Walking machine variable displacement pump, if dirt clogged pores balancing valve, leading to the parking brake can not be released, resulting in walking deviation. Because the machine is in walking variable pump maintenance., If not through the oil pressure balance valve orifice into the balancing valve spring chamber to promote balanced valve spool moves, the pressure balance valve oil can not pass through the slot on the system into its hydraulic variable pump monopoly., resulting in parking brake force can not be lifted, the results can not rotate the motor running, so there walking deviation. Remedy; cleaning Valves; when disassembly, to avoid dirt; regularly replaced to meet the requirements of hydraulic oil and filter. Variable hydraulic variable displacement pump and variable mechanism motor pump has a variety of variables refinement, which can be divided into two categories: the first category divided according to type manually operated, motorized, electric, hydraulic and electro-hydraulic proportional control control belonging to external signal control variables; second class by adjusting the way to distinguish, which automatically controls the pump (motor) basic parameters (including pressure, flow, power, etc.) change according to certain rules, such as constant power, constant pressure, constant flow. Variable hydraulic pump specializing ._ crystal Chong (certified) _ variable pump provided by Jinan Jing Chong Hydraulic Machinery Co., Ltd .. 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.