US2854154A - Sea elevator - Google Patents

Description

SEA ELEVATOR 3 Sheets-Sheet 1 Filed March 21, 1956 INVENTOR zEw mm Alk 7 lllllllllllllll lfil tillllvlllllllltrllllllliil I ATTORNEYS Sept. 30, 1958 R. E. HEPINSTALL SEA ELEVATOR 3 Sheets-Sheet 2 Filed March 21, 1956 INVENTOR ATTORNEYS SEA ELEVATOR 3 Sheets-Sheet 3 Filed March 21, 1956 Unite States This invention relates to apparatus for effecting the transfer of personnel or equipment between relatively moving stations, and more specifically, the invention pertains to elevator means to accomplish the transfer.

One of the primary objects of this invention is to provide hoisting apparatus having a hoisting device for transferring loads to and from a pair of base structures moving relative to each other and which apparatus includes means for imparting a predetermined movement to said hoisting device relative to its supporting base structure and means for automatically superimposing a further movement thereon equal to the relative motion between said base structures.

Another of the primary objects of this invention is to provide elevator apparatus for transferring personnel and/or equipment from an elevated base to a vessel at sea moored below the base, and vice versa.

Another object of this invention is to provide elevator means for transferring personnel and/or equipment to and from a vessel at sea and a stationary base, or a second vessel, and to provide such means for effecting transfer of men or apparatus between vessels each of which may be moving vertically relative to a horizontal plane at the same or differing speeds.

A further object of the present invention is to provide elevator apparatus of the type described including an elevator car mounted for movement longitudinally of a pair of guide cables held under constant tension and extending from an elevated base to a lower base and wherein one of the bases may move relative to the other.

A still further object of this invention is to provide elevator apparatus of the type referred to supra which includes an elevated base having a boom mounted for lateral swinging thereon, the boom having an elevator car movable horizontally thereon to a predetermined position, and constant tension guide cables connected between the boom and a lower base and along which the elevator car may be moved toward and away from the two bases.

Other and further objects and advantages will become more apparent from a consideration of the following specification when read in conjunction with the annexed drawings, in which:

Fig. l is a diagrammatic side elevational view illustrating a sea elevator embodying the present invention.

Fig. 1-A is a top plan view, partly in cross-section, taken on the horizontal plane of line 1-A--1A of Fig. 1, looking in the direction of the arrows.

Fig. 1-B is a fragmentary perspective view illustrating the connection between the vertical standard and its stabilizing beam.

Fig. 2 is an enlarged cross-sectional view partially in end elevation, taken on the vertical plane of line 22, of Fig. 1, looking in the direction of the arrows, the view illustrating the driving means for the control car and the suspension means for the hydraulic conduits.

Fig. 3 is an enlarged fragmentary detail cross-sectional view, partly in elevation, and taken substantially on the line 33 of Fig. 1, looking in the direction of the arrows.

Fig. 4 is a cross-sectional view, partly in side elevation, taken on the line 4-4 of Fig. 3.

Fig. 5 is a cross-sectional view, partly in elevation, taken on the vertical plane of line 5-5 of Fig. 3, looking in the direction of the arrows.

Fig. 6 is an enlarged detail, cross-sectional view of the control valve for the elevator car.

Fig. 7 is an enlarged exploded perspective view illustrating the pivotal bracket means for securing the upper ends of a plurality of guy wires to the elevated boom supporting structure.

Fig. 8 is an enlarged fragmentary detail cross-sectional view, similar to Fig. 2, and illustrating in clearer detail the rail, rollers, and hangers for supporting the hydraulic lines on the boom.

Fig. 9 diagrammatically illustrates one of the relative positions assumed by the elevator car cable guides upon the canting of a vessel at sea to one side of its keel.

Referring now more specifically to the drawings, reference numeral 10 designates, in general, a sea elevator constructed in accordance with the teachings of this invention. As shown in Fig. 1, the sea elevator 10 is seen to comprise a platform 12 supported upon a plurality of piling or caisson members 14, sunk into the bed of a body of water 15, and which are held in their respective relative positions by means of conventional diagonal and horizontal cross-brace members 16, 18, respectively.

