A DEVICE FOR PICKING UP, TRANSPORTING AND DEPOSITING LOADS, SUCH AS LOADED PALLETS

Abstract: The invention relates to a device (1) for picking up, transporting and depositing loads, such as loaded pallets, comprising a carrying body (3) with at least one load supporting element (4) extending therefrom of the type, that is adapted to be inserted from aside under a load, said load-supporting element (4) being of an articulated construction, in the manner of a laminated chain as seen in the transverse direction, and being adapted to be retracted from its operative position, in which its upstanding links (4a) are extending outwardly, in a cantilever manner, from a straight horizontally disposed guide track (8) in the carrying body (3) and in which the links (4a) are locking one another against forward tilting from the horizontal supporting position, along an arcuate track (9) that links up with said horizontal straight guide track (8) and bends upwards through the carrying body (3), and vice versa. According to the invention the upper sides of the links (4a) are profiled in correspondence with the inner curve (9a) of the arcuate guide track (9). In a practical embodiment the device (1) is mounted with its carrying body (3) for up and down movement on the vertical guide track (5) at the front side of a fork lift truck (2).

Description: Short title: A device for picking up, transporting and depositing loads, such as loaded pallets. . The invention relates to a device for picking up, transporting and depositing loads, such as loaded pallets, comprising a carrying body with at least one load supporting element extending therefrom of the type, that is adapted to be inserted from aside under a load, said load-supporting element being of an articulated construction, in the manner of a laminated chain as seen in the transverse direction, and being adapted to be retracted from its operative position, in which its upstanding links are extending outwardly, in a cantilever manner, from a straight horizontally disposed guide track in the carrying body and in which the links are locking one another against forward tilting from the horizontal supporting position, along an arcuate track that links up with said horizontal straight guide track and bends upwards through the carrying body, and vice versa. Such a device is disclosed in US-A-2.574.045. With this well-known device, which is carried out as a fork lift truck, the links of the load supporting elements (fork legs) have a straight upper side, whereas the lower sides of the links are of an arcuate shape and have a radius that corresponds to that of the outside curve of the arcuate guide track. It is a drawback of this well-known embodiment, that when retracting the fork legs, the links must slightly tilt downwards at the transition between the straight guide track and the connecting arcuate guide track before they can move upwardly along the inner curve of the arcuate guide track. As an individual link is not allowed to tilt downwardly from the straight fork leg, however, the vertical clearance within the straight guide track has to be such, that the required tilting movement can be carried out by the entire extended fork leg. This means, that the guiding and clamping of the extended fork leg is rather poor, while a retracting movement of the fork leg from under a deposited loaded pallet will be accompanied By a "tip-up'^movement of the free end of the fork leg, which may render retraction more difficult. According to the invention this drawback is overcome due to the upper sides of the links being profiled in correspon¬ dence with the inner curve of the arcuate guide track. Due to this feature the links may move from the straight guide track into the arcuate guide track in a smooth way, i.e. without making first a downward tilting movement. This enables to keep the vertical clearance in the straight horizontal guide track to a minimum, so that a n tip- up free" guidance and an effective clamping of the load supporting element in the extended position is secured. The lower sides of the links may be kept straight, which contributes to a still better clamping and guidance and will result in less wear. The improved device according to the present invention is particularly adapted for use with the traditional, compact fork lift truck. A fork lift truck according to the invention, i.e. provided with an articulated retractable fork may - with its fork in the retracted position - be advanced with its front side close to the load to be picked up, after which the fork can be simply extended to pick up the load. In reverse order the load may, after being deposited, simply be released from the stationary fork lift truck by retracting the fork rather than moving the entire fork ligt truck rearwardly through a distance corresponding with the length of the fork. During retraction there is no interference by a "tipping-up" fork. Moreover the manoeuvring of a truck according to the present invention in a working space while in unloaded position - i.e. with retracted fork - is much easier and - due to the absence of extending forks - much less dangerous than with the traditional fork lift trucks. A special use of the device according to the present invention is that as a "pallet hook". A "pallet hook" is used when loading and unloading ship's holds and similar storage rooms. In this case the carrying body is designed to be suspended from a crane hook. With the well-known pallet hooks the load supporting elements are constituted by rigid "forks" extending permanently beyond the carrying body. According to the common practice these pallet hooks are put down onto the bottom of the ship's hold with the extending fork adjacent the load to be picked up, after which the pallet hook is manually inserted under the load to be picked up. When depositing a load into a ship's load or onto the quay, the pallet hook is manually retracted from under the deposited load. The particular advantage of a device according to the present invention, carried out as a "pallet hook" is to be seen in that