The dumb waiter
The dumb waiter serves as a symbol for the broken, one-sided communication between Gus and Ben. If messages are to be sent via the dumb waiter, then only one person at a time can send them, and one cannot simultaneously speak and listen through the dumb waiter's speaking tube. Correspondingly, Gus and Ben never have a fully open dialogue—minimized even more by Ben's knowledge of his impending betrayal of Gus—and whenever Gus tries to bring up something emotional, Ben refuses to speak with him. This disconnection is the essence of their relationship. They do not speak with, but to each other. They are like the dumb waiter—mute carriers of information, not sharers of it. Moreover, Ben, especially, is manipulated by Wilson in the same way that the dumb waiter is controlled by its system of pulleys.