Fig. 2.5 shows one example of DF200 running data. Due to measurement conditions, only the acceleration current of two motors, locomotive speed and DC link voltage are indicated.
3 High-Speed Engine Maintenance
As described earlier, in Japan, 1500 - 1800 rpm engines are used as locomotives. Compared to that of high-speed marine boats, the operation of railways does not place engines under any mechanical strain because average power consumption is low. However, long periods of idling mean that combustion is not good. Maintenance suited to railway operation is required. It is generally held that as long as the maintenance of four items; engine oil, cooling water, fuel, and air, is performed properly, the service life of the engine will be lengthened for products of engine manufacturers with a good current track record, unlike older products. To test this idea, Table 3.1 shows the maintenance situation of JR Freight as reference. These four items will now be described briefly.
3.1 Oil
The purposes of engine oil are described below:
(I) Reducing wear and tear (anti-friction effect)
(2) Filling in spaces (sealing effect)
(3) Reducing the temperature of the friction surface and high temperature parts (cooling effect)
(4) Removing dirt (cleaning effect)
(5) Preventing metal from rusting (anti-corrosion effect)
Oil grades as classified by the American Petroleum Institute (API) constitute the international standard, and of the CA-CE classes, the CD class or better is considered most suitable. Adhesion, dependent on the operating environment, is also important and follows the classification set by the Society of Automotive Engineers (SAE). This stipulates that there are two groups of oil; one which guarantees low temperature adhesion (0W, 5W, 10W, 15W, 20W, 25W), and another which guarantees high temperature adhesion (20, 30, 40, 50). In addition, there are oils which guarantee both groups (multi-grade oil, for example 15W - 40).
Oil degradation occurs as a result of the use of additives and the addition of inflammable and foreign substances, and cannot be avoided. It is advisable to replace the oil filters at intervals recommended by the engine manufacturer and set guidelines for when to change the oil by measuring the kinematic viscosity and base value. JR makes observations of deterioration using a ferrography, when changing the oil.
