The current invention relates to a play crane comprising a loop supporting frame, a flexible closed loop supported in a vertical orientation around the loop supporting frame and a lifting element connected to the flexible closed loop whereby the lifting element can be moved up or down by displacing the flexible closed loop around the loop supporting frame.

According to this specification, the term "flexible closed loop" should be understood as a flexible elongated element formed into a closed loop. For example a chain or a rope formed into a closed loop. In certain embodiments the material of the flexible closed loop should be a type having an essentially constant length, ie not very stretchable. Two examples of such flexible elongated elements with an essentially constant length are a chain and a rope with a braided steel wire core. The flexible elongated element will typically have a width/diameter/thickness.

The term "vertical orientation" should be understood in that the closed loop is hung up so that it hangs from the loop supporting frame. Typically, the closed loop will be arranged such that the closed loop is in a vertically arranged plane, however, due to the flexible nature of the flexible loop, the loop can be brought out of the vertically arranged plane.

The term "lifting element" should be understood as a play element which can be used to lift other elements. Some examples of lifting elements are a bucket like element, a sling, a hook and a shovel.

A typical use of such a play crane is in a sandbox, in a playground or in a sand or water play area where a child can move sand or water with a bucket like element as the lifting element. It should be noted that the play crane in certain embodiments shown in the figures is suitable for use with sand or water, but this should not linnit the play crane from being used with other substances as well. For example, the play crane of the current invention could also be used with dirt, mud, marbles, etc... However, the scope of protection should be limited to play cranes for playing and should not be expanded to include industrial cranes or other professional type cranes.

Description of related art

Play cranes as described above have been known in the art for many years. Figures 1 and 2 show examples of typical prior art type play cranes for playing with sand and water. In figure 1 , the crane comprises a frame 1 , a pulley 2 suspended at the top of the frame and a rope 3 running over the pulley and down to a bucket 4. The bucket 4 can be raised or lowered by pulling or releasing the rope 3 respectively. This type of play crane closely simulates real cranes. However, this type of play crane can be dangerous on a playground since children could get entangled in the rope and could get strangled. Another disadvantage with this type of play crane is that the rope needs to be quite long in order that it is possible to reach the rope when the bucket is on the ground. Another type of prior art type play crane is shown in figure 2. In this embodiment, a frame 1 is provided, again with a pulley 2 suspended at the top of the frame. However, this time, a rope 6 in the form of a closed loop 6 is provided. In this way, as the person pulls on the rope, the loop just rotates around and it will be easy to always get a hold of the rope no matter the position of the bucket. Since the bucket 4 is attached to one part of the loop, as the loop is rotated, the bucket moves up or down depending on the direction of motion of the loop. This type of play crane can however also be dangerous on a playground since it is also possible to get tangled in the loop and possibly even get strangled. Summary of the invention

It is therefore a first aspect of the current invention to provide a play crane as mentioned in the introductory portion which is safe to use for children in a play area without any risk of getting tangled in the flexible closed loop.

A second aspect of the current invention is to provide a play crane which is easy to use for children. These aspects are provided according to the current invention by a play crane as mentioned in the opening paragraph where the play crane further comprises a barrier element arranged inside the flexible closed loop between two sides of the flexible closed loop at any location where the maximum possible displacement of a portion of the loop is greater than the minimum distance between the two sides of the flexible closed loop at the location of said portion; or where the loop supporting frame and the total length of the flexible closed loop are arranged and/or chosen such that the maximum possible displacement of any portion of the loop is less than the minimum distance between the two sides of the loop at the location of the portion.

In this way, it is prevented that the sides of the flexible closed loop can cross over each other and form loops which could be dangerous to the users of the play crane and/or bystanders. In one embodiment, the barrier element could extend upwardly from a lower portion of the loop supporting frame. This will be a typical situation where the bottom portion of the flexible closed loop will be narrow, therefore a barrier element located at the bottom of the loop will provide a greater degree of safety. In one embodiment, the loop supporting frame and the flexible closed loop could be arranged such that the total length of the flexible closed loop could be chosen so that the flexible closed loop does not bind on the loop supporting frame when the flexible closed loop is displaced around the loop supporting frame. In one embodiment, the length is at least 20mm greater than the minimum length of the flexible closed loop around the loop supporting frame. In other embodiments, the length is at least 30mm greater, at least 40mm greater or at least 50mm greater than the minimum length of the flexible closed loop around the loop supporting frame.

