Abstract:
The present invention discloses a device for restricting the movement of a hydraulically actuated rudder assembly on a large ocean-going vessel during failure of the hydraulic system. It comprises a half-collar made of a material that is substantially incompressible along its lengthwise axis and is adapted to fit over a ram rod or a guide rod in a steering assembly between a cross-head and a ram rod sleeve or guide rod. The length of the half-collar is minimally less than the length between the cross-head and the terminus of the ram rod or guide rod when the rudder is in a neutral position.

Description:
FIELD OF INVENTION 
     This invention generally relates to devices that are useful in controlling the steering of a marine vessel. Here, the preferred embodiment is designed to mechanically arrest the movement of a hydraulically powered steering assembly. 
     DESCRIPTION OF THE BACKGROUND ART 
     Large marine vessels are usually steered by large hydraulically operated rudders. This, of course, is nothing new, and some type of hydraulic rudder has been in existence at least since the patent to Christensen, U.S. Ser. No. 641,192, Jan. 6, 1906. However, these systems have been evolving into more complexed rudder assemblies which, in turn, rely more heavily on increasingly complex safety mechanisms. These large rudder assemblies, if they suffer a loss in hydraulic fluid, can render an large vessel completely helpless and at the mercy of the prevailing environmental forces. Furthermore, when there is a complete loss of hydraulic fluid, the rudder assembly may uncontrollably lash back and forth creating an extremely hazardous condition for those persons who are in the immediate vicinity of the device. 
     Safety mechanisms on large ocean-going vessels use systems that replenish the hydraulic fluid to the ram cylinders. For example, see U.S. Pat. Nos. 4,209,986; 3,949,696; and 3,913,517. 
     Other attempts at providing a secure hydraulic system are: blocking valves to block the hydraulic fluid in the ram cylinders (see Reliability Improvements for Vessel Steering Systems, page 6-1, U.S. Dept. Comm./NTIS, J. J. Henry Company, Incorporated, New York), or some type of mechanical stop, as shown in U.S. Pat. No. 3,818,853, and Norwegian Patent No. 33,429. 
     OBJECTS OF THE INVENTION 
     The present invention seeks to provide a device that may easily arrest the movement of the rudder in the event of a loss in fluid pressure to the hydraulic ram cylinders. It is a further object of this invention to create a device that may perform the above function simply and inexpensively. 
     SUMMARY OF THE INVENTION 
     The present invention is a device to arrest the movement of a hydraulically actuated rudder on a large ocean-going vessel. The device is essentially a half-collar made of a material that is substantially incompressible along its lengthwise axis and may fit over a guide rod or a ram rod in the steering assembly. When fit over a guide rod, or ram rod, the ends of the device abut the neighboring sleeve and cross-head and thereby restrict the sleeve from sliding along the rod. The sleeves are immobilized from moving once a pair of devices are fit over opposing guide rods or ram rods to restrict the rudder assembly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an overhead view of a hydraulic steering system; 
     FIG. 2 is a sideways view of a hydraulic steering system as shown in FIG. 1; 
     FIG. 3 is a view of a rudder stopper device; 
     FIG. 4 is an overhead view of a larger hydraulic steering system than the device of FIG. 1; and 
     FIG. 5 is a sideways view of the device of FIG. 4. 
     FIG. 6 is a side veiw of an ocean-going vessel. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 6 shows an ocean-going vessel 40, with a rudder 41 and a steering assembly 1. 
     The present invention is a mechanical rudder stopper for large marine vessel steering systems when they suffer a loss in hydraulic fluid. Now, referring to the drawings, FIG. 1 shows a typical steering assembly 1 for a vessel of 35,000 DWT such as the Chevron Oregon. Assembly 1 may be further broken down into a ram cylinder 13, a main ram sleeve 3, a main ram rod 5, and a cross-head 7 with armature 42. Sleeve 3 has a load-bearing surface 9 and cross-head 7 has a load-bearing surface 11 (the opposing members are shown by the designation &#34;a&#34; after the corresponding reference numeral). 
     FIG. 2 shows a sideways view of the steering assembly 1 with all the above referenced components in place. 
     FIG. 3 shows a enlarged view of the stopper 15. Stopper 15 comprises a U-shaped collar that fits over the ram rod 5 (as shown in phantom FIGS. 1, 2, 4, and 5). It has two end bearing surfaces 17 and 19, an aperture 21 for a securing pin, and a handle 23. The U-shaped or curved portion of the device is designated by referenced numeral 25 and the flat portion by referenced numeral 27. 
     FIG. 4 is a typical steering assembly 10 on a larger vessel than FIG. 1, for example, a vessel such as the Cheveron California, which is 70,000 DWT. Here, as in the device of FIG. 1, there is: a ram sleeve 3, a ram rod 5 (which make up a ram cylinder 13), and a cross-head 7. However, there is the addition of a guide rod sleeve 33 and a guide rod 35. 