As illustrated in Fig. 1, the platform 12 supports an elevated open frame lighthouse or similar structure 20 having upwardly converging side members 21 supported in their respective positions by horizontal and diagonal cross-braces 22 and 23, respectively. The upper ends of the side members 21 terminate in a horizontal platform 25 that supports for rotation thereon, by conventional means (not shown), a signal light 24. Suitable crews quarters and storage space are erected on the platform 12 and are indicated, in general, by the reference numeral 26. A ladder 28 extends from the platform 12 to the platform 25 to provide access to the signal light 24 for its maintenance and repair.

The upper ends of a plurality of guy wires 30 are fixedly secured to a plurality of conventional connectors 32 rigidly mounted on a pair of the side members 21 of the open frame 20 adjacent their upper ends, and the guy wires extend downwardly therefrom and are affixed by anchorage elements 34, also of conventional design, to the platform 12. The guy wires are, of course, utilized to stabilize the lighthouse 20 in its erect position.

A vertically extending cylindrical standard 35 is provided with an enlarged flanged base 36 which is bolted to the platform 12. The standard 35 is provided with an upper end 38 of reduced diameter (see Figs. 1 and l-B) which telescopically receives thereover a collar 39 for rotation thereon. A pair of support arms 40 (see Fig. 3) have one of their respective ends fixedly secured as by welding 42 to opposite sides of the collar 39 and their other respective ends project laterally away therefrom.

Means for preventing the vertical displacement of th collar 39 and for bracing the standard 34 are provided. These means (see Figs. 1, l-A and 1-B) comprise an elongated substantially horizontal I-beam 44 having a centrally disposed enlarged hollow boss 46 which is bored at 48 to receive the upper reduced end 38 of the standard 35 therein. As is seen in Fig. 1-A, the opposed ends of the beam 44 are firmly secured, respectively, to one of the ends of a pair of brace members 50. The other ends of thebrace members 50 extend downwardly from the beam 44 and terminate in substantially rec- 3 tangular plates 52 which are secured by bolts 54 to the platform 12.

The outer ends of the support arms 40 are apertured as are the arms 56-of apair of spaced L-shaped-brackets 58 having their respective legs '60 fixedly secured to the inner end wall 62 of a boom designated,infgeneralfiby the reference numeral 64. The apertures in the arms 40 and 56 arealignedto receive-the cross-shaft'66'whereby the boom is connected 'to the standard 34 for horizontal rotation thereon as Welles for pivotal vertical movement relative thereto.

The boom 64 (Fig. 2) issubstantially rectangular in configuration and includes a plurality of longitudinally extending top and bottom corner 'elements'70, '72,having arms-74, 76 and legs 78, .80, respectively. Thejle'gs 78, 80 are rigidly connected by vertical braces 82 and diagonal cross-braces 834 in-the conventional manner.

The upper arms :74 of the boom.64.have rigidly secured thereto a catwalk84, while the lower arms 76'support an elongated bottom wall 86. An elongated pair of .substantially L-shaped members 88 have their respective legportions 90 rigidly secured, as by welding.91, to the leg'and arms 80, 76, respectively, .of' the corner elements 72 and-depend therebelow and terminate in inwardly extending spaced-and confronting flange members 92 which, as will be described below, form a pair of longi- V tudinally extending rails.

