Patent Description:
Recently it has become more desirable that the passenger cabin of an aircraft may be used in a more flexible manner. In particular, since the number of passengers during flights varies to a larger extent than in the past, it is often desired that part of the passenger cabin may also be used for cargo. To this end cargo supports which are movable along the floor of the passenger cabin have been developed.

<CIT> discloses a cargo container that is provided with engagement parts arranged at the four corners on both the bottom surface and top surface of an outer shell. These parts can be engaged with a spreader of a container crane. The container also includes wheels that can support it to enable travel. The wheels are designed to be switchable between a travelable state, where at least the lowest part is positioned lower than the bottom surface of the cargo container so that the wheels can support the container during travel, and a mounted state, where the wheels move towards the inner side from the bottom surface so that the bottom surface can come into contact with the mounting surface of the cargo container.

<CIT> discloses a caster provided with a caster body and a supporting body. The caster body has a wheel and a guided part composed of a portion of a shaft member that constitutes the shaft center of the wheel. The supporting body includes a supporting part that supports the guided part so that the wheel can project below the placement surface of the supporting body to roll on a floor. The supporting body has an allowable space that allows the guided part to move within it. Thus, the guided part can move in the allowable space between a first position, where the guided part is supported by the supporting part, and a second position, where the supporting body is placed on the floor with the lower end of the wheel at the same height as the placement surface. <CIT> discloses retractable caster mechanisms.

In this regard it is to be noted that the term "cargo support" in the sense of the present invention has a broad meaning and covers any kind of support member which is configured to carry cargo elements such as large items, luggage etc. and has a base member comprising a bottom surface and a support surface, the support surface being configured to support the cargo elements. However, it is not required that the cargo support also comprises flexible or rigid wall members such as lateral and top walls which define a receiving space for the cargo elements. Instead, such wall members are merely optional, and the term "cargo support" encompasses also those supports that do not comprise a flexible or rigid enclosure for the cargo elements.

However, the floor of the passenger cabin of an aircraft is often configured such that it may only bear limited point loads. This in turn limits the maximum weight that can be carried by a cargo support especially, when the latter comprises wheels on its bottom surface so as to allow to move the cargo support along the floor surface. These wheels may apply significant point loads to the floor surface especially during landing when high inertia forces in the Z-direction occur in addition to the gravitational forces.

On the other hand such wheels are required, since the passenger cabin does not comprise a cargo loading system, i.e., means on the floor of the passenger cabin that move cargo supports along the floor surface, and the cargo supports have to be moved to the desired position in the cabin by personnel.

In order to increase the maximum weight carried by a cargo support in the passenger cabin, the supports may be arranged such that they vertically abut on the seat rails which may carry higher loads than other regions of the floor of the passenger cabin. However, this requires that the entire cargo support is lowered to such an extent that support sections on the bottom surface of the cargo support will rest on the seat rails. In order to achieve this the wheel members must be vertically adjustable and the position must be actively adapted when the cargo supports have reached their final positions in the passenger cabin.

Another problem with the cargo supports having wheels at its bottom surface occurs when such supports are maneuvered across elements projecting from other portions of the floor surface such as steps are seat rails. After having passed such elements the wheels on the bottom surface of the cargo supports will impinge onto the lower regions of the floor which results in high point loads in those regions adjacent to the aforementioned elements having a greater height.

Hence, it is the object of the present invention to provide a cargo support which may be maneuvered over a floor surface on wheels wherein the maximum loads applied to the surface is limited both when the cargo support is maneuvered and after having reached its final position.

This object is achieved by a movable cargo support for being received in the cargo hold or passenger cabin of an aircraft comprising:
a base member having a support surface and a bottom surface opposite the support surface, wherein the support surface is adapted to support one or more cargo elements, wherein the bottom surface comprises one or more support sections, which are adapted to support the base member on a floor surface, and wherein the one or more support sections extend in a common support plane, wherein the base member comprises a plurality of wheel assemblies, wherein each wheel assembly comprises a wheel member which may rest on a floor surface and is rotatable about a rotation axis that is parallel to the support plane, the wheel member being movably mounted on the base member such that it may pivot about a steering axis of that wheel assembly which steering axis extends perpendicular to the support plane and that its position parallel to the steering axis may be altered between an extended position and a retracted position, wherein in the extended position the wheel member protrudes beyond the support plane, wherein in the retracted position the wheel member is retracted from the support plane towards the support surface, so that it does not extend beyond the support plane, wherein each wheel assembly comprises a biasing member biasing the wheel member towards the extended position with a biasing force acting in the direction of the pivot axis, and wherein the biasing member is configured such that the biasing force is higher than the maximum gravitational force which acts on the wheel member and forces it towards the retracted position when the wheel members are placed on a horizontal floor surface and one or more cargo elements are placed on the support surface having the maximum allowable weight of the one or more cargo elements for the cargo support and wherein the biasing force exceeds the maximum gravitational force by <NUM> % at most.

