Stadler Rail AG uses its innovations and countless proprietary developments to keep setting new standards. These include the latest transmissions for standard-gauge rolling stock, in which the gear oil faces a Herculean task. MOTOREX’s PENTA CT SAE 75W/90 is a safe and long-lasting gear oil that has proved a great success in longterm service at Schweizerischen Südostbahn AG (SOB). An interview with Bernhard Höger, Head of Transmission Engineering at Stadler Rail.
Mr. Höger, why does Stadler Rail attach such great importance to proprietary developments for its rolling stock transmissions?
15 years ago, Peter Spuhler, Chair of our Board of Directors, decided that Stadler Rail would no longer source its transmissions externally, but develop and produce them itself. Rail vehicles are judged primarily on their availability. Gearboxes are an essential part of this and crucial in determining whether or not a vehicle can run. If a transmission hits a problem, it must be possible to fix it quickly and efficiently. External suppliers can be a hindrance in resolving problems quickly. If we use our own transmissions, our engineers can respond quickly and efficiently at any time, which is what rail operators want.
How did your partnership with MOTOREX come about?
It started with a meeting at Schweizerische Südostbahn AG (SOB), because we had factory-filled the transmissions with a different oil from the MOTOREX product SOB wanted. We explained that this was because the oil we had used had a 600,000 km change interval. Ralf Willkommen, SOB's Group Head of Fleet Management Engineering, suggested putting the fluid used by Stadler Rail head to head with the MOTOREX product. In summer 2019, we, SOB and the two fluid suppliers started a multi-year field trial in various vehicles. SOB was the driving force, taking samples and having them tested by MOTOREX and a neutral laboratory. At Stadler Rail, we monitored the tests and came to a positive conclusion.
In which products are the new highperformance transmissions installed?
We have various transmissions that we produce ourselves, starting with the T2 transmissions for our SMILE (fast, multi-system, innovative, lightweight express train), KISS (comfortable, innovative, high-acceleration, suburban train) and FLIRT (nimble, lightweight, innovative regional motorized train) products. These have an output of up to a megawatt—1,000 kW no less! We have now also started to produce transmissions for underground railways and streetcars, which have a lower output of 150 or 200 kW.
What are the advantages of the new generation of transmissions?
Off the top of my head, they’re quite a lot lighter, more compact and much easier to install and remove. This has a positive impact on service friendliness and reduces the work involved in overhauling them. The bottom line is that the design of our new transmissions has reduced their life cycle costs compared with the transmissions we used to install.
Noise emissions are an important consideration in public transport. How do you keep them down?
A vehicle’s overall noise levels are crucially important. Right from the concept stage, we design the gearing to keep noise as low and as unintrusive as possible, both onboard and in the surrounding environment. We calculate the macro geometry so that the gearing excites as little noise as possible.
How important is gear oil for the new generation of transmissions?
Gear oil is an important design element. Not only does it lubricate the roller bearings and gearing, it conducts heat out of the unit. When the vehicle is in operation, the heat is dissipated through the oil sump casing.
What were the results of the real-world tests with PENTA CT SAE 75W/90?
MOTOREX’s gear oil held its ground in a field test with a competitor’s product with flying colors. We tested the fluid in the SOB fleet over 700,000 km of running and all key criteria were well within the permissible values at the end. Thus, we can safely say that the MOTOREX gear oil is very much compatible with oil change intervals of 600,000 km.
What insights did you gain from the oil analyses?
The regular analyses were a very important part of the field trial, providing information on characteristics such as viscosity, acid number, wear, additive depletion, etc. All values were consistently within limits and the oil itself was still completely usable after the trials. So in other words, the vehicles could have kept running on it.
How would you sum up the partnership?
We now have a second gear oil that lets us guarantee compliance with challenging oil change intervals of 600,000 km. This enables us to reduce life cycle costs, protect the environment by using the product for longer (i.e. lower fluid consumption) and offer our customers a second source of supply.
Schweizerische Südostbahn AG (SOB) has relied on MOTOREX products and services for years. In 2023, SOB’s trains traveled over 11 million kilometers and carried around 21 million passengers. Punctuality is essential, given the high traffic volume on the line and the tight basic interval timetable. But punctual services depend on extremely reliable rolling stock.
One major advantage of SOB’s new vehicles with Stadler transmissions is the reduced maintenance requirement. The oil change intervals have been extended from 300,000 to 600,000 km. Not only that, the interval between transmission overhauls has quadrupled from a million kilometers to an impressive four million kilometers. The impetus to establish MOTOREX as an alternative lubricant manufacturer (see interview with B. Höger) stemmed from SOB’s longstanding partnership and extensive positive experience with the company. Since MOTOREX was a longstanding regular supplier of a familiar and reliable product, it was an obvious step to adopt it for SOB’s current vehicles and transmissions.
Constructive cooperation
Although Stadler Rail suggested a different supplier’s fluid for its new generation of transmissions, Ralf Willkommen was keen to stick by his successful partnership with MOTOREX. Stadler was receptive to the idea of evaluating a second gear oil. Although the clearance process for it was arduous—the project was expected to last three to four years—cooperation between MOTOREX, Stadler and SOB was extremely partnership-driven and constructive from the outset. Without this, it would not have been possible to field-test the new MOTOREX gear oil, evaluate the tests and derive mutual benefits from them.
Future-facing solutions
As Ralf Willkommen attests, “Close cooperation and active support when issues arise are the hallmarks of our longstanding and extremely constructive partnership with MOTOREX. We are confident that we are still far from the end of the line in development terms, and will keep working on new solutions together. We already have ideas to drive forward our development”.
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