A HEAVY-DUTY FORE-AND-AFT WORKING SHIP'S CRANE

Abstract: The primary jib (9) of the crane is supported, at its upper end (10), by first and second jib control lines (17 and 19) extending to the upper end (10) of the primary jib (9) from first and second parts (6 and 7) of a cross-member (5) extending laterally of a supporting mast (3). The first jib control line (16) also extends from the upper end (10) of the primary jib (9) to a base (1). The second jib control line (18) has no such extension. Adequate support is provided because the second part (7) is spaced further than the first part (6) from an intermediate reference point (8) cross-member (5) disposed above the pivotally supported lower end (11) of the primary jib (9). The first part (6) of the cross-member (5) and said reference point (8) are disposed on the same side of the mast (3) and so the primary jib (9) can be swung around the mast (3).

Description: A Heavy-duty Fore-and-Aft Working Ship's Crane • TECHNICAL FIELD OF THE INVENTION The invention relates to a ship's crane which is capable of servicing fore-and-aft holds, between which it is situated, having a single mast or derrick, a single jib, and rigging which enables the jib to be moved rapidly and easily between opposite sides of the mast, for servicing the different holds . BACKGROUND ART One known form of ship's crane, suitable for this purpose, comprises a base; universal pivot means mounted on the base; a mast upstanding from the base and having an upper end; a cross-member supported by and extending laterally of the mast and having first and second parts which lie on opposite sides of a reference point on the cross-member directly above the universal pivot means, with the first part lying on the opposite side of the reference point to the mast; a primary jib having an upper end and lower end supported by the universal pivot means for universal pivotal movement of the primary jib relative to the base; hoisting pulley means at the upper end of the primary jib; a hoisting line which extends from the upper end of the mast or the cross-member to the upper end- of the primary jib and is trained over the hoisting pulley means; control pulley means supported by the upper end of the primary jib; a first jib control line extending from the first part of the cross-member to the control pulley means, around the control pulley means and down to anchorage means, on the base, which are disposed on the same side of the universal pivot means as the first part of the cross-member; and a second jib control line extending from the second part of the cross-member to the upper end of the primary jib, above the first jib control line extending from the first part (6) of the cross-member (5) to the upper end of the primary jib. " With this form of construction, the first and second parts of the cross-member are equally spaced on opposit sides of the reference point on the cross member dis¬ posed directly above the universal pivot means and the second jib control line is also trained around control pulley means at the upper end of the primary jib so as to extend downwardly to releasable anchorage means, pn the base, which are disposed on the same side of the universal pivot means as the second part of the cross- member so as to provide the primary jib with the same lateral support when it is equally inclined on opposite sides of the longitudinal axis of the ship. However, when it is desired to swing the primary jib from one side of the cross-member to the other, when changing over between fore and aft holds, it is necessary to disconnect the second jib control line from the releas- able anchorage means and then to carry the free end of the second jib control line around the other side of the mast, in the same direction of movement as the jib swings around the mast, and then to reconnect the free end of the second jib control line to the releasable anchorage means. This is a time consum ng operation an for heavy duty cranes capable of lifting heavy loads of around 100 tonnes, the rigging of the first and second jib control lines is complicated and heavy so that the readjustment of the second jib control line is very laborious and must De carried out with painstaking care in order to avoid disarrangement of the rigging. The Stulken crane, produced by Blom and Voss in Germany was designed to overcome these deficiencies. In cranes of this construction, the jib is pivotally mounted between two laterally spaced masts and jib control lines extend from the upper end of the jib to the upper ends of the two masts. Thus, in order to change over between working fore and aft holds, it is merely necessary to swing the jib between the two masts into its required new position. This construction of crane works quite satisfactorily, but obviously is very heavy and costly as a result of the requirement of two masts. Moreover, to facilitate rapid handling of lighter cargo fore and aft of