Shaft assembly for stump cutter

A stump grinding apparatus of the type adapted to be mounted in a frame on the end of a boom is described. The apparatus comprises a grinding wheel mounted between hubs keyed to a shaft that is connected though belts and gears to a source of motive power, such as a diesel engine. A pair of non-adjustable roller bearings are used to provide relative movement of the shaft and grinding wheel in the frame. The apparatus includes means for providing lubrication between relatively moving parts so that the life of the bearings and other component parts can exceed 5000 hours of use without failure. The shaft assembly includes dimensional tolerances that protect the moving parts from the ingress of dirt and other debris. The materials of construction are selected to also enhance trouble-free operation.