US2372347A - Grab - Google Patents

Description

March 27,1945, I A. J. G. WATSON GRAB Filed Nov. 3, 1945 3 SheetsY-Sheet 1 a March 27,1945, A 1J G WATSON 7 2,372,347

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GRAB

l Filed Nov. 3,v 1943- 3 Sheets-Sheet 5 Patented Mar. 27, 1945 GRAB Alfred Jaim.4 Goodrick Watsc1i,'eec1es, England Application November 3, 1943, Serial No. 508,851

In Great Britain October 16, 1942 42 Claims.

This 'invention relates to grabs, and has for one of its objects to provide an improved construction of grab which, owing toits buoyancy, shall be particularly adapted for use in salvaging submerged objects, such as wrecked watercraft, e. g. submarines, and parts thereof.

According to the invention there is provided a grab comprising in combination a cylinder, a pis-v ton movable vertically therein, jaws that are operatively connected with the piston and are arranged to engage an object to be raised when the piston is moved upwards in the cylinder, and pneumatic means for creating at opposite sides of the piston a difference of air pressure for moving the piston in the cylinder. Owing to the presence of air in 'the cylinder when the grab is operated, its buoyancy tends to raise the object gripped by the grab.

Preferably the cylinder has a jacket to contain air for increasing the buoyancy of the grab.

vThe pneumatic means may comprise means for supplying compressed air, or air at atmosphericv pressure to the cylinder belowl the piston, and means for evacuating air from vthe cylinder above the piston and thereby creating a partial vacuum.

Jaw-closing means comprising guides, cams or the like, may be. provided for causing the jaws to approach one another for engaging anobject when the piston moves upwards from its lowest position inthe cylinder.

An operative connection between each jaw and lil The grab I0 is supported by means of chain cables II and IIa from two ships I2 and I2a, and each ship has a power-driven capstan for paying the cables in and out. Each cable II and IIa, is led into the ship in the manner shown in Figure 4 for the cable II. The cable is led to the hawsehole I3 over the top of a multi-plate leaf-spring I4 and through rings I5 which guide it. The springV I4is supported by a bracket I6 and a projecting part I3a o the hawse-hole frame, and

serves to ease the strain on the cable in a rough.

sea.' A third ship Il supports a diving bell I8 by a chain cable i9, and the occupants of the bell lare in communication with all three ships through telephone cables 20. The -bell I8 is lighted and provided with a powerful searchlight to illuminate the sea bed.

The drum I0 is provided with two identical grabbing devices 2l,` one of which is shown in Figures 2 and 3. Each grabbing device comprises a large cylinder 22 carried by the main frame 23 g ated within the drum and can turn on the piston the piston may comprise an arm that is attached i provided with packing means for closing the hole i duid-tight in all positions of the arm and thejaw attached to it.

One embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure l shows the grab in use in raising a sunken submarine;

Figure 2 is a transverse section through the grab;

Figure 3 is a section taken on the line 3-3 of Figure 2, and

Figure 4 shows the manner in which a cable supporting the grab is led into a co-operating ship.

Like reference characters designate like parts in all the iigures of the drawings which are diagrammatic.

As shown in Figure 1, the grab is in the kform of an armour-plated drum I0 shaped like a. cigar.

rod. The bar 26 is formed with jaw-closing means comprisingslots 27 or guideswhich are engaged by pins 28 on the ends of arms 29 that are pivoted at 30 in'the skin of the drum I0. The arms 29 are integral with jaws 3| which are formed with teeth 32, prongs or thelike to'grip the submarine 33 or other article to besalvaged. The drum I0 is formed with a double skin formed by an inner cylindrical shell 34 and an outer cylindrical shell 35, the pivots 30 for the drums 29 and jaws 3| being formed between these shells. The openings through which these parts pass are packed by means of steel shutters 36 provided with strong flat springs 31 for keeping them seated and other springs 38 above them. An airtight joint may be provided between the periphery of the piston 24 and the cylinder walls by means of a rubber ring 39.

