Major Results of Research and Development in Fiscal 2004 II-6

6. A new pantograph contact strip for electric locomotives

Development of an arc-resistant copper-base sintered alloy contact strip that suppresses wear on trolley wire

Mounting of the newly developed contact strip on a DC electric locomotive, and confirmation that its wear rate is lower than that of the conventional one

New DC electric locomotives are mounted with only a single pantograph, which is required to collect twice the amount of current collected by those of two-pantograph locomotives. This subsequently increases the electric load on the pantograph contact strip of the new-type locomotives, leading to a significant increase in the wear on the conventional sintered alloy contact strips used for electric locomotives in high-speed operation. This poses a serious problem for inspection and maintenance work. In recent years, carbon-base contact strips have been widely used for EMUs on narrow-gauge railways to minimize wear on trolley wire. Contact strips that would increase wear on trolley wire should therefore not be used for electric locomotives either.
The RTRI therefore developed new contact strips by improving the component materials and their distribution in the sintered alloy contact strip (Fig. 1), performed laboratory tests to confirm their wear resistance and effects on the wear of trolley wire (Fig. 2). The RTRI then implemented a long-term durability test with the new strips mounted on DC locomotives to evaluate their practical performance (Fig. 3). Consequently, the RTRI selected a high-lubrication-type contact strip, (developed in recent years by the RTRI and now used for revenue service), replaced its solid lubrication component (graphite) with a sulfide, to give a contact strip with higher resistance than the one used in high-speed operation.
The newly developed contact strip is considered capable of extending the life of both the contact strip and the trolley wire. Its application to electric locomotives is therefore currently under discussion.

Fig. 1 Surface conditions of the contact strip under test on an electric locomotive (top: developed material, bottom: currently-used material)

Fig. 2 Effects of the currently-used and developed materials on the wear of trolley wire (laboratory test)

Fig. 3 Wear rate of the currently-used and developed contact strips (long-term durability test on an electric locomotive)

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