PURPOSE: To enable durability to be improved of a cylinder with no necessity for providing an overload relief valve by providing the steering hydraulic cylinder to be vertically swiveled with a front axle further to be placed in the same height in front of the car body and behind the axle.

CONSTITUTION: A steering hydraulic cylinder S is pivotally supported in its one end to a part of a differential gear case cover 1 of a front axle 2 and in the other end to a knuckle arm 16b of a turn bevel gear case 16 provided in both ends of the front axle 2. Further the cylinder is connected to a tie-rod arm of a turn bevel gear case 20 in the left end through a tie-rod 23 from a tie-rod arm 16a protruding from the turn bevel gear case 16. While providing a cut recessed part 2d in a position interfering with the cylinder S similarly even in a part of a flange 3c, interference is avoided by steering telescopic action of the cylinder S.