At spaced intervals, the top corner elements '70 of the boom 64 have rigidly secured on their arms 74 a plurality of anchoring means '94, of. conventional design, and are-adapted to-secure one of the ends ofa plurality ofzgu'y Wires, 9.6. Theguy wires;96 extend upwardly from the boom 64 and are threaded through apertures 98, formed :in'a pairef flanges-100, 102. As is seen in Fig. 7 of the, drawings, the ,flanges 100, 102, project radially from an elongated'substa'ntially hollow cylindrical sleeve 104 which is adapted to be mounted between a pair of bracket arms 106 of a substantially .U-shaped bracket member 108. The arms are :apertured at 110 and are aligned with: the axially extending bore 112 of the sleeve 104. An elongatedheaded bolt114 extends through the aligned apertures 110.-and bore 112and is secured against displacement by means ofzthe lock-washer116 and locknut:118. The bight portion120 of the U-shaped bracket member 108 is .fixedlyfsecured, as by welding, to one of the horizontal brace members22, disposedadjacent the upper end of the lighthouse structure 20. Means (not shown) are employed to prev ent the withdrawal of the upper ends of the guy wires96 from their respective flanges 100, 102.

'Acontrol cab122 (see Figs. l, 2 and 3) is mounted on the boom 64 for longitudinal movement thereon, and the control cab is provided-with an extension 123 which projects longitudinally of the boom to serve a purpose to be described. Asis seen 'in Fig. 2- of the'drawings, the top wall 124 of the control cab-122 and extension 123 have'secured thereto the lower ends or aplurality ofoppositely disposed-and longitudinally spaced suspension members 126. The upper ends of the suspension members terminate in blocks 128 which support shafts 130 having roller Wheels'132 at the outer ends thereof. The roller wheels-1'32 are, in turn, supported upon the rails 92 referred to above for rolling movement'therealong.

The bottom wall 86 of the boom64" has fixedly secured thereto a centrally disposed "longitudinally'extendinggear rack 134. A reversible hydraulic 'motor 136 is, provided with an'elongated'drive shaft138'on which is fixedlysecured intermediate its ends a gear 140. The outer end of the shaft 138 is supported in a bearing 141 carried at the upper end of a substantially vertical standard 142 having the lower end thereoffixedly secured to the top wall 124 of the control cab'122. The hydraulic motor 136 is connected by a high-pressure hydraulic fluid conduit'144'and by a low pressure return- 4 conduit 146 with a hydraulic pump and associated elements which'will be described later.

Thus it is seen that the control cab 122 may be moved longitudinally of the boom 64 to any pre-determined position relative thereto.

Referring now more specifically to Figs. 1-A and 3, it is seen that a suitably driven hydraulic pump 148 is supported on and is secured to the platform 12. The pump 148 has the .high-pressure side thereof connected by a conduit 150 toan accumulator 152 for hydraluic fluid, thefluid in the accumulator being maintained under a constant predetermined pressure. A fitting 154 connects the outlet port of the accumulator 152 with one end of a flexible conduit 156 which extends through an opening 62-A in the end wall 62 and is threaded through a plurality of rings 158 (Fig. 8) fixedly secured to the lower ends of a plurality of hanger bars 160. The upper ends of thehanger ,bars 160 are formed with eyes .161 through .each of which extends a shaft 162. A pair ofrrollers 164, 166 ismounted for rotation on theends of each of the shafts 162. As is 'seen in Fig. 8, the rollers 164'are supported on the flange 168 on one side of the web 170 of an I-beam 172 having its other flange 174 fixedly secured to the bottom wall 86 of the boom 64. The rollers 166 are supported on the flange 176 of a channel member 178, the latter having its other flange 180 fixedly secured to the bottom wall 86 of the boom.

The return side ofthepump148 is connectedby a fitting 182 with one end of a flexible hydraulic. fluid return conduit .184. They conduit 184 extends throughan opening 62-B in the end wall 62 and is threaded through rings.188 which depend from the lower endsof a plurality of hanger bars 190, having their respective other ends terminating in'eyes 191 whichengage around shafts .192.

The opposed ends of the shafts 192 are connected with rollers 194, 196. The rollers .194 .are supported on the flange 198 of a channel member 2'80, and the other fiange'202 thereof is fixedly secured to the bottom wall 86offthe boom 64. The rollers 196-ride ,onthe flange 168 onthe other side of the web 170 of the ,I-beam 172. Flexible cables201 connect the outermost hangers 160, with the extension 123 ofthecontrol cab 122,.and it becomes now apparent that the high-pressure and return conduits 156, 184 may be extended longitudinally of'the boom. 64 and retracted thereon, and in their-retracted position, the conduits-will assume a substantially sinusoidal configuration.

