The thing about rail transport – how grease is putting railroads on the right track

In the articale you will learn:

• Where lubricants and oils are used in rail transportation
• Why the use of lubricants is essential in rail vehicles
• How rail lubricants are tested
• What are the places of application of lubricants in rail vehicles

Rail transportation is gaining momentum. We are breaking speed records, implementing new technological solutions, developing infrastructure. Technology must be increasingly safe and meet exacting quality standards. However, whether we’re talking about high-speed trains, freight trains or suburban trains, we need to keep one thing in mind – no train set will get off the ground if we don’t take care to properly lubricate its key components. This was the case in the days of diesel locomotives, and it is still the case today, when trains reach speeds close to 600 km/h.

A rail vehicle is a complex machine, full of technological nooks and crannies. If we realize its universal nature and the variety of forms in which it can manifest itself – we can see how many factors there are that determine the selection of the right lubricant.

Some rail machines operate at extreme temperatures with large diurnal amplitudes; others must withstand the loads of the large volume they carry. Every machine running on the tracks, without exception, has to fight corrosion and absorb hundreds of vibrations every working day – and it makes no difference whether it carries passengers or goods. With such a wide variety of needs and high vehicle operating costs, it is not only the safety and reliability aspect of the lubricants selected that counts, but also the economic factor.

Tests in specialized laboratories

Given the diverse needs and risks posed by a wrongly matched lubricant, companies supplying oils to railroads must meet stringent quality standards. The approval of a lubricant for use is determined by the European standard EN 12081, which defines the quality requirements for lubricants designed to lubricate the rolling bearings of railroad axleboxes.

At FUCHS, for example, oils for railway are subjected to meticulous monitoring in ultra-modern laboratories that reflect the various external conditions and loads to which machinery is subjected. Lubricants’ mechanical stability, anti-corrosion properties, wear resistance, oil separation, pressure and temperature properties are tested.

Lubricant mechanical stability is evaluated by shear strength after 100,000 double strokes (Pw 100,000) and lubricant leakage due to continuous shocks and vibrations (V2F test).

Corrosion protection properties, on the other hand, are tested using distilled water (the so-called Emcor test) – the effects of contact with the outer ring bearing are evaluated after about 7 days of exposure to the agent.

Bearing grease lubrication and wear protection are determined in FE8 tests. After test runs with specified bearing speeds, temperatures and axial loads, the wear of rolling bearings and their cages is determined. Static separation of oil from the bearing supply at low temperatures (at least -20 °C) is also determined. Low-temperature suitability is evaluated in terms of stiffer consistency at correspondingly low temperatures.

Like all structural components in an axlebox, the lubricants are tested under extreme conditions for their specific areas of deployment on a complex test bench applying demanding conditions corresponding to EN 12082.

In addition to FUCHS experts, the suitability of the oils for railroad use is also confirmed by external technology laboratories and certified quality standards ISO 9001: 2008 and ISO / TS 16949: 2009.

Operations in demanding conditions

Among the components that are most often subject to lubrication in trains, it is necessary to pay particular attention to the previously mentioned axleboxes – that is, the rolling bearings of the vehicle, shafts and non-separable couplings – the so-called Cardan joints that connect individual cars to each other.

Rolling bearings in particular have an extremely important function and must meet a number of technical requirements in rail vehicles. The quality of the lubricant used in this case must be subject to tests that are rated as “Class I quality testing.” Grease is one of the key design elements here, performing a critical task. Depending on the type of wheelset, cylindrical roller bearings, tapered roller bearings and even spherical roller bearings are used. In rail transportation, the bearing is subject to high radial forces and therefore generally has special internal polyamide cages adapted for use in axleboxes.

Due to the growing trend of using high-speed and heavy freight trains on increasingly long routes in the rail transportation sector, modern axleboxes need to provide a longer service life while carrying increasingly high loads and stresses in terms of weight and temperature.

These are not, of course, the only rolling stock components that must be lubricated on a rail vehicle. Indeed, the full range of places where lubricants must be applied includes not only running components, but also: door guides, pantographs – which receive electricity from high-voltage lines, rail buffer heads, braking systems, shock absorbers, motors, hydrodynamic couplings, gearboxes, transmissions, hydraulic running drives and compressed air supply. Only the proper lubrication of all these running components and equipment ensures trouble-free operation for rail vehicles, and safe transportation for rolling stock operators, passengers and freight.