| 摘要 |
<p>The present invention concerns a valve device for automatic adjustment of the fluid pressure to a hydraulic tightening valve (5) active in a sawing gear between a holder (1) and a saw bar (2) displaceable in a longitudinal direction relative to the holder for adjusting the tightness of a saw chain (3) running around the saw bar and a drive gear arranged on the holder, where the tightening piston (5) is connected to a hydraulic system via the valve device, whereby the valve device includes a cylindrically-shaped space (7) and the piston device (8) suitable to fit and move between two stop positions in that space, characterised in that the space (7) before the piston device (8) in its forward position, has opening connections, partly to the hydraulic system and referred to below as the inlet (9), and partly to the tightening piston (5) and referred to below as the outlet (10), in that an openable check valve device is arranged in the outlet (10), and that in its active position allows fluid to flow only in one direction from space (7) to tightening piston (5), in that the piston device (8) is put under tension by a spring in a forward direction towards the outlet (10) and that in its forward stop position is capable of affecting the check valve device (11) so that it takes up an open position, whereby the piston device (8), when the hydraulic system is in a non-pressurised state, is caused by the influence of the spring to take up its forward position and open the check valve, and that in the hydraulic system's pressurised state, is pushed back by the pressure in space (7) to its rear position which activates the check valve (11) to prevent hydraulic fluid from flowing from the tightening position (5) to space (7).</p> |