The lower end of each cylinder 22 communicates with a, iexible pipe 40 which extends to the ship Il (Figure 1) and connects to an air pump in that ship, so that compressed air can be pumped into the lower half of the cylinder to raise the piston 24 therein, as shown in Figures 2 and 3. The upper part of the cylinder communicates with a exible pipe 4I which extends to the ship Il and communicates therein with a vacuum pump so that the 'upper part of the cylinder can be evacuated to assist in raising the piston 24. Valves are provided in the ship I1 for reversingfthe connections between the pipes 40 and 4| and the pumps, so that the piston 24 can be forced down in the cylinder. As can be seen from Figure 2, when the piston 24 is raised, the jaws 3l close and grip the article to be salvaged. When the piston is lowered, as indicated in broken lines, the jaws 3l open and release the article. In use,l thedrum Il) is positioned oyer` the articleto kie-salvaged with the jaws '3| open; then the piston 24 is raised so that the jaws 3| close on the article and grip it. In order to sinkr the drum l0, water may be pumped into the' therein. The pipe 42 can also be .connected to.

a suction pump in the ship I1 so that the water can be pumped outy of the space between the S.l1s.1.1sV Comer-.ossodar oanfbe .admitted :to the Si@ hei/Wsw 6.19.8 Shells 34, @M135 through .at-pipe' 43 Wliiohalsoextonds to the ship rl1 .aridcom` rnuniates with an air pump therein. By-l dis.- placing the wate-rby air, the drum lcan be made morebuoyantwhen itis to be raised withthear-y ticle torbe salvaged. A non-.return valve 44 is provided in the pipe 4.3. Anotherlpipe 45. extends to a valvein `the -ship Il and permits the Aescape of air when water is pumped' into the drumto sinlitiit.` v

In use, the drum is filled Withwaterand then lowered over the article -to be salvaged together with the diving bell. The ships are manoeuvred i-n accordance with instructions telephoned from a-person in the diving bell lto bring Ithe drurn to the lcorrect position. The jaws'i are then closed and air is pumped into, andV the water is vpiriniped outof, the drum to make it/more buoyant. The drum is then raised by means of the cables ll. The drum. supporting the article to be salvaged, oanthon be towodto oortiby the attendantships.

If desired., the drum may ,be ttod witha low-i powered .origine (not Shown) todrive asolewso that it ycan Hbe manoeuvred under its own power when injport as, for` example, toallow .it to onor a dry dook. origine would 'also drive oom- Pressed. air and vacuum pumps for, maintaining; tho arprossure and. vacuum Within it. andvalvos would .be provided to allow of thosopumps. bei si ooanootod 11s in plaooof. the pipes A4.0,.4 i, .1.4.3 ynd 3f.. 'rneensne and pumps ,Wouldhe .housedinia means of strong coiled steel springs within them,

for enabling them to withstand high hydraulic pressure. Also, where the arms extend out of the drum,v the outer shell may be oi double thickness with a space between them for the dat-springs aforesaid. A similar arrangement may be made in connection with the inner shell of the drum.

, Further, all three ships should be fitted with wirelesstransmitting and receiving apparatus.

vI claim: 1,. Aagrab, comprising in combination a buoyant `drum, acylinder therein, a. piston movable ver throughthe in all positions of the jaws.

.2. A .grab Acomprising -in combination an airialreted drum, a vertical cylinder therein, a piston thatis movable in the cylinder, and hasits rod extending through the lower end of the cylin- 8 dorf, apar oijaws outside the drum, jaw-closing means ,ffn ailsing the ijaws to 'approach one another for .engaging an object. when the piston moves upwards from its lowest position in the cylinder, pneumatic means for moving the piston g in the lcylinder comprising means for supplying compressed lair to the cylinder below the piston, andinlans for -evacuating air from the cylinder above thepiston Vand thereby creating a partial vacumnwhich l.aw-,'closing means comprises two guides. `carried 4by :theipistonrod lbelow the cylindeig-anda `pair of arms vwhich are slidably connested at. one end to the guides and form each a rigid extension of an allotted jaw, which arms extend eachthrough a hole inthe drum, which holes are provided with packing means for closing v:them:iiud-.ti-ght in all positions of the arms and "the, WS.

ALFRED JQHN GOODRICK WATSON.

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