PURPOSE: To achieve complete straight advancing and smooth turning by operating independently right and left drives for crawler drives each other during turning without moving to one side.

CONSTITUTION: Drives for crawler drives 11 and 12 are not moved to one side at a curve but operated independently of each other, and comprise a drive pump 3 or 4 and a corresponding hydraulic motor 7 or 8. A clutch 16 for straight advancing is provided and comprises a multiple disc joint, which is electronically operated on, e.g. a road surface via the handle of a finisher. When the handle is in its neutral state, the two hydraulic motors 7, 8 connected to the clutch 16 can be connected by joint shafts 17 and 18. However, since the two drives are not completely the same, a connection made by the clutch 16 may render the hydraulic drives inoperative only if operating fluid has leaked.