Patent Publication Number: US-3971148-A

Title: Dredge cutter head

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to improvements in dredging machines of the type disclosed in U.S. Pat. No. 3,521,387 granted July 21, 1970. 
     In dredging machines of the design of the aforesaid patent, there is a tendency to disperse the dredged fines through surrounding water causing objectionable pollution. Present environmental requirements dictate nonstirring dredging operations. Such operations are particularly difficult to perform, especially in eutrophied waters where the dredging involes the harvesting of a large amount of vegetation. 
     BRIEF DESCRIPTION OF THE INVENTION 
     It is an object of the invention to provide a self-cleaning, nonstirring, dredging cutter head combining parallel and geared together timed augers that turn together inside a shrouded hood so the augers mutually clean each other as they turn to transport material to the suction pipe. 
     The shrouded hood and suction pipe act as an underwater vacuum cleaner and contain the moving dredged material, thereby insuring that cut material and fines are not dispersed through surrounding water, but instead are processed through the suction pipe for disposal. 
     In the illustrated form, the shrouded head extends over both augers and consists of two sections, one of which is preferably hinged to act as a backhoe as well as to closely approach the front auger when sand alone is being dredged. Raising and lowering the hinged section will assist in pulling down floating vegetation into the auger teeth without the suction pipe losing its prime by breaking the surface of the water. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The aforementioned objects and advantages of the invention will be appreciated from the following description and accompanying drawings wherein: 
     FIG. 1 is a top view of the cutter head with the dredge boom supporting the head being shown in dotted outline, 
     FIG. 2 is a front view of the cutter head shown in FIG. 1, 
     FIG. 3 is an end view of FIG. 1 taken from the right hand end, 
     FIG. 4 is a sectional view taken on line IV--IV of FIG. 2, and 
     FIG. 5 is a sectional view taken on line V--V of FIG. 2. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The improved dredge cutter head 10 is shown supported on the dredge boom 12 which may, in turn, be supported and raised and lowered in any suitable manner, for example, as shown in the aforesaid patent. 
     The head 10 comprises an elongated frame member 14 extending in opposite directions from the bearing mounting bracket 16 shown in FIG. 5. The center bearings 18 for the auger shafts 20 and 22 are carried on the bracket 16 with the outboard bearings 18&#39; for the shafts 20 and 22 being carried in the gear boxes 24 and 26 attached to the outer ends of the member 14 through plates 28. 
     An elongated plate 30 is attached to the front side of the member 14 to which the flat spaced teeth 32 are attached to provide a serrated cleaning bar 32&#39; extending substantially the full width of the cutter head 10. Mounted on the shafts 20 and 22 are augers 34 and 36, respectfully, of suitable shape to carry the dredged material toward the center of the head 10. 
     Teeth 38 are so spaced on the augers 34 and 36 that, upon rotation of the augers 34 and 36, the teeth 38 freely pass between teeth 32 of the cleaning bar 32&#39;. The total number of teeth 38 on the augers 34 and 36 correspond to the number of adjacent pairs of teeth 32 on the bar 32&#39;. In FIG. 4 it will be noted that the spacing of the shafts 20 and 22 and the length of the teeth 38 is such that upon rotation the teeth 38 slightly clear the shafts 20 and 22 for reasons hereinafter described. 
     A suitable drive motor, such as an hydraulic motor 40, actuated from a pump on the dredge (the hydraulic lines being omitted) rotate the shafts 20 and 22 in the same direction through the gear boxes 26, the direction of rotation being indicated by the arrows in FIG. 4. 
     The shrouded hood 42 of the cutter head 10 in the illustrated form comprises a rear section 44 fixed to the member 14 by an angle bar 44&#39; and extending substantially the entire width of the head 10 to project above and partially embrace the auger 36. In the center of the head 10 an opening is provided in the section 44 to receive the flanged intake pipe 46 to which the suction line 48 (shown in dotted outline in FIG. 4) is attached. 
     To complete the hood 42, a front section 50, coextensive with the rear section 44, is pivoted at spaced points 52 to the brackets 54 attached to the member 14. A reinforcing channel 56 is attached to the section 50 has an upright portion 58 to which the hydraulic piston 60 (shown in dotted outline) is attached. A similar upright and piston (not shown) is preferably employed on the opposite side of the center of the head 10. Teeth 62 are shown spaced along the lower edge of the section 50 to aid in pulling floating vegetation down into the auger 34 and to permit effective use of the section 50 as a &#34;backhoe&#34;. 
     OPERATION OF THE ILLUSTRATED FORM 
     Referring to FIG. 1, it will be noted that the screw surfaces of the augers 34 and 36 are similar and they are similarly arranged on their respective shafts 20 and 22 and timed through the gear boxes 24 and 26 so as to rotate with the relationship shown. Thus, there is no rotational interference between the projecting teeth 38 yet lines parallel to the axes of rotation of the shafts 20 and 22 and through the teeth 38 will intersect. This results in chopping and cutting the vegetation as the teeth 38 pass between the teeth 32 of the cutter bar 32&#39;. The teeth 38 also perform a cleaning operation on the shaft of the opposite auger due to the slight rotational clearance between the teeth 38 of one auger and the shaft of the other auger. 
     By having a common cutter bar 32&#39; for the augers 34 and 36, each tooth 38 tends to shear vegetation, roots, etc., on the same side of the bar 32&#39; and remove vegetation, roots, etc., from the other side. Thus, there is a continuous unidirectional cutting and clearing action taking place in the passageway 64 defined between the under side of the shrouded hood 42 defined by the sections 44 and 50 and the shafts 20 and 22. The mixture of water and dredged material flows upwardly and inwardly toward the center of the cutter head 10 into the passageway 64 which, in turn, communicates with the intake 46. This action is quite comparable to a vacuum cleaner nozzle with the result that the dredging fines are not substantially dispersed into the surrounding water.