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Getting efficient shunting locomotives without negative impacts

German freight traffic would practically come to a standstill without diesel-powered shunting locomotives. The Voith technology company has developed a sophisticated start/stop system to reduce the high idle times that often exceed 60 percent. The special difference here: ‟OnEfficiency.StopStart“ can be retrofitted and adapted to different product series of any manufacturer. This can save fleet operators an average of 11,000 liters of fuel annually and 30 tons of CO2 – for every vehicle that is. Non-interference with safety functions and, thus, protection of the locomotive is achieved technically using relay and optocoupler modules from WAGO.

When you imagine a train running you most likely also see an overhead line in the picture in your mind. This is because anywhere you see tracks, the scene is also marked by catenary line systems – or so you would think. But it's not always that way: Only around 60 percent of the German railway system is electrified, not even including freight traffic. In particular in marshalling yards without catenary systems, the combustion engine continues to rule.

Enhancing efficiency in freight traffic – with interface electronics and automation technology from WAGO:

  • Relay and optocoupler modules ensure freedom of interference with safety functions.



  • Compact, modular solutions for non-air-conditioned control cabinets

  • Standard-compliant technology stands up to mechanical loads and the most extreme ambient temperatures.


Product Highlights

The Story

High Idles Times due to Long Standing and Waiting Periods

‟Two-thirds standing and waiting, one-third in operation – that is a typical service profile of a diesel-powered shunting locomotive“ explains Sebastian Günther, system and project engineer at Voith. Voith has developed an automatic start/stop system to reduce these high idle times. Its special feature: ‟OnEfficiency.StopStart“ can be retrofitted, making it an interesting option for decades-old rail vehicles. Compared with proprietary motor stops from other providers, this start/stop system is not bound to any one manufacturer and can be adapted to a wide variety of product series.

‟OnEfficiency.StopStart“ is already in use in a number of locomotives. For example, the system is in use in locomotives of Rurtalbahn (G1206), ETF (G1206) and Northrail (G1206).

Source: RTB Cargo®

Retrofit Solution without Negative Impacts

‟One key question our customers ask is to what extent does a retrofit solution have an adverse impact on the vehicle or on the vehicle control system“, states Günther. With ‟OnEfficiency.StopStart“ this vital safety aspect is solved technically using interface electronics from WAGO. At the input side the acquired digital signals of the locomotive – above all those from the controller – are routed via optocoupler modules to the I/O System 750 XTR. Analog signals such as motor speed and cooling water temperature are integrated directly via differential inputs. At the automation system outputs, also from WAGO, relay modules in turn interrupt the conducting paths for the motor stop.
The consistent galvanic isolation of the control and load circuits reliably prevents intervention of any kind in the existing vehicle systems. ‟This renders safety functions immune to adverse impacts, and our solution operates autonomously. Even a system failure would not affect proper functioning and availability of the locomotive“, stresses Jan Bock, employed as an automation systems engineer at Voith.

The WAGO I/O System 750 XTR is the key component for continuous efficiency evaluation and enhancement and ensures that the ‟OnEfficiency.StopStart“ start/stop system from Voith offers much more than just a simple motor stop for locomotives.

Source: Voith Group

Relay and Optocoupler Modules in Accordance with Railway Application Requirements

There are a number of reasons why the WAGO Series 788 and 859 relay and optocoupler modules were chosen for use in the compact control cabinets of the retrofittable, automatic ‟OnEfficiency.StopStart“ start/stop system from Voith. The most important one being that the WAGO interface components satisfy the strict requirements in the railway industry, set out, among others, in DIN EN 50155, DIN EN 50121-3-2, DIN EN 45545 and DIN EN 61373 and which go above and beyond the standard demands of the industry. Vibration, oscillation and shocks are high in railway applications – but no problem for WAGO products, thanks to their proven spring connection technology.
Besides mechanical stress, ambient temperature is a critical factor, especially in non-air-conditioned control cabinets, as with the automatic start/stop system from Voith. With a permissible temperature range of -40 °C to +70 °C, WAGO relay and optocoupler modules are versatile without additional cooling or heating. ‟We have been in very close collaboration with WAGO for years now in a partnership relationship, so we know the company, its products and its services. And we know that we can always depend on them“, praises the technical expert Bock.

Striking a Balance Between Savings and Protection of the Locomotive

Voith's experience with automatic start/stop systems goes back more than ten years. ‟When developing 'OnEfficiency.StopStart' we did not want to rashly just develop some type of simple logic, but we instead put a great deal of thought into aspects such as practical applicability, efficiency and low-wear operation“, declare Günther and Bock in agreement.
The goal was to strike the perfect balance between savings and protection of the locomotive, which ultimately materialized in a rational operating principle: If all shutdown conditions are fulfilled and it is thus ensured that no power requirements will be made in the near future, an obligatory waiting period initially begins. When this freely configurable waiting time expires, an illuminated pushbutton responds in the driver's cab. The time that the button flashes and, thus, how long the pre-warning lasts, can also be individually configured. The train driver can then manually suppress the automatic stop, for example when he knows that the journey will shortly resume. If he does not react at all, the motor stops.

Stop or Keep Going? The driver is notified in the driver's cabin by flashing pushbuttons and can then decide whether to manually suppress the automatic start/stop function, perhaps because he is aware that the train should start moving again in a very short time, or to simply not react and let the motor be switched off automatically.

