In the light of the frequent breaking of the rod string in a surface driven screw pump well, the force condition of the string in the well is analyzed by means of the elastoplasticity theory.
针对井口驱动螺杆泵抽油杆柱断脱频繁的问题，应用弹塑性理论分析了抽油杆柱在井中的受力状况。
2
Motor-driven push-rod design, adjust arbitrarily the angle of the crus and the back.
电动推杆设计，任意调节小腿和靠背高低角度。
3
A hydraulic step cylinder system (HSCS) used as a new kind of nuclear control rod driving system is driven by dynamic pressure.