US3069704A - Launching and lowering gear, particularly for ships' lifeboats - Google Patents

Description

W. G. MOORE Dec. 25, 1962 LAUNCHING AND LOWERING GEAR, PARTICULARLY FOR SHIPS LIFEBOATS 2 Sheets-Sheet 1 Filed Dec. 7, 1959 INVENTOR WALTER G. M ooRE ATTORNEY W. G. MOORE Dec. 25, 1962 LAUNCHING AND LOWERING GEAR, PARTICULARLY FOR SHIPS LIFEBOATS 2 Sheets-Sheet 2 Filed Dec. 7, 1959 FIG. 7-

INVENTOR WALTER G. M R

ATTORNEY as compared with the rear pillar.

ilnited rates Patent @flice 3,069,764 Patented Dec. 25, 1952 3,069,704 LAUNCHTNG AND LGWERKN G GEAR, PARTICU- LARLY FOR SHEPS LIFEBOATS Waiter Gordon Moore, Tankerton, Whitstahle, England,

assignor to Marepa Trust Limited, Tankerton, Whitstahie, England, a company of Great Britain Filed Dec. 7, i959, Ser. No. 857,722 Ciairns priority, application Great Britain Dec. 10, 1958 3 Claims. (Cl. 9-36) This invention is for improvements in or relating to gravity davits of the kind comprising an arm pivotally supported on front and rear links and adapted to operate on the advancing pivot principle so as to have an adequate outreach whilst requiring a minimum of headroom. Our British patent specification No. 688,495 describes such a davit.

In gravity davits of the above-mentioned kind it has heretofore been the practice to support the link from and enclose the arm within a single constructional unit known as the stand; The function of the stand is to carry the pivots about which said link or links operate whilst at the same time serving as a guide forthe davit arm and su portingit laterally against side play. The rigid parts of the stand which, as just stated, are intended to provide lateral support for the arm against side play have the serious disadvantage that they present frictional resistance to movement of the arm and under icing conditions accumulate ice to such an extent that movement of the arm may be prevented entirely. One object of the present invention is to provide a gravity davit which operates on the advancing pivot principle but in which these rigid lateral supporting members for the arm may be dispensed with and thereby free movement of the arm under all conditions is assured.

The unitary construction of the stand above referred to also inevitably makes it a bulky and weighty structure and presents difliculties in the matter of manufacture, delivery and erection at the ship, quite apart from the heavy cost of construction. A further object of the present invention is to provide a davit in which the construction and particularly the nature of its supports is such that these difficulties and objections are overcome.

According to the present invention there is provided a gravity davit of the kind above set forth wherein at least one of the pivotal supports for the arm is wide enough to give it lateral stability without requiring side guides.

Conveniently the invention is carried into effect by constructing at least one of the links, by which the arm is pivotally supported, of two widely spaced side-by-side link-members between which the lower end of the arm is located. Such an arrangement gives a three-point support to the arm and after the manner of sheer legs provides the required lateral stability throughout movement of the arm. This movement is substantially friction free, the arm only bearing against its pivotal supports.

According to a further feature of the present invention there is provided a davit or the like in which, in lieu of the normal stand, the means for supporting the movable arm comprises front and rear sectionalized units or elements.

In one preferred embodiment of the invention the arm supporting means comprises a rear or inboard pillar and a front or outboard pillar or stool which is relatively short The rear pillar carries a pivotal support for a rear link, which supports the heel of the davit arm, whereas the stool or front pillar carries a pivotal support for a pair of widely spaced front linkmembers between which the fore foot or toe of the arm is pivotally supported. The pillars or the like are made of simple and easily transported units which, together with the arm and linkages, are readily mounted and assembled on arrival at the ship.

Heretofore, the widths of the pivotal supporting bearings for the arm have necessarily been limited by the permissible clearance between the guide members of the stand which for purposes of limiting weight and bulk were necessarily closely spaced. This is not the case with the supporting means provided by the present invention.

A still further feature of the invention is the bringing of the davit arm to rest in its outboard position, by a flexible arresting member (cg. one or more flexible wire ropes) instead of by impact with a rigid body. The degree of resilience set up by the association of the flexible arresting means and the swinging front linkage together afford the advantage of cushioning the outfit at the limit of outreach or against any uneven stresses on lowering. The arresting member or wire preferably comprises a pair of steel wire strops which, in association with the forward linkage, allows a high degree of cushioning action. Alternatively a plunger of telescopic nature or a fold-up member or linkage may be employed. The end of the limiting member remote from the davit arm may be anchored to the ships deck or to, for example, the rear pillar of the arm supporting means.

One particular embodiment of the invention will now be described, by way of example. In the following description reference is made to the accompanying semidiagrammatic drawing wherein:

FIGURE 1 is a side elevation of the davit with the arm in the inboard position,

FIGURE 2 is a rear elevation of the davit in the inboard position,

FIGURE 3 isa fragmentary front elevation of the davit FIGURE 8 is a detail view of a means for holding and locking the arm in its inboard position, and

FIGURE 9 is a side elevation showing that the davit arm is still effective to operate under the action of gravity even when subjected to an adverse list of 25 and will not kick back when being brought inboard to the stowed position.

Referring to the drawings the davit has a supporting means for the arm comprising a rear pillar or upright 10 of simple form and also a simple constructed front unit or short pillar 11. The pivot 12, on the upper part of the pillar 10, supports the rear link 13 whilst the pivot 14 on the pillar 11 supports the somewhat shorter front link which comprises widely spaced link-members 15.

