Lube-Tech of reducing CO2 emissions may necessitate such changes in the future. Table 2: Condemning Limits for In-service engine lubricating oils [8].
A full locomotive engine oil change-out event is not done very frequently and is typically done in 3-6 month increments. The oil maintenance frequency relies heavily on numerous factors, including TBN depletion, high soot content, fuel dilution, and oil oxidation. Each of these individual factors, or several of them combined, can lengthen or shorten the service period of the oil. To avoid potential issues, Wabtec recommends frequent testing of engine oils (every 7 to 10 days) and an oil trend analysis program to monitor the outlined limits shown in Tables 2 and 3, to ensure that the engine oils aren’t being used beyond their in-service life.
PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
No.148 page 4
traction motors can be powered by either AC or DC drives, although AC drives have gained popularity due to their superior traction control and reduced maintenance requirements [11]. Like any other mechanical component, lubrication is essential to minimise wear, reduce friction, and enhance overall performance. In the case of locomotives, the traction motor gear lubricant serves the additional purpose of lubricating the main bearings. Typically, a synthetic oil based on polyalphaolefins and classified as ISO VG 460 grade, complemented with mild extreme pressure (EP) and anti-wear additives, is used for this application. An example of such a lubricant is the Mobil SHC 634 [12]. Recent specifications outlined by Wabtec for AC traction motor lubricants are depicted in Table 4 [8].
Table 3: Recommended oil change intervals for Generation 4 “Long Life” oils utilised in Wabtec FDL locomotives alongside general life expectancies according to service load as determined by field experience in Wabtec diesel engines using ASTM D975 specified fuel (No. 2 S500)[N2D] [8].
Traction motor gear oil The wheels of the locomotives are driven by electric motors called traction motors. Locomotives are typically equipped with four to six traction motors that drive the wheels. These motors are connected to the drive axle through a gearbox, which incorporates bevel gears along with pinion and bull gears. The
34 LUBE MAGAZINE NO.177 OCTOBER 2023
Table 4: GE (now known as Wabtec) AC traction motor lubricant specifications with required ASTM test methods [8].
These oils are specifically formulated without the use of active sulphur-phosphorous EP additives due to their potential ability to damage the yellow metals (bronze, brass, etc.) used in many bearing components. Opting for synthetic gear oils provides a substantially extended oil drain interval (ODI) of
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