Patent ID: 7040428
Filing Date: 2006-05-09
Classification: B60G,B60P,B62D

Abstract:
1. A chassis structure for a forest machine moving on a terrain, the chassis structure comprising at least: a pair of adjacent front wheels arranged to support a first frame part placed therebetween, a pair of adjacent rear wheels arranged to support a second frame part placed therebetween, and a pair of adjacent middle wheels arranged to support the second frame part, a frame joint arranged to fold the first frame part and the second frame part in relation to each other at least around an axis that is vertical and transverse in relation to a horizontal longitudinal direction to the forest machine, a first actuator to control the folding, a suspension between each wheel of the pair of front wheels and the first frame part and between each wheel of at least the pair of middle wheels and the second frame part, wherein each suspension comprises a second actuator arranged to change the position of the suspension in relation to the corresponding first or second frame part for elevating and descending the corresponding wheel, wherein: each suspension is arranged to elevate and descend the corresponding wheel with respect to the corresponding frame part in a plane that is vertical and transverse in relation to the horizontal longitudinal direction of the forest machine, and each wheel is mounted in a rotatable and turnable manner to the corresponding suspension, wherein each suspension further comprises a third actuator arranged to turn the corresponding wheel with respect to the suspension and with respect to the corresponding frame part around an axis that is vertical and transverse in relation to said horizontal longitudinal direction, wherein the third actuator is arranged to guide the wheels to a correct position at each moment of time during driving, and wherein, during driving a curve for bypassing an obstacle after driving straight ahead, the third actuator is arranged to control both the pair of front wheels and the pair of middle wheels to follow said curve for bypassing the obstacle, the pair of middle wheels being controlled to drive the curve by first driving straight ahead until the curve is reached and then following the curve, the pair of middle wheels being controlled to drive straight ahead even if the pair of front wheels is already following the curve.