this crane, lighter duty jibs are mounted on or adjacent both sides of both masts and both jibs on each side of the masts are provided with separate hoisting lines which are connected at their load engaging ends to provide a "union purchase" crane because the rigging for this type of crane can be easily dismounted so as to avoid foulding the rigging of the heavy duty jib when this • is required once more. DISCLOSURE. OF THE INVENTION It is an object of the present invention to provide a heavy-duty fore-and-aft working ship's crane which can be rapidly and easily changed over between fore and aft holds without the necessity or laborious , time consum¬ ing and difficult rearrangement of the rigging, but without having to resort to the provision of two lat- erally spaced masts. It is a further, subsidiary object of the invention to provide a crane such as this which is so desired as to be capable of speedy and easily effected conversion from heavy duty operation to lighter duty operation without having to rely on the use of "union-purchase" rigging of four lighter duty jibs. According to the invention, the known heavy-duty fore- and-aft working ship's crane, having a single mast, is modified so as to ensure that the lateral distance between the second part of the cross-member and the reference point on the cross-member, directly above the universal pivot means, is greater than the lateral distance between this reference point on the cross- member and by arranging the rigging so that the second jib control line has no extension from the upper end of the primary jib to the base. Thus, according to the invention, there is provided a heavy-duty fore-and-aft working ship's crane comprising a base; universal pivot means mounted on the base; a cross-member supported by and extending laterally of th mast; a primary jib pivotally supported on one side of the mast by universal pivot means on the base for universal pivotal movement relative to the base ; a firs jib control line extending from a first part of said cross-member, on the same side of the mast as the universal pivot means, to control pulley means at the _ upper end of the jib, around the control pulley means and down to anchorage means, on the base, disposed on. the same side of the universal pivot means as the first part of the cross-member; and a second jib control line extending from a second part of the cross-member, on th opposite side of a reference point on the cross-member, directly above the universal pivot means, to the first part of the cross-member, to the upper end of the primary jib, above the first jib control line extending from the first part of the cross-member to the upper end of the primary jib; the lateral distance between said reference point on the cross-member and the second part of the cross-member being greater than the lateral distance between the reference point and the first part of the cross-member. When using this form of crane construction, during heav duty working of fore and aft holds, on opposite sides o the cross-member, the first and second jib control lines are capable of supporting the primary jib on both sides of the cross-member. The lateral support for the primary jib provided by the first jib control line results from the fact that the first jib control line extends from the control pulley means at the upper end of the primary . jib to the first part of the cross-member and to anchorage means, on the base, disposed on the same side of the universal pivot means as the first part of the cross- member. Conversely, although the second jib control line has no extension from the upper end of the primary jib to the base, the second jib control line provides adequate lateral support for the primary jib because it extends from the second part of the cross-member which is lat- erally spaced from the reference point on the cross-member by a greater distance from the first part of the cross- member, on the opposite side of the reference point. Moreover, when it is desired to swing the primary jib from a position on one side of the cross-member to a position on the other side of the cross-member, to change between the working of fore and aft holds, the primary jib can simply be swung around the same side of the mast as the anchorage means. As there is no extension of the second control line from the upper end of the primary jib to the base, on the opposite side of the mast to the anchorage means, it is not necessary to release the second control line from the base and to carry it around the mast, in the same direction of movement as the jib, and then to re-fasten it to the base, as in prior art con- structions. This facilitates and expedites change-over, saving much time and effort. Because the primary jib must always move around the mast , from one side of the cross-member to the other, on the same side of the universal pivot means as the • anchorage means, the first jib control line extending