DRIVE MEANS FOR CHAIN SAW

Abstract: Drive means for a chain saw with low vertical extent for timber harvesting vehicles, comprising a drive motor (13), a holder (16) with clamping means (17) for clamping a chain saw guide bar (18), a bearing assembly (15) allowing the holder to rotate in relation to the motor and a swivel device (21) to convey liquid from the motor to the guide bar through closed channels and grooves, where the bearing assembly (15) and the swivel device (21) have large inner diameters and are mounted concentrically around the motor (13).

Description: DRIVE MEANS FOR CHAIN SAW Background Timber harvester vehicles are commonly equipped with a feller head mounted on a mobile boom and comprising a chain saw, gripper arms, feed mechamisms and measuring equipment. Two desirable features of such a chain saw are that it shall be able to cut a tree close to the ground without risk of damage to sensitive saw parts, and that it shall allow locating two sets of gripper arms as far apart as possible within a limited height of the feller head. The present invention is an improvement upon previous chain saw designs in these respects. Description A chain saw being part of a feller head comprises a drive motor, usually hydraulic, a guide bar with a saw chain, a guide bar holder with clamping means for the clamping end of the guide bar, a bearing to allow rotation of the holder a limited angle relative to the feller head, a torque drive means to apply a torque for rotating the holder, and liquid transfer means to convey liquids such as lubricant, wood preservative or paint between the feller head body and the guide bar. In feller heads according to prior art, the parts of the chain saw are mounted vertically on top of each other, with the drive motor on top, and lower down the bearing, the torque means, the holder and clamping means, the guide bar and the liquid transfer means. As the liquid transfer means are often flexible hoses, these vulnerable parts are located closest to the ground and are easily damaged by rocks or wood debris . According to the invention, the total height of the chain saw is reduced to allow a greater distance between the gripper arms and thus a firmer grip on the tree. This is achieved by making the bearing with such a large inner diameter that it can be located concentrically around the drive motor instead of below. The liquid transfer means is made without hoses as a swivel device with two matching parts with concentric grooves and gaskets, similar in principle to the patent GB 2 000 568 but with a much larger central bore to allow locating it concentrically around the drive motor and the bearing. One of the matching parts is solidly connected to the holder and has internal drilled channels to convey the liquids from the liquid transfer means to the clamping means and further into the guide bar, while the other matching part is solidly connected to the motor. This allows working closer to the ground without damage to the liquid supply. The large diameter of the bearing makes it more resistant to vertical loads on the guide bar, and the motor is protected by being surrounded by the bearing and the holder. Figure 1 shows a partly cut-through chain saw according to the invention, located between an upper protective plate (11) and a lower protective plate (12) , both of which are rigidly attached to the feller head. A drive motor (13) is partly recessed through the upper protective plate (11) and attached to it by a flange (14) . A bearing assembly (15) , preferably a roller bearing, is attached to an outside part of the motor below the upper protective plate (11) and allows rotation of a holder (16) concentrically around the drive motor. The underside of the holder carries a clamping means (17) which clamps a guidebar (18) from below and above at a clamping end. To allow tensioning of a saw chain around the guide bar, the clamping means is preferably movable in the lengthwise direction of the guide bar. On the lower side of the holder (16) a torque drive means is attached, comprising a pin (19) and a hydraulic cylinder (20) applying a force from the feller head to the pin (19) . The torque drive means (19,20) may be partly located in the same plane as the clamping means (17) . The lower side of the flange (14) of the drive motor and the upper side of the holder (16) are made as matching parts of a swivel device (21) with concentric grooves and gaskets to convey liquid from the protected and non-moving upper part of the flange (14) which is safely and easily accessible with hoses or tubes from the feller head and the carrying vehicle. The liquid is further conveyed through channels (23) in the rotatable holder (16) and the clamping means (17) to the guide bar (18) . The surfaces of the matching parts of the swivel (21) are preferably flat or conical to allow controlling the clearance between them by means of part of the bearing (15) being able to support axial forces. The force needed to move the clamping means (17) in the direction of the guide bar to tension the saw chain may be produced by a liquid conveyed from the drive motor through the swivel device (15) . This liquid may be a separate liquid supply, or a side function of the lubricant flow or the motor drive fluid.

Claims: CLAIMS 1. Drive means for a chain saw with low vertical extent, comprising a drive motor (13) , a holder (16) with clamping means (17) for clamping a chain saw guide bar (18) and a bearing assembly (15) concentric with the drive motor allowing the holder to rotate in relation to the motor, characterized by the bearing assembly (15) having a large inner diameter and being directly fastened to the outside of the motor (13) . 2. Drive means according to claim 1, characterized by comprising means to convey liquid from the drive motor (13) through a swivel device (21) with concentric grooves and gaskets in matching parts connected to the motor (13) and the holder (16) , and further through channels (23) in the holder (16) and in the clamping means (17) to the guide bar (18) . 3. Drive means according to claim 2, characterized by the swivel device (21) having a large inner diameter and being located concentrically around the bearing assembly (15) in the same plane. 4. Drive means according to claim 3 , characterized by the matching part of the swivel device (21) connected to the motor (13) being one surface of a flange (14) also used to attach the motor to a feller head of a timber harvester vehicle. 5. Drive means according to claim 2, characterized by the bearing assembly (15) comprising parts for supporting axial forces .

Inventors: LEINI ARVO, LEINI, ARVO
Applicants: SANDVIK AB, SANDVIK AKTIEBOLAG
Application year: 1996
Main classification: A01G23
IPC codes: A01G23, B27B17