Hinged floating caissons and unfolding devices therefor
BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to articulated or hinged floating box caissons provided with means for unfolding or spreading the elements thereof from a transport position to an operative position. 
     It is the primary object of the present invention to provide a hinged box caisson and control structure therefor, the arrangement being such that the ratio of the overall width of the caisson in its transport position to the width in its operative position will be approximately 1:3. 
     A floating box caisson according to the instant invention comprises a central caisson and a pair of lateral caissons each associated with an end ballast, these elements being adapted, in the transport position, to be folded on one another. The floating caisson includes a system for straightening the ballasts and another system for unfolding the lateral caissons. Such systems are designed such that they are capable of rotating the lateral caissons through an angle of 180° and of simultaneously straightening the end ballasts, such movements being obtained by using a single actuator. 
     According to an essential feature characterizing this invention, the system for unfolding the lateral caissons comprises a cylinder, a rocker and a link assembly, and the system for straightening the ballasts comprises a constant-length rope system interconnecting a fixed point of the central caisson to a fixed point of the respective ballast. Operation of the cylinder simultaneously causes the unfolding of the lateral caissons and the straightening of the end ballasts. 
     According to a further feature characterizing this invention the constant length rope system includes means for taking up slack in the rope, notably when the component elements of the floating caisson are in their transport or folded position. These means may consist for example of a spring-urged arm pivoted at one end to a fixed point of the end ballast, the rope passing around the opposite or free end of the arm. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of this invention will appear as the following description proceeds with reference to the accompanying drawings, illustrating diagrammatically by way of example a typical embodiment of the invention, and wherein: 
     FIG. 1 is a side elevational view illustrating diagrammatically a hinged floating box caisson in its folded or transport position; 
     FIG. 2 is a side elevational view of the caisson of FIG. 1, but shown in its operative position; 
     FIGS. 3 to 5 are side elevational views showing diagrammatically the means contemplated for unfolding the lateral caissons during the successive steps of an unfolding operation; and 
     FIGS. 6 to 9 illustrate diagrammatically the means provided for straightening the end ballasts during the successive steps of the straightening operation. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As clearly shown in FIGS. 1 and 2 of the drawing, a hinged floating box caisson according to the present invention comprises a central caisson 10, a pair of lateral caissons 12, 12&#39; disposed on either side of the central caisson, and a pair of end ballasts 14, 14&#39; each disposed at the outer ends of the lateral caissons, respectively. As already mentioned in the foregoing, this hinged floating caisson comprises means for unfolding its component elements from the transport position shown in FIG. 1 to the operative position shown in FIG. 2. By way of non-limiting example, the invention may provide a hinged floating caisson having a width of 3.5 meters in the transport position and a width of 9.2 meters in the operative position. 
     The means for unfolding this caisson are so arranged that the passage from the transport position to the operative position is obtained by rotating simultaneously the lateral caissons 12, 12&#39; through an angle of 180° with respect to the central caisson, and subsequently straightening the end ballasts 14, 14&#39;. 
     Reference will first be made to FIGS. 3 to 5 for describing the means contemplated for unfolding the lateral caissons 12, 12&#39;. 
     Each lateral caisson 12, 12&#39; (FIG. 3) is hingedly mounted by means of a corresponding hinge shaft 16&#39; to the corresponding upper lateral edge of the central caisson 10. A rocker and link assembly 20, 18 is pivoted on the one hand by a shaft 22 to the lateral caisson 12 and on the other hand by a shaft 24 to the central caisson 10. The movement of this assembly 18, 20 is controlled by means of a hydraulic cylinder 26 pivoted to a pin carried by the central caisson 10. 
     Now reference will be made to FIGS. 6 to 9 to describe the means provided for simultaneously unfolding the lateral caissons and straightening the end ballasts 14, 14&#39;. These means are so designed that they can be actuated by cylinders 26 alone, without resorting to any subsidiary source of power. 
     These means each comprise essentially a rope 30 attached at one end to a fixed point 32 of the central caisson 10 and at an opposite end to another fixed point 34 of the respective end ballast 14. This rope has a fixed length set upon assembling the elements, whereby during the unfolding of the lateral caisson 12 to which the end ballast 14 is pivoted or hingedly mounted at 28 the ballast 14 is automatically straightened and held in its unfolded or spread position. This rope 30 is guided during the unfolding operation by passing over a pulley 40 secured to one corner of the lateral caisson 12. 
     Means are also provided for taking up any slack developing in the rope, notably when the component elements of the floating hinged caisson structure are folded in their transport position. In the embodiment illustrated, these means comprise a mechanism including an arm 36 pivoted at one end thereof to the ballast 14 and urged by spring means 38. This arm 36 is shaped to facilitate the straightening of the end ballast (the distance between the rope and the hinge axis 28 of the ballast being increased, thus reducing the reaction torque and therefore the traction effort exerted in the rope). 
     The hinged box caisson according to this invention operates as follows. 
     The component elements 10, 12, 12&#39;, 14 and 14&#39; of this hinged floating caisson structure are normally folded as shown in FIG. 6, any slack of the constant-length rope 30 being taken up permanently by the arm 36 urged by spring 38. 
     As already explained in the foregoing, each lateral caisson begins its unfolding movement and since the distance between the anchorage points 32, 34 of rope 30 increases, the arm 36 pivots in the counter-clockwise direction until it reaches a mechanical abutment position (FIG. 7). 
     As the unfolding movement of lateral caisson 12 continues (FIG. 8), the distance between the anchorage points 32 and 34 of rope 30 tends to increase and when the arm 36 is stopped mechanically, the rope 30 is tension-stressed and in turn rotates the end ballast 14 in the counter-clockwise direction. During this movement the rope 30 is guided by pulley 40. 
     At the end of the unfolding movement of the lateral caisson (FIG. 9), the constant-length rope 30 has straightened the ballast completely, thus completing the unfolding of the floating caisson structure to its operative position. 
     Of course, it will readily occur to those conversant with the art that this invention should not be construed as being limited by the specific embodiment described and illustrated herein, since many modifications and changes may be brought thereto without departing from the basic principles of the invention, as set forth in the appended claims.