Abstract: Means for driving the back walls of the buckets of an excavating wheel having a plurality of circumferentially arranged digging buckets. Each digging bucket is provided with a pivotal back wall mounted on the excavating wheel. The excavating wheel is rotatably mounted on a central shaft. A central sprocket is freely rotatably mounted on a bucket wheel hub which is mounted on the central shaft. A mounting bracket is attached directly to the main frame of the vehicle and extends outwardly therefrom. An offset sprocket which is smaller in diameter than the central sprocket is rotatably attached to the opposite end of the bracket. The axes of rotation for the central sprocket and the offset sprocket are parallel. A continuous chain passes around the sprockets with the chain constrained to move in a predetermined path. Push rods are pivotally attached at one end to connecting links of the chain so that the push rods are disposed at equal intervals along the length of the chain.