Lightweight contact strips reduce the pantograph sprung mass, improve compliance characteristics, reduce the contact loss ratio and feature an extended lifespan. To improve the performance of carbon-based contact strips, therefore, the RTRI promoted the development of lightweight versions and subsequently manufactured a mixed/sintered carbon-based product by mixing dendrite metal power and reducing the metal ratio by about 10% from that of conventional strips. The new product is 10% lighter, with the resistance ratio and decreased mechanical strength kept within a practical range. After checking the wear characteristics with a wear-testing machine, the RTRI tested it on a commuter vehicle and confirmed that the wear ratio decreases by 25% from the present level (Fig. 1).
The RTRI also manufactured a special shoe for screw-fixing-type contact strips made of C/C composite material and installed the strips for testing on another commuter vehicle. It was confirmed that the wear ratio decreases to about 50% that of metal-impregnated carbon-based strips fixed to an existing shoe (Fig. 2).
This is a result of the combined effect of using C/C composite material for the contact strips (making them lighter and 14 mm wider than existing versions for each shoe), the improvement of pantograph compliance characteristics, and the dramatically extended lifespan of the strips.
The RTRI plans to improve the wear resistance and strength of contact strips made of C/C composite carbon-based material and enhance the screw-fixing method/material to improve the reliability of the strips.