Central swivel joint composed by the housing and the mandrel, the casing attached to the upper body to the lower body mounting the mandrel. There are open on the mandrel and an equal number of annular groove tubing, hydraulic oil from the housing to walk through these sump hole flowing from the vertical spindle motor on the refinement of variable pump ', so even with the upper part of the body shell constantly swing, groove on the mandrel and the oil port can also be kept open on the housing. Hydraulic oil can freely in and out. Failure to timely replacement of hydraulic oil filter maintenance variable pump 'that can lead to open the bypass valve on the filter, hydraulic oil due to unfiltered impurities in the oil directly into the center of the sliding surface of the variable pump swivel joints, making it on ring damage, the machine while walking side pressure due to oil spills caused by both sides of the travel speed of the motor is not the same, resulting in a machine running deviation. Remedy is: rotary joint replacement center seal; hydraulic oil and filter replacement. Variable radial piston pump variable displacement pump includes a piston and shaft eccentric eccentric, including a swash plate type axial piston variable displacement pump and Cline - variable motor speed control circuit is equal to the pump speed range and speed range Rp motor speed range Rm seed multiplication circuit for high-power hydraulic system is particularly suitable for systems with two or more hydraulic pumps and hydraulic motors can require separate occasions for speed variable pump repair phone '_ _ crystal create a variable hydraulic pump by Jinan Jing Chong Hydraulic Machinery Limited. Jinan Jing Chong Hydraulic Machinery Co., Ltd. (www.jnjcyy.com) (www.jnjcyy.com) strong, credible, in Jinan, Shandong mining machinery industry has accumulated a large number of loyal customers. The company better work attitude and continuous improvement to create innovative ideas will lead crystal hydraulic and you hand into the brilliant, for a better future!