<p>Some six-group low-floor trains are operated on light rail lines in Changchun of China. These trains use traditional motor bogies and independently rotating wheelset (IRW) trailer bogies. The natural curving is not available in IRW, and so some lines are suffering from severe wheel-rail wear, especially on curved track. In addition, train running safety also degrades. In view of the restricted space inside the existing train, this investigation proposed a novel auxiliary steering device. The key component of this device was a steering bearing consisting of upper and lower parts, which were connected to the motor and trailer carbodies, respectively. During curve negotiation, the relative motion between the upper and lower steering bearings caused the lateral steering force pointing to the curve center and exerting on trailer carbody. The action of the steering force resulted in the improvement of contact state between IRW and rail, and consequently the improvement of train curve passing performance. Some key design parameters of the auxiliary steering device were deduced. The light rail train-track coupled dynamics model was established and simulated to evaluate the guidance ability of the steering device. The influence degree and influence law of curve radius and device variable on the device guidance ability were also assessed. Field experimental test was performed using a full-size train on the test line to measure the IRW curving performance. The results of the field tests with and without auxiliary steering device were analyzed comparatively for validation, which revealed the effectivity of the proposed auxiliary steering device in alleviating the difficulty about IRW steering problem drastically.</p>