| 摘要 |
A rock cutting tool with a plurality of independently rotatable cutter units and with a shaft, a sleeve located around the shaft, and at least two rotatable hubs located around the sleeve. At least one cutter unit is located on each of the two rotatable hubs for rotation about an axis of rotation with respect to a rock-face. Bearings between the sleeve and each of the hubs rotatably support the hubs. The bearings comprise at least one cylindrical roller bearing set and at least one ball bearing set for each hub. Each roller bearing set is located substantially entirely under the cutter unit of its associated hub to absorb radial loads, and each ball bearing set is located remotely from the cutter unit of its associated hub to be isolated from radial loads. The shaft has first and second key receiving openings. The key is located on the interior surface of the sleeve. The key is mateable with the first and second key receiving openings in the shaft whereby the sleeve is rotatable with respect to the shaft from a first position to a second position to disengage the key from the first key receiving opening and engage the key in a second key receiving opening to extend the bearing life. |
