US3365075A - Hoisting block apparatus - Google Patents

Description

Jan. 23, 1968 A. w. VAN GILS ETAL I 3,365,075

HOISTING BLOCK APPARATUS Filed Nov. 17, 1966 2 Sheets-Sheet l F'IGA.

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ATrORNEyS Jan. 23, 1968 A. W. VAN GILS ETAL HOISTING BLOCK APPARATUS Filed Nov. 17, 1966 2 Sheets-Sheet 2 FIG.4

Mmmuu; w. v4 SILs "4:. By; 01 {01% ArrMNeyS United States Patent HGISTING BLOCK APPARATU Adrianus W. van Gills and Willem Joset G. Strolenberg, both BSA. Co, Ltd, Seria, Brunei Filed Nov. 17, 1966, Ser. No. 595,103 Claims priority, application Netherlands, Feb. 2, 1966, 66-1,357 Claims. (Cl. 212-3) ABSTRACT OF THE DISCLOSURE A hoisting block apparatus which is to be used with a hoisting crane, particularly for loading and unloading ships and the like, which are likely to move when the sea is not calm, and under conditions where the load is to be transferred between such a ship and a stationary location. A hoisting cable is connected to the hoisting block and interconnects the latter with the crane so that through the hoisting cable the entire hoisting block can be raised and lowered. A rotatable drum is mounted on the block and a load cable is windable on the drum and has one end fixed thereto, While at its free end the load cable has a hook or the like for fastening the load cable to a load. A means coacts with this drum for applying to the latter a constant torque which is just sufficient to maintain the load cable taut, so that there can be no slack in the load cable. A separable and independently controllable pawl means is constructed and arranged to arrest the rotation of the drum during the time that the load hangs on the load cable, and the means which controls the pawl means can be actuated at any desired time.

This invention relates to a novel hoisting block apparatus, and more particularly to a pulley block depending from a hoisting cable which moves up and down when in operation, together with accessory apparatus.

The invention provides a hoisting block apparatus particularly adapted for use with a crane on a stationary load site or a drilling platform in the loading and unloading of cargo upon a ship at anchor on a body of turbulent water.

When the cargo upon a ship anchored on turbulent water has been secured to the hoisting cable of a hoisting crane upon a substantially immovable base, there are times when the upward and downward movement of the ship causes it to sink beneath the load secured to the cable. When the ship subsequently rises, the ship will cause the cargo mounted on its decks to rise and thus cause the hoisting cable connected to the crane of the stationary platform to slacken. When the ship sinks into a wave trough, the load will lift olf the deck with a jerk which will cause substantial stresses in the cable and which will cause the cargo to lift and swing freely above the deck. This action continues until the stationary hoisting crane raises the cargo to such a height that the ship, when raised on a wave crest, is no longer in contact with the cargo.

In loading and unloading the cargo of a ship anchored on turbulent water with a crane upon a stationary platform, it is often found that the cargo is damaged by being repeatedly bumped against the ships deck, and often packing cases are smashed and their contents are scattered over the deck, and even the open sea. Often when the cable slackens, due to the rising of the ship, the cargo hook slips ofi its yoke and becomes disconnected from the cargo. Thus, because of the above mentioned difiiculties, the loading and unloading of cargo upon or from a ship from or to a stationary platform can only proceed satisfactorily under calm sea conditions. This seriously restricts the number of days in which the transfer of the cargo can take place.

3,365,075 Patented Jan. 23, 1968 Therefore, it is an object of the present invention to solve these hazardous problems by providing a hoisting block and crane apparatus which will compensate for the pitch and roll of an anchored vessel delivering cargo to or receiving cargo from a stationary platform.

It is another object of the present invention to provide an improved hoisting apparatus capable of permitting the loading and unloading of cargo during all types of sea and weather conditions.

It is also an object of the invention to provide means to enable the cable operator to observe the movement exerted on the cable by the ship riding up and down on a wave crest and wave trough.

