Constant pressure valve is turned on, the pressure on the oil into the variable chamber piston, variable piston pressure in the lowest position, full displacement pump output pressure oil; it is set when the pump is constant pressure of work, the role of the constant pressure hydraulic spool it is set equal to the spring force of the thrust, constant pressure into the oil discharge port of the valve is turned on at the same time, the variable hydraulic thrust of the piston is equal to the upper and lower chambers, a variable balanced position in the piston, when hydraulic damping (load) increase, oil instantaneous pressure increase, constant drain port valve to open big, oil inlet off small, relatively lower chamber pressure variable piston upper chamber reduced variable piston moves upward, the pump flow is reduced until the pressure drops to the constant pressure it is set, Then variable piston working in the new equilibrium position. Conversely, if the hydraulic damping (load) decreases, hydraulic transient drop, constant oil inlet valve to open big, drain port off small, variable piston upper chamber rises relatively lower chamber hydraulic variable displacement pump refinement - variable the piston moves down, the pump flow rate increases, the pressure rises until it is set to a constant pressure. Hydraulic transmission with manual with variable axial piston pump, by subject and body composition variables, body by the pump casing, drive shaft, cylinder, a plurality of pistons, Slipper, return plate, return spring, a small spring, with oil pan, pump, etc., between the drive shaft and the cylinder splined plunger piston mounted on the cylinder bore, the plunger and ball associated shoe, shoe stuck in the return plate The hole, pump and pump housing associated with the oil pan fitted between the cylinder and pump, variable by variable body shell, variable head, large dial block, small block dial, dial columns and variable valve consisting of a variable Nursing pumps, variable valve mounted on the shell variable, the variable head and variables associated bearing housing through a small dial mounted on the rear derailleur block column variable valve installed in the variable displacement pump -, set aside the lower cylinder block is inserted in the large dial inside, a large block with screws aside variable variable pump head maintenance -, the main body and the variables associated with screws, Slipper close at variable head, respectively, by the drive shaft bearings mounted on the pump and variable housing , small size, light weight, low noise, and long life. Variable pump hydraulic record sales -_ crystal (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.