Model railway control
An electric model railway system will generally only satisfy higher demands when trains can run there; But especially when these locomotives can stop and change their speed and direction. Locomotives, points and signals must therefore be controlled in some way .
The first running locomotive models were equipped with a clockwork and ran until the spring was relaxed; Initially, it was not possible to influence the speed and direction of travel while driving or stopping. With the introduction of electrical operation with transformers , the locomotives were supplied with the running voltage through the rails; by changing this voltage, the speed could also be regulated continuously. The need quickly arose to allow several trains to run on one system at the same time and to control them independently of one another.
Depending on the concept of the system, electrically powered trains can be controlled manually or automatically.
Manual control of locomotives
Analog control
Before the introduction of digital technology, electric model railway locomotives were operated directly by an electric voltage applied to the track : a higher voltage results in a higher analog speed. In the case of railways operated with direct voltage, the direction of travel is changed on such a system by reversing the polarity of the supply voltage; with alternating voltage, this function is performed by a switch in the locomotive, which is switched by brief pulses with a significantly higher voltage. Standstill is only possible if the motor can no longer perceive the direction of the current, which can be achieved, for example, by switching off the current. It is not possible to illuminate the vehicles independently of the journey without additional effort.
A circuit
Basically the easiest way is to control just a single train. If another locomotive is added, there is a need to park one of the two. One possibility would be a switch on the locomotive itself, which has proven to be of little practical use, especially in larger systems. Therefore, siding are often separated electrically from the main track and only connected to it via a switch or button . So it is still only a single drive control (transformer) used; Certain areas of the system can be excluded from the control, i.e. switched off. This makes it easy to turn off one locomotive and continue with the next.
Ü circuit
In the case of multi-lane track layout, it makes sense to assign a separate speed controller to each track. Typical H0 layouts of the 1970s simulate a two-lane main line and a single-lane secondary line (or a few shunting tracks) and use a separate transformer for each of these routes. In a similar form, a separate speed controller was used for each of the intermediate routes in systems with several stations. This made it possible to control several locomotives independently at the same time in a simple manner and with little wiring effort; The main disadvantage, however, is the need to switch to another speed controller when changing the circuit; at the moment of change their tensions should also correspond to one another. In the literature this is also sometimes referred to as an A connection.
Z-circuit
To avoid changing the throttle, the individual sections are the throttles here for ugeschaltet. The route is divided into sections, all of which are connected to the desired speed controller before the start of the journey (which remains the same for the entire journey), and after the end of the journey the sections are released again. At the same time, other locomotives on other routes can be controlled with another speed controller.
On the one hand, the system requires a considerable amount of wiring, but on the other hand it corresponds very precisely to the situation in the prototype, where the start and destination of each individual trip are known before the start of the journey and all points on this route must be set correctly before the journey is released.
Additional ladder
Another way to have several locomotives run on the same track is through another parallel conductor. There are several possibilities for this:
- When using electric locomotives , the overhead line can be used for power supply as in the prototype. This is certainly the most prototypical solution for an analog multi-train control; Before the introduction of digital technology (see below) it was supported by almost all well-known manufacturers.
- In 1935, the Trix company introduced a three- rail, three-wire system in which the rails were electrically separated and an additional central conductor formed the ground connection. One locomotive was powered by the left rail, the other by the right rail, and the third by the overhead line.
- A third possibility would be additional busbars, for example on the side, as is usual with the example of subways. Such systems were never supported by the big manufacturers, but occasionally built by private individuals or model railway associations; because of the effort, they did not prevail.
Addressed manual control
A completely different concept arises when the control of the locomotive is technically separated from the voltage on the track. This means that the full voltage is always available for the locomotive and car lighting; however, other methods must now be used to communicate the desired driving style to the individual locomotive. This can even allow the operation of several locomotives on the same track (e.g. for push operation, double traction); At the same time, special functions such as whistling, uncoupling and switchable light are possible.
The simplest method is mainly used for battery-powered and clockwork-powered railways: appropriately constructed track sections operate lever-like switches on the underside of the locomotive as they pass and can thus stop the locomotive or influence its speed and direction of travel. These pieces of track need not always have the same effect on every locomotive in every direction of travel; they can also be built so that the player can switch the function on, off or over from the outside.
Because of the obvious limitation here, with the development of electronics, increasingly sophisticated circuits have been developed through which a specific locomotive can be acted upon directly:
Half-wave control
At the end of the 1960s, the Faller company introduced the option of inserting small diodes into the cabs and car models for its AMS model car system. The system was then operated with alternating current, and the diodes only responded to one of the half-waves when two vehicles were driving in a row. This enabled real independent control with very little effort - but no change of direction; probably the reason why the system has not caught on with model railways.
