FIELD OPERATIONS 351 



CONTINUOUS MIXERS 



Drake Mixer. One of the best known forms of continuous- 

 mixing machines is the Drake mixer. This mixer consists 

 of an open trough fitted with a longitudinal shaft, to which 

 are fastened blades, or paddles, some of which are set at an 

 inclination, so that they will not only mix the ingredients, 

 but also feed the mixture toward the discharge end. The 

 mixer is so set that the shaft revolves on a horizontal axis. 

 The ingredients are deposited by wheelbarrows or from a 



FIG. 4 



measuring box at the upper, or feeding, end of the trough. 

 The straight blade, or knife, at that end cuts or stirs the 

 mass, which is then turned over by the adjacent curved 

 blade, or scoop, and advanced to the next knife, where it is 

 again cut and then turned over by the next scoop, and so 

 passed on. This process is repeated until the end of the 

 trough is reached, when the material is pushed out and falls 

 into a receptacle as mixed concrete. The ingredients are 

 mixed dry for about one-half the length of the trough and 



