Locomotives also carry external pushbuttons, readily accessible to personnel standing on the ground. These are used to immobilize the train when personnel are preparing to board, and to release the train to automatic operation after personnel have detrained.
Warning horns are carried on the locomotive and tail car which sound intermittently, approximately five seconds on and five seconds off, when a train command for speed of 7.5 mph or more is received. The horns are silent during slow-speed terminal movements.
Figure 1411. Locomotive control and indication panel, automatic railroad for ore transport.