US3436113A - Rotatable and convertible lifting spreader - Google Patents

Description

April 1, 1969 Q ZWE|FEL ET AL 3,436,113

ROTATABLE AND CONVERTIBLE LIFTING SPREADER Filed June Q. 1967 INVENTORS CHARLES H. ZWEIFEL GEORGE W. COOPER Sheet 7 ATTORNEY c; H. ZWEIFEL ET AL April 1, 1969 ROTATABLE AND CONVERTIBLE LIFTING SPREADER Filed June 6, 1967 Z of? Sheet INVENTORS CHARLES H. ZWEIFEL. QEORGE W. COOPER ATTORNEY Hire 3,436,113 Patented Apr. 1, 1969 3,436,113 ROTATABLE AND QONVERTTBLE LTFTENG SFPREADER Charles H. Zweifel, Oakland, and George W. Cooper, San Leandro, Calif, assignors to Pacific Coast Engineering (Zompany, a corporation of California Filed Sane 6, 1967, Ser. No. 643,993

int. Cl. B66c N42 US. Cl. 294-67 2 Claims ABSTRAQT OF THE DISCLOSURE A lifting spreader having upper and lower assemblies interconnected by a rotatable frame supported from the upper assembly by a combination gear-bearing with the lower assembly pin connected to the rotatable frame.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to lifting spreaders and more particularly to a lifting spreader which is rotatable in a horizontal plane about a vertical axis and is convertible for handling different lengths and different types of cargo containers.

The relatively new practice of handling all types of cargo in pre-packed standard sized cargo containers has required the development and use of many different types of cargo containers handling equipment. Certain standards have been developed for cargo containers by the American Standards Association and the International Standards Organization and provide for containers in lengths of approximately, twenty, thirty, and forty feet. The end cross sections are approximately eight feet square.

In addition to the standardization of sizes, there is standardization among the means utilized for picking up the cargo containers. One such means includes a lifting spreader positioned on top of a container and having bottom lift grapples which reach down and grasp the lower edges of the container. Another means utilizes twist locks disposed at the corners of a lifting spreader which engage twist lock receptacles disposed in the upper corners of the upper surface of the cargo containers. A third means utilizes books at the corners of the lifting spreader which engage receptacles in the corners of the containers. Thus, it is necessary to provide lifting spreaders and lifting spreader assemblies which can be interchanged for picking up different length cargo containers with the different type of cargo container engagement means.

A further problem in handling containers is that the spreader must be aligned with the container for engagement therewith. This often requires the lifting spreader to be rotated in a horizontal plane to achieve alignment. Likewise, it is usually necessary to align a suspended load with the position in which it is to be deposited, such as within the guides of a storage cell in a ship.

Description of the prior art There have been many assemblies devised for handling cargo containers and many of these assemblies have been constructed with a view to handling different sized and different type cargo containers. The closest prior art reference which has been uncovered with respect to the present invention is the United States Patent No. 3,081,- 884 to J. E. Minty for a Crane With Anti-Sway Mechanism. There shown is a mobile crane of the type with which the present invention can be utilized. The prior art device includes a lifting frame 8 to which is connected a lifting beam 9 by a rotary arrangement. Associated with the lifting beam 9 is a plurality of foldable lifting hooks or grapples 10 secured to a transverse bridge bar 11 which is adjustable along the beam 9 by rollers 12.

There are problems with the cited reference which are overcome by the present invention. The lifting beam 9 is suspended from the lifting frame 8 by a hub 60. This arrangement makes the lifting beam very unstable and very sensitive to inaccurate suspension of the lift load because of the small size of the connection between the beams and the frame. Further, the lifting beam 9 is very susceptible to bending as a result of being picked up only at the center thereof. This is especially true with handling containers since they are not usually picked up at their midpoints, but at positions Well spaced from their midpoints for balance. If the lifting beam of the prior art is somehow furnished with twist locks to pick up containers which must be handled only by twist lock engagement, such as when the containers must be placed in, or taken from, storage cells on board ship, the lifting beam is subject to even greater bending because the engagement of the beam with the container is only at the very ends of the container. As a result of these factors, the device of the prior art is very unstable and is subject to extremely large bending moments, especially when used to handle 40 foot containers.

The prior art device does not, in fact, appear to be convertible to use with twist locks and this restricts its use to handling only cargo containers which may be bottom lifted and to container handling operations where the bottom lift grapples do not interfere with the containers stacking structures or arrangements. Since there is no coordination between the bridge bars 11 for accurate location of the grapples with respect to the central hub d0, the prior art device must be constantly adjusted for each lifting sequence to be sure that the lifted load is not unbalanced.

Other means have often been provided for rotating a lifting spreader in a horizontal plane about a vertical axis. These generally comprise a rotating platform, or a rotatable trolley, on the crane which supports the spreader. However, in converting many of the presently utilized and serviceable older type cranes to use for handling cargo containers, it is economically unfeasible to provide the rotating apparatus on the crane itself or to convert the trolley to provide this capability. It is therefore often necessary in converting cranes to container operations to provide this capability within the spreader itself.