According to the present invention, the cargo hook is not secured directly to the hoisting cable, as is usually the case. On the contrary, the hook is secured to a cargo cable wound about a freely rotatable drum and having one end fixed thereto. Means are provided which exert a moment on this drum in such a direction that it winds the cable around the drum. In addition, a pawl is provided for arresting rotation of the drum. The moment which acts on the drum, is smaller than the moment which the cargo exerts on the drum through its connecting cable, but this moment is greater than the moment exerted by the unloaded cargo cable and the load book so that tension is automatically maintained in the cable when the ship rises and the cable tends to slacken. Thus, when the hoisting cable of the stationary hoisting crane is connected through the cargo hook to the cargo on the deck of the ship and the ship rises, the cable will slacken and the drum will take up the slack of the cable. When the ship begins to sink into a wave trough, the arresting pawl will prevent the drum from returning to its original position. The means providing the moment to the rotatable drum may be in the form of a coiled or windable spring having one end coupled to the drum and the other end coupled to a stationary support. In this manner it is possible to maintain the hoisting cable under constant tension despite the movement of the ship with respect to a stationary platform. In addition, the position of the pawl may be sensed in that its upward position away from its corresponding ratchet may be detected when the cable drum is taking up the slack of the cable when the ship rises on a wave crest. A means may also be provided to maintain the pawl against the corresponding ratchel wheel so that the drum will not slip during the time when the ship rises on the wave crest and then suddenly drops into a wave trough.

-It is also possible to maintain constant tension in the hoisting cable by providing the drum with a non-linear spring which compensates and corrects for the amount of moment corresponding to the amount of length of cable which is payed out to the ship. In addition, a motor drive frictional'ly coupled to the driving axis of the drum is provided along with a corresponding brake disc coupled to the drum to selectively lock the drum from rotation.

A constant tensile force in the operation cable may be obtained according to the invention by various means. For example, a weight may be connected to the cable and the movement of the weight with respect to the up and down movement of the ship may be observed or indicated. For this operation a cable clamp may be employed for temporarily arresting the movement of the cable during the motion of the ship.

A preferred embodiment of the invention provides a means for maintaining a constant tensile force in the hoisting cable connected to the stationary crane and a means for temporarily arresting the cable coupled to the cable winding drum, said means consisting of a slip coupling and a brake acting on this drum. The slip coupling and brake devices may be constructed in all kinds of manners. The pawl may be a slidable or rotatable pawl. The hoisting box may also include a number of pulleys for guiding the hoisting cable to and from the drum in accordance with the upward and downward movement of the ship.

The invention will be more easily understood from the following specification, taken with the accompanying drawings wherein:

FIG. 1 is a side view, partly in section and partly broken away, of an apparatus constructed and arranged according to the invention, one outer plate of the hoisting block being removed to show its interior, the view being taken on the line I-I of FIG. 2;

FIG. 2 is a vertical cross section of FIG. 1 taken on the line 11-11 of FIG. 1;

FIG. 3 is a side view similar to that shown in FIG. 1 showing a hoisting block having a different type of pawl, the view being taken along the line III-III of FIG. 4; and

FIG. 4 is an elevation of the hoisting block shown in FIG. 3 as viewed from the left of FIG. 3.

Referring now to FIG. 1, there is shown an upper end of a stationary crane arm 1 having one or more cable wheels 2 for a hoisting cable 3. The hoisting block cornprises two outer plates 4, one of these plates being removed in FIG. 1 to show the interior of the hoisting block. Spacing bolts 5 are shown, which connect the outer plates in four places. Axially connected to the central portion of outer plates 4 is a shaft 6 having a pair of cable pulleys 7 for the hoisting of cable 3.

Slidable between vertical guide flanges 12 fixed to one or both outer plates 4 are a pair of vertical movable pawl supports as slidable pawl plates 8 spaced apart by spacing bolts 10, 10', 10" and 10" and respectively positioned between the outer plates 4 and the cable pulleys 7. See FIG. 2. A vertical aperture 13 in each pawl plate permits it to slide with respect to the shaft 6. At the lower edge of each of pawl plates 8 is a pawl tooth 9' formed by a notched or cutaway portion at the base of said pawl plate. A tensile spring 14 is also provided coupled to plates 8 at one end and an adjustable screw 14 at the other end in order to bias the sliding plates upwardly toward crane arm 1. The spring coupling 14 to plates 8 is made through bolt connection 10' and to screw 14 through spacer bolt 5'.

