Assembling Sucker Rods Again and Again
Each female sucker rod end is dimpled (arrow). The dimple functions as a mechanical disruption of the threads, and therefore mechanical lock. As the male end is screwed in, when the two sucker rods are just about completely tightened, shoulder to shoulder, the male threads are disrupted, creating a lock.
The more a Simple Pump has been installed and removed, the more likely this mechanical lock is going to be ineffective. So, on the third time that the Simple Pump is installed, it may be wise to use Loctite non-permanent thread bonder, or a similar compound, before threading the male end into the female. This prevents the unlikely possibility that the sucker rods will slowly unscrew over years of use.