'As is seen in Figs. 1 and 3, the extension123 of the control cab 122 is substantially rectangular intransverse cross-section to provide a substantially hollow rectangular compartment 204 to accommodate apparatus to be described below.

The'extension 123 includes .the top wall,124 from which depend side walls 212, 2141and. a transversely'extending bottom wall 216 spaced upwardly from the bottom wall 218 of the control cab 122. The outer end of the extension 123 is closed by an end wall 219 having a pair of transverse openings 220, 222 extending therethrough.

As seen in Fig. 3, three pairs of transversely spaced brackets 224 are fixedly mounted on the bottom wall .216 and rotatably support a pair of outersheaves 226, 228 and a third sheave 230 positioned intermediate the outer sheaves 226, 228.

Three pairs of transversely spacedbrackets 232 .are

also fixedly secured on the bottom wall 216 and-are spaced longitudinally from the brackets v224. The outer pair of brackets 232 have pulleys 234, 236 rotatably mounted therein which are aligned with thesheavesv226 and 228, respectively. The third pair of brackets 232 rotatably supports a pulley-238positioned intermediate the pulleys 23 4, 236 and is aligned with the sheave 230.

Three winch drums 240, 242,244, driven by hydraulic motors 246,248 and 250, respectively, are supported on three pairs'of brackets 252,-=the latter also being fixedly secured to the bottom wall 216. As illustrated in Fig. 3, the winch drum 240 is in substantial alignment with the pulley 234 and sheave 226; the winch 242 is substantially aligned with the pulley 238 and sheave 230; and the winch drum 244 is seen to be substantially aligned with the pulley 236 and the sheave 228.

A plurality of vertically extending, longitudinally spaced, plates 254, 256 and 258 extend transversely across the bottom wall 216 and are fixedly secured to the side walls 212, 214 as by welding 260. The plates 254, 256 and 258 are each provided with aligned arcuate cutouts 262 (Fig. which extend inwardly from the upper edge thereof in longitudinally spaced relation. Similar cutouts 264, 266 are also formed in the upper edges of the plates 256, 258, respectively. The aligned cutouts 262 adjacent each end of the plates 254, 256 and 258 receive and have fixedly secured therein, as by welding 268, the cylinders 270 and 272. A third cylinder 274 is fixedly secured, as before, in similar cutouts 262 formed in the plates 254, 256, 258, and is disposed intermediate the cylinders 270, 272. Each of the cylinders 270, 272, 274 are provided with pistons 278, 280, 282 adapted for reciprocation therein and to which are connected one end of the piston rods 284, 286 and 288, respectively. The

outer ends of the piston rods project through openings- 290 formed in cap members 292 which extend across the other ends of the cylinders 270, 272 and 274. The outer ends of the piston rods 284, 286, 288 have fixedly secured thereto substantially U-shaped brackets 294 in which are rotatably supported pulleys 296, 298 and 300. The pulleys 296, 298, 300 are disposed in spaced confronting relation with respect to the winch drums 240, 242, and 244, and are aligned with the pulleys 234, 238 and 236, respectively.

A cable 302 has one of its ends fixedly secured on the winch drum 240 and is trained around the pulleys 296, 234 and the sheave 226. From the sheave 226 the cable 302 is threaded through a grommet 304 in the bottom wall 216 and is suspended therebelow. A hook 306 (Fig. 1) is fixedly secured to the free end of the cable 302.

A second cable 308 has one end secured to the winch drum 244 and is trained about the pulleys 300, 236 and sheave 228, and passes through a second grommet 304, as described above, and the free end thereof is fixedly secured to a second hook 306. A third cable 310 has one of its ends flxedly secured to the winch drum 242 and is trained about the pulleys 298, 238, and sheave 230 in the manner previously described. The free end of the cable 310 extends through a third grommet 304 and has secured thereto a third hook.