Between the outer plates 4 and beneath pawl plates 8 is drum 15 axially mounted on shaft 16 and freely rotatable thereon. Shaft 16 is secured transversely to outer plates 4. At the ends of drum 15 and between outer plates 4 are secured a pair of ratchet wheels 17 adapted to engage pawls 9 of slidable plates 8.

In the embodiment illustrated in FIGS. 1 and 2, hoisting cable 3 extends from a hoisting winch (not shown), and runs around cable wheel 2, thence around cable pulley 7 secured within the hoisting block, and has its end fastened to spacing bolt 10" secured to pawl plates 8. In addition, a load cable 18 has one end attached to the load hook 19, is wound around drum 15 and has its other end secured to an eye 21 in ratchet wheel 17. Moreover, an operating cable has one end also secured to drum 15 at an eye 22 thereof, and extends therefrom around a cable pulley 23. Cable pulley 23 is rotatably on spacing bolt 10" secured to pawl plates 8. Thence operating cable 20 runs around a pulley 24 which is journalled at one end of a vertical arm 33a of a bell crank lever 33 rotatable about a pin 34 secured between outer plates 4. Thence the operating cable passes around a pulley 25 rotatable about a shaft extending between the outer plates 4 inwardly of the pin 34. From the pulley 25, the operating cable extends vertically and over a pulley 26 which is rotatably carried by the crane arm 1. Thence the operating cable 20 extends downwardly at an. angle to a control apparatus for the operating cable.

This control apparatus comprises a winding drum 27 upon which cable 20 may be wound. A motor 28 is coupled through slip coupling 29 to drum 27 and may be set to transmit only a predetermined amount of rotational force to drum 27. The apparatus also includes a brake disc 30 for applying a braking force to drum 2'7 and opcrable by a handle 31. In the operation of said apparatus, motor 28 maintains a predetermined tensile force on operating cable 26 by a proper adjustment of slip coupling 29.

It is obvious that motor 28 may employ a constant coupling apparatus or device in which slip coupling 29 is thus not necessary. Operating cable 21 which is looped around cable pulley 24, is also shown coupled to an indicating pointer 32 intermediate between a pair of idler pulleys, and the pointer can indicate to the crane operator, the up and down movements of the operating cable during operation of the hoisting winch 27.-

Referring again in detail to the apparatus of FIG. 1, it is noted that the horizontal arm 33!: of hell crank lever 33 is inserted into a recess 35 cut into one of the pawl plates 8. Thus if tension occurs in the operating cable 20, this will cause pulley 24 to be drawn toward the center of the hoisting block. The bell crank lever 33, due to the tension in cable 20 acting on the pulley 24 connected to its vertical arm 33a, causes horizontal arm 33b inserted in recess 35, to move both pawl plates 8 in a downward direction.

In the position of the apparatus as shown in FIG. 1 there is no load on hoisting hook 19. Brake 31 is released and motor 28 runs free thereof. In this position, the end of hoisting cable 3 secured to spacing bolt 10" on the sliding pawl plates tends to push these plates downward. Furthermore, as a result of the constant pull on the operating cable 20, lever 33 also tends to push pawl plates 8 downward. Tension spring 14, however, exercises a sufliciently strong bias so that pawl plates 8 are nevertheless kept in their highest or neutral position.

When a load is to be transferred from a ship moving up and down in the sea to a fixed or stationary platform, the crane operator lowers the hoisting block by swinging out hoisting cable 3 over the ship. Operating cable 20 then unwinds from drum 27. while slip coupling 29 maintains a constant tensile force on operating cable 26. Load hook 19 is then pulled down by hand and secured to cargo load with load cable 18 in a low tension position. Then hoisting cable 3 is carefully wound up. When load cable 18 is constantly stretched by a tensile force, the hoisting winch is stopped. Thus as the ship, with the cargo still on its deck, moves downward, load cable 18 unwinds from freely rotatable drum 15, which at the same time winds up operating cable 20 and draws it from drum 27. The movement of the ship can be observed by the crane operator from indicator 32. As the ship moves up and down with the cargo coupled to hook 19, indicator 32 will swing to the left and then to the right. The deflection of indicator 32 is a measure of the distance to which hook 19 coupled to the hoisting block moves. The crane operator will have to reel in hoisting cable 3 sufficiently so that indicator 32 swings constantly to the left and to the right. This will indicate that load cable 18 is constantly stretched.

