US2742655A - Gravity-davit - Google Patents

Description

Filed Oct. 17. 1951 INVENTOR. 41-12026! us J; Murzck United States Patent Oifice GRAVITY -DA;VIT

Arnoldus-de Munck, Utrecht, Netherlandgassignbr to Mij. tot Yrwerving en Explrvan: Davitoctrooien Davit- Company N V., Utrecht, Netherlands, a corporation of the Netherlands Application October 17, 1951, SerialNo; 251,804

Claims priority, application Netherlands October 18, 1950 2 Claims. (Cll 9- -38) The invention relates to a gravity-davit for a lifeboat, which davit is provided with at least one roller track and with an arm at the lower endof which there are provided rollers cooperating with the-roller track.

In the known devices the roller track practically consists of two separate guideways, the foremost rollers cooperating. with one of the said guideways and the back rollers with the other guideway. This. construction has the drawback that the davit armwhen. lowered, will not be able to tilt to a suflicient degree, since the back rollers 'vvill abut against the bottom of the guideway for the foremost rollers, so that in order to turn the lifeboat sufiiciently outboard the said arm must be made comin which the common centre of gravity of the said davit and the boat is not situated high above deck, since in that case the boat will be suspended low above deck.

The present invention has for its purpose to provide a davit of the type described above, which davit will satisfy the said requirement.

For this purpose, according to the invention, the guide way for the rollers is made of a single uninterrupted profile, so that when the arm is moved outboard, the foremost and the back pairs of rollers will run in the same guideway, whereby when the swung-out position has been attained, the back pair of rollers will not abut against the guideway of the foremost pair of rollers.

It is also possible, according to the invention, for the back pair of the rollers to take, in the extreme swuug-out position, the place that is taken by the foremost pair of rollers when in the inboard position. abutting of the back roller or the back pair of rollers against the guideway of the foremost roller or the foremost pair of rollers will become absolutely impossible so that the swinging arm will now be able to swing much farther outboard, which in itself will result in the fact that the said arm may be much shorter and that in the inboard position the lifeboat can be positioned close above deck.

In order to prevent these drawbacks the guide-way consists of a straight part and a curved part, or in case an angle is provided in the said guide-way in which the foremost supporting rollers will partly turn over the said angle, which would prevent the outboard movement, the said foremost supporting rollers, according to the invention, may in the inboard position, be supported by a projecting lug or lid which is situated in alignment with one of the parts of the guide-way. The said lug or lid is adapted to be tilted by the back pair of rollers when the arm is moved outboard. It is even possible to construct the said lug or lid in such a way that it may be completely tilted back by the back rollers.

In that case the Patented Apr. 24, 1956 t a In order to reduce as muchas possible the forces required for moving the lifeboat outboard, it is possible,

according to the invention, to shape the arm and the guideway in such a manner that the common centre of gravity of the boat. and the davit arm will, in theinboard position, be situated above the foremost pair of rollers.

In order to explain the invention still more clearly,

an embodimentthereof will now be explained, by way of example, with the aidof the accompanying drawing, Fig.1. of which is aside view in which the davit has been drawn in the two extreme positions.

Fig. 2 is aside view of the guideway only.

In the said drawing the reference numeral 1 represents a life boat suspended by means of pulleys and blocks in the present case from two davit arms 2.

Eachof the said arms 2 is provided at its lower end with pairsof rollers 3 and' 4. The said pairs of rollers move in. a guide way 5, which guideway consists of a straight part 6 and a curved part 7. In Fig. 1 the device is represented in the two extreme positions; In the inboard position the pair of rollers 4 is situated in. the extreine left portion. of the curved part 7 of the guide Way while the pair of front rollers 3 are in cont-act with the straightpart 6 of the guide way. When the boat is to be launched, the rollers will move through their respective parts of the guide way, whereby the davit arm 2 is dis placed in the outboard direction, while performing a tilting motion. The guide way is stationary and the construction of the arm 2 is so designed that the boat adjacent the davit arms has its keel as low as possible, that is, slightly above the guide way 5.

