US2202457A - Luffing davit - Google Patents

Description

May 28, 1940. M. c. LE @Eu 2,202,457

LUFFING DAVIT f Filed Sept. 2'7,V 1958 2 Sheets-Sheet 1 M. C; LE GEU LUFFING DAvIT Filed Sept. 27, 1938 2 Sheets-Sheet 2 Patented vMay 28, 1940 2,202,457 LUFFING nAvI'r Marinus C. Le Geu, Hamburg, Germany, assignor to Ane Pieter Schat, Utrecht,'Netherlan ds Application September 27, 1 938, Serial No. 231,983 In Germany September 30, 1937 1 Claim.

This invention relates to a luiling davit of the: type, in which the top end of the davit arm or boom is engaged by an element, such as a screw spindle, by means of which t'he davit arm is w adapted to be positively urged inboard and outboard.

My present invention has for its main object an improved davit of the type referred to, in

which the davit arm is vsubstantially free from bending and torsionalfstressesl With this object in view, my novel davit comprises a boom, the topI end of which is connected to a lateral brace adapted to be pivoted to the ships deck.

The invention lwill be further described with reference to the accompanying'fdrawlings, ing' which like references. indicate similar parts throughout.

Fig. l is a side View of a ships davit in ac-y cordance with the invention, the full lines indieating the normal inboard position of the davit, and the dotted lines the outboard position, i. e.

the position in which the boat suspended from the davit is fully swung out.

Fig. 2 is a corresponding front view. Figs. 3-8 are views showing in detail the construction of the upper end of the davit arm, and the forces acting thereon.v Fig. 9 is a side elevational viewfof second embodiment of the invention.

Referring now particularly to Figures 1 and 2, I denotes the davit arm or boom pivoted as at I2 to a stanchion 3 which issecured to the ships boom I, the other end being rotatably housed in a casing I I, which itself is pivotally connected as at I2 to the stanchion'3. The screw spindle is adapted to be operated by means of a crank4 handle I3.

A diagonal brace or tie rod I4 is pivoted aty itsupper end to an eye I5 of the boom I, and

at its lower end to a bracket 4I6 secured to the deck 4. f l

It will be seen that in any position of the davit, the boom is kept in balance by three forces, viz., the tensions in therope l, in. the screw spindle 9 and in the brace I4. These three forces are denoted by L, W and N, respecaxis of said arm. The moment of torsion or.

be raised (Cl. 9-22) Y tively in Figs.- 3-7, whichshow the head of the boom with the parts 8, I 0 and I5 for attaching the boat f5, the screw spindle tand thebrace I4, respectively. 'I heycan be resolved, in the wellknown manner, :intocompo-nents parallel with and at right angles to the' axis ofthe boom I.

Fig. 4 shows the resolution" of the stress Lv in rope I into its horizontal-`cornponent H and its vvertical component' V.4 In Fig. 3, the component V is further resolved into the forces P and O.

As will appear from Figs. 3 and 5, the stress in the spindle 9 and the tension N Vin the brace I4 are resolved into the components X, Y, and M, J, respectively, it being understood that the forces P and H are substantially `equal to theVv forces X and M, respectively.

Fig. 6. shows the boom head in "transverse section and the forces acting at right angles to the torque acting upon theboom vis;

` T=H.a-P.b

Figs. 7 and 8 showv the forces acting in a vdi rection parallel to the axis of the davit arm. 'I'he bending moments inthe plane of Vswinging movement of the boom, andina planeV at right angles thereto are, respectively:

1 B1=O.h- Y.g-J.m and p I B2=O.e|-Y.d-J.`c

According to the invention,the various dimensions a, b, c, d, e, g, hand m are preferably so chosen as to render themoments T, B1 andr B2 substantially nil, wherebyl the davit arm I is substantially free from bending and torsiona stresses. n Fig. Qshows afurther embodiment ofthe invention. Instead of being pivoted to the davit arm, the bracey I4 is vrigidly secured to the head, and also, by braces I'I, I8, to the. portion inter-` mediate the ends of said arm,

WhatIclaim is: 1

lA luing davit comprising a boom vpivo-tally connected to a ships deck, means for suspend ving a life boat from the topfendof said boom, an element engaging the'top end of lsaid boom and adapted ywhen operated to positively urge said boom inward or outward, and a lateral brace Vconnected'to said boom, said element and said brace being arranged in offset relation .with the boom in such a manner that'the torsional and bending moments acting upon said boom under theinfluence of a boat suspended therefrom are substantially nil: l 55 '-MAnIrIrLsC LEVGEU,`

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