US2623222A - Ship's davit - Google Patents

Description

H. G. TAYLOR SHIPS DAVIT Filed Jan. 5, 1951 INVENTOR HUMPHREY GEORGE TAYLOR ATTORNEY Patented Dec. 30, 1952 SHIPS DAVIT Humphrey G. Taylor, Lower Penn, near Wolverhampton, England Application January 3, 1951, Serial No. 204,138 In Great Britain January 9, 1950 4 Claims.

so as to overhang the bow and stern of the susv pended boat. would be suitable for withstanding the stresses imposed on the arm but when the arm is built up, as it usually is, from flat plates or strips suitably shaped and bent and then welded together it has the disadvantage that the welds occur at \points of high stress concentration. The present invention provides a rectangular box-section construction in which this disadvantage is largely avoided.

A davit arm according to the present invention comprises inner and outer members of boxsection for at least the greater part of their length, the inner and outer members being interconnected by one or more web or side plates of suitable thickness to give lateral rigidity, the said plate or plates being welded electrically or otherwise to the box-section members.

The invention further comprises a davit arm in which the box-section inner and outer members are extruded in aluminium alloy and the web or side plates are of similar material. Alloys which are suitable for this construction and are resistant to sea-water corrosion, are British Standards Institution Specifications BS/STA7., A. W. 4., A. W. 5., A. W. 6., A. W. 7., A. W. 9., and A. W. 10.

The invention will now be described with reference to the embodiment shown, by way of example, in the accompanying drawings; wherein- Fig. 1 is a side elevation of a ships davit with the ships boat suspended therefrom, the inboard position being shown in full lines and the outboard position in chain lines.

Fig. 2 is an elevation of the davit as seen from inboard.

Fig. 3 is a section taken on the line 3, 3 of Fig. 1 and drawn to a larger scale for the sake of clearness.

Referring to the drawings, each davit is of the kind comprising a davit arm I which is approximately crescent-shaped in the vertical plane in which it is swung or luifed about the pivot pin 2 connecting its lower end to a deck fitting or A simple rectangular box-section frame 3, such swinging movements being effected by screw gear 4 operated through bevel gearing 5 from a crank handle 6 at one end and connected at its other end to a bracket I on the davit arm I. The ships boat 8 is suspended from the free ends of the davit arms I by the usual wire falls 9 and fall blocks ID.

The crescent shaped davit arm I is of fabricated construction, being built up from inner and outer members I I respectively which are of tubular box section, extruded in aluminium alloy, and web or side plates I of suitable thickness to give lateral rigidity, said web or side plates I being edge welded, electrically or otherwise, to the tubular box section members I I The tubular box section members I I are formed or bent to the required shapes and the web or side plates I, which are flat, are edge shaped or profiled to suit, that is to say so that their inner and outer edges will conform to the confronting faces of the box section members I", I to which they are Welded. In this connection the Web or side plates I are welded to the box section inner and outer members I I so that they lie flush with, or almost flush with, the side faces of said box section members, and to facilitate the correct loca tion of said plates I the box section members I", I may be formed at appropriate positions on their confronting faces with longitudinal ribs or other abutments (not shown) against which the plates I can be positioned for welding.

The complete section of the davit arm I comprises, as shown in Fig. 3, the two box sections of the inner and outer members I, I and an intermediate box section defined by the confronting faces of these members and the interconnecting plates I which are edge welded thereto in laterally spaced relation.

At the lower end of the davit arm I the box section members I I have their end portions bifurcated and spaced or separated laterally to afford two widely separated bearings I3 for pivotal engagement with the pivot pin 2, the gaps between the separated parts of the lower end portions of said members I", I being filled in by appropriately shaped gusset plates welded in position.

If the arm is to have an end portion which is tapered in the lateral plane perpendicular to the web or side plates, this can be attained by cutting away the confronting end portions of the inner and outer box-section members to remove the requisite amount of material to allow the cut edges to be brought together and welded.

When the davit arm is manufactured from aluminium alloy, steel or other brackets may be riveted to it for connection to the deck fitting or frame, luffing gear and the boat suspending and lowering gear.

In the construction employing, for the davit arm, inner and outer box-section members interconnected by one or more web or side plates which are edge welded to the confronting faces of saidmembers, the lines of weld are nearer to the vertical axis of the arm than would be the case if the arm were of simple rectangular boxsection fabricated from inner, outer and side wall plates; consequently the welds are subjected to comparatively less stress.

When the davit arm accordin to this invention is made of aluminium alloy there is a considerable reduction in weight as compared with a steel davit of similar strength.

Having fully described my invention, what I claim and desire to secure by Letters Patent is:

l. A davit arm construction curved throughout a substantial portion of its length and of varying depth over a substantial portion of its length and being of a minimum depth at its ends, said davit arm being of substantially constant width, pivot means at one end thereof with the axis of said pivot being transverse to the depth of said arm, each edge of said arm including a tubular member extending fromend to end of said arm, said arm including at least one web extending between said tubes and secured thereto throughout substantially the entire length of said arm.

2. A light weight davit arm comprising a pair of tubular members arranged in spaced relation and lying in substantiall the same plane, said tubular members being spaced from each other a substantial distance intermediate their ends forming a beam of varying depth, at least one substantially continuous web extending between and contacting said tubular members throughout substantially the length of said tubular members and secured to said tubular members substantially throughout the length thereof whereby resistance to buckling of the tubular members is increased.

A S o li W ight davit arm comprising a pair of tubular box section members arranged in spaced relation in substantially the same plane, said tubular box section members bein spaced from each other a greater distance intermediate their ends than at their ends, the distance between the remote edges of the tubular box members determining the depth of the arm, a pair of web plates each positioned on one of the opposite sides of said tubular box members and secured throughout its length to said tubular box members, said web plates bein continuous from one end to the other end and shaped to correspond with the shape of the tubular box members.

4. A strong light weight davit arm comprising a pair of tubular box section members arranged in spaced side by side relation with the remote edges of the members determining the depth of the arm, a first web plate positioned between the members adjacent the side edges of the members and within the sides of said tubular box section members and secured thereto throughout the length of said first web plate, a second webplate positioned between the members adjacent the other side edges of the members and secured to said members throughout the length of the second web plate, said first and second web plates being continuous from one end to the other and approximately the length of said members.

HUMPHREY G, TAYLOR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,538,783 Dingertz May 19, 1925 2,048,561 Neveling July 21, 1936 2,304,718 Swart Dec. 8, 1942 2,460,982 Gilpin Feb. 8, 1949 FOREIGN PATENTS Number Country Date 593,307 Great Britain Oct. 14, 1947

Images