A plurality of accumulators 312, 314, 316 are fixedly secured as by welding in the aligned arcuate cut- outs 264, 266, formed in the plates 256, 258. The high pressure hydraulic supply line 156 is connected to a distributing valve 332, to be described later, and a branch thereof connects with a flexible conduit 338, also to be described later. A further branch 320 of conduit 156 connects to the accumulators 312 and 316 through control valves 322. In operation, accumulator 316 and its associated cylinder 272, and also accumulator 312 and its associated cylinder 270, comprise completely closed hydraulic systems. The connection from those accumulators to the line 156 through valves 322 is provided for the purpose of replenishing fluid in the closed systems when fluid loss takes place as a result of leakage or the like. Conduits 334 connect accumulators 312 and 316 to their respective cylinders. Accumulator 314 communicates, through pipe 336 and flexible conduit 338, with a regulator or servo valve 340.

The accumulators 312 and 316 may be of any conventional or suitable type to provide a supply of pressure fluid at a substantially constant predetermined pressure to operate the pistons in cylinders 270 and 272 and to exert a constant force thereon regardless of the position of either piston in its cylinder.

The accumulator 314 insures an adequate supply of high pressure fluid for the regulator valve 340 at all times, even when fluid is flowing from conduit 156 through valve 332.

As is shown in Figs. 3 and 4 of the drawings, the regulator valve 340 is fixedly secured on the piston rod 286 of the cylinder 274.

The valve 340 comprises a substantially hollow cylindrical casing 341 having opposed open and closed ends. The open end of the valve 340 is internally threaded to receive an externally threaded cap 342. One end of the valve 340 is provided with a port 344 which is connected by a pipe 346, a T-connector 348, and a flexible, tubular member 350, with a reservoir 352 which is vented at 354 to the atmosphere. A by-pass pipe 356 has one of its ends connected with the T-connector 348 and the other of its ends connected with a port 358 disposed adjacent the other end of the valve. A port 360 is con nected by means of the flexible conduit 362 with the cylinder 274. The moveable member 364 reciprocates within the casing and is provided with a circumferential groove 366 intermediate its ends. One of the ends 367 of the member 364 is provided with a radially-extending passage 368 connecting at its inner end with an axial passage 369 which extends through the other end 370 of the member 364. As is seen in Fig. 6, the valve member 364 is connected to one end of a rod 371 which reciprocates through a packing 372 disposed in the closed end 373 of the valve 340. The other end of the rod 371 terminates in a clevis 374 (Figs. 3 and 4). An inlet port 339 communicates with conduit 338 and is positioned to admit pressure fluid to the groove 366.

The distributing valve 332 selectively controls the supply of fluid under pressure through conduits 390, 392 and 394 to the hydraulic motors 246, 248 and 250, respectively. Spent hydraulic fluid is discharged from the motor 246 through the pipe 396 to the reservoir 352. As is seen in Fig. 3, the pipe 396 has connected therein a pair of T- connectors 398, 400 which, in turn, are connected to the discharge side of the motors 248, 250, through pipes 462, 404. The return side of the pump 148 is connected by the flexible conduit 184 with the reservoir 352, the outer end of the conduit 184 extending through the opening 222 hereinbefore described.

The piston rods 284, 288 are pivotally connected at 406 and 408, respectively to the ends of a bar 410. The bar 410 is connected intermediate its ends by means of the pivot pin 412 to the clevis 374 of the rod 371. Thus it is seen that if the piston rods 284, 288 move in the same direction at the same rate, similar movement will be applied to the rod 371. On the other hand, should the piston rods 284, 288 move in opposite directions at the same rate of speed or through the same amounts, no movement will be transmitted to the rod 286 since the bar 410 will merely pivot about the pivot pin 412.

The regulator valve 340, previously described, is a more or less conventional pressure regulating follow-up valve. the valve 340 operates to regulate the fluid pressure in the cylinder 274 in such manner as to cause operation of piston 288 to maintain the valve parts in the relative positions shown in Fig. 6 and thereby cause piston rod 286, valve casing 341 and pulleys 298 to exactly follow movements of the pivot 412 at the center of bar 410.