The present invention provides a lifting spreader which overcomes each of the problems as will be pointed out hereafter.

SUMMARY OF THE INVENTION The present invention is a lifting spreader which is rotatable in a horizontal plane about a vertical axis for versatile manipulation thereof and is convertible to use with a number of different type lifting beams. This permits the spreader to easily align with a container for engagement or for alignment of a suspended container with its intended release. position. It also permits the spreader to handle all of the different types of cargo containers presently utilized by the transportation industry. It includes an upper spreader assembly supported from above and having a first bearing race secured to the lower surface thereof. A rotatable frame having a second bearing race secured thereto mates with and engages the first bearing race by means of anti-friction bearings disposed between the races. A slewing drive is provided for rotating the frame, and a unitary lower spreader assembly is detachably connected to the rotatable frame and includes cargo engaging means. By use. of this arrangement, a stable and structurally strong but lightweight lifting 3 spreader assembly is provided. A more rapid change from one type of lifting beam to another can be effected, and a relatively inexpensive and versatile spreader assembly is provided for converting presently existing cranes to cargo container handling.

It is therefore an important object of the present invention to provide a lifting spreader which is rotatable in a horizontal plane about a vertical axis.

It is another object of the present invention to provide a lifting spreader which can be quickly converted from one type of lifting engagement means to another.

It is a further object of the present invention to provide a lifting spreader which can be quickly converted for handling different lengths of cargo containers.

It is still another object of the present invention to provide a lifting spreader which supports a rotatable lifting beam in a manner to give it strength and stability.

And still a further object of the present invention is to provide a lifting spreader which can be adapted to presently existing cranes and provide a versatile and relatively inexpensive conversion therefor for handling all types and sizes of cargo containers.

DESCRIPTION OF THE DRAWINGS FIGURE 1 is a partial side elevation of a crane utilizing the lifting spreader of the present invention;

FIGURE 2 is a plan view of the'lifting spreader of the present invention;

FIGURE 3 is a side elevation in partial section showing the lifting spreader of the present invention; and

FIGURE 4 is an end elevation showing the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference is made to the drawings for a description of the preferred embodiment of the invention. FIGURE 1 shows a dockside crane 11 lifting a cargo container 13 by means of the lifting spreader 15 of the present invention which is suspended from the crane gantry by wire ropes 17.

FIGURES 2, 3, and 4 show the details of construction of the rotatable and convertible lifting spreader. There shown is a generally rectangular upper spreader assembly 19 having wire rope blocks 21 disposed proximate the ends thereof and a power conductor cable coiling tub 22 in the upper surface thereof. The lifting spreader is suspended from the crane by the wire ropes 17 which are reeved through the blocks.

A first bearing race 23 is secured to the lower surface of the upper lifting spreader assembly, such as by bolts 25, at many points around the periphery of the race. The bearing race 23 is of a relatively large diameter and approaches the width of a cargo container, but it is necessarily less than that width since these containers must be lowered into guides for container storage cells on board ships. These cells leave very small clearances between the. containers; therefore, the structure of the lifting spreader must reside within the maximum external dimensions of the cargo containers to be handled.

A generally rectangular frame 27 is disposed immediately below and closely adjacent the upper spreader assembly. A second bearing race 29 is secured to the frame and mates with and engages the first bearing race. This is effected by means of anti-friction bearings 31, usually ball bearings, which are disposed between the races and carry the vertical shear loading between the upper spreader and the rotatable frame. The relatively large diameter of the bearing assembly permits considerable displacement of the center of gravity of the load in the container, either laterally or longitudinally, with respect to the vertical axis of the bearing assembly. The degree of displacement which can be tolerated is a function of the bearing diameter. A larger bearing allows greater displacement of the center of gravity of the suspended load and lessens the sensitivity of the spreader to the positioning thereof.

The second bearing race, the one secured to the rectangular frame, forms a fixed gear 33 with respect to the rectangular frame and is integral to the second bearing race. In the preferred invention, this gear is formed as a ring gear with the gear teeth projecting radially inward of the bearing race on the internal surfaces thereof. This affords protection to the gear teeth, and the associated mechanisms, from damage by some external force of which there are many when working with loads of the weights here involved. However, it is conceivable that the two bearing races could be interchanged in their relative positions and the gear teeth formed on the outer periphery of the outer race. That race would be secured to the rectangular frame with the inner race secured to the upper spreader assembly.

A slewing drive 35 is secured to the upper spreader assembly and has a pinion gear 37 which meshes with the ring gear. Again, it is possible that the slewing drive could be secured to the rectangular frame but since space between the upper and lower spreader assemblies is at a premium, it is easier to mount the slewing drive on the upper spreader assembly.

