The second is the damper (3) is clogged, Hanzhong roller hydraulic repair, hydraulic transfer on less than the cone valve, the pilot valve will lose its regulatory role supporting the main valve pressure. Rear dampers (holes) blockage, at any pressure poppet valve will not open overflow oil, always no oil flow valve, the main valve upper and lower chamber pressure remains the same, roller hydraulic repair price, since the upper end of the main spool annular pressure area is greater than the lower end of the annular pressure area, so the main valve is always closed, roller hydraulic repair factory, will not overflow, roller hydraulic maintenance unit, the main valve pressure rises with the load increases. When the actuator is stopped, the system pressure will be up indefinitely. In addition to these reasons, still need to check the external control port is blocked, the poppet valve installation is good and so on. The average load factor of engine purely mechanical transmission is low, it is generally only stepped transmission, and layout is limited. But because it has a high transmission efficiency and steady low manufacturing cost advantage terms, in the speed range relatively small areas of GM passenger cars agricultural tractors and demanding economy, constant speed operation to date still holds a dominant position.