between the . first part of the cross-member and the upper end of the primary jib must be below the second jib control line extending between the second part of the cross-member and the upper end of the primary jib. This ensures that the first jib control line cannot foul the second jib control line. The second part of the cross-member may therefore be dispose above the first part of the cross-member. In addition to the foregoing advantages of the present invention, the primary jib can be rapidly and easily stowed by nesting it against the end of the cross-member on the same side of the universal pivot means as the anchorage means, as in prior art constructions. However, with cranes constructed in accordance with the present invention, two lighter duty, • secondary jibs can be pivot- ally mounted on or above the base , on opposite sides of the cross-member; hoisting means, including two further hoisting lines, may be provided, respectively, for co-operation with these secondary jibs; and these second- ' ary jibs can be controlled by two sets of further control lines extending from the two secondary jibs to the upper end of the mast or to the cross-member for working holds on opposite sides of the cross-member without interfering with the stowed primary jib or with the first and second jib control lines of the stowed primary jib. It is therefore possible to ef ect rapid and easy change-over between heavy duty and light duty working and to carry out light duty work on fore and aft holds without having to rely on "union-purchase" rigging. In practice, the distances between the reference point on the cross-member, directly above the universal pivot means, and the first and second parts of the cross-member on opposite sides of this reference point, depend on the dimensions of the base, mast and jib and also on the loading to be carried by the crane. For a 100 tonne crane having a mast height of 12 metres and a jib length of 20 metres the distance between the first and second parts of the cross-member should be approximately 8 metres, the reference point on the cross-member, directly above the universal pivot means, dividing this distance in the ratio 1 : 3 so that the first and second parts of the cross-member are spaced, respectively, 2 metres and 6 metres from the reference point on the cross-member. The cross-member must be positioned on the mast so that the cross-member is attached to the mast at or adjacent the second part of the cross-member so as to allow the primary jib to swing underneath the first part of the cross-member. This means that the mast can be spaced sufficiently far away from the universal pivot means to allow the primary jib to swing towards the mast through relatively large angles , typically of the order of 6 " degrees from the fore-and-aft axis. When the primary jib extends laterally of the mast, on the same side of the mast as the anchorage means, the first and second jib control lines between the cross- member and the primary jib are aligned with each other, along the cross-member, and so are imcapable of exercis¬ ing any control on slewing movement of the primary jib. Thus, there is no particular advantage in fixing the anchorage means laterally of the mast. The anchorage means may therefore be movable between positions on opposite sides of the cross-member at which the first and second jib control lines can exercise effective control of slewing movement of the primary jib. This further facilitates movement of the primary jib from one side of the cross-member to the other. In one preferred form of construction incorporating this feature, a radius arm is pivotally mounted on the base at a. pivotal point disposed laterally of the mast and mid-way between the two desire positions of the anchorage means on opposite sides of th cross-member; the anchorage means are mounted on the radius arm, spaced from the pivotal point; and releasabl locking means are provided for securing the radius arm to the base so that the anchorage means are held, alter¬ natively, in either of the two desired positions on opposite sides of the cross-member. In order to reduce bending stresses in the upper end of the primary jib, a carrier member may be pivotally mount at the upper end of the primary jib, and may be arranged so as to support the hoisting pulley means, the control pulley means and connector means for supporting the second jib control line extending between the second part of the cross-member and the upper end of the primar jib. By this means, transverse loading on the upper end of the primary jib is concentrated at the first point.