When the ship having the cargo on its deck floats on a wave crest so that the cargo is at its highest position, the crane operator executes the following three actions.

(a) Brake 31 is set. (b) The hoisting cable 3 is pulled up. (0) The brake is released.

(a) When the load goes down with the ship as the ship enters into a wave trough, load cable 18 will cause drum 15 to rotate slightly and thus simultaneously wind up operation cable 20 also wound around drum 15. However, operating cable 20 is locked by brake 31. Thus operating cable 20 experiences a severe tensile force and causes that portion of the cable between pulleys 23, 24 and 25 to straighten. This forces pulley 24 to move inward toward shaft 6 and turn bell crank lever 33. This will cause horizontal lever arm 33b, which is positioned in recess 35 of sliding plates 8, to force the plates downward against the force of retaining spring 14. Pawl 9 then comes into engagement with ratchet wheel 17 so as to prevent any further rotation of drum 15. This simultaneously locks cable 18 and prevents the cargo suspended on hook 19 from any further movement either up or downward.

(b) The crane operator then :begins winding up hoisting cable 3 which simultaneously lifts the cargo further from the deck of the ship, since the novel hoisting block is supported by cable 3. Operating cable 20 then becomes slack. However, brake 31 still prevents cable 20 from being wound upon drum 27. Operating cable 20 is no longer subjected to tension since pawls 9 cannot slip from ratchet 17. Since hoisting cable 3, in which a greater tension force has now developed, pulls upward upon the shaft 6, the cable pulley 7 and the outer plates 8, because its terminal end is secured to the spacing bolt it maintains the pawl plates in a downward position against the force of tension spring 14.

(c) When the crane operator releases brake 31 operating cable 20 becomes wound up on drum 27 due to the winding action of motor 28 and becomes stretched in tension once again so that it does not become entangled with the other parts of the apparatus.

When the cargo is transferred from a stationary platform to a ship moving upward and downward in the sea, the hoisting block is positioned so that pawls 9 engage ratchet wheels 17 so as to temporarily arrest the motion of operating cable 20. In addition, brake 31 is released when the cargo is suspended from the crane. Pawls 9 remain engaged with ratchet wheels 17 due to the tension force of hoisting cable 3. The cargo is then swung out to a position immediately above the ship and carefully lowered. During this operation, indicator 32 remains pointing in the same direction. As soon as the moving ship comes in contact with the cargo and momentarily releases the tension on load cable 18 and hoisting cable 3, pawl plates 8 are drawn up by spring 14 and release drum is free to rotate. Load cable 18 can then once again be wound or unwound upon drum 15 and a constant tensile force can be maintained on operating cable 20.

In FIG. 1, there is shown a pull rope 40 secured to the horizontal arm 33]) of the bell crank lever and hanging downwardly therefrom. This makes it possible for an operator on the ship to operate the apparatus by pulling down rope 40 at the moment he deems the position of the ship favourable. In this particular operation, brake 31 and indicator 32 for cable are not necessary. It is also possible that pull rope 40 may be secured directly to the pawl.

As indicated earlier in the specification, 'by securing the end of hoisting cable 3 through bolts 10" of slidable pawl plates 8 insures that pawls 9 will not slip from ratchet wheel 17. It is also possible to obtain this effect by constructing the pawl teeth 17 in the shape of hooks and designing pawls 9 so that they protrude sufficiently to slide into these hooks.

It is also possible to construct the hoisting block in such fashion that the free end of the lever arm 33b is the pawl engaging the ratchet wheel 17. Instead of the tensile spring 14 there is a spring drawing upwardly the horizontal arm 33b of the bell crank lever 33. The end of the hoisting cable 3 can then be connected to the lever arm 33a. The slidable pawl plates 8 may then be omitted. A construction embodying this idea is illustrated in FIGS. 3 and 4.

