A dam

I was born and raised right next to where the Jordan river starts in northern Israel.  Right next to where I used to live there's a small dam that helps diverting the flow of the river between two routs (the natural one and a man-made canal).  It's a manual dam with a big wheel that opens and closes the shutters.  

Whenever I feel emotional and that tears are about to wet my eyes, I'm imagining myself at the big wheel, turning it to close the dam.  Many times, I found, it really works.  I'm holding the wheel and the tears are kept in bay.  (Not that I'm afraid of crying, but I hate to keep boasting CVS` tissue sales.)  But sometimes even when I'm turning the wheel, tears are still flowing down my cheeks.  It's like those thorny blackberry shrubs, or a dead nutria, that used to get stuck inside the dam's shutters, preventing it from closing completely.  So if I will refer to the wheel every now and then, you know what I'm talkin` about.  I will say (dam) and that means that I'm holding the tears at bay - have a Clean-ex handy.