- Where the first control line is rigged to provide a plural-part purchase extending between the first part of the cross-member and the upper end of the primary jib an a part of the control pulley means is supported at the upper end of the primary jib for co-operation with this plural-part purchase, the reduction in bending stresses imposed on the upper end of the primary jib by the use of the pivotally mounted carrier member may be enhanced by supporting this part of the control pulley means on the carrier member. An embodiment of the invention is hereinafter described, by way of example, with reference to the accompanying drawin s. [ BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an elevational view of a heavy-duty fore- and-aft working ship's crane, according to the inven¬ tion, during adjustment; Figures 2, 3 and 4 are schematic plan views of the crane shown in Figure 1, showing the crane adjusted for heavy- duty working of fore and aft holds; Figure 5 is a schematic elevational view of the crane shown in Figures 1 to , adjusted for light-duty work¬ ing; and Figure 6 is a schematic plan view of the crane, adjusted for light-duty working of fore and aft holds, as shown in Figure 5• BEST MODES FOR CARRYING OUT THE INVENTION As shown in Figure 1, universal pivot means 2, for a heavy-duty, primary jib 9, are mounted on a base 1 provided by the deck of a ship. A mast 3 projects from the base.l, and, at its upper end 4, supports a cross- member so that a reference point 8 on the cross- member 5 lies directly above the universal pivot means 2. A carrier member 3 1 is pivotally supported on a swivel pin 33 at the upper end 10 of the primary jib 9 and the lower end 11 of the primary jib 9 s pivotally supported by the universal pivot means 2. A first jib control line 17 extends from a first topping and slewing winch 34, mounted on the base 1, over a guide pulley 35 at the upper end 4 of the mast 3, over upper and lower guide pulleys 36 and 37 supported at a first part 6 of the cross-member 5 to a pulley block 15 supported by the carrier member 3*» ^ L Three reaches of the line lβ extend between the pulley block 15 and a further pulley block 38 supported at the first part 6 of the cross-member 5 and pass around contr pulley 16 supported on one side of the upper end 10 of 5 the primary jib 9 and down to a pulley 39 supported on anchorage means 18 supported on a radius arm 28 for attachment to the base 1. The line 17 then passes aroun the pulley 39 . U P "to a pulley 40 supported at the upper end 10 of the primary jib 9, around pulley 40 and back 10 to an attachment point on anchorage means 18. A second jib control line 19 extends from a second toppi and slewing winch 4l, over a pulley block 42 supported a a second part 7 of the cross-member 5, over a pulley on the pulley block 42 to a pulley block 43 supported on 15 the carrier member 3 1 * This line 19 passes around a pulley on the pulley block 3, back to a pulley block 44 supported at the second ' part 7 of the cross-member 5, " around a pulley on pulley block 44 and back to a point o attachment on the pulley block 43.' 20. Topping of the primary jib 9 is ef ected by operating first and second topping and slewing winches 3^ and 4l together, winding-in together to raise the primary jib 9 or winding-out together to lower the primary jib 9 . As hereinafter described, slewing of the primary jib 9 is 25 effected by winding in one of the topping and slewing winches j h. and 4l and simultaneously winding out the oth Hoisting of a load hook 44 is effected by a hoisting winch 4 and a hoisting line 14. The hoisting line 14 extends from the hoisting winch 45 around a pulley in 30 pulley block 42 around hoisting pulleys 12 and 13 supported on the carrier member 3 1 . down to a pulley block 46 supporting the cargo hook 44. Three reaches of the hoisting line 14 extend between the pulley block 46 and a further pulley block.47 supported by the carrier o..:π member 31 . with the end of the hoisting line 14 attached, to the pulley block 7. As shown in Figure 1, the primary jib 9 extends laterally of the mast 3 between two working positions, fore and aft of the mast 3» A s shown, the pulley block 42 mounted on the second part 7 of the cross-member 5 is supported at a higher level than the upper guide pulley 37 mounted on the first part 6 of the cross-member 5 and the guide pulley 12 for the hoisting line 14 is supported by the carrier member ^ 1 so that the hoisting line 14 extending between the pulley block 42 and the pulley 12 lies above the reaches of the first and second jib control lines 17 and 19 extending between the cross-member and the upper end 10 of the primary jib 9« Similarly, the pulley block 15 and the pulley 16 are supported so that the reaches of the first jib control line 17 extending between the first part 6 of the cross-member 5 and the upper end 10 of the primary jib 9 lie below the reaches of the second jib control line 19 extending between the second part 7 of the cross-member 5 and the upper end 10 of the primary jib 9« In this configuration, the radius arm 28 is pivotally mounted on the base 1 by brackets 48, but its free end is released from the base 1 so as to allow the radius arm 28 to extend perpendicularly from the base 1. As shown, the