| 摘要 |
<p>A valve device including a cylindrically-shaped space and a displaceable piston dimensioned to fit and move between forward and rearward stop positions within the space, having a first opening connection or inlet to the hydraulic system and a second opening connection or outlet to the tightening piston in the space and an openable check valve positioned in the outlet such that the check valve allows fluid to flow only in one direction from the cylindrically-shaped space to a hydraulic tightening piston in a sawing gear for adjusting the tightness of a saw chain. The displaceable piston, with the hydraulic system in a non-pressurized state, is urged by the influence of a tensioned spring to its forward stop position opening the check valve and with the hydraulic system in a pressurized state, is pushed back by the pressure in said cylindrically-shaped space to its rearward position which permits the check valve to close preventing hydraulic fluid from flowing from the hydraulic tightening piston and into the cylindrically-shaped space.</p> |
