FIELD OPERATIONS 



349 



The chute b, Fig. 2 (b), through which the mixer discharges, 

 is kept in the position shown in Fig. 3 (a) while the concrete 

 is being mixed. When it is time to empty the mixer, the 

 handle c, Fig. 2, is turned. This turning of the handle, which 

 is connected to the chute by means of a chain, as shown, tips 

 the chute b, as illustrated by dotted lines in the figure. Mean- 

 while, the drum is revolving and lifting masses of concrete 

 up one side in the 

 direction of its motion. 

 These masses finally 

 fall by the action of 

 gravity to the bottom 

 of the drum. 



The path followed 

 by the concrete in the 

 mixer is shown dia- 

 grammatically in Fig. 

 3. The blades are 

 represented by short 

 radial lines. When 

 the chute is tipped 

 down, as shown by 

 dotted lines in Fig. 2 

 (6), the upper end in- 

 tercepts the flow of 

 concrete, as shown in 

 Fig. 3 (&), and the 

 mass slides down the 

 chute and out of the 

 drum. 



The Ransome mixer FlG - 2 



is made in several sizes, with varying capacities. 



Smith Mixer. In Fig. 4 is illustrated the Smith mixer. 

 The machine consists of a drum of double conical form that 

 is supported and guided by a frame that can be tilted at will 

 while the drum is revolving. The ingredients are fed in at 

 one end of the drum, and after the required number of 

 revolutions the mixed concrete is discharged at the other 

 end by tilting the drum while it is running at full speed. 



