The invention relates to a crane of the type used in machine workshops, warehouses, etc. for lifting heavy objects.
Specifically, the crane of the invention is of the type which can be transported by the user and which position can be easily changed for operating in locations where it is most needed as a result of having wheels or rolling elements.
Workshop cranes are apparatus that are widely known and used, for example, in vehicle workshops or other places where mechanical works are performed, where they are used for lifting heavy objects safely and without the operator having to make any effort.
Said cranes, an example of which can be seen in Spanish patent
As mentioned, one of the main functionalities of such cranes is that they can be easily transported by the user. Their mobile nature makes them an ideal alternative with respect to another type of cranes that are heavier or structurally more complex, such as overhead traveling cranes, for example, in those working environments where the parts to be transported do not exceed certain volume or weight.
More specifically and as can be seen in the example of the state of the art mentioned above, such cranes have in their base a pair of legs of a considerable size providing stability to the crane when it is operating, i.e., when it is supporting certain load. In that case, the center of gravity of the assembly will be located virtually in the vertical of the free end of the articulated arm where the hook or the like securing said load is located. Therefore, to achieve mobility, the cranes comprise respective pairs of wheels or rolling elements, a first pair at the end of said legs and a second pair located either in other small legs or directly on the base, slightly shifted towards the outside of the vertical projection of said column and in the direction opposite the first pair of wheels. Although said wheel arrangement allows such cranes to be transported by the user, the maneuverability achieved is reduced, requiring a large amount of space to be able to perform turning movements.
However, given that the loads to be moved can be rather bulky, the free end of the articulated arm must be significantly separated from the column, leaving sufficient space to prevent the load and said column from hitting one another. For this reason, the legs of the base must also be extended in a length such that, as mentioned, they assure stability, which means that they must be extended substantially beyond the vertical projection of the free end of the articulated arm.
This means that said legs are of a considerable length, so they obstruct human and machinery passage as well as prevent storing the crane when it is not in use.
To solve this problem, some of these cranes have extendable or deployable legs having one or several sections that can be fitted to one another, being attached to one another in a simple and fast manner by means of pins, bolts, etc.
This solution, however, has the drawback that when the operator needs to modify the length of the legs either for extending or retracting them, he/she needs a second operator who tilts the crane from the back so that the weight thereof does not prevent the insertion or removal of the bolt or pin with which the sections thereof are attached to one another.
More specifically, when the operator wants to disengage the legs, the weight of the crane itself causes the bolt or pin to be pressed, in the two sections of the legs to be disengaged, by the edges of the opposing holes with the bolt or pin going through them transversely, so the removal thereof will be complicated if there is no one to lift the crane such that said pressure and the pin or bolt are released.
In contrast, if the operator wants to engage two sections of said legs to one another, it would be impossible for him/her to make the mentioned holes, through which the pin or bolt is to be inserted, line up with or face one another if a second operator does not lift the crane enough so that said sections can be suitably "fitted".
Another known solution of the state of the art is that shown in said document
Nevertheless, in said solution, there is still a need to secure the legs by means of a bolt or pin both in the folded position and the unfolded position thereof, so the operator will still need the help of a second operator in a manner similar to the foregoing, i.e., lifting the crane slightly from the rear portion so that the first operator can make the holes, through which there are inserted the pins or bolts structurally securing the legs and preventing unwanted relative movements that may destabilize the crane when it is under load, line up with one another.
Finally, other examples are shown in
The workshop crane object of the present invention solves the drawbacks of the state of the art mentioned above insofar as it allows the operations of extending, shortening or lowering the legs of the crane to be performed in a safe and comfortable manner by a single operator, which results in time and cost savings.
To that end, there is proposed a workshop crane having all the technical features as defined in independent claim 1.
The workshop crane comprises the conventional elements:
But furthermore, in order to facilitate maneuverability and as will be explained below, the crane additionally comprises at least two intermediate wheels located on the front face of the base, on both sides of the vertical projection of the arm and between the front rolling elements and the rear rolling elements such that when the crane is without load it is supported on the rear rolling elements and the intermediate wheels.
In this manner, since it is supported on the rear rolling elements and on the intermediate wheels, located very close to one another, this results in improved maneuverability of the crane and, therefore, in faster, safer and more comfortable handling for the operator.
In contrast, when the crane is in the operative phase, i.e., with load, the center of gravity will shift substantially forward, so the crane will be supported on the front rolling elements located at the ends of the legs and on the intermediate wheels, obtaining maneuverability similar to that obtained conventionally in the state of the art, where said intermediate wheels do not exist.
Last but not least, the structure of the crane of the invention significantly improves the operations of extending-folding or lowering the legs, since it will no longer require the intervention of a second operator lifting the crane slightly from the rear portion so that the first operator can make the holes, through which there are inserted the pins or bolts whereby said legs are secured to the base, line up with one another.
As described above, said help will no longer be necessary because, when the crane is in a non-operative position, it is supported on the rear rolling elements and on the intermediate wheels and not on the front rolling elements located at the ends of the legs. The operator can thus operate the bolt with one hand and the leg of the crane with the other hand, given that said leg is in a raised position, facilitating the operations of removing and placing the bolt.
To complement the description that is being made and for the purpose of aiding to better understand the features of the invention according to a preferred practical embodiment thereof, a set of drawings is attached as an integral part of said description in which the following is depicted with an illustrative and nonlimiting character:
In view of the described drawings, it can be seen how the crane of the present invention is formed such that it comprises:
Furthermore, as seen in the drawings, particularly in
According to the preferred embodiment shown in the drawings, the intermediate wheels (10) will be those referred to as swivel or "idler" wheels, such that when they are in operation they allow the user to follow non-rectilinear paths, making turns, etc.
On the other hand, said intermediate wheels (10) will preferably be located on the outer sides of the legs (7) in order to increase stability, although possible embodiments (not shown) in which they are located on the inner side thereof are not dismissed.
Likewise, the rear rolling element or elements (9) can be assembled either directly on the rear portion of the base (1), as shown in the drawings, or through small legs or intermediate protrusions (not depicted) provided that they are still located close to the base. In other words, in the case in which there are two rolling elements, these elements will be located on both sides of the vertical projection of the column (2) such that the imaginary or real axis joining them intersects or is under the vertical projection of the column (2). Likewise, if there were only one rolling element, not depicted, this rolling element will be located under the vertical projection of said column (2) to assure stability.
Finally, it is possible to see, particularly in
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.