Lube-Tech
approximately two years, depending on the specific service conditions and the effectiveness of the gearbox’s sealing against dust and contaminants [13]. Although the oil itself can remain in good condition for up to two years, the presence of dirt or other impurities can lead to potential damage to the gears and bearings. Therefore, adhering to the OEMs’ recommendation on oil change intervals, like engine oil, is crucial for maintaining the optimal health of the traction motor gears.
Greases
In addition to oils, greases are equally utilised in various locomotive module lubrication systems, particularly in areas where greases are more suitable than oils. Locomotives utilise greases for lubricating bearings in key components such as the main generator, traction motors, U-tube bearings, radiator fans, and wheel bearings. These bearings vary in size, endure different loads, and rotate at different speeds, necessitating greases with optimised compositions specific to each application and environment. Consequently, distinct grease specifications and recommendations are provided for each application type. In general, traction motor greases employ lithium NLGI 3 grade greases formulated with mineral base oils, while U-tube bearings require NLGI 2 synthetic greases such as Mobilith SHCTM 100 and UnirexTM (Table 5).
PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
No.148 page 5
(Table 5), respectively [8]. Synthetic greases are also commonly used for wheel bearings and generator applications. The choice between synthetic or mineral oil-based greases depends on a number of factors, including service life and ambient operational conditions, and seasonal temperatures [8].
According to a study conducted by the Railway Tie Association, regular rail lubrication can result in a substantial decrease in annual fuel costs. The study found that trains operating on unlubricated rails consumed an average of 5,900 gallons of fuel per million gross tons (MGT). However, the fuel consumption decreased by 31% when proper lubrication was used. Another similar study conducted by the Federal Railway Administration claimed that top-performing rail lubrication systems offered an average fuel savings of 7.7%, with fully loaded trains achieving a 10% reduction in fuel consumption [2]. The rail lubricant must fulfill several key requirements. These requirements include reducing friction to prevent premature wear, providing sufficient adhesion for safe locomotive operation, meeting environmental regulations by being biodegradable and non-toxic, performing well under varying environmental conditions, and minimising noise pollution during braking and on sharp curves [14, 15, 16].
To achieve these goals, two common methods of lubricant application are used, wheel-flange lubrication and wayside lubrication. Wheel-flange lubrication involves a system within the locomotive itself, where the lubricant is dispensed onto the wheel flanges of the first axle in the direction of travel. The lubricant then spreads to the rail surface and other wheel flanges [17].
Table 5: GE Specification D6A2C17 for Ball and Roller Bearing Greases [8].
Both grease types are governed by the GE (now Wabtec) Specification D50E34 and D6A2C17
In contrast, wayside lubrication involves the application of lubricating grease or liquid friction modifiers directly onto the track from wiper bar dispensers positioned on the sides of the rail. These dispensers are electronically controlled to regulate
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