| 摘要 |
<p>In a system for controlling the clamp means in a tree harvesting machine, especially grapple harvester, there are means controlling the flow of pressure medium to actuators (B8) which are connected to the clamp means in a power transmitting way, said control means being placed on a line (P) for pressure medium. For adjusting the clamping pressure, a pressure-reducing valve (3) is placed on the line (P) and it is designed for permitting the flow of pressure medium at a predetermined pressure to the actuators (B8), and a relief valve (2) is further provided on the line (P) after the pressure-reducing valve (3). The pressure-reducing valve (3) and the relief valve (2) are connected to a pilot valve (5, 6) determining the pressure level. The pressure-reducing valve (3) and the means situated after it and being connected to the line (P) for pressure medium are placed in a part carrying the clamp means, such as in a felling head.</p> |
