Variables constant pressure pump control called constant variable pump, its control principle shown in Figure 1, where 1 is the control slide valve, pressure regulator spring 2, 3 is a control variable cylinder pump maintenance, 1 and 2 are collectively referred to constant pressure valve. When the system pressure is low, there is no right of control oil pressure cylinder, control cylinder runs right under the action of the spring, pushing the pump variable variable pump body, the pump at maximum displacement state. Refinement variable pump when the system pressure increases to the set pressure of the constant pressure valve control spool ends fluid pressure is greater than a spring force of the regulator valve to the right, the right pressure oil into the control cylinder, push control cylinders Run to the left, then push the pump variable variable pump body care, so that the pump displacement is reduced, thus reducing the output flow, pump working pressure with constant variable pump control reduces the pressure limiting principle 123 type variable vane pump can automatically adjust the flow according to load size, power use is reasonable, can reduce heating oil, so often used to perform elements require fast or slow or packing requirements of the occasion. Fast load is small, low pressure, flow, pump in characteristic curve segment. Slow feed, load, high pressure, low flow, the pump automatically switches to characteristic curve segment. When packing, at near point work, provide a small leakage flow to compensate for this limited-pressure system variable vane pump rated pressure 6.3pa? Variable pump hydraulic repair phone ,, crystal Chong (certified), variable pump from Jinan crystal 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.