Due to this particular requirement of the stator profile, deceleration curves such as acceleration and other accelerations are typically used as the transition curve for the stator length and the short radius arc. In the range of length and short radius, it allows the blade to accelerate radially in the first half of the transition curve, while the latter half does not suddenly change speed in the same deceleration motion, nor does it produce rigid impact and inefficiency.

The working cavity of the double-acting vane pump is to ensure that the suction and pressure oil chambers are closed to each other without communication, and the center angle corresponding to the interval between the suction and pressure oil windows on the distribution disc is not less than the central angle between the adjacent two vanes. In addition, considering the thickness of the blade, when machining the stator curve, the center angle and the sum corresponding to the length and the radius and the transition curve are appropriately adjusted. The pump's flow pulsation and pressure fluctuations are significantly improved. Practice has shown that when the general (R-r) is not more than 7.3 mm, the vane pump with reasonable structure, stable pressure, uniform flow and good performance can be obtained.

Although the acceleration curve and other deceleration curves do the pressure of the transition curve pump, the flow rate is uniform, and the performance is good, but there are also different degrees of rigid impact or flexible impact, and high pressure backflow causes pressure shock. At present, the latest method adopts the high-order curve design transition curve, optimizes the design of the large radius arc to become the pre-compression curve segment, and then adjusts the curve adjacent to the arc to maintain the smoothness of the transition curve, so that the pump is neither rigid. The impact has no flexible impact, and at the same time solves the phenomenon of high pressure reflow. Therefore, the maximum allowable value of the long and short radii has important guiding value for the design and research of new pumps of the same type.