回程速度 meaning in Chinese

opening speed
return speed
speed of return stroke

Study on the backing velocity of the vacuum booster
汽车真空助力器回程速度的研究
The double air regulator to control riveting speed effectively
气路加装双向调节阀，有效控制铆接速度和回程速度。
( 2 ) in the original system because of the area between the piston and the piston pole is too small , the system pressure will rise when in the return stroke . and the reliever valve will open . the return velocity will reduce
( 2 )原设计中，由于活塞和活塞杆的面积差很小，回程上行时，系统压力会迅速升高造成溢流阀的溢流而使回程速度降低，从而降低了系统的工作效率。