To quickly move a mud cover at the start of a hydraulic shovel even in snowy areas etc.

A truck frame 8 is provided with a mud cover 22 located between a crawler 19 and a sideframe 12 to cover the top of the truck frame 8. By vibrating the mud cover 22 by means of a hydraulic cylinder 23, mud dropping from the crawler 19 onto the mud cover 22 is discharged. Further, a heating conductor 26 is provided on the back side of the mud cover 22 and electric power is supplied to the heating conductor 26 to heat the conductor 26. Thereby the mud cover 22 is entirely heated so that snow frozen on the mud cover 22 is melted in a short time.