The phrase "minimum length of the flexible closed loop around the loop supporting frame" should be understood as the minimum length of loop which would still be able to pass entirely around the loop supporting frame. It should be understood, that as the thickness of the flexible closed loop increases, the minimum length of the flexible closed loop would increase. Likewise, as the thickness of the flexible closed loop decreases, the minimum length would also decrease. The term "thickness of the flexible closed loop" should be understood as referring to the thickness of the elongated element of which the flexible closed loop is made of. For example, in the case where the flexible closed loop is made of a chain, the thickness of the flexible closed loop should therefore be understood as the thickness of the chain.

In one embodiment, the total length of the flexible closed loop can be less than the minimum length of the flexible closed loop around the loop supporting frame plus 127mm plus the thickness of the flexible closed loop times pi. In other embodiments, instead of 127mm, the figures 120mm, 1 10mm, 100mm, or 90mm are used instead. According to this embodiment, it is prevented that a loop is formed in the flexible closed loop due to slack in the loop which would be unsafe for the users or the bystanders of the play crane. In one embodiment, the loop supporting frame could be pivotable about a vertical axis. This increases the play value of the play crane as the user of the crane can move the material in the bucket in more degrees of freedom. In another embodiment, the loop supporting frame comprises a lower elongated element around which the flexible closed loop passes. In one typical embodiment the lower elongated element connects two posts, which posts support a platform. In one beneficial embodiment, the barrier element could be a wall which extends upwardly and away from the lower elongated element. In one embodiment, the length of the wall or the width of the barrier element perpendicular to the plane of the flexible closed loop could be greater than 10cm, greater than 20cm, greater than 30cm or greater than 40cm.

In one embodiment of the crane where it is able to rotate about a vertical axis, the lower elongated element is a bar which could be angled slightly with respect to the horizontal. This is advantageous in the case where as the crane is rotated, the angle between the closed loop and the lower bar is changed. As the angle is changed, the distance across the bar for the closed loop also changes. Hence, the closed loop could tighten up around the loop supporting frame as the crane is pivoted. By slightly lifting the bar as the crane is pivoted, the tightness of the flexible closed loop can be adjusted. When the bar is angled slightly with respect to the horizontal, the tightness of the closed loop can be held more constant as the angle between the closed loop and the lower bar changes. In one embodiment, the bar is angled such that when the angle between the flexible closed loop and the bar is 90 degrees, the bar is lower than when the angle between the flexible closed loop and the bar is less than 90 degrees. In one embodiment, the bar could have two angled portions meeting at a common low point. The low point being arranged at the location where the angle between the flexible closed loop and the bar is 90 degrees. The two angled portions rising from both sides of the low point.

It should be emphasized that the term "comprises/comprising/comprised of when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

Brief description of the drawings

In the following, the invention will be described in greater detail with reference to embodiments shown by the enclosed figures. It should be emphasized that the embodiments shown are used for example purposes only and should not be used to limit the scope of the invention.

Figure 1 shows a prior art arrangement of a play crane. Figure 2 shows a second embodiment of a prior art arrangement of a play crane.

Figure 3 shows a playground play structure comprising two play cranes according to a first embodiment of the current invention.

Figure 4 shows a schematic representation of the play crane of figure 3 in cross section to better illustrate the invention.

Figure 5 shows a schematic representation of a second embodiment of a play crane according to the current invention. Figure 6 shows a schematic representation of a third embodiment of a play crane according to the current invention.

Figure 7 shows a schematic representation of a fourth embodiment of a play crane according to the current invention.

Detailed description of the embodiments

Figure 3 shows a playground structure 100 comprising a number of different structural play elements. These won't be described in detail here as many of them should be known to the person skilled in the art of playgrounds.

