Definitions for "Balance Beam"
The beam projecting from a lock gate which balances its weight, and by pushing against which the gate is opened or closed.
A wooden timber attached to the lock gates. One on each side. These were used by the lock keeper to open and close the gates.
A beam projecting from a lock gate which balances its weight, and is used as a lever to open and close the gate. Normally constructed of wood or steel, occasionally cast iron, and painted black with the ends picked out in white.
Keywords:  aren't, concerned, want, needed, tool
a very simple tool, and just what is needed if you want to compare the weights of two objects but aren't concerned about their actual weight