Referring to the embodiments illustrated in FIGS. 3 and 4, there is shown a hoisting block having a pair of side plates 4 coupled together by spacing bolts 5 in a manner similar to the embodiment shown in FIGS. 1 and 2. Around shaft 16 supported by side plates 4 is a freely rotatable drum 15 having several turns of load cable 18 wrapped therearound with its end fastened to the drum as at 21. The operating cable 21 is also wound about the drum 15 to which it is secured as at 22. At each of the ends of drum 15 within side plates 4 there is secured a ratchet wheel 17 adapted to be engaged by pawls 9. A biasing spring 14 coupled to a U-shaped pawl support 41 which carries pawls 9 biases the pawl support and the pawls out of engagement with ratchet wheels 17.

This embodiment of the hoisting apparatus differs from the first embodiment in that pawls 9 are integrally part of the U-shaped pawl support and can oscillate about a shaft 42 supported by side plates 4. Biasing spring 14 in this case has one end coupled to a tension adjusting screw 14' secured to through spacing bolt 5'. The other end of spring 14 is coupled through eyelet 43 along a transverse portion of the U-shaped pawl support.

Adjacent to eyelet 43 on the support is an eyelet 44 to which one end of hoisting cable 3 is secured. Hoisting cable 3 is further guided around pulleys 45 and 46, extending upwardly from the latter pulley and being guided over cable wheel 2 on crane arm 1, as illustrated in the embodiment shown in FIG. 1. Pulley 45 is contained and supported within pawl support 41 and is also rotatable around the shaft 42 about which the pawl support oscillates. The pulley 46 is rotatable between the outer plates 4 of the hoisting block upon an axle carried thereby. I1 is further noted that a spacing bolt 47 is positioned at the open end of the U-shaped pawl support 41 to stiffen that member without interfering with the other elements of the hoisting block, and for a purpose which will presently appear.

Near the open end of the pawl support 41, two similarly shaped plates 48are disposed between the outer plates 4 and spaced apart by spacing bolts 50' and 51. The plates 48 are thus held together as a unit. A shaft 49 passes through both similarly shaped plates 48 and to the outer plates 4, by which it is supported. The unit formed by the similarly shaped plates may be oscillated about the shaft 49, and is so formed that it will make contact, upon clockwise oscillation, as viewed in FIG. 3, with the spacing bolt 47 at the open end of the pawl support 41 to turn the latter in a counterclockwise direction as viewed in FIG. 1, about its shaft 42.

The rope 4G is attached to spacing bolt 51 in order to turn the similarly shaped plates 48 in clockwise direction as viewed in FIG. 3.

Pulleys 52 and 53 are rotatably mounted on the shaft 49 and the spacing bolt 50, respectively; and a guiding pulley 54 is rotatably mounted between the outer plates 4 of the hoisting block above the spacing bolt 47 at the open end of the U-shaped pawl support 41. The operating cable 20 passes from the freely rotating drum 15 to the pulley 53 around which it is looped, thence around the pulley 52, then in contact with the inner side of the guiding pulley 54, from which it passes vertically over the pulley 26 which is rotatably carried by the crane arm 1 (FIG. 1) and thence downwardly at an angle to its control apparatus. Thus, tension upon the operating cable 20 causes the spacing bolt 50 to swing the similar plates 48 in a clockwise direction about the shaft 49. The similar plates are positioned so near to the spacing bolt 47 that a slight clockwise movement of these plates will cause them to bear upon this spacing bolt and to rotate the pawl support 41 about the shaft 42 in counterclockwise direction, thereby causing the pawls 9 to engage the teeth of the ratchet wheel 17. The tension spring 14 is thereby elongated.

The similar plates may clearly be similarly rotated by pulling the rope 40.

It will be noted that arcuate plates 55 are shown surrounding a large portion of the perepheries of the ratchet wheels 17. These plates surround the ratchet wheels so closely that the cables 18 and 20 cannot be engaged by the ratchet teeth.