However, the main structure comprises a number of posts 102 mounted in the ground, a number of raised platforms 104 connected to and supported by the posts and a number of wall elements 106 arranged around the periphery of some of the platforms. Playground structures of this kind are well known in the art and can be assembled in many different ways. As such more details will not be provided here.

The playground structure also comprises two play cranes 1 10 according to the current invention. The two play cranes are essentially identical. The cranes comprise a closed chain loop 1 12 to which is connected a bucket 1 14. The crane further comprises an upper portion 1 16 which comprises a pipe 1 18 bent into an L shape. The chain loop 1 12 runs through the pipe where it enters the pipe at a first lower inner end 120 and exits the pipe at a second upper outer end 122. The base portion 124 of the pipe is pivotably attached to a post via a mounting bracket 126 such that the upper portion 1 16 of the crane can swivel about the base portion 124. As the upper portion of the crane is swivelled, the chain loop 1 12 is also displaced. A wheel 125 is attached to the base of the pipe section making it easy to pivot the crane. The chain loop 1 12 is also supported at its lower end via a lower bar 130. The lower bar 130 is integrated into the playground structure between two posts 102 and is arranged to pass through the chain loop at the lower end of the chain loop. The chain loop 1 12 is therefore supported by the upper portion 1 16 of the crane and the lower bar 130. The lower bar 130 and the upper portion 1 16 of the crane form a loop supporting frame according to the terminology of the current application. While not shown in the figures, the lower bar 130, or lower elongated element in another embodiment, could be provided with stop elements which limit the distance the lower portion o fhte flexible closed loop can displace in a direction parallel to the longitudinal axis of the lower bar. In one embodiment, the lower bar 130 could be a cylindrical elongated element. In one embodiment, the lower bar could be a metal pipe. In one embodiment, stop elements also in the form of elongated cylindrical elements could be arranged joined to the lower bar 130 and extending in a direction with a component which is perpendicular to the longitudinal axis of the lower bar. In one embodiment, the lower bar is a metal pipe and the stop elements are also metal pipes which are welded to the lower bar.

With reference to figure 4, it can be imagined that as the total length of the chain loop 1 12 is decreased, at some point, the chain loop will be tightly engaged with the loop supporting frame, ie tightly engaged with both the upper portion 1 16 of the crane and the lower bar 130. In this situation, it will be nearly impossible to operate the crane as there will be too much friction between the chain loop and the loop supporting frame 1 16,130. This can be considered to be the minimum length of the flexible closed loop around the loop supporting frame 1 16,130 and is shown by the thin dotted line 132 in figure 4.

It should be noted that the figures show the chain loop as a thin line.

However, in the real world, the chain loop, or other form of flexible closed loop, will have a thickness. The greater the thickness of the flexible closed loop, the greater will be the minimum length around the loop supporting frame.

In order to allow the crane to be used, it is necessary to make the total length of the chain loop at least slightly larger than the minimum length of the flexible closed loop. In the current example, the total length is approximately 60mm longer than the minimum length. This means that there is some space 131 between the bottom of the lower bar 130 and the bottom of the chain loop 1 12, see figure 4. One example recommendation with a chain loop, is to have enough space at the bottom of the loop such that there is a space of around 1 -2cm between the loop and the bottom part of the loop supporting frame.

It can also be imagined, again with reference to figure 4, that if the total length of the chain loop 1 12 were large enough, it would be possible for one side 1 12a of the loop to cross over the other side 1 12b of the loop. This would be dangerous for people using the crane since a small loop would be formed between the two sides of the chain which could cause a person to get entangled in it or even strangled. As such, a barrier element 134 is provided at the lower end of the chain loop 1 12 between the two sides 1 12a, 1 12b of the chain loop. This barrier element 134 prevents the chain loop from crossing over itself at its lower end. In the current embodiment of a

playground structure, this barrier element 134 is provided in the form of a wall 106. The wall would be there in any case, and the crane is therefore arranged such that the two sides of the chain loop are arranged to pass on either side of the wall 106.