the pallet hook - suspending from the hook of a crane controlled by a crane driver - may be positioned, with retracted articulated fork (i.e. with the absence of danger by extending parts) , through the hatch way in direct contact with the load to be picked up from the ship's hold, after which the fork may, either by depressing a button or by remote control, inserted under the load to lift the latter from the ship's load, without the need for additional manpower to establish the transport connection between the carrying body and the load. In reverse orer, after a load has been deposited, the transport connection between the carrying body and the load may be simply released by retracting the articulated fork into the carrying body either by depressing a button or by remote control. Further features and advantages of the present invention will be understood from the following description and drawing of a number of practical embodiments. Fig. 1A is a diagrammatic side view of a fork lift truck designed in accordance with the present invention, with retracted fork legs; Fig. IB is a diagrammatic view as shown in fig. 1A, but now with the extending fork legs engaging a load; fig. 2 is an enlarged diagrammatic side view of a part of a load supporting element or fork leg and of the carrying body with the fork leg guiding track provided therein; fig. 3 shows a plan view of the articulated fork leg in fig. 2; fig. 4A is a diagrammatic side elevation of a pallet hook designed in accordance with this invention, with the fork legs in the retracted position; fig. 4B is a diagrammatic side view as shown in fig. 4A, but now with extended fork legs and fig. 5 is a diagrammatic perspective view of a pallet hook, the carrying body of which is provided on opposite sides with extendible and retractable fork legs. In the embodiment shown in fig. 1 the device of the present invention is generally indicated at 1 and applied with a fork lift truck 2. The device 1 comprises a carrying body 3 and a plurality of load supporting elements or fork legs 4 extending therefrom. The carrying body is mounted for an up and down movement on the sliding track 5 at the front side of the fork lift truck 2. The fork legs 4 are composed of articulated links 4a. In the carrying body guiding tracks are provided, which will be further described below. The articulated fork legs are mounted to move along said tracks between a retracted position (fig. 1A) and an extended position (fig. IB) . The links 4a are designed to lock one another in the extended position shown in fig. IB, so that they are prevented from tilting forwardly from the supporting surface of the straightly extending fork legs and the extended fork legs are behaving like rigid fork legs relative to a vertical load. In the position shown in fig. 1A the fork lift truck 2 may be manoeuvred easily and safely (no extending fork legs) . In this position the fork lift truck 2 may be simply placed with its body 3 engaging a load to be picked up, e.g. a loaded pallet 6. Subsequently the fork legs are, by exerting a force in the direction of arrow P (fig. 1A) such as by means of a hydraulic cylinder device of similar driving means, extended and thereby inserted into the pallet 6 (fig. IB) . The load 6 may then be transported in the usual manner towards another place and deposited there. Upon depositing of the load the advantages of the articulated fork legs will become manifest. In order to release the deposited load from the fork legs 4, the latter may be simply retracted along the guide tracks within the carrying body (vide arrow Q in fig. IB) , after which the fork lift truck 2 may drive off safely (no extending fork legs) while being turned sharply. Fig. 2 and 3 show an articulated fork leg in one embodiment of the invention in a partially retracted position. The links 4a have a pitch s and comprise a series of outer links 4a' and a series of intermediary links 4a". The outer links 4a' are united, in pairs to double links 4a', 4a' by means of two pitch-spaced pivot pins. The double links or link pairs 4a', 4a' are mutually connected by the intermediate links 4a". As may be seen in fig. 2 and 3, each outer and inter- mediate link 4a' and 4a" respectively is extended beyond the respective right hand pivot pin by a portion 4b' and 4b", that continues up to the left hand end of the adjacent link 4a' and 4a" respectively. The free ends of the thus extended links are shaped such that the successive outer links 4a and the successive intermediate links 4a" are locking one another in the extended position of the fork leg - in which said links are in one plane - so as to be prevented from tilting forwardly from this plane. More specifically those portions of the ends 7' (of the outer links 4a') and 7" (of the intermediate links 4a") that are situated below the horizontal midplane X of the extended fork leg 4, lockingly engage the adjacent links 4a' and 4a" respectively. Those portions of the ends 7' and 7" respectively which are located above the plane X are terminated substantially at right angles to the axis X, so that there is space for movements relative to the adjacent links allowing said links to turn from the plane of the extended fork leg upwardly and allowing the fork leg to bend from said plane upwardly. This freedom of movement is illustrated to the right in fig. 2, where the right hand part of the partially retracted fork leg 4 is bending upwards along an arcuate guide track 9. In the example shown this guide track is delimited by an inner curve 9a in the shape of a quarter of a circle having a radius R, and an outer curve 9b which is partially formed by an arc having the same centre as the inner curve 9a. The guiding track 9 links up with a straight guiding piece 8, the internal height of which corresponds with the height of the individual links 4a' and 4a" and by means of which the fork leg is getting properly clamped in its extended position within the carrying body 3 through a length which is preferably larger than pitch s. The upper guiding surface 8a is directly corrected to the (90°) inner curve 9a, whereas the lower straight guiding surface 8b of the guiding piece 8 is continuing through a certain distance before connecting to the arcuate outer curve 9b. The guiding track 9 continues at the upper end of its quarter of a circle into a straight guide track 10, of which the (horizontally measured) internal height corresponds with that of the guiding piece 8. The front surface 10a of the straight guiding track 10 is directly connected to the quarter of a circle of the inner curve 9a, whereas the arc of the outer curve 7b connects to the rear surface lOb of the guiding track 10 through a transitional surface 11. Within the (relative to the height of the straight guiding piece 8) radially widened guiding track 9 the extension pieces 4b' and 4b" of the links 4a' and 4b' may deviate laterally outwardly before retaking their aligned positions as of the upper end of the guide track 9 into the straight, narrower guiding piece 10. An important feature of the guiding of the articulated fork leg is to be seen in the fact that the links 4a' and 4a" are guided in uniform contact with the inner curve 9a. For this purpose the upper surfaces of the links 4a' and 4a" between the pivot pins are preferably shaped by an arc that corresponds with the inner curve 9a. Fig. 4A and 4B show the device of the invention, applied as a "pallet hook". In this case the carrying body 3 is constituting the "upstanding" portion of the pallet hook, whereas one or more retractable fork legs 4 has (have) replaced the fixed, lying portion of the well-known pallet hook. Like the well-known pallet hook the carrying body 3 is provided at its upper end with a forwardly extending arm 11 with a (spring) mechanism (not shown) incorporated therein for a self-adjusting suspension point. Fig. 4A shows the position, in which the pallet hook according to the invention with retracted fork leg(s) has been placed against a load 6 on a supporting surface 12 or in which a load 6 has been placed against the carrying body of the pallet hook lowered (with retracted fork leg(s)) onto the surface 12 in a position ready for extending the fork leg(s) and subsequent lifting of the pallet hook together with the load (fig. 4B) . As remarked hereinabove a pallet hook according to the invention allows ship's holds to be loaded and unloaded respectively more rapidly, more efficiently and with less danger. As will be understood the number of fork legs 4 and associated guiding tracks may vary. The width of the articulated fork leg according to the present invention may also vary, e.g. by composing the fork leg from a larger or smaller number of link elements, as seen in the transverse direction, in a way similar to that with the so-called laminated chains. Such an embodiment increases the strength and thereby the load capacity of the fork leg. A particular embodiment is diagrammatically shown in fig. 5, in which the carrying body 3 is provided with (four) fork legs 4 extending to both sides and wherein the carrying body is consequently provided with two groups of guiding tracks (not shown) . With such a double sided pallet hook a loaded pallet may be placed in contact with either side of the carrying body of the pallet hook that has been placed, with retracted fork legs, on a supporting surface; thereupon both groups (of four) fork legs are extended to lift both of the two loads. Such a two sided design would lead to insuperable difficulties with the well-known pallet hook and more particularly also during unloading. Such a two-sided application of the invention has the additional advantage, that the overhanging arm 11 and the spring mechanism incorporated therein with the single side construction may be omitted (vide lifting point 11'). It will be understood that the invention is not limited to the embodiments shown in the drawing. Within the scope of the claims various modifications are possible with respect to the design of the articulated load carrying elements and of the guiding tracks for the same.

Claims: C L A I M S 1. A device for picking up, transporting and depositing loads, such as loaded pallets, comprising a carrying body with at least one load supporting element extending therefrom of the type, that is adapted to be inserted from aside under a load, said load-supporting element being of an articulated construction, in the manner of a laminated chain as seen in the transverse direction, and being adapted to be retracted from its operative position, in which its upstanding links are extending outwardly, in a cantilever manner, from a straight horizontally disposed guide track in the carrying body and in which the links are locking one another against forward tilting from the horizontal supporting position, along an arcuate track that links up with said horizontal straight guide track and bends upwards through the carrying body, and vice versa, characterized in that the upper sides of the links are profiled in correspondence with the inner curve of the arcuate guide track. 2. A device according to claim 1, characterized in that the links have their upper sides in uniform contact with the inner curve of the arcuate guiding track. 3. A device according to claim 2, characterized in that the upper edge of the links is in form of an arc having a radius corresponding to that of the arcuate guiding track. 4. A device according to claims 1-3, characterized in that the lower sides of the links are straight. 5. A device according to claims 1-4, characterized in that it is designed as a pallet hook. 6. A device according to claim 5, characterized in that the carrying body is provided with extendible and retractable fork legs and corresponding guide tracks in either side. 7. A device according to claim 6, characterized in that the suspension point is in a central position relative to the carrying body.

Inventors: PRINS WILLEM FREDERIK, PRINS, WILLEM, FREDERIK
Applicants: PRAXIS INGENIEURSBURO BV, PRINS WILLEM FREDERIK, INGENIEURSBURO PRAXIS B.V., PRINS, WILLEM, FREDERIK
Application year: 1995
Main classification: B66F9
IPC codes: B66C1, B66F9