The links 13 and 15 constitute a pivotal suspension arrangement for the davit arm 16, the link 13 being piv0tally connected to the heel of the arm at 17 whilst the front link 15 is pivotally connected to the toe or fore foot part of the arm at 18. The davit arm has a horn 16b at its upper end for supporting a boat.

The davit includes tackle 16a adapted to be operated by a winch 16c having a hand brake 16a. This tackle, winch and brake are of the well known kind usually provided for gradually and controllably moving the davit arm to and from its outboard position.

Outboard movement of the davit arm is limited by a pair of flexible wire strops 22 coupled to the pivot pin 17 and to the rear pillar 10 at 23. A spreader 22a may be secured to and between the strops 22. The arresting wires 22 may be adjustable for length to give the required outreach.

It will be noted that the rear link 13 is slotted at 13a where it is pivotally connected to the davit arm. This lost motion connection avoids opposed linkage action in the transference of load from the inboard to the outboard position, and vice versa, the object being to ensure that the arm is afforded full support during lowering and in the outboard position by the tension in the front link and in the arresting wires 22 connecting the heel of the davit to the pillar 10. p

The length of the flexible arresting wires 22 is such that the davit arm is arrested with the pivot pin 17 free between the ends of the slot 13a in the rear link so that the arm is brought to rest without shock and there is no material resistance to inboard movement of the arm.

It will be noted, particularly from FIGURE 4, that the front pivotal bearings 14, 18 for the davit arm are of substantial width so that there is little, if any, tendency to lateral movement in the davit arm and the provision of special guide-members between which the arm moves is not required.

The davit arm supporting means and/or keel guidance may be assisted by providing a pair of tie-wires 23a on opposite sides of the davit arm. One end of each flexible steel tie 23a is anchored to the pillar as indicated at 24 whilst the other and lower end is anchored to the front pillar 11 as indicated at 25 by means which enable the ties to be tensioned. These tie wires may, if desired, bear against the arm so as to give it some lateral support as such wires are little if at all liable to material icing up and therefore under icing conditions would not obstruct the free movement of the arm.

The arm holding and locking device shown in FIG- URE 8 comprises a lever 26 pivoted to the rear pillar 10 at 27. The lever has an arm 28 which engages in front of an abutment 29 on the davit arm so as to hold the arm in its inboard position and a pivoted shackle 30 adapted to be swung over a hook 31 on the davit arm to lock it in said position. The levers 26 of a pair of davits may be connected together so that after their locking shackles 30 have been released all that is necessary to free the davit arms, so that they will move outboard, is to pull on the connecting means between the two levers.

I claim:

1. A gravity davit comprising a stand, a davit arm having a horn at its upper end for supporting a boat, a rear link, means pivotally supporting said rear link by an upper end thereof from said stand, means pivotally connecting a lower end of said rear link to the davit arm at a lower rearward part thereof, a front link, means pivotally supporting said front link by an outer end thereof from the stand, means pivotally connecting an inner end of said front link to the davit arm at a lower forward part thereof, the davit arm swinging with and on said links from a stowed position to an outboard position in which it is operative to launch a boat from the horn on its upper end, an arresting link extending between the stand and the davit arm and operative to arrest movement of the arm at the outboard position, and means for gradually and controllably movingthe davit arm from said stowed position to said outboard position, the pivotal connection of the rear link to the davit arm including a slot in the end of said rear link and a pivot pin in the davit arm which passes through said slot and is free to move longitudinally thereof whereby the rear link does not act to arrest outboard movement of the arm, said arresting link being a flexible member, the length of which is such that outboard movement of the arm is arrested with said pivot pin free between the ends of said slot in the rear link whereby the arm is brought to rest without a shock and there is no material resistance to inboard movement of the arm.

2. A gravity davit comprising a stand having front and rear parts, a davit arm having a horn at its upper end for supporting a boat, a rear link, means pivotally supporting said rear link by an upper end thereof from said stand, means pivotally connecting a lower end of said rear link to the davit arm at a lower rearward part thereof, a front link, means pivotally supporting said front link by an outer end thereof from the stand, means pivotally connecting an inner end of said front link to the davit arm at a lower forward part thereof, the davit arm swinging with and on said links from a stowed position to an outboard position in which it is operative to launch a boat from the horn on its upper end, an arresting link extending between the stand and the davit arm and operative to arrest movement of the arm at the outboard position, means for gradually and controllably moving the davit arm from said stowed position to said outboard position, the pivotal connection of the rear link to the davit arm including a slot in the end of said rear link and a pivot pin in the davit arm which passes through said slot and is free to move longitudinally thereof whereby the rear link does not act to arrest outboard movement of the arm, said arresting link being a flexible member the length of which is such that outboard movement of the arm is arrested with said pivot pin free between the ends of said slot in the rear link whereby the arm is brought to rest without shock and there is no material resistance to inboard movement of the arm, and a pair of flexible members secured under tension between the front and rear parts of the stand and iocated one on each side of the davit arm.

3. A davit as claimed in claim 1 wherein the arresting link is adjustable for length.

References Cited in the file of this patent UNITED STATES PATENTS 581.,925 Storm May 4, 1897 668,660 Roche Feb. 26, 1901 1,094,348 Tjader Apr. 21, 1914 1,180,322 Sanford Apr. 25, 1916 1,868,043 Barclay July 19, 1932 2,038,233 Oppenheim Apr. 21, 1936 2,260,772 Coates Oct. 28, 1941 2,550,087 Rouse Apr. 24, 1951 2,647,269 Cappel Aug. 4, 1953 2,667,649 Elling Feb. 2, 1954 2,683.,271 Taylor July 13, 1954 FOREIGN PATENTS 269,136 Great Britain Nov. 17, 1927

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