anchorage means 18 comprise a linkage connecting pulley 39 to a swivel 49 rotatably mounted in jaws 50 at the outer end of the radius arm 28. As shown in Figures 2, 3 and 4, the universal pivot means 2 are mounted on the c,entre line 51 of the deck 1 of a ship 52 between fore and aft holds 53 and 54. As shown in Figures 2 and 3,- when the primary jib 9 is adjusted for working the fore hold 53 , the radius arm 28 extends forwardly of the brackets 49 and is held against the deck 1 by a shear pin 30 which is received in holes formed in OiV-PI a first pair of jaws 55 attached to the base 1. A second pair of similar jaws 5 are also mounted on the base 1 for receiving a second shear pin 3 "fco hold the radius arm 28 flat on the base 1, when the radius arm « 28 extends aft, as shown in Figure 4. Slewing movement of the primary jib 9, between the positions shown in Figures 2 and 3 is effected by windin topping and slewing winches 3^ and 4l in opposite directions. Thus, when moving the primary jib 9 from the position shown in Figure 2 to the position shown in Figure 3, the topping and slewing winch 4l is unwound an the topping and slewing winch 34- is wound in so that the first jib control line 17 pulls the primary jib 9 in the required direction. As shown, this pulling is effected from the first part 6 of the cross-member 5 and from the anchorage means 18 which are held in their position 26. When moving the primary jib 9 from the position shown -■ in Figure 3 "to the position shown in Figure 2, the first topping and slewing winch 3^t i unwound and the second topping and slewing winch 4l is wound in so that the second jib control line 19 pulls the primary jib 9 in the required direction from the second part 7 of the cross-member 5» Although the second jib control line 19 has no reach extending from the upper end 10 of the primary jib 9 to the base 1, adequate control is effected during this movement as a result of the fact that the second part 7 is spaced by a larger distance 21 from " the reference point 8 on the cross-member ι above the universal pivot means 2, than the distance 20 between the first part 6 of the cross-member 5 and the reference point 8. As shown, the ratio of these distances 20 and 2 is 3 : 1. To move the primary jib 9 from the position shown in Figure 3 "to the position shown in Figure 4, the shear pins 30 are removed from the pairs of jaws 55, so as,-to--~ OMP release the radius arm 28 for pivotal movement about the brackets 49. The primary jib 9 is then pulled as far as possible in the required direction by means of the first jib control line 17 and then pulled through a position in which the primary jib 9 extends laterally of the mast 3 ? as shown in Figure 1, and into a position on the aft side of the cross-member 5 by pulling on the loading hook 44. The first jib control line 17 is then slackened so as to allow the radius arm 28 to be locked against the base 1, between the aft jaws and held in place by reinserting the shear pin 30. Thereafter, slewing movement " of the primary jib 9 is carried out in an analogous matter to that already described with reference to Figures 2 and 3. For simplification, the pulley 16 has been shown on opposite sides of the primary jib 9. However, as here- - inbefore described, it is actually permanently mounted,, on one side of the primary jib 9 * Although not shown in Figures 1 to 4, the crane is prov- ided with secondary jibs 22 for lighter duty working of the fore-and-aft holds 53 and 54. As shown in Figures 5 and 6, these secondary jibs 22 are mounted on universal pivot means 5 disposed fore and aft of the universal pivot means 2 for the primary jib 9. In order to change over from heavy-duty working to light-duty working, the primary jib 9 is pulled sideways from the position shown in Figure 1 so as to nest in a recess in the end of the cross-member 5, adjacent the first part 6 of the cross-member 5« One or both secondary jibs 22 are then raised from stowed positions on the base 1 and supported by further jib control lines 25 which are rigged, . respectively, on opposite sides of the cross-member 5 - Further hoisting means 23, respectively co-operable with the light-duty, secondary jibs 22 each include a hoisting winch and hoisting line 24 and jib control lines 25, on the fore and aft sides of the cross-member 5 re provided for supporting the secondary jibs 22. As shown in Figure 5, the hoisting and jib control lines co-operable with each secondary jib 22 are trained over pulleys supported on' the cross-member 5 and so these lines may be held clear of the lines rigged for the primary jib 9 when the secondary jibs 22 are stowed on the base 1. Although reference numerals have been used in the appended claims to improve the intelligibility of these claims, it is expressly stated that these reference numerals should not be construed as limiting the claims to the constructions illustrated in the accompanying drawings.

