Transport device
The invention relates to a transport device for heavy loads mainly comprising one or more parallel guides along each of which one or more load carrying slides are dis¬ placeable. By such a transport system relatively small level differences of the supporting surface, for example, the ground can be overcome.
The invention has for its object to provide a transport device by which larger level differences than hitherto can be bridged so that the load to be transported can be retained in the same horizontal or sloping plane in any transport position.
According to the invention the transport de¬ vice comprises hydraulic lifting means for obtaining a load displacement vertical to the guide.
The lifting means are preferably formed by one or more rams or worm conveyors. By means of the hydraulic ram the load remains sufficiently supported in the area of a lower part of the substrate so that it is now possible to displace loads of particularly large width and length within the range of permissible deformation of the loads.
In order to maintain uniform pressures of the slide on the load the hydraulic rams of the slides are con¬ nected parallel to one another. In this way the variation in length of the hydraulic rams is automatically matched.
In order to improve the stability of the load
at least two groups of parallel-connected rams are provided. Thus the transport device can be adapted to non-uniform dis¬ tribution, for example, a deck with machines or suchlike wor¬ king units at different places. If a slide consists of a base plate with stif¬ fening constructions it is preferred, in order to limit the height, to a ram reaching to- near the base plate on which the stiffening construction is formed by box-shaped bodies on both sides of the ram and a tie member arranged between them at a distance from the base plate. '
In one embodiment the ram- is pivoted near the base plate to the slide so that the slide can move through an angle with respect to the load to be carried.
If the guide has a U-shaped cross-sectional area, the slide is preferably equipped with tracking members pressed against the inner side along the side of the guide.
The tracking members are preferably pivotally driven by pressure cylinders in the horizontal plane, said cylinders of consecutive slides being connected parallel to one another so that the lateral pressure of the loads with respect to the guide is absorbed by all slides.
The invention will be described more fully with reference to the figures.
The drawing shows in: Fig. 1 a perspective view of a transport system embodying the invention on a shipyard for a heavy load to be carried to pontoons at the shipyard,
Fig. 2 a perspective view of part of the guide with a slide displaceable theron, Fig. 3 a plan view of a guide with a number of slides provided with tracking members,
Fig. 4 a perspective view of a further embodi¬ ment of a slide.
Fig. 5 a hydraulic feed diagram for the rams of each slide,
The transport system shown in Fig 1. comprises
six guides 1, which may be of any design. In each guide a number of slides 2 are arranged one after the other, the in¬ tervals between and the number of slides being adaptable to the construction and the weight of the load to be carried and to the stability of the substrate.
The transport system shown extends from a shipyard 3 to pontoons 4 floating on the water. Between, the pontoon 4 and the bank of the- shipyard 3- are arranged bridge parts 5, which are pivotally connected with the pontoon and the shipyard respectively.
Fig. 1 represents a load to be transported formed by the deck 6 of a drilling platform, on which deck are built a number of machines such as drilling derricks, cranes as well as lodgings for the crew. The completed deck with its superstructure is shifted from the yard to the pon¬ toons 4 by means of the transport device embodying the inven¬ tion, after whgich the lower structure of the drilling plat¬ form indicated in Fig. 1 by the. broken line 7 can be arraged beneath the deck and secured thereto. As a matter of course, this load handling lies outside the scope of the invention.
The transport device is distinguished in that level differences can be readily overcome by means of the slides 2, which will be explained more fully hereinbelow. It will be obvious that level differences due to 'tide variations of the advancement of the heavy loads on the yard to the pon¬ toons have to be neutralised. This is enabled by the ram pro¬ vided in each slide matching the distance variation between the guide 1 and the load. The supporting pressure of each slide is maintained. For the sake of completeness it is stated that the advancement of the slide in the guide 1 is performed by means of pressure cylinders 9, which are located at the brid¬ ge portions 5 at the moment illustrated in fig. 1. The pres¬ sure cylinders 9 bear on the one hand on the guide 1 and on the other hand on the hindmost slide. After the slide has been advanced over a given distance, the pressure cylinder 9 itself can be displaced so that the cycle of operation can ϋ
restart. All cylinders 9 are fed from a central pump 10 of the yard.
