Abstract：There are problems of variable displacement impact and unpreset of maxium displacement on pressure-compensated variable displacment pump. For the pumps analyzed and compared their adjust performance. And presented a method of improveing pump structure, use double-spring of rigidity-changed on the pressure-limited variable displacment vane pump and take measures adding pre-adjusting frame of swash plate angle on constant output axial pistom pump. Now it has be effectively applied to hydraulic press.