Hence, the cargo support of the present invention comprises a base member or base plate which is provided with a normally upwards pointing support surface and a downward pointing bottom surface so that the latter is opposite the support surface. The support surface is adapted to carry one or more cargo element wherein the term "cargo element" in the sense of the present invention is to be understood broadly, i.e., it covers luggage, large items etc. Furthermore, the present invention does not require that the cargo support comprises rigid or flexible wall members defining a receiving space. Instead, the present invention also covers cargo supports being merely in the form of a plate member and do not comprise wall elements encompassing a space for receiving the cargo elements.

The bottom surface of the base member comprises one or more support sections which are configured such that they extend in a common support plane and the base member is adapted such that it may be supported on a horizontal floor surface by the support sections which then are in contact with the floor surface, i.e., the entire bottom surface of the base member is configured such that it does not comprise additional elements which permanently extend beyond the common support plane and prevent the support sections from being in direct contact with a floor surface.

Moreover, according to the present invention the base member comprises a plurality of wheel assemblies each of them comprising a wheel member which is rotatable about a rotation axis extending parallel to the support plane. The wheel member of each of the wheel assemblies is steerable, i.e., it may pivot about a steering axis of the respective wheel assembly which extends perpendicularly to the support plane. In addition, for the wheel member of each of the wheel assemblies the position relative to the steering axis may be altered between an extended position and a retracted position such that the wheel member may project beyond the common support plane when being in the extended position and being retracted towards the support surface so that it does not extend beyond the common support plane.

Finally, each wheel assembly is provided with a biasing member that biases the wheel member into the extended position. The biasing member is configured such that the biasing force acting on the wheel member is chosen such that it is higher than the maximum gravitational force which is applied to the wheel member when the support surface carries the maximum allowable weight and which forces the wheel member towards the retracted position. Further the biasing force exceeds the maximum gravitational force <NUM> % at most, i.e., the biasing member exerts a force on the wheel member which pushes the wheel member towards the extended position and which is <NUM> times as high as the maximum gravitational force as specified before.

With this latter feature is achieved that even when the cargo support of the present invention carries cargo elements having the maximum allowable weight, the wheel members of the wheel members are in the extended position so that the cargo support may be maneuvered across a floor surface of a cargo hold or passenger cabin with the wheel members rolling thereon. However, when for example during landing in addition to the gravitational forces further inertia forces act in the vertical direction and the biasing force is exceeded, the wheel members will be shifted towards the retracted position so that the support sections of the base member will come into contact with the floor surface or at least projecting members thereon and high point loads due to the limited contact surface between the wheel members and the floor surface are avoided in such situations. In particular, in order to ensure that in case of high forces acting in the direction perpendicular to the floor surface no extreme point loads will be applied to the floor surface, it is not necessary with the design of the present invention to lower the cargo support by actively retracting the wheel members such as by actuating a corresponding mechanism. Instead, due to the choice of the biasing force according to the present invention, such retraction is automatically effected.

Moreover, when the cargo support of the present invention rolls with its wheels over a step such as the light strip and thereafter impinges onto the floor surface adjacent to the strip, the point loads applied by the wheel members will also be limited, since in case the forces applied in such situations on the wheel members exceed the biasing force, the wheel members will be retracted and the support sections will get into contact with the floor surface so that high point loads are prevented as well.

In a preferred embodiment, the biasing member is configured such that the biasing force exceeds the maximum gravitational force by <NUM> % at most, preferably by <NUM> % at most, which acts on the wheel member and pushes it towards the retracted position when the wheel members are placed on a floor surface and one or more cargo elements are placed on the support surface having the maximum allowable weight of the one or more cargo elements for the cargo support. When these values are chosen, the wheel assembly is even more sensitive to situations where the applied forces exceed the limit at which the floor surface on which the cargo support is currently resting, may be damaged due to too high point loads.

Furthermore, it is preferred that in each wheel assembly the steering axis and the rotation axis are arranged such that when seen in the support plane the rotation axis is at a distance from the steering axis. Thus, in a preferred embodiment the rotation axis of the wheel member is eccentrically arranged relative to the steering axis, which has the effect that the wheel members align themselves to the direction along which the cargo support is maneuvered by a user.

In a further preferred embodiment, each wheel assembly comprises a mount member fixedly supported on the base member and a carrier assembly, wherein the carrier assembly is rotatably supported on the mount member about the steering axis of the wheel assembly and the wheel member of the wheel assembly is rotatably supported about the rotation axis on the carrier assembly. When the wheel assemblies comprise a mount member and a carrier assembly being separate from the base member, the wheel assemblies can easily be replaced in case of a malfunction.

