Shaking machine for fishing nets
The invention relates to a shaking machine for fishing nets, and more particularly to drifting nets for use in fishing for herring and other small fish. 
     It is well known in herring fishing with drifting nets that the catch must be shaken out of the nets just as they come onboard the fishing vessel. Right from the beginning of fishing with drift nets, which were originally made of hemp, there was no other way of cleaning them than shaking them by hand. As use of much stronger and more durable nylon nets began, it was noticed that cleaning the catch out of these nets was much harder and took more time than for hemp nets. This fact led to the idea of machine cleaning the nets to ease the work and shorten the cleaning time. 
     The object of the present invention is to provide a shaking machine for drift nets which is efficient and safe in operation. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a shaking machine for shaking fish, such as herring and other small fish, out of drift nets comprising at least first and second spaced apart housing members, a shaking fence mounted between the housing members for receiving a drift net to be shaken, the shaking fence being at the forward end of the shaking machine; and drive means coupled to the shaking fence for reciprocally moving the shaking fence relative to the housing members. The shaking machine further comprises an upper rotatably driven drum rotatably coupled to the housing members and located above the shaking fence, the upper drum receiving the drift net from the shaking fence over the upper drum and pulling the net. 
     In one preferred arrangement, a lower drum is rotatably coupled to the housing members and located below the upper drum, the lower drum receiving the drift net from the upper drum, the drift net being passed under the second drum. The upper and lower drums are driven in different rotational directions to propel a drift net received by the drums from the shaking fence at the forward end of the machine to the rear end of the shaking machine. 
     In another preferred arrangement, a freely rotatable lower drum is provided, under which the net is passed, to permit the net pulled by the upper drum to be laid out on a boat. 
     In accordance with a preferred embodiment, the shaking fence is pivotally mounted to the housing members and the first drive means reciprocally pivots the shaking fence relative to the housing members. Still further, in a preferred embodiment having the pivotable shaking fence, the shaking fence comprises a pair of spaced apart elongated members (such as wire-ropes or the like) mounted at the forward end thereof and extending between respective pivotally mounted arms, and at least one elongated member (such a wire-rope or the like) mounted at the rearward end of the shaking fence and extending between the arms, the drift net being passed through the pair of spaced apart elongated members and over the at least one elongated member which is located at the rearward end of the shaking fence. 
     Other objects and features of the invention will become apparent from the following detailed description taken in conjunction with the appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top perspective line drawing of the shaking machine of the present invention; 
     FIG. 2 is a side view, partly sectioned, as seen from the motor side; 
     FIG. 3 is an end view, partly sectioned, looking at the machine where it takes the nets in; 
     FIG. 4 is a top view, partly sectioned; 
     FIG. 5 illustrates the shaking machine as seen from a side with a net-drum mounted thereon; 
     FIG. 6 is an end view looking at the machine where the nets come out; 
     FIG. 7 is a front view of a further simplified embodiment of the invention; 
     FIG. 8 is a top view of the embodiment of FIG. 7; and 
     FIG. 9 is a line-type sectional view, with section lines omitted for ease of understanding, of the embodiment of FIG. 7 taken along the lines 9--9 in FIG. 7. 
    
    
     DETAILED DESCRIPTION 
     The shaking machine comprises two end housings 1a, 1b holding rotatable drums 2, 3 and a shaking fence 4 in position. The whole driving mechanism is installed in housing 1b. In housing 1a there are only mounted the necessary bearings for the axles of the drums 2, 3 and the shaking fence 4. 
     As seen in FIGS. 2 and 3, the driving power comes from a motor 31, in this case a hydraulic motor, working at high speed, and is geared down by a gear drive 5 to the proper RPM for the main drive shaft 6. The drive shaft 6 is fully floating through the drum 3. Flywheels 7a and 7b are mounted at the respective ends of drive shaft 6. Shaking arms 8a, 8b are connected to respective flywheels 7a, 7b eccentrically, and are further coupled to the shaking fence 4 (see FIGS. 1 and 2) to shake the shaking fence 4 by their motion back and forth. Flywheels 7a, 7b are shaped so that opposite to the mounting of the shaking arms 8a, 8b there are additional balance masses 9 to balance the extra weight of the shaking arms 8 for smoother running and preventing unnecessary vibration. 
     The drums 2, 3 are driven by a separate hydraulic motor 10 (FIG. 3) which drives the shaft 11 via gearwheels 10a. This allows a good control of the drum speed independent of shaking frequency. The gearwheel 12 on the shaft 11 drives gearwheel 13 and thereby turns the lower drum 3. The gearwheel 14 on shaft 11 drives gearwheel 15 and at the same time drives the chaindrive 16, which in turn drives the upper drum 2 over gearwheelset 17. The upper drum 2 can be stopped by moving the operation arm 18 upward, thereby disconnecting the coupling 19 between gearwheel 15 and chaindrive 16. 
     As seen in FIG. 1, the shaking fence 4 is mounted with bearings in the bearing housings 20a, 20b. The shaking fence 4 comprises end arms 21a, 21b, a single wire-rope 22 at the back and a double wire-rope 23 at the front of the fence. These wire-ropes are preferably coated with a plastic hose to prevent damaging the nets. The double wire-rope 23 lies over a roller 24 (FIG. 4) on the arm 21b and is fastened and tightened with screwnuts 32 on arm 21a. The shaking arms 8a, 8b move the arms 25a, 25b back and forth as the driveshaft 6 turns and thereby swings the shaking fence 4. 