Claims: CLAIMS . 1. A heavy-duty fore-and-aft working ship's crane comprisin : a base (l) 5 universal pivot means (2) mounted on the base (l) ; a mast (3) upstanding from the base (l), to one side of the universal pivot means (2), and having an upper end (4); a cross-member (5) supported by and extending laterally of the mast (3) and having first and second parts (6 and 7) which lie on opposite sides of a reference point (8) on the cross-member (5) directly above the universal pivot- means (2), with the first part lying on the opposite side of the reference point to the mast; a primary jib (9) having an upper end ( 10) and a lower end (11) supported by the universal pivot means (2) for universal pivotal movement of the primary jib (9) relative to the base (1); hoisting pulley means (12 and 13) at the upper end (10) of the primary jib (9), hoisting line (l4) which extends from the upper end (4) of the mast (3). or the cross-member (5) to the upper end (lO) of the primary jib- (9) and is trained over the hoisting pulley means (12 and 13); control pulley means ( 15 and l6 ) supported by the upper end ( 10 ) of the primary jib ( 9 ) ; a first jib control line ( 17 ) extending from the first art ( 6 ) of the cross-member (5 ) to the control pulley means (15 and 16), around the control pulley means (15 and l6) and down to anchorage means ( 18) , on the base (l), which are disposed on the same side of the universal pivot means (2) as the first part (6) of the cross-member (5) . and a second jib control line (19) extending from the secon part (7) of the cross-member (5) to the upper end (10) o the primary jib (9), above the first jib control line (17) extending from the first part (6) of the cross- member (5) to the upper end (l) of the primary jib (9) . characterized in that : the lateral distance (20) between the reference point (8 on the cross-member (5) and the second part (7) of the cross-member (5) is greater than the lateral distance (21) between the reference point (8) on the cross- member (5) and the first part (6) of the cross-member (5) . and the second jib control line (19 ) has no extension from the upper end (10) of the primary jib (9) to the base (1) . 2. A ship's crane, according to Claim 1_, characterized in that :- two secondary jibs (22)., for lighter duty than the primary jib (9), are pivotally mounted on or above the base (1), on opposite sides of the cross-member ( ); hoisting means (23), including two further hoisting lines (24), are respectively provided for co-operation with the secondary jibs (22); and two sets of further control lines (25) extend, respect- C.-IPI ively, from the two secondary jibs (22) to the upper end (4) of the mast (3) or to the cross-member (5). 3. A ship's crane, according to Claim 1, characterized in that the anchorage means ( i8 ) on the base (l), are movable between two positions (26 and 27) on opposite sides of the cross-member (5). 4. A ship's crane, according to Claim 3, characterized in that : a radius arm (28) is pivotally mounted on the base (1) at a pivotal point (29) disposed laterally of the mast (3) and mid-way between said two positions (26 and 27) on opposite sides of the cross-member (5) . the anchorage means (18) are mounted on the radius arm (28), spaced from the pivotal point (29); and releasable locking means (30) are provided for securing the radius arm (28) to the base (1) so that the anchorage means (l8) are held, alternatively, in either of said two positions (26 and 27) on opposite sides of the cross- member (5). 5« A ship's crane, according to Claim 1, 2, 3 or 4, characterized in that : a carrier member (31) is pivotally mounted at the upper end (10) of the jib (9); the hoisting pulley means (12 and 13) and at least part (-'1 ) o£ the control pulley means (15 and l6 ) are supported by the carrier member (31); and connector means (32) for. supporting the second jib control line (19) extending between the second part (7) Jl OMPI of the cross-member (5) and the upper end (10) of the primary jib (9) from the upper end (10) of the primary jib (9) are mounted on the carrier member (31) 6. A ship's crane, according to Claim 5 . characterized in that : the first jib control line (17) is rigged to provide a plural-part purchase extending between the first part (6 of the cross-member (5) and the upper end (10) of the primary jib (9), and said part (15) of the control pulley means (15 and l6) supported by the carrier member (31) co-operates with said plural-part purchase. 