SEA-GOING LADDER DREDGES 81 



supply either one of the engines or both. The grate is of an improved 

 type, which permits fuel of every description to be burnt. 



The turning of the upper tumbler commanding the bucket 

 chain in by a system of shafts and cogwheels. A friction clutch, 

 easily handled, is attached to the upper tumbler in order to 

 prevent any break in the various parts of the machinery in case 

 very hard rock or other serious obstacles are encountered. 



The dredge is provided with two sets of buckets; those to be 

 used is loose soils or in soils of the average consistency have a capacity 

 of 21.5 cu.ft. each; while those designed to work in soils of greater 

 resistance, as conglomerates, ledges of rock, etc., are of 12.4 cu.ft. 

 capacity and are strongly reinforced with steel teeth, which are fixed 

 to the buckets in a very simple manner, so as to be easily changed 

 when worn out. 



Starting gears allow the engines to be turned at a very slow speed 

 in order to facilitate the mounting or dismounting of the buckets. 



The hopper is located amidship and has a capacity of 700 tons. 

 The hopper is filled through a central chute. There are also two 

 lateral chutes in order that the debris may be dumped on scows 

 placed alongside. 



The bottom of the hopper is formed by 12 gates made of wood 

 lined with sheet iron. Each pair of gates is controlled by 6 chains 

 wound around a horizontal axis. After the material in the hopper 

 has been dumped the gates are closed again by means of a special 

 engine acting directly upon the horizontal axis commanding the 

 chains. 



The bucket ladder is arranged to work at different depths, varying 

 from 10 to 40 ft. The special construction of the hull allows the 

 bucket ladder to move in a parallel direction and also to be raised 

 and lowered. On account of such an arrangement the dredge may 

 cut its own way and also dredge against the bottom of quay walls. 



On the back of the ladder there is a pentagonal wheel for the 

 support and guide of the bucket chain. Such an arrangement has 

 the advantage of allowing the ladder to work in a more vertical 

 position and to shorten at the same time the length of the bucket 

 chain. Besides, the bucket chain resting on this wheel will run 

 more smoothly than before, thus avoiding shocks and much wear. 



The journals of the axles of the upper tumbler of the ladder are 

 provided with Belleville springs, absorbing the shock produced 

 by the buckets encountering some extraordinary obstacle. Owing 