Referring now to Figs. 1 and 9, the control cab 122 supports the elevator car 422 by means of the cable 310, its hook 386 and an eye member 424 rigidly secured to the top wall 375 of the elevator car. Normally the car 422 rests adjacent the bottom wall 216 of the extension 123, and this position is retained during the travel of the control cab 122 along the boom 64. The guide cables 306, 308 are also normally threaded through eyes 377 fixedly secured to the opposite sides of the elevator car 422.

It will be obvious to those skilled in the art that 7 -Fig. 1 of the-drawings illustrates one application of this invention. As shown therein-a boat or'vessel414 is moored to a buoy '415'on 'the'boom's'ide 'of'the platform 12, below the boom 64. The operator-nowopens a valve (not shown) to supply fluid underpressure from the conduit 156 to the hydraulic motor 136. The motor '136 drives the gear 140 to efiect movement-ofthe control cab andelevatorcar outwardly away from'the'platform 12. When'the elevator car is disposed over the deck416 of the vessel 4-14, the' motor 136-is'deactivated and braked.

vThe reversing distributor-valve-332 is then operated (by any suitable meansgnot shown) to efl ectthe driving of the winch motors 246 and 250 to lower, in dependently, the cablesl'302, 308. "Thereafter the hooks 306of these cablesare secured in eyes 418 on the deck 416. The motors-246, 250 are then reversed. 'As the motors 246, 250 run in reverse the piston rods 284, 288 are extended against the-pressure on their associated pistons, provided 'by the a'ccumulators 312, 316. Thus the desired tension is placed on the guide cables 302, 308 and the motors 246,250 are stopped and braked when the pistons have been'moved to positions giving the desired range of movement.

The valve 332 is'then operated to supply fluid under pressure to the winch motor 248 so that the elevator cab 422 descends as the hoistcable 310 is payed out. 'The descent of'the cab 422 maybe halted when the concave bottom wall 379.is proximate the deck 416. It is' to be noted that thehoist cable 310, in passing over pulleys 238 and 298 in the manner shown (Fig. 4),'is provided with a supply of'slack between those pulleys and that the load tension in the cable tends to pull piston rod 286 outwardly.

Assuming now that there is no relative movement betweenv the deck 416 andthe car 422, personnel and/or equipment may be transferred between the car 422 and the vessel 414 through the access door 430.

Should,'however, the deck 416 rock laterally as suggested by full line in Fig. 9, pressure on the piston 278 efiects a withdrawal of the rod 284 and a backing movement of the pulley 296. Thismovement takes up any potential slackening in the cable 302 and maintains it under the predetermined tension- .Simultaneously, downward movement of the cable 308 causes the pulley 300 to move in the opposite direction and withdraws the rod 288 against the constant pressure on the piston 282 whereby the tension on the cable 308 is constantly maintained.

The same sequence of operations results, in reverse, when the vessel rocks in the other direction as indicated by the broken lines of Fig. 9.

During the above-described conditions, the bar 410 merely pivots about the pin 412. Consequently, the

' rod 286 remains stationary. If, however, the deck 416 should also bob up and down as is usually the case, both cables 302, 308 move upwardly and/or downwardly, the pulleys 296 and 30!? mounted on the shafts 234, 288 then move toward or from the cylinders 270, 272 While the fluid pressure exerted on the pistons. 278, 282, maintains the predetermined tension on the cables 302, 308, as described above. The thus described movement of the rods 284, 288 causes corresponding movement of the rod 371 and movement in the same direction of the valve member 364 in its casing 341.

The fluid pressure in line 362 is thus changed to cause movement of piston 280 in a direction to follow" pivot 412 and thereby effect movement of the pulley 298 in the same direction whereby the payed out length of the cable 310, is shortened or lengthened as the case may be and the elevator car 422 is maintained a uniform distance from deck 416. Thus it is seen that the movement of the pulleys 296, 298 and 300 are synchronized and thecenterpoint X on the lowest point of the curved bottom wall 379'of-the elevator cab 422 is maintained at a constant distance from a point Y on the centerline of the deck 416.

