DH300 high quality Track Roller Undercarriage Parts excavator for PC200-5 CAT235 The supporting roller is often in the lower part of the track, and the track is supported upward, so that the track ensures a certain tension and prevents deviation and deviance.It is widely applied in bulldozers and excavators Caterpillar, Komatsu, Hitachi, Kobelco, Kubota, Yanmar and Hyundai etc. Our products are according to the standard of OEM to manufacture.