The hydraulic cylinder can be used alone or connected in series. One end of the hydraulic cylinder connects to the motor driven change valve, the other end connects to the rod string.
液压油缸可单独使用，也可串联使用，它一端与机动式换向阀连接，另一端与抽油杆柱连接。
2
The motor case is a steel cylinder closed tight at one end. the other end is the open throat and nozzle.