7. In a heavy-duty fore-and-aft working ship's crane comprising: a base (1) ; universal pivot means (2) mounted on the base (1); a mast (3) upstanding from the base (l) , to one side of the universal pivot means (2), and having an upper end (4) ; a cross-member (5) supported by and extending laterally of the mast (3) and having first and second parts (6 and 7) which lie on opposite sides of a reference point (8) on the cross-member (4) directly above the universal pivot means' (2), with the first part (6) lying on the opposite side of the reference point (8) to the mast (3) » a primary jib (9) having an upper end ( 10) and a lower end (ll) supported by the universal pivot means (2) for OM universal pivotal movement of the primary jib (9) relative to the base (l); hoisting pulley means (12 and 13) at the upper end (10) of the primary jib (9); a hoisting line (14) which extends from the upper end (4) of the mast (3) or the cross-member (5) to the upper end (10) of the primary jib (9) and is trained over the hoisting pulley means (12 and 13) ; control pulley means ( 15 and l6) supported by the upper end (10) of the primary jib (9); a first jib control line (17) extending from the first part (6) of the cross-member (5) to the control pulley means (15 and i6), around the control pulley means (15 and' l6), and down to anchorage means ( 18 ) , on the base (1), which are disposed on the same side of the universal pivot means (2) as the first part (6) of the cross member (5); and a second jib control line ( 19 ) extending from the second part (7) of the cross member (5) to the upper end (10) of the primary jib (9), above the first jib control line (17) extending from the first part (6) of the cross- member (5) to the upper end (10) of the primary jib (9); the improvement comprising: the lateral distance (20) between the reference point (8) on the cross-member (5) and the second part (7) of the cross-member (5) is greater than the lateral distance (21) between the reference point (8) o the cross-member (5) and the first part (6) of the cross-member (5) . the second jib control line (19) has no extension from ( OMPI the upper end (10) of the primary jib (9) to the base (1) ; two secondary jibs (22), for lighter duty than the primary jib (9), are pivotally mounted on or above the base (l), on opposite sides of the cross member (5) , hoisting means (23), including two further hoisting lines (24), are respectively provided for co-operation with the secondary jibs (23); two sets of further control lines (25) extend, respect- ively, from the two secondary jibs (22) to the upper end (4) of the mast (3) or to the cross-member (5) > a radius arm (28) pivotally mounted on the base (l) at a pivotal point (29) disposed laterally of the mast (3); .anchorage means ( 18) mounted on the radius arm (28) for movement between two positions (26 and 27) on opposite sides of the cross-member (5)j releasable locking means (3) for securing the radius arm (28) to the base (1) so that the anchorage means (18) are held, alternatively, in either of said two positions (26 and 27) ; the first jib control line (17) is rigged to provide a plural-part purchase which extends between the first part (6) of the cross-member (5) and the upper end (10) of the primary jib (9); part (15) of the control pulley means cop-operate with the plural-part purchase; connector means (32) for supporting the second jib control line (19) extending between the second part O (7) of the cross-member (5) and the upper end (10) of the primary jib (9) from the upper end (10) of the primary jib (9); and a carrier member (31) , pivotally mounted at the upper end (10) of the primary jib (9), which supports the hoisting pulley means (12 and 13) , said part (15), at least, of the control pulley means ( 15 and 16 ) , and the connector means (32). _OMPI S WIPO <

Inventors: MORRISON R
Applicants: MORRISON R, SPEEDCRANES LTD
Application year: 1980
Main classification: B66C23
IPC codes: B66C23