Audio frequency control
Systems with frequency filters built into the locomotives and appropriately equipped speed controllers allowed several locomotives to operate independently on the same track as early as the early 1970s. Trix EMS ("Electronic Multi-Train System"), for example, controlled an additional locomotive in each of the three circuits using a superimposed alternating voltage in addition to a classically operated locomotive. Alternatively, Philips had developed its EZR system , but it quickly disappeared. The Jouefmatic system from Jouef , which allowed up to eight independent locomotives on a single track without overhead lines, was never well known outside of France .
However, these systems were very cost-intensive and time-consuming in terms of construction, adjustment and, above all, the space required in the locomotive, and therefore all of them could not yet become established. In Germany, audio frequency control was used to trigger individual functions rather than for multi-train operation, especially the locomotive whistling.
Wireless remote control
On a larger scale (such as nominal size I or II), radio remote control ("RC remote control") is not uncommon today; Because of the large distances, for example in a garden, this is a good idea, since the train driver wants to walk next to his locomotive anyway and prefers to do without a cable. The receivers are built into the locomotives. It is not even unusual there to operate the trains with batteries or live steam, so that there is sometimes no voltage at all on the rails.
Digital control
After digital components became available in large numbers and small sizes, a number of competing digital systems were developed. Here a constant supply voltage is applied to the track, which is superimposed by digital control signals. A receiver in the rail vehicle reads out control commands from these signals, which can be used to influence the speed, the direction of travel and additional functions such as sound effects or light. Every remotely controllable vehicle is identified by an address . In this way, an independent control of any number of rail vehicles is possible without the need for separation points in the track.
In addition to a few others, two standards are particularly widespread: In the two-wire area, it is the Digital Command Control System (DCC), which is based on the development of the Lenz Elektronik company . In the central conductor area, namely Märklin H0, the Märklin-Motorola digital system is predominant, which has been systematically replaced by a new system, Märklin Systems (mfx) since 2004 ; this offers similar possibilities as the DCC system. For the small N scale which is usually SelecTRIX system of the company Trix used. Some other providers, above all Fleischmann and ZIMO , offered their own systems for a while, which experienced a certain spread, but have since been replaced by DCC.
If the systems become larger / more complex, different power supply areas (distribution of the load over several so-called boosters) and feedback areas (which vehicle is in which system section?) Must be taken into account.
Controlled by computer
Control is also possible via a computer . In addition to the digital receivers in the vehicles, an interface and a program (e.g. TrainController, mobastWIN or Digital-S-Inside) that addresses them are required. Since the operation now takes place with a mouse and keyboard on the computer screen, additional control and switching devices can be omitted, which means a considerable price advantage. Most digital centers can also process commands from the computer via a PC interface. In this case the PC is just a control element. So you can z. B. Locomotives by hand, but set the points using a software track diagram. Recently, some programs have been created that realistically display the driver's cab of various locomotives on the screen, so that a kind of simulator operation with the model railroad is possible.
Route switching
The secured route of the prototype is determined by the position of the switches and secured by signals . While options for setting points and signals and for influencing trains developed early on, the switching of entire routes, including appropriate route protection, was only rarely implemented in analog controls because of the effort involved. With today's digital control and corresponding software programs, this is no longer a problem.
Mechanical circuit
A mechanical switch on the turnouts and signals sets them; Such “hand switches” are built by all well-known manufacturers. For higher demands, the control elements can be moved to the edge of the system using levers and cables or Bowden cables.
Another - slightly contrary to the original but very effective - possibility is the use as a so-called "folding switch", which is driven on from the switch ends and cut open in the process. Only one direction of travel is used in the opposite direction (“sharp approach”), so no external control is necessary.
A major disadvantage of the mechanical circuit was the lack of a so-called "frog polarization". Two-wire model railway systems require a voltage supply with the correct polarity at the heart of the switch, depending on the route. The problem arises because the centerpiece, depending on the position of the switch, guides the right or left wheel and the minus or plus pole of the driving voltage must be applied there accordingly. When polarizing the frog, it is essential to ensure that the switch must never be cut open when driving on, but must always be switched, otherwise a short circuit will occur. In the case of mechanical circuits, there is usually no frog polarization, which in two-wire systems means that vehicles with few current pick-up points stop in this area when driving slowly.
Turnouts in a system with a center conductor do not require frog polarization.
Analog electrical control
Here the turnouts and signals are equipped with electromagnetic drives that operate the mechanical elements. The drives are controlled via current pulses, which simultaneously form the drive's supply voltage. These impulses are triggered by buttons on the edge of the system. The disadvantage of this solution is an extremely high cabling effort, since each drive has to be connected with three, signal drives sometimes even with significantly more cables.
In the case of higher demands, the electrical control offers the option of a track diagram interlocking , which makes orientation much easier for larger systems.