What we claim is:

1. A hoisting block apparatus adapted to be raised and lowered from a hoisting crane, comprising a hoisting block, hoisting cable means fastened to said block and adapted to be connected with the crane for hoisting the block upwardly to the crane and lowering the block downwardly away from the crane, a freely rotatable drum rotatably mounted in said block, a load cable windable upon said drum and having one end fixed to said drum,

said load cable having a means for fastening the latter to a load, means for applying a constant torque to said drum to wind said load cable thereupon and to apply to said load cable a tension only sufiiciently great to eliminate slack therefrom, separable pawl means constructed and arranged to arrest rotation of said drum and control means coacting with said pawl means for actuating the latter at any desired time to arrest rotation of said drum.

2. A hoisting block apparatus as claimed in claim 1, wherein said means for applying a constant torque to said drum is an operating cable also windable upon said drum and having one end fixed to said drum, and means operatively connected with the other end of said operating cable for applying a constant tension thereto.

3. A hoisting block apparatus as claimed in claim 2, wherein said separable pawl means comprises a ratchet wheel rotatably mounted in said hoisting block and fixed to said drum, and a pawl support member mounted for oscillation within said hoisting block, spring means biasing said pawl support member to situate the latter out of engagement with said ratchet wheel, and said control means including an actuating member for the spring biased pawl support member to displace the latter into engagement with said ratchet wheel, said actuating member being mounted for oscillation on said block.

4. A hoisting block apparatus comprising a hoisting block, a freely rotatable drum rotatably mounted in said block, a load cable windable upon said drum and having one end fixed to said drum, means for applying a constant torque to said drum to wind said load cable thereupon, and separable pawl means constructed and arranged to arrest rotation of said drum, said means for applying a constant torque to said drum being an operating cable also windable upon said drum and having one end fixed to said drum, and said separable pawl means comprising a ratchet wheel rotatably mounted in said hoisting block, and a pawl support member mounted for oscillation within said hoisting block, said pawl support member being spring biased with its pawl out of engagement with said ratchet wheel, and being moved into engagement with said ratchet wheel by tension of said operating cable.

5. A hoisting block for use with a crane having a load cable, said hoisting block comprising a freely rotating drum having the load cable of said crane wrapped therearound, means for providing a constant torque on said drum, and pawl means for arresting the motion of said rum in a direction opposite to the winding up of the load cable, a plurality of pulleys supported transversely in said block, an operating cable being looped around said pulleys, a displacement means, one of said pulleys being coupled to said displacement means, a pawl coupled to said displacement means, a ratchet wheel coupled to said freely rotating drum and adapted to engage said pawl, and spring biasing means maintaining said pawl out of engagement with said ratchet wheel when the tension in said operating cable decreases to predetermined tension, and means for holding said freely rotating drum when the tension in said operating cable increases, said displacement means urging said pawl against the tension of said spring bias.

6. A hoisting block apparatus as claimed in claim 3, wherein a rope has its upper end fixed to pawl support engaging means and depends freely from the hoisting block, whereby a downward pull upon said rope effects engagement between said pawl means and said ratchet wheel.

7. The hoisting block as recited in claim 5, additionally comprising indicator means for determining the tension of said load cable.

8. The hoisting block as recited in claim 7, additionally comprising a hoisting cable secured to the hoisting crane, said hoisting cable maintaining tension against said displacement means in order to maintain said pawl in engagement with said ratchet wheel when tension is applied to said load cable.

9. The hoisting block as recited in claim 8, additionally comprising means for maintaining a constant tensile force on said operating cable, and means for arresting the motion of said winding drum in order to prevent the backward movement of said operating cable.

10. The hoisting block as recited in claim 9, additionally comprising a depending cable secured to said pawl, said pawl being responsive to the downward motion of said depending cable for releasing said pawl from said ratchet wheel drive so as to permit said operating cable to move freely on said rotating drum.

References Cited UNITED STATES PATENTS 2,670,177 2/1954 Pearson 254184 FOREIGN PATENTS 85,758 6/ 1955 Norway.

H. C. HORNSBY, Assistant Examiner.

EVON C. BLUNK, Primary Examiner.

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