Abstract: An improved brush assembly for horizontally rotating brushes on street sweeping machines. A circular disk carries brush holders for holding bristles in the desired configuration. The brush holders are clamped to the disk by a clamp having a clamp bar that engages the brush holder and is maintained parallel to the brush holder with an offset support. A bolt between the brush holder and offset support presses the clamp bar firmly against the brush holder to hold it in place. Alignment holes in the brush holder cooperate with pins on the clamp bar to maintain the brush holder in the proper position. Holes through the brush holder have transverse walls so that U-shaped bristles can be extended through the holes with legs of the U-shape on opposite sides of the transverse walls. Preferably, the holes position the bristles outwardly of the disk at about 62.degree. to the disk.