Digital control
This approach reduces the wiring effort enormously, since all elements are controlled by the same two or four-wire bus . Turnouts and signals have a decoder which, like rail vehicles, is identified by an address. Here too, the control signal can be the supply voltage at the same time.
These decoders can be located directly in the turnouts and signals. More often, however, analog accessories are connected via decoder modules with mostly 4 addresses. The base address of a module can be set or learned. Depending on the function, there are different decoders for
- Magnetic items (switches, signals) that are controlled with electrical surges
- motorized drives (switches with servomotor) that have to be reversed
- Light signal decoder (at least 2 addresses are required per signal if 4 signal aspects are to be displayed)
- Servomotors
- other loads that have to be switched on and off
- special tasks such as turntables
In aircraft and ship model construction, servomotors have become increasingly cheaper. This has led to the fact that signals, switches, uncouplers, etc. are often controlled with them in the model railroad sector. The big advantage is that these motors are independent of the location of the turnout - the travel range can sometimes be moved up to a distance of more than 100 cm to the edge of the system, which massively improves maintainability. In addition, the servomotors enable a high actuating force with which switches with a continuous switch tongue can be set.
see main article model train decoder
feedback
The feedback of the actual turnout and signal setting is basically possible in all systems, but this always requires more effort for the cabling. This feedback is not only important for the display, but also to increase the operational safety with automatic control. In an otherwise manually operated system, locking and security systems of the prototype can also be implemented.
For automatic control it is essential to know where the trains are currently located so that certain actions can be triggered. For this purpose, feedback is required at the relevant points on the tracks. Feedback is possible through
- Contact bars
- Current sensor (short sections or entire block sections)
- Light barriers (one-way light barriers on the sides or reflective light barriers from below)
- Reed switch
- Hall sensors
These feedbacks can also be transmitted to the control center in a complex analogue or more simply digitally via a BUS system. Since digital feedback is processed separately from the control commands, these usually run on their own information string. This even enables feedback via RFID or barcode , which can not only determine that a vehicle is at the point, but also which one.
The most common digital feedback system is the s88 feedback bus system , which originally came from a Märklin supplier. Two other feedback systems are the Loconet or the RS bus. With the S88, the feedback is given by modules plugged one behind the other, the 8 or 16 addresses of which are usually only given by the position within the chain. The connection is often made via an interface directly to the serial interface or the universal serial bus of a computer.
Automatic control
In the British and American model railway tradition, a model railway is aimed at one or more players who take on the role of train driver and dispatcher . In Germany, on the other hand, systems tend to be built for spectators, so that from a certain size the need to automate the system quickly arises. With the advent of digital model railroad controls, it became possible - primarily in combination with computer controls - to combine fully automatic operation with partial automation. While public systems are mostly operated fully automatically due to operational safety, the combination of full automation and manual control is increasingly found in the private sector. The PC takes over the route security by means of an appropriate control program, while the operator acts as a train driver at the same time .
A combination of analog and digital technology is also possible for the automatic control, but is rarely used and mainly in the context of migrations. The advantage of analog control is that the setting of a signal (for example through additional contacts attached to it) can immediately switch the section in front of it currentless, so that the next train - regardless of which train it is and when it arrives - stops there; when the signal is reset, it will start up again immediately. In such a case, a digital control system must determine that a train is approaching a signal indicating a stop and which one it is, and this train must receive the corresponding control commands; when switching the signal to "green", it must be determined which train is waiting in front of it. This example clearly shows that when using a digital controller, it makes sense to use computer technology. In this case, the control program on the PC has precise knowledge of the engine characteristics of the locomotives used and can therefore stop the locomotives at a certain point in front of the signal with a centimeter accuracy. For this a feedback is absolutely necessary so that the computer can determine where a locomotive is at the moment and at what speed it is traveling.
The digital automatic control allows a very extensive influence on the locomotive through prototypical shaping of the starting and braking processes and the triggering of special functions such as noises and light effects. Those who want automated operation will usually use computer-based digital control with the current state of the art.
The automation allows a multi-train operation in a very simple way. However, it still quickly reaches its limits - at least in the non-professional area - as soon as it comes to modeling further prototypical processes such as the coupling and uncoupling of locomotives and wagons or their (virtual) loading and unloading.
Web links
Modellbahnheute.de about the conversion from analog to digital (tips, tricks, basic ideas, experiences, advantages and disadvantages)
Individual evidence
European model railroad standards - NEM
- ↑ http://www.grinsen.de/trix/ems/index.htm - private page on the topic.
- ↑ http://lestrainsjouef.free.fr/pdf/alim/jouef-matic76.pdf Original document from the company - French.
- ^ Gerhard Rosenzweig, Our Model Railway , Gütersloh 1966, without ISBN, p. 128
DCC - Digital Command Control Working Group of the National Model Railroad Association - Development and continuation of the DCC standard