PURPOSE: To prevent unstable steeing when running in unleveled ground, by enabling equipment of a detachable damper to prevent unstable movement of front wheel in a steering system of moving form machines.

CONSTITUTION: One side of a drag rod 5 is combined with one side of a drag arm 4, and the other side of the drag rod 5 is freely adjustably combined with a rod end 9. And, a fixed bracket 12 is secured to a frame 11, a damper 13 is detachably mounted between the bracket 12 and a movable braket 10 provided at the connecting part of the drag rod 5 and the rod end 9. Accordingly, a stable operation can be performed on even unleveled ground, because the damper can be mounted or removed as occasion calls.