The height of the wall 106 (or the height of the barrier element 134) is chosen such that it is not possible for the two sides of the chain loop to get into contact with each other. With reference to figure 4, it can be imagined, that as the total length of the chain loop is increased, thereby increasing the amount of slack in the chain loop, the barrier needs to be made higher.

Likewise, the shorter the total length of the chain loop, the lower the height of the barrier needs to be. In the case where there is absolutely no slack in the chain loop and the chain loop is tightened around the loop supporting frame 1 16,130, then there would not really be any need of a barrier element.

However, as previously mentioned, some slack is necessary to operate the crane.

Likewise, if one considers the length of the upper portion of the crane, ie, the length of the "jib" or "swing arm" portion of the crane, then one could imagine that as the length of the upper portion was increased, then the height of the barrier could be decreased. Likewise, as the length of the upper portion was decreased, the height of the barrier should be increased. Hence the minimum safe height of the barrier element 134 will be dependent on the total length of the chain loop, the length of the upper portion of the crane and the minimum perimeter of the loop supporting frame.

Another consideration which should be kept in mind is that if the chain loop is made too long, then the chain can loop back on itself and a loop can be formed in a portion of the chain. This can be dangerous for users of the play crane. According to certain standards, the inside perimeter of the largest allowed loop is 127mm (5 inches). Hence, according to one embodiment of the current invention, the total length of the chain loop is at most 127mm plus the chain thickness times pi larger than the minimum length 132 of the flexible closed loop around the loop supporting frame. In the current embodiment, the total length of the chain loop is around 60mm larger than the minimum length around the loop supporting frame. In this case the maximum central perimeter of a loop that could be formed is 60mm.

Depending on the thickness of the chain, the actual inside perimeter will be smaller. In the embodiment shown in figures 3 and 4, the upper portion of the crane is formed as a tube 1 18 in which the chain is arranged. In this situation, there is no risk that the chain loop can cross over the part of the chain loop arranged at the upper portion of the crane since this part of the chain loop is arranged inside the tube. However, in a case where the upper portion of the crane does not comprise a tube, then it could be imagined that additional barrier elements could be necessary.

In the schematic embodiment shown in figure 5, the upper portion of the crane comprises two bars 140 (or two pulleys) around which the chain loop 1 12 is supported. In this embodiment, the loop supporting frame is defined by the two spaced apart upper bars 140 and the lower bar 130. In this case, there is a risk that the upper portion 1 12c of the chain loop arranged at the upper portion of the crane could cross over one of the two side portions 1 12a, 1 12b of the chain loop. Therefore, one could also arrange barrier elements 142 and/or 144 extending from the upper bars 140. For the sake of illustration, in the figure, two different options 142,144 of barrier elements are shown at either upper bar, but it would not be necessary to have both. It can be noted that the same considerations with regards to the necessary length of the barrier element as described previously with respect to the necessary height of the lower barrier element 132 can be made here.

Figure 6 shows a third embodiment of a play crane almost identical to the embodiment shown in figure 4, and as such, it will not be described in detail. However, instead of a barrier element in the form of a wall 134 arranged at the lower end separating the two sides 1 12a, 1 12b of the chain loop, in this embodiment, a barrier element is provided as a tube 150 in which one side 1 12b of the chain loop runs. Figure 7 shows a fourth embodiment of a play crane. In this embodiment, a horizontal table element 200 has been added inside the chain loop 201 . In this example, the outer sides 202 of the table will form a part of the loop supporting frame together with the top 203,204 and bottom bars 205, and as such that flexible closed loop must go around the table sides as well as the top and bottom bars. By choosing the length of the chain loop to be small enough, it will not be possible for the chain loop to cross itself, since the maximum possible displacement of a portion of the chain loop due to the slack in the chain loop will be smaller than the distance between opposing sides 201 a, 201 b of the chain loop at any location. It is to be noted that the figures and the above description have shown the example embodiments in a somewhat simple and schematic manner. Many of the specific mechanical details have not been shown since the person skilled in the art should be familiar with these details and they would just unnecessarily complicate this description.