Improving running safety in sharp curves, especially in transition curve, reducing wheel load variation is very important. When railway vehicle runs in transition curve section, superelevation gradually reduces continuously and the plane consisted of right and left rail is twisted. This track twist produce diagonal differential pressures of secondary suspensions in the car which makes unbalance of wheel load in the car. So we developed newly system "connecting front and rear air springs" to reduce wheel load variation. Connecting front and rear air springs has an effect of cancellation of diagonal differential pressures, which can be realized by additional air pipings and differential pressure valves. We installed this system in Tokyo Metro Chiyoda line train, and carried out test run to evaluate the effect of this system. The test data show wheel load variation rate of proposed system was improved compared to conventional system. And the diagonal differential pressure (equal to car body twist) was significantly improved with this system.The test results show that wheel load variation rate is improved approximately from 20% to 30%, as a result, derailment coefficient data was improved approximately from 15% to 25% for each curves in the test.