     As seen in FIGS. 1 and 5, at the rear end of the shaking machine, where the nets come out of it, there are mounted to rearwardly extending housings 26a, 26b for bearings to hold the net drum 27 in place. The net drum 27 is driven by a motor 28 via a variable gear arrangement 29 so that the drum 27 can be run at any speed for holding the pulling speed of the nets constant to compensate for increased diameter of the nets on drum 27. The speed of pulling by drum 27 can be set independent of the shaking frequency. The motor 28 and gear 29 can be replaced by a suitable variable speed hydraulic motor drive. The drift nets are wound up on the net drum 27 after the catch has been shaken out of them. 
     OPERATION OF EMBODIMENT OF FIGS. 1-6 
     As indicated by the heavy arrowed lines in FIG. 1, the drift nets are pulled onboard the fishing vessel through the double wire-rope 23 (i.e., between the wire-ropes 23), over the wire-rope 22, over the upper drum 2, under the lower drum 3 and from there are wound up on the net drum 27. The shaking of the catch out of the nets takes place on the way from the double wire-rope 23 to the upper drum 2. The pulling speed of the machine can easily be varied by varying the oil flow through the hydraulic motor 10, which drives the drums 2,3. Furthermore, the pulling of the nets can be stopped by disconnecting the drum 2 by operating operation arm 18 to uncouple the coupling 19 as explained above, during which time the drum 3 continues to turn and hold the nets tight to prevent them from slipping out of the vessel. Even during the time the roller 2 is stopped, the shaking of the nets can still go on by means of independently driven shaking fence 4. 
     EXAMPLE (FIGS. 1-6) 
     In an embodiment of the invention useful for shaking small fish, such as herring, out of nets, the apparatus is as follows: 
     diameter of drums 2, 3=190 mm 
     length of drums 2, 3=2:4 m; 3:3,8 m 
     typical speed of rotation of drums 2, 3=60 rpm 
     typical speed of rotation of net drum 27=40-80 rpm 
     length x (FIG. 4) of shaking fence=4 m 
     width y (FIG. 4) of shaking fence=550 mm 
     spacing z (FIG. 2) between wire ropes 23=165 mm 
     typical time period for one cycle of oscillation of shaking fence=320 cycles per minute. 
     FIGS. 7-9 illustrate a modified embodiment which is simpler than the arrangement of FIGS. 1-6 and which is suitable for use on small vessels. The arrangement of FIGS. 7-9 not only permits winding of the nets around a drum, but also permits laying out of the nets on a boat, the nets being pulled by the same drum which would ordinarily be used for winding and storing the nets. 
     The shaking machine of FIGS. 7-9 comprises two end housings 51a,51b, holding a motor driven rotatable drum 52, and a freely rotatable drum 52a if the nets are to be laid in the boat, and a shaking fence 53 in position. 
     The driving power for the shaking fence 53 is supplied by a motor 54, in this case a hydraulic motor working at low speed and geared down by a gear drive 55 to the proper RPM for the main drive shaft 56. Flywheels 57a,57b, are mounted at the respective ends of drive shaft 56. Shaking arms 58a,58b are eccentrically connected to respective flywheels 57a,57b, and are further coupled to the shaking fence 53 through shaking arms 59a,59b. Flywheels 57a,57b are shaped so that opposite to the mounting of the shaking arms 58a,58b there are additional balance masses to balance the extra weight of the shaking arms 58a,58b for smoother running and for preventing unnecessary vibration. 
     The drum 52 is driven by a separate hydraulic motor 100 which is mounted direct to the end of the drum 52. This allows good control of the drum speed independent of the shaking frequency. Drum 52 is driven to normally pull and take up the nets, and to wind the nets therearound for storage thereon. 
     The shaking fence 53 is mounted with bearings in the bearing housings 111a,111b, which are respectively welded to the main housings 51a,51b. The shaking fence 53 comprises end arms 112a,112b, a single wire-rope 113 at the back and a double wire-rope 114 at the front of the fence, similar to the construction shown in FIG. 1. These wire-ropes are preferably coated with a plastic hose to prevent damaging the nets. The double wire-rope 114 lies over a roller on the arm 112b and is fastened and tightened with screw nuts on arm 112a. The arms 58a,58b move the arms 59a,59b back and forth as the drive shaft 56 turns and thereby swings the shaking fence 53. 
     The drum 52 is provided to wind the nets up on it. However, if the nets are to be laid in the boat a second drum 52a is provided (FIG. 9), which is free rolling in bearings mounted on the back of the main housings 51a,51b. In such a case, the nets are pulled through the machine over and around the upper driven drum 52 and under the free rolling lower drum 52a which then ensures a big enough angle of lap around the driven drum 52. The path of feed of the nets when they are to be laid in the boat, is shown by the line A in FIG. 9. The lower drum 52a may be removed, if the nets are only to be taken up and wound on upper drum 52. 
     OPERATION OF EMBODIMENT OF FIGS. 7-9 
     As indicated by the arrowed line A in FIG. 9, the nets are pulled through the double wire-rope 114 (i.e., between the wire-ropes 114), over the wire-rope 113 and are wound over the drum 52 so as to be pulled over by drum 52, and then under the drum 52. The shaking of the catch out of the nets takes place in front of the wire-rope 114 and on the way from it to the upper driven drum 52. The pulling can even be stopped and at the same time the shaking can go on at any desired frequency which can easily be controlled by varying the oil flow through the hydraulic motor 4.