If you walk inside the main valve spring soft or broken, or the valve is stuck, are likely to cause lower oil pressure, appear to walk deviation. Variable pump maintenance check *, walking the main valve manifold to measure the pressure of the variable displacement pump, normal if 32.5Mpa. If you walk the main valve is damaged, replace or repair. My unit PC200 excavator has twice appeared walk deviation, are due to damage caused by walking the main valve. Therefore, the variable pump refinement * in the event of failure to walk deviation, you should first consider whether to walk the main valve is damaged variable pump * care to avoid detours. One revolution each plunger and its amount of oil discharged to go stroke related to the larger stroke of the larger amount of oil is discharged, and the stroke of the plunger depends on the angle of the swash plate when the swash plate angle A greater the plunger the greater the pump stroke the greater the amount of oil discharged. So changing the swash plate angle can change the pump displacement. In the swash plate angle of the variable displacement pump is controlled by the servo piston, the servo piston moves to the left when the big end of the servo piston oil pressure, boost mobile swash plate to the left, so that the angle A smaller, smaller displacement smaller stroke . Control of critical control servo piston pump displacement becomes, currently there are many factors to control it, such as system pressure, back to the oil pressure valve and electronic control devices. Variable pump sales *, Jing Chong hydraulic (certified), variable pump from Jinan Jing Chong hydraulic machinery Limited. Jinan Jing Chong Hydraulic Machinery Co., Ltd. (www.jnjcyy.com) (www.jnjcyy.com) Shandong Jinan, mining machinery leaders, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, the maximum meet customer needs. In the crystal to create a hydraulic leadership with the staff warmly welcome all inquiries negotiations to create the crystal to create a better future for the hydraulic.