Abstract: Cutting horizontal, cantilevering objects of splittable material, such as de-barked tree trunks and the like is carried out with the aid of a guided, endless circulating saw chain (10), the upper cutting part of which is moved from below and upwards through the object. The lower edge portions of the cut surfaces at the cut are allowed to bear against each other under the action of the bending moment of the cantilevering object, while the return portion of the saw chain in the cutting area is kept free from the cut surfaces. The saw chain is guided by a chain guide (12) extending curvilinearly under the object and guides the return part of the chain. The chain guide and the guided return part are both outside and below the object during the whole of the cutting operation, while the upper cutting portion of the chain runs straight between the end points of the curved portion of the chain guide.

Abstract: Apparatus for suspending a tree felling and gripping unit on a jib, the unit having a frame, and the apparatus including a rotator between the jib and a felling and gripping unit for rotation of the unit relative to the jib, the rotator having a stationary portion and an inner portion rotatable about an axis, the rotatable portion having a lower end; a horizontal axle pivotally suspending the stationary portion of the rotator from the jib; a first hydraulic device connected between the jib and the stationary portion of the rotator for swinging the rotator about the horizontal axle; a further axle extending perpendicularly to the rotation axis of the rotatable portion of the rotator and pivotally suspending the frame of the unit from the lower end of the rotatable portion of the rotator; and a second hydraulic device connected between the rotatable portion of the rotator and the frame of the unit for swinging the unit about the further axle.

Abstract: The invention relates to a forest thinning device for forest working vehicles with an operator's cabin (2) and a crane beam (13) operated from this cabin, at the end of which a felling and gripping aggregate (14) is mounted. A markedly greater reach and increased operating possibilities at forest thinning are obtained in that the operator's cabin (2) together with the crane beam (13) according to the invention is supported at its end by a boom arrangement (4) attached to the vehicle and extendable from this.

Abstract: When a tree stump has been split into several parts by a chopping action, the invention provides a gripping, shaking and cutting unit rigidly connected to the end of a vehicle-carried rotatable crane boom, having an adjustable effective length, for pulling out the stump parts along with their roots one by one from the earth in a direction substantially corresponding to the extension of the roots, and then shaking and cutting the stump parts.

Abstract: At the end of a vehicle-carried crane arm a vertically extending frame is supported which at its lower end carries a movable split head with spreadable chopping blades. A ram raisable to the top of the frame drives, when released, by the impact on the split head the blades into the center of a tree stump that is to be extracted from the earth. Then the blades are spread to break the stump into separate portions which are easily individually removable in a direction substantially following the extension of the roots.

Abstract: At the end of a crane arm on a base vehicle is fixed a frame, the inclination of which is controlled by double-acting hydraulic cylinders, and which supports hydraulically operated grip arms and a cutting unit. The frame is moved with an estimated inclination against a tree, and the grip arms urge the frame into conformance with the actual inclination of the tree, thereby inducing strains in the tree as well as the firmly based crane arm. A valve connecting the inlet and outlet of each hydraulic cylinder is momentarily opened from its hitherto closed position, so that the fluid in the cylinder is forced to equalize under the strains from the biased tree which consequently will be relieved from tension before cutting, otherwise resulting in cracks in the root end of the tree.

Abstract: A crane jib includes a support, a base arm pivoted in the support, and a jib lever pivotally connected to the base arm. The jib lever supports at its free end a work tool and is oscillated on its support by two hydraulic jacks, the first of the jacks is placed at a point from the journal place of the base arm, while the second jack is placed adjacent the jib lever. The second hydraulic jack has its line of action approximately parallel to a line through the bearing points of the base arm, while its lower bearing point is disposed at a lower level than the bearing place of the base arm.