Fig. 2 shows an embodiment of a slide in ac- cordance with the invention. This slide comprises a base plate 11, which i slightly curved upwards at both ends. To the base plate 11 are welded two hollow bodies 12 of triangular shape, a tie member 13 being welded between the peaks of the bodies 12 in the form of a closing plate. In this way a light-weight, but rigid construction is obtained by which the peak load can be distributed along a large surface, i.e. the base plate 11. The base plate 11 can freely travel in the guide 1, which is essentially constructed in the form of a channel-shaped gut¬ ter open at the top side. The bottom of the gutter is covered with preferably removable plates of teflon 1a reducing the friction between the base plate 11 of the slide and the bot¬ tom of the open gutter 1. At least three teflon plates are each time required for displacing the base plate 11.
Between the two triangular hollow bodies 12 is arranged the cylinder 14 embodying the invention, which is pivotally connected below at 15 with the slide. At the top the cylinder is provided with a plate 16, which is pressed against the bottom side of the load. Owing to the pivotal connection between the cylinder 14 and the sl'ide 2 and to a slot-like recess 17 in .the tie member 13 the cylinder can perform a given angular turn with respect to the longitudinal direction of the slide so that small unevennesses in the rail can be overcome by the swing of the slide with respect to the load. In a transverse.direction the cylinder 14 comes into contact with the side of the slot-like recess 17 so that transverse forces can be transferred through the cylinder wall to the slide.
Each slide 2 is provided at the front and at the rear with two pivotal arms- 18 adapted to pivot about the axis 19 in a horizontal plane. The end of each arm 18 is pro vided with a guide wheel 20 rolling along the inner side of the channel-shaped guide. Between the pivotal arms is
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arranged a pressure cylinder 21 , which moves the two arms outwardly. The outward movement of each pivotal arm is limi¬ ted by a stop- rim 22 positioned so that, when the slide moves in the middle of the guide 1, the rollers 20 do not touch the inner wall of the gutter-shaped rail. However as soon as the slide moves out of the middle, the rollers will exert pressure on the pivotal arms 18, which thus tend to move inwardly, which is counteracted by the cylinder 21. In this way a tracking system is obtained, which has minimal frictional resistance.
In the event of lateral pressure of the load on the slide 2 and hence in tracking right the slides 2 it is preferred for all slides, to exert a uniform reactive pres¬ sure on the load. For this purpose, in accordance with the invention, each cylinder 21 is connected parallel to the further tracking cylinders in the guide 1.
In order to absorb the weight of the load as uniformly as possible it is preferred to feed the cylinders or set of cylinders 14 of the slide groupwise from the same pressure source. This is illustrated in fig. 5, in which each circle represents a cylinder. In fig. 5 three feeding groups can be distinguished, in which different pressures may pre¬ vail, which depends on the magnitude of weight above the pressure group concerned. The pattern of a pre-ssure group may be fully adapted to the requirements.
The circles 30 symbolize the pressure force of each group, the locations of which clearly show that a stable support of the load L is obtained owing to the three-point support. The circle Z indicates the centre of gravity of the load, which has to stay inside the triangular support formed by the circles 30.
The cylinders of a group can be fed by means of flexible conduits 31 (see also fig. 1).
Fig. 4 shows an alternative embodiment of the slide 2, which is suitable for heavier lateral forces. Also in this case the slide comprises a base plate 11 on which two hollow bodies 12 of triangular shape are arranged.
Between the hollow bodies 12 are arranged two cylinders 14 fastened by bolts 40 to the base plate 11. Each hollow body has two vertical guide bars 41, along which' a tie member for med by a stool 42 can move up and down. The cylinder 14 exerts pressure on the underside of the stool 42, which is provided at the top with a pressure plate 43, which can transfer a moment produced by a transverse load by means of a hinge 44. The pressure plate 43 bears on the underside of the load. The transverse loads are absorbed in this case by the guides 41 and directly transferred to the base plate 11. The embodiment shown in fig. 4 is extremely suitable for a rapid exchange of the cylinder 14 for matching.the operational con¬ ditions or for carrying out repairs.
The invention is not limited to the embodi- ments described above. For example, the tracking members may be formed by a cylinder transversely fastened to the slide and having two piston rods protuding along the inner side of the channel-section guide.
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