Owing to the fact that the guide way 5 is built in a single piece, which makes it possible for the rear pair of rollers 4 to approach, to take the place of or even to pass by the place occupied by the pair of rollers 3, the

arm 2, when being moved into the outboard position, will be able to tilt further outboard than is possible with the known constructions. In view thereof it is possible that the keel of the boat may be positioned very low relative to the deck. Also the davit arm extends quite a distance so that the possibility is present of using a shorter davit arm, if it is desired that the davit arm shall have a shorter reach.

On account of the above mentioned features the com mon centre of gravity of the boat and the davit arm will be located lower than with the known constructions.

Fig. 2 only represents the guide-way 5. 1n the said guide-way the straight part and the curved part gradually merge into each other without any interruption, the construction being such that in the outboard position of the davit-arm the pair of rollers 4 will contact with the curved part 8, while the pair of rollers3 will rest in the part 9.

The construction may also be such that the pair of rollers 3 will travel along a portion of the straight part 6 of the guide-way 5. This involves merely a modification in which the part 6 is a little longer than as shown in Figure 1 or the ends 8 and 9 are at a slightly further distance from one another. In this way, when the roller 3 is in the end at 9, the roller 4 will be slightly beyond the point 8 to the right. Thus, to achieve this possibility, it is only necessary that said portions 6 of the guideways must be made longer than in the embodiment shown in the drawing. In other words, the length of the portions 8 to 9 of the guideways must then be greater than the distance between the rollers 3 and 4 of the davit.

With the construction as shown use is made of a lug or fiap 10 the top surface of which during the inboard position of the davit arm, is supported against the lower edge of the part 6 of the guideway.

In this position the pair of rollers 3 will be supported by the flap. The flap 10 is provided with a pivot 11 3 and with a projecting part 12 extending into the guideway. When the arm 2 is moved outboard, the pair of rollers 4 will turn the said flap. The pivot 11 of the flap 10, 12 is mounted on the part 6 of the guideway. Part 12 of the flap reaches through an opening in the lower side of part 7 of the guideway into said part 7 in such a manner that in the position according to Figure 1, part 12 of the flap forms an extension of part 6 of the guideway which extension is located adjacent the sharp bend 8 and on which extension the roller 3 rests. Part 10 of the flap then bears against the lower side of part 6 of the guideway, so that the flap cannot tilt backwards under the pressure of the roller 3. If now the davit is moved into the outboard position, the roller 4 will run against the rear of part 12 of the flap just before said movement comes to an end, and said roller will force part 12 to the right (as seen looking in the direction of movement of the davit arm) until roller 4 has reached the bend. When the davit is returned to the inboard position, the flap is returned to its original position by roller 3.

When the davit arm is moved back, the pair of rollers 3 will cause the flap to move into its initial position.

I claim:

1. A gravity davit for a boat comprising a davit arm from one end of which the boat is to be suspended and having a pair of spaced front and rear rollers at the other end, and a stationary base member for the davit arm having a continuous guideway for the rollers with closed ends one for the inboard position of the davit arm and boat and the other for the outboard position of the davit arm and boat, said guideway having a slightly curved bottom section and an upwardly-directed straight section for the inboard position of the arm and a straight downwardly-directed portion for the outboard position of the arm with a sharp bend at the junction of both straight section approximately at the mid-point of the guideway, the rear roller being at the closed end of the inboard part of the guide-way and the front roller at the sharp bend junction when the davit arm is in the inboard position, and the rear roller being in the sharp bend junction of the guideway with the front roller at the other closed end when the davit is in the outboard position, and the guideway being V-shaped in an inverted position, the apex of which V-shaped guideway constituting the sharp bend junction of both straight sections.

2. A gravity davit according to claim 1, in which a flap member is provided pivotally mounted on the guideway at the sharp bend junction to project into the path of the inboard section of the guideway to act as a support for the front roller in the inboard position of the davit.

References Cited in the file of this patent UNITED STATES PATENTS 581,925 Storm May 4, 1897 2,527,060 Dohn Oct. 24, 1950 FOREIGN PATENTS 885,897 France June 15, 1943

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