Cause: (5) pumps, the oil port adapter or elbow connector "O" ring damaged or bent connector fastening bolts into or out of the flare nut is not tight, the air into the hydraulic system; Remedy: Replace the O- seals, bolt or nut failure reasons tightened joints: (6) Drain pumps, seals and aging; Remedy: replace the seals Cause: (7) end or the main pump, the end face of the driven gear sleeve wear or scratch injury pump maintenance, both sleeve end surface roughness tolerance; Remedy: Replace worn gear pump or pump bushings, wear light when flat end mill will be smooth. Its flatness tolerance 0.03mm; the end face of the sleeve is less than the pump on the plane (normal less than 2.5 ~ 2.6mm) pump repair as ultra-poor should be at the hub plus 0.1 ~ 0.2mm copper to compensate should be put into the rear axle sets output flow fluctuations related to many factors during installation. Variable pump can be considered controlled variable caused by poor organization, such as foreign matter into the variable mechanism, set aside the order marks in the control piston, wear marks, scars, resulting in unstable control piston movement. Because the amplifier energy shortage or damaged parts, comprising a spring damper control piston pumps poor efficiency of the agent, can cause instability in the control piston movement. Unstable flow is often accompanied by pressure fluctuations. Such failures are generally open hydraulic pumps, replacement of damaged parts, increased damping, spring rates and improve control pressure. Hydraulic pump test _ crystal create quality assurance (certification) _ pumps 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 creating hydraulic leadership with the staff warmly welcome all inquiries negotiations to create the crystal creating hydraulic better future.