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MARINE 1901.) _ REVIEW. 44 necessary for such construction. Following the general practice, the bearing was brass bushed and the upper part was made in the form of a stuffing box, a gland and the necessary bolts being provided. In considering the last method of construction, a glance will suffice to show the superiority of this fitting over the one with which the pre- vious discussion had to do. As regards the first requirement, rudder bearing, it has all the good points of the former types with the advantage of being so constructed as to distribute the strains in a better manner than the foregoing type, and of being placed where a better connection can be made to the surrounding structure. White metal was used for the bearing surface and carried the brass sleeve shrunk on the rudder stock. A stuffing box gland, bolts and packing provided for water-tightness around the stock. The manner of securing a water-tight connection is very simple. Tap rivets and through rivets secured the shell plating to the casting, the edge being carefully caulked. The whole design of this fitting indicates a careful study of its various requirements and functions and all seem to be well taken care of. Ample connections to the floor plates and intercostal j -- 2 : | ye +4 4% j e. eh Mee Re es oN Se te 4+- S = ° oN 7 oe oO o e > fvaser a) Sree Waseca A Th, Ph plates are made by the vertical palms and with the rivets and taps. con- necting the casting to the doubled shell plate, a very strong arrangement was secured. From a summary of all the different requirements and the proper fulfilling of the same it would seem that the first and the last types of. this all important fitting are the best to follow in the design of the different types of rudders. RUDDER QUADRANTS AND TILLERS. In connection with this fitting there are several important considera- tions, the combination of which is generally followed in the best design. The principal functions devolving upon this fitting are those of transmit- ting the power from the steering ropes to the rudder, by way of the stock, and to carry the steering ropes along in such a manner as to eliminate the possibility of any slack appearing in them between the quadrant and the last riding sheave. Having a knowledge of the power to be applied and the consequent strains to be resisted, for performing the first of these, the quadrant can be designed of sufficient strength to fulfil the same. In addition to this it must be of such strength as to carry its own weight properly. The general practice followed in caring for the other require- ment is to allow for single or double grooves in the quadrant in which 'the ropes are carried. This practice is beneficial in distributing the strains along the periphery of the quadrant and increasing the efficiency of the steering arrangements. The majority of rudder quadrants are made in two parts, the dividing line being in different places. This practice is followed as being easier to install. Generally the quadrants are clamped in position as the rudder stock enters the ship through the lower bearing, it being found more easily done in this way. The rudder stock, as shown in previous sketches, is turned down at a point under the deck to receive the quadrant and a collar is formed to carry the weight. In some cases the stock at this point is made square to receive such a shaped quadrant. In reviewing the various types of quadrants extant I have chosen three styles to show the diversity of construction to obtain practically the same idea. It remains to prove the advantage of one over the others and accept it as an efficient type. The first of these to be dealt with was used on a medium-speed class of boats, about 24%4 knots, and the power applied can be seen by reference to the-table-in one of the foregoing articles. This quadrant was made up in two parts, the dividing line being the same as a fore-and-aft line through the center of the boat, the material used being cast steel. : The rim carrying the wire rope was made of the same section as wire rope sheaves are generally made. A lug cast on the rim on each side allowed for an adjusting bolt. This bolt was fitted with a nut and lock-nut and engaged the wire rope by means of an eye in the bolt, through which the rope was worked, turned back, and spliced. The shape of this quadrant, the rim extending back as it does beyond the central point and having only a single groove, allows for sufficient wrapping of the rope to do away with any possibility of slack occurring in the rope and gives good frictional bearing surface for the rope. This quadrant was fitted over a square bearing on the rudder stock and was bolted together after the stock was in position. A stopper, built of plates, angles and rubber bumper, was located forward of the stock under the deck and engaged the two end arms of the quadrant. This et ah: PiaATeE ooo ies 3 ° x. eS ° Beso ""( it ° oO 50 oo 6 ky | © ae | 3 a | | : ° 0 ' 1 Md t - | \ 4 Puers. ~ } & '6 6 * 0 mo 02 Olloa larPure 5 ' oS i | Of i 3 | eal i EsAzs=3 Fh : ey. eae ear J en ees) ee 7 | | pi, llama formed a very efficient rudder stopper and was located at the extreme angle of the rudder. This quaurant is shown on plate 17. The next quadrant under consideration is shown in plate 18 and rep- resents one installed on a 30-knot boat of about 350 tons displacement. The construction in this case varies considerably from that previously discussed, and has points in its favor and against it. In this case the quadrant proper was made of cast steel, the casting being simply the hub, arms and a wide flat rim. The grooves, two in number, extending the entire length of the rim, were built up of angles riveted to the wide rim. An arrangement for fastening the rope at the end of each groove engaged the steering rope from the opposite side of the boat; that is, the star- board rope was fastened at the port side of the quadrant and vice versa. This arrangement, it will be seen, precludes any tendency for slack in the rope to occur and forms a friction bearing for the rope all the way around the quadrant. These grooves, being formed of angle bars riveted heel to Lave: 20. The saan toe, as they were, cannot compare in efficiency with the groove in the quadrant just under discussion, in that the grooves are flat-faced while in the former type the groove was made semi-circular to fit the rope, thus preserving the rope from any tendency to flatten out and deteriorate. The great length of these grooves was somewhat in error, considering the extra weight it entailed, as a single groove proportionate in length to that of the former quadrant would have been all that was required. The principal faults of this quadrant are its excessive weight and its flat grooves. In dealing with the last quadrant, shown on plate 19, the conditions were a 29-knot boat of about 420 tons displacement. In this construction the weight was materially reduced from that of the foregoing type, con- sidering the vast difference in the displacement and the small difference in the speed. But this fault being overcome, there are still other im- provements which could have been made in the design of this quadrant had previous designs and features been available. This quadrant, as can be seen, is of the built-up type, the casting forming the main arm and the hub being the foundation of the construction. On top of this was riveted a plate of the peculiar shape shown with flat bars around the edge to form the grooves. The whole construction was very light-and-made a. very rigid quadrant. The fault of the groove being flat is a parallel error with the foregoing quadrant. The length of the groove in this case was