Thus it *is' seen *that"the*upward and downwardunovement-of the deck"416,*and the *canting thereof, for' any combination 'of'verticalmovement accompanied-'by'-cant ing "will not change the tension on theguide 'cables' 302, 308 and that the vertical'movement ofboth cables 302, 308 at the same time and "in the samedirectio'n; effects similarmovements oftheelevator car 422 and in the same direction.

The above-description of-operation ofthe apparatus assumed that the elevator car had already 7 been lowered to a position close toithe 'deck 416'and then stopped. However, it-will'beobvious-that the described operations of the valve 340,"bar- 410,- piston 280 and pulleys 298 take place .even' when the hoist winch 242"is operating to raise or l'ower'theelevator'car 422. Thus, the upaird-- down movement of 'the -vessel 414'issuperimpdsdupon the movement imparted to thej'elevator car by hoist winch 242 and resultsin a' controllable rate of'movement'pf the' car rela-tive to the deck. -In this manner "there is no danger that-a "risi-ng deck will crack into a descending cal. Likewise,-upon-"starting to lift the car from is lowered position =there' is no danger'that the deck will suddenly fall away from-the car and apply an undue shock load on 'the hoisting cable and mechanism.

As the elevator car is 'lifted toward :and-approaches-the control cab 122, it is' desirable that the motions thereof induced by the-movementsof'the boatdeck be elimi nated and-that movement of the car be under the absolute control of thewinch 242. *To thisend the'operator may cause operation of'the- winches 240 and 244 to gradually pay outguide-cables-"302 and 308'while the-elevator car'is rising. "This'results in inwardmovement OfjPiS tons 278 and 282 'to' the'limit e f-their movement While maintaining their tension and also results in -followin'g of pulley 298 to1its' innermost position. As the-elevator car approaches the 'car "1'22-the guiding'function of cables 302-and 308 is'no longerneeded so'theirtension can be completely-released and thnsrender valve 340 nolonger A responsive to'movements 0f the boat. As an alternative means couldbe provided for disabling valve 340 in a manner to holdpulleys 298 in fixed position irrespective of movements of pivot 412.

It is furthercontemplatedithat 'suitable means (not shown) be provided whereby the-operator of the. apparatus may cause and control lateral swinging movements of boom '64-to thusmaintain "the guide cables 302: and

308 substantially verticalat alltimes in spite of lateral drifting of vessel 414.

As will 'be obvious 'to those skilled in the art, the basic principles of this invention may bev employed with modified apparatus. For'instance, a single control cable or line corresponding to cable 302 or 308.may be employed-to actuate a hoistlinefslack control to facilitate depositing or removing loads from a boatldeck,.or similarly'moving structure, by: conventional hoisting equipment and without'usingthe. control cable as a guide for'the load as shown inthe drawings.

The drawings herein disclose but one embodiment of the invention. It is manifest, however, that the inven-' tion may find other applications, for example, the invention may be utilized in conveyancing between two waterborne vessels,ior. between other vertically spaced decks having relative movement, and. that means. other than the disclosed fluid pressure means may be employed to maintain a constantxpredetermined tension on theguide cables or to' operate'the'various motors.

Having describedandillustrated one embodiment of this invention, it will be understood that this is offered merely by way of example .and that the invention is .to be limited only 'by'the scopeof the appended claims.

What -I claim is:

1. Hoisting apparatus for usebetween an upper fixed structure and a lower moveable structure, comprising; hoisting means 'on'said upper structure and including a power source and a hoisting cable, for lifting or lowering a load from or to the lower structure by imparting vertical movement to said load at a controlled rate, means separate from said hoisting means, extending between said structures, for detecting relative vertical movements between said structures and means responsive thereto for actuating a separate power device controlling said hoisting cable for imparting additional vertical movements to said load independently of said power source and corresponding to said relative movements so as to add to said controlled rate when said lower structure is descending and to subtract therefrom when said lower structure is rising.