     As shown in FIG. 5, there is a proper load-bearing surface on the guide rod sleeve 9 as well as on the cross-head 11. FIG. 5 is a side view of the device of FIG. 4. 
     The steering assemblies of FIGS. 1 and 4 selectively admit and expel hydraulic fluid into a ram cylinder 13 or 13a. This causes the ram rod 5 to either move in or out of the ram sleeve 3 which causes cross-head 7 to turn and consequently move the rudder. A secondary effect of this in and out movement is that the distance between the cross-head surface 11 and the sleeve surface 9 is either shortened or increased as shown in phantom on FIG. 1. It is in this area that the present device operates. The steering assembly 10 of FIG. 4 operates in much the same way. However, the ram cylinder 13 does not articulate, and the device adds a guide rod 35 with a guide rod sleeve 33. The guide rod 35 and sleeve 33 hold the ram cylinder 13 in place and limit the extraneous movement of the cross-head 7. 
     In both steering systems 1 and 10, a mechanical rudder stopper 15 may be inserted between the cross-head surface 11 and the sleeve surface 9 to prohibit the movement of the ram rod 5 into ram sleeve 3. The rudder stopper 15 may be inserted when the opposing ram rod 5 is moved out of its ram sleeve 3 in the device of FIG. 1 or FIG. 4. 
     The dimensions of the present stopper 15 (as used on the Chevron California, i.e., FIGS. 4 and 5) are 183/4 inches along the lengthwise axis, 7/8 inches thickness at the U-shaped portion 25, and 3/4 inches thickness at the flat portion 27. The length of the flat portion 27 is 43/4 inches and the internal diameter of the collar 15 itself is the external diameter of the guide rod 35 (that the collar 15 is designed to fit over) plus approximately 1/16 inch. Obviously, the dimensions will vary with the size of the steering gear system. 
     The collars (or stoppers) 15 may be used in the following manner. (Other uses may be made of the present invention, to immobilize the rudder assembly in dry dock while workers repair the hydraulic system, etc.) Once the steering assembly 1 loses the hydraulic fluid, the rudder may move from side to side in an uncontrollable fashion, which will cause the ram rods 5 to move in and out of the ram sleeves 3 also in an uncontrollable fashion. When this happens, a crewman aboard the vessel may take the collar 15 (usually by the handle 23) and deploy it over ram rod 5, or guide rod 35, whose exposed length between stop 11 and terminus 9 is at least as long as the collar 15. He may then fix it in place with a securing pin set through the aperture 21. When the rudder is moved, the distance between the end-bearing surfaces 9 and 11 is lengthened which allows the rudder stopper 15 to be put into position. Once the stopper 15 is in place, it restricts movement of the rudder in one direction only. However, to restrict the movement of the rudder in the other direction, another (identical ) stopper 15 is put in place on an opposing ram rod 5a, or guide rod 35a, when there is enough room between end-bearing surfaces 9a and 11a for the stopper 15. A crewman places the stopper 15 on the opposing rod 5a or 35a when the rudder swings back in the other direction to compress the ram rod 5 (which then lengthens the distance between 9a and 11a). (The length of the collar 15 has been previously determined to be no longer than the length between the cross-head surface 11 and the sleeve surface 9 when the rudder is in a neutral position, i.e., that being the position where the distances between the cross-head surface 11 and the sleeve surface 9 is equal for both opposing rams.) Once the crewman deploys the collar 15 for both opposing ram cylinder assemblies 13 and 13a, the rudder may not move either way because each ram cylinder 13 and 13a may not move in or out due to the blocking of the collar 15 that is placed over the ram rod 5 and 5a or guide rod 35 and 35a. At this point, the uncontrollable movement of the rudder has been neutralized and the vessel may be controlled by other means. 
     The stoppers 15, if they are fit on a rudder system for a vessel that is different from the Chevron California class, would have to be modified slightly to work properly. For example, the stoppers 15 that may be used on the Chevron Oregon class are formed of 2 pieces because a one-piece stopper 15 would be too heavy. Furthermore, when a stopper 15 is applied over a ram rod 5, there is a danger of scratching the surface of the ram rod 5 which would cause a loss in hydraulic fluid. So, to cure this problem, a protective, soft surface may be applied to the inside surface of the stopper 15 to prevent scratching the ram rod 5. And lastly, the end-bearing surfaces of the stopper 15 would have to be modified slightly to accommodate the particular configuration of this rudder system 1. Basically, the stopper 15 should mechanically immobilize the rudder by the placement of some imcompressible object over a guide 35 or ram rod 5 to prevent the respective sleeve (33 or 3) from increasing or decreasing in distance from the cross-head 7. 
     Since many modifications and variations of the present invention are possible within the spirit of this disclosure, we intend that the embodiments disclosed are only illustrative and not restrictive. For that reason, we refer to the following claims rather than to the specific description to indicate the scope of this invention.