美国马歇尔航天飞行中心应用了一种线性移动的驱动机构,它能按所供应的压力大小调整其三个不同的位置。图示中的小活塞可在大活塞中滑动,而大活塞可在该驱动机构的孔内滑动。大活塞右端由赋子弹性的活塞环支持,左端则由对开环(二个半环)支持,由壳体凹槽中向外伸出的返回弹簧还能在驱动杆(活塞杆)伸出位置时起承托作用。 The United States Marshall Space Flight Center uses a linearly-moving drive that adjusts its position to three different pressures. The small piston in the illustration can slide in a large piston while the large piston can slide in the hole in the drive mechanism. The right end of the large piston is supported by the elastic piston ring and the left end is supported by the split ring (two half rings). The return spring extending outwardly from the groove of the housing can also protrude from the driving rod (piston rod) Position from the supporting role.