2. Hoisting apparatus as defined in claim 1 wherein said hoisting means includes a flexible cable connected to said load and wherein said last-named means comprises a device holding a supply of said flexible cable and responsive to said detecting means to pay out or take up cable to thereby impart vertical movements to said load independently of operation of said hoisting means.

3. Hoisting apparatus as defined in claim 1 wherein said hoisting means comprise a winch on said one structure and a flexible cable extending therefrom for supporting and moving said load, said detecting means comprising a flexible line having one end fixed relative to said other structure and extending to control means on said one structure, said responsive means comprising devices defining a devious path of movement for a portion of said cable, said devices being relatively movable in response to actuation of said control means by said flexible line to change the length of said devious path and thereby produce vertical movements of said load, relative to said one structure and independently of said winch, corresponding to movements of said other structure relative to said one structure.

4. Hoisting apparatus comprising in combination: a generally horizontal boom, a control cab mounted on said boom, an elevator device, means suspending said elevator device from said control cab for vertical movement relative thereto; a pair of winches mounted in said control cab, each of said winches being provided with a cable drum, a cable for each of said drums, each of said cables being wound around its respective drum and having a free end adapted for connecting to a station disposed below said boom, independently operable reversible driving means connected with each one of said pair of winches, a pulley system interposed in each of said cables, means connected with each of said pulley systems, respectively, for maintaining a constant tension thereon upon connection of said free ends of said cables with said station, means slidably connecting said elevator device with said cables, said suspension means for said elevator comprising a third winch disposed in-said control cab and connected in driving relation with a third cable drum, a third cable Wound around said third drum and having a free end, means connecting said last-named free end with said elevator device, reversible means for driving said third winch independently of each of said first two reversible driving means, a third pulley system interposed in said third cable, a control means connected with said third pulley system to change the effective length of said third cable, and means connecting said control means with the first and second constant tension means to effect actuation of said control means in response to the actuation of said first and second constant tension means to change the effective length of said third cable and synchronize movements of said elevator with movements of said station relative to said boom.

5. Hoisting apparatus comprising in combination: a fixed support, means mounting said support in an elevated position above a movable station, a control cab mounted on said support, an elevating device, adjustable suspension means connecting said device to said cab for vertical movement relative thereto toward and from said station, a pair of reversible winches disposed in said control cab, a cable drum for each of said winches and operably connected therewith, means for driving said winches, a guide cable for each of said winches, said guide cables being wound around each of said drums and each having a free end extending outwardly of said control cab for detachable connection with said station, a pulley system interposed in each of said cables, each of said systems including one pulley movable relative to the other pulley of its said system, means independent of each other connected with each of said movable pulleys to efiect movement thereof relative to said other pulleys of said systems to maintain a constant predetermined tension on said cables, means slidably connecting said elevating device with said cables, said adjustable suspension means comprising a third winch and cable drum therefor disposed within said cab, reversible driving means for said last-named winch, a third cable wound around said last-named winch and having a free end extending outwardly of said cab, means connecting said last-named free end of said third cable with said elevating device, a third pulley system interposed in said third cable, said third pulley system including a first pulley movable relative to a second pulley, means connected with said first pulley of said third pulley system to effect relative movement of said first pulley with respect to said second pulley of said third pulley system, and control means operatively connecting said movable pulley means together to effect operation of said third pulley moving means simultaneously upon simultaneous movement in the same direction of the others of said movable pulleys.

References Cited in the file of this patent UNITED STATES PATENTS 637,143 Miller Nov. 14, 1899 685,579 Delaney 'Oct. 29, 1901 691,719 Greth Jan. 21, 1902 820,464 Adam May 15, 1906 1,079,159 Bird Nov. 18, 1913 1,177,751 Williamson Apr. 4, 1916 2,402,789 Tweedale June 25, 1946 FOREIGN PATEl TS 269,801 Great Britain Apr. 28, 1927

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