Here is the rig. A mixer dumps its load into the hopper of the pumper. The pumper pumps it through the 2-inch line to the men at the pour. The pump operator has a remote control that controls the flow. He stays with the concrete men and pumps when they call for more and turns it off when they say. Neat. Pumping two mixers full of concrete took about 3 hours. The pump operator said he could pump that amount in 30 minutes if they didn't need him to stop. Fun.