122 



A TREATISE ON DREDGES AND DRED(;i.\<; 



The suction pipe is suspended from a double steel A frame over 

 the forward end of the well, and the lifting winch for raising and 

 lowering the suction pipe is carried on top of this frame. 



The main engines are of the triple-expansion marine type, having 

 cylinders 20, 31 and 50 in. in diameter with 25-in. strokes. They 

 are adapted to run at 150 revolutions per minute. 



The material is excavated by an improved rotary cutter (see 



FIG. 36. Floating Discharge Pipe of the Dredge "J. Israel Tarte." 



Fig. 26), 9 ft. 6 in. diameter by 9 ft. long, the weight of which is 

 10 tons. It is formed of steel blades with especially designed clear- 

 ance spaces between them, so as to avoid clogging with the material, 

 and the suction pipe and passages through the pump are madr 

 very large for the same reason. The cutter is driven by a pair of 

 engines placed on top of the suction pipe at the upper end. 

 These engines are of the double tandem type of 300 I.H.P.; 

 the gearing and power transmission for these engines is of exceptional 

 strength and capable at all times of encountering immovable 