The lower spreader assembly 39, or the lifting beam as it is commonly called, is pin connected to the rectangular rotatable frame proximate the corners thereof by means of removable pins 41 inserted through the pin connections 43 on the lifting beam into the corners of the frame. These pins are easily removable to disengage the lower spreader assembly. By providing the pin connections at the corners of the rectangular frame, a stable engagement with the lifting beam is created both laterally and longitudinally. In addition, the longitudinal spacing of the pin connections 43 along the lifting beam reduces the maximum bending moments which are imposed on the beam. The spacing also reduces the whip or bending which would occur in the longer beams and which is most severe in a centrally supported beam.

The lower spreader assembly 39 is unitary in that it is of a fixed size, length, and type. It carries only one type of engagement means for a single length of spreader. A different lifting beam is employed for each different length of container handled or for each different type of engagement means to be used for picking up the containers, such as rotatable bottom lift grapples, twist locks, etc. One type of engagement means is shown in the drawings herewith and includes the male portions or studs 45 of a twist lock engagement means. These are disposed at the corners of the lifting beam. The twist locks are operable by hydraulic cylinders 47 which twist the lock studs to engage with the receptacles on the containers. Naturally, a universal spreader for handling all of the different sizes and types of containers could be used with the present invention if one were available. In addition, wire rope slings could be utilized with a lifting spreader for picking up loads of pipe or other elongated material.

Hydraulically operated corner guides 49 are also shown. These are utilized to guide the lifting spreader onto the container for accurate engagement therewith. They rotate to a position within the periphery of the spreader so that they do not interfere with lowering of the spreader into a storage cell. For this capability, the guides are sometimes called flippers. They are fully described in the U. S. patent application Ser. No. 575,659 for Lifting Spreader Corner Guides by Jules G. Nagy.

The power conductor cable 51 carries the electrical control for the slewing drive and the hydraulic control for the twist locks and flippers. The basic hydraulic power unit on the upper spreader assembly is provided with quick disconnect, non-leak, hydraulic fittings, and positive connection electrical plugs, so that the initial power unit and its electrical operating devices can be easily connected to the lower spreader assembly.

The present invention has many advantages over the prior art. As a primary advantage it is a lifting spreader which engages a rotatable lifting beam with a relatively large diameter connection whereby sensitivity to the location of the center of gravity of a suspended load is moderated. This increases the speed with which cargo containers may be handled. The detachable pin connections which secure the different lifting beams to the rotatable frame permit quick and easy interchange of the beams for handling different types and sizes of containers or elongated cargo. The use of the rotatable frame effects a stronger lifting beam as a result of supporting the beam from longitudinally spaced connections. The rectangular lifting beam has great lateral stability. The rotatable spreader provides a relatively inexpensive conversion unit for presently existing cranes to permit cargo container handling.

It will be apparent from the foregoing description of the invention, in its preferred form, that it will fulfill all of the objects attributable thereto.

What is claimed is:

1. A rotatable and convertible lifting spreader comprising a generally rectangular vertically movable upper spreader assembly having wire rope blocks disposed proximate the ends thereof, said spreader being suspended by wire ropes reeved through said blocks,

a first annular bearing race secured to the bottom of said upper spreader assembly and having an outside diameter less than the maximum width of the lifting spreader when arranged for lowering into a cargo storage cell,

a generally rectangular horizontally rotatable frame having a second annular bearing race secured thereto mating with and engaging said first bearing race to support said rotatable frame by means of anti-friction bearings disposed between said races, said second bearing race forming a fixed ring gear internally thereof and integral thereto, the center line of the track of said anti-friction bearings having a diameter equal to or greater than one-third the maximum width of the lifting spreader arranged for lowering into a cargo storage cell,

a slewing drive secured to said upper spreader and having a pinion gear meshing with said ring gear, and

a lower spreader assembly detachably pin connected to said frame proximate the corners thereof and having cargo engagement means.

2. A rotatable and convertible lifting spreader comprising a vertically moveable suspended upper spreader assembly having a first annular bearing race secured thereto,

a horizontally rotatable frame having a second annular bearing race secured thereto mating With and engaging said first bearing race to support said rotatable frame by means of anti-friction bearings disposed between said races, said second bearing race forming a fixed ring gear internally thereof and integral thereto, the larger of said bearing races having an outside diameter less than the maximum width of the lifting spreader when arranged for lowering into a cargo storage cell, and the center line of the track of said anti-friction bearings having a diameter equal to or greater than one-third the maximum Width of a lifting spreader arranged for lowering into a cargo storage cell,

a slewing drive secured to said lifting spreader and including a pinion gear meshing with said fixed gear for rotating said frame anywhere within the range of operation of said lifting spreader, and

a lower spreader assembly connected to said rotatable frame and including cargo engagement means.

References Cited UNITED STATES PATENTS 1,136,939 4/1915 Colby et al. 212127 3,081,884 3/1963 Minty 21214 3,250,401 5/1966 Davidson 21269 X 40 ANDRES H. NIELSEN, Primary Examiner.

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