Source: Voith Group

720 Fewer Idle Hours, 20,000 Euros Less Costs

‟The multi-stage functioning of ‟OnEfficiency.StopStart“ protects diesel motors and gearboxes against unnecessary stress“ declares Sebastian Günther. Simply put, this means that short-term shutdowns and the resultant intermittent operation can be avoided, as can cold starts and deep discharging of the battery. In the Stop mode the vehicle and auxiliary systems remain ready for immediate use – even with radio remote control the locomotive begins rolling again within three to five seconds.

As a result, the positive effects of the automatic start/stop system on the environment and on operating costs are considerable. Even a cautious assumption of 60 percent standstill and waiting times for a typical shunting locomotive – in actual practice this figure is normally much higher – would yield 720 hours less idle time per year. And this makes itself noticeable in around 11,000 liters less diesel fuel, around 20,000 euros less per year for fuel and maintenance costs and 30,000 kilograms less CO2. Based on these figures, the average return on investment for operators using ‟OnEfficiency.StopStart“ is less than two years. ‟Our solution closes a market gap while also making a real contribution to climate protection at the same time“, sums up mechanical engineer Günther: ‟WAGO is a real partner on the road to achieving a more efficient shunting locomotive. It is readily apparent from their products and services that the company has been rooted in the railway industry for decades.“

Text: Kilian Fröhlich, WAGO

Besides mechanical stress, ambient temperature is a critical factor. With a permissible temperature range of -40 °C to +70 °C, WAGO relay and optocoupler modules are versatile without additional cooling or heating.

Source: Voith Group


‟We wanted to do more than develop just a simple motor stop.“

An automatic start/stop system has long become a standard feature for cars. Now, after a development period of three years, the Voith technology company also provides this feature with its ‟OnEfficiency.StopStart“ in shunting locomotives – with value added for fleet management. The WAGO I/O System 750 XTR forms the core of this solution. Sebastian Günther, system and project engineer at Voith talks about the background, the challenges and the technical requirements for the system.

Mr. Günther, it has long become standard that the engine in cars switches off at red lights. Why haven't automatic start/stop systems established themselves yet in the railway industry?

Firstly, this is because a major portion of the diesel vehicle fleet in the German railway system is very old and at a development level preceding the 1990s. This type of technology did not exist in the company back then. Secondly, operational readiness of locomotives is the top priority in the rail system. Many operators may have concerns that an automatic start/stop feature would cause the diesel motor to continuously switch off and then switch back on again a short time later – potentially resulting in damage to the engine. It's exactly this behavior that we can prevent with our system through monitoring of numerous parameters.

You mean that there is a favorable market for ‟OnEfficiency.StopStart“?

Absolutely! Our automatic start/stop system has two important advantages: For one, it can be retrofitted, making it an interesting option for any diesel-powered shunting locomotive that has been in service for many years or decades. Secondly, ‟OnEfficiency.StopStart“ can be used with the systems and products of any manufacturer.

There are in fact a wide range of demands – and challenging ones at that. We decided relatively quickly [...] on the WAGO I/O System 750 XTR.

What requirements does your automatic start/stop system make on automation systems?

There are in fact a wide range of demands – and challenging ones at that. Besides the lack of interference or adverse impacts that we achieve using WAGO relay and optocoupler modules, an I/O system must above all satisfy all the applicable railway standards, otherwise it cannot be used. This requirement alone narrowed our selection options considerably. In addition, the control cabinet we use is small and is not air-conditioned; as a result, the automation system must be very compact and withstand large temperature fluctuations. It was also important to us that the system have a modular design to enable our solution to be easily adapted to different types of locomotives. We decided relatively quickly on the WAGO I/O System 750 XTR.

And what tasks does the WAGO I/O System 750 XTR ultimately perform?

In a nutshell: the entire control system for the automatic start/stop system. All analog and digital signals entering and leaving our control cabinet are routed through the modules of the WAGO I/O System 750 XTR. This includes motor speed at 0 … 10 V, brake pressure and cooling water temperature at 4 … 20 mA. Data is processed in the CANopen 750-838 controller. In CODESYS V2.3 we have mapped all the necessary stop conditions for this quite conveniently using function blocks.

You spent around three years developing and optimizing ‟OnEfficiency.StopStart“. What were some special challenges you faced?

We did not want to develop just a simple motor stop, we could have done that a lot quicker. Instead, we wanted to offer real value added that goes beyond the actual start/stop function. On request, our system also generates specifically prepared savings reports based on the operating data that is collected. Fleet operators not only see in this report exactly when the motor is switched off and switched back on again, for example, but are also provided with very detailed information about why this occurred – or why it didn't occur. On the one hand this enables idle times to be continuously optimized and, on the other, allows the technical conditions of the vehicle to be monitored at the push of a button. The WAGO I/O System 750 XTR also forms the core of this solution.

Mr. Günther, thank you for this interview.



Whether on rails, switches or signals, our products fulfill the requirements of DIN EN 50121-5 and DIN EN 50155 railway standards - without application limitations.


  • Screwless connection technology provides maximum contacts reliability.
  • The plastics used as insulation for rail-mount terminal blocks fulfill the requirements of EN 45545 without limitations.

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