Furthermore it is preferred, that the carrier assembly comprises a carrier member rotatably coupled to the mount member about the steering axis, and an arm member, wherein a first end of the arm member is pivotably connected to the carrier member about a pivot axis which is parallel to the rotational axis, and a second end of the arm member opposite the first end carries the wheel member, and wherein the biasing member is arranged between the carrier member and the arm member. With such configuration where the wheel member is supported on the distal end of a pivotably mounted arm member, the biasing member can be formed in a simple manner such as in the form of a helical spring or the gas spring, the biasing force of which can precisely be adjusted. Thus, with such kind of mechanism the threshold defined by the biasing force at which the wheel members move to the retracted position, can easily be adapted to the specific conditions of the cargo support at issue.

In another preferred embodiment, the wheel member comprises a first wheel and a second wheel which are spaced along the rotational axis and supported on a shaft member, wherein the arm member and/or the biasing member extends between the first and second wheels. With such arrangement the contact surface between the wheel member and the floor surface can be enlarged. In addition, such arrangement allows to arrange the carrier assembly, such as the carrier member and the arm member, and or the biasing member in the center of the wheel assembly which in turn is a space-saving arrangement for a given contact area.

In another preferred embodiment the biasing member is formed as ring member, preferably a circular ring member, wherein the ring member extends in a plane perpendicular to the pivot axis, wherein the ring member is arranged between the carrier member and the arm member, wherein the ring member is supported on the arm member at a point spaced from the pivot axis and on the carrier member such that when the arm member pivots towards the mount member, the ring member is elastically deformed. Since the biasing forces are significant, which have to be chosen so as to fulfil the above requirement that the wheel members move to the retracted position only in those cases where the maximum gravitational forces occurring with a maximum weight on the support surface of the cargo support is exceeded, the biasing member must have a significant stiffness which can be achieved in a simple manner when using a ring member, preferably formed of steel, as a biasing member.

Moreover, it is preferred that when seen along the pivot axis the cross section of the carrier member has a coupling section extending perpendicularly to the steering axis and being rotatably coupled to the mount member, and an arm section extending away from the mount member with a distal end spaced from the coupling section along the steering axis, wherein the first end of the arm member is pivotably coupled to the distal end of the arm section, and wherein the ring member is supported on the coupling section. With the coupling section extending perpendicularly to the steering axis a support portion for the upper part of the ring member is provided so that it is supported on the one hand by the coupling portion and on the other hand by the arm member. This in turn allows for the ring member to be squeezed when the wheel member moves towards the retracted position by a pivoting movement of the arm member. In this way the required deformation of the wheel member generating the biasing force can be achieved in a mechanically simple manner.

Finally, it is preferred that the first end of the arm member is coupled to the carrier member by a bolt member, wherein the wheel member comprises a shaft member which is carried by the arm member at its second end, and wherein the ring member is support via the bolt member and the shaft member. In such arrangement the bolt member and the shaft member may directly or indirectly supported the ring member. In particular, it is conceivable that the shaft member and the board member carry brackets which in turn supports the ring member. Since the in such arrangement the ring member either arrests on the boat member and the shaft member just along a narrow line or the bracket pivots to get well maybe may pivot relative to the arm member the friction between the ring member and its support during the formation is significantly reduced. This in turn allows that the above mentioned threshold can precisely be adjusted and not is not altered due to friction effects.

In the following a preferred embodiment of the present invention is described with respect to the attached drawing.

As can be taken from <FIG> the preferred embodiment of a cargo support <NUM> according to the present invention comprises a base member <NUM> which is essentially planar and formed as a rigid body comprising an upper support surface <NUM> and a downwardly pointing bottom surface <NUM> which during normal use of the cargo support <NUM> may face a floor surface <NUM> of the floor <NUM> of a cargo hold or passenger cabin. The bottom surface <NUM> comprises a plurality of support sections <NUM> which extend in a common support plane <NUM>. The bottom surface <NUM> of the base member <NUM> is further configured such that it does not comprise any rigid elements which permanently project beyond the support plane <NUM>, i.e., the base member <NUM> may rest on the floor surface <NUM> of the floor <NUM> when the wheel members <NUM> of the wheel assemblies <NUM> are in a retracted position as it will be discussed in more detail below.

A first alternative of the configuration of the wheel assemblies <NUM> arranged in the bottom surface <NUM> of the cargo support <NUM> of <FIG> is shown in detail in <FIG>. As can be taken from <FIG> the wheel assembly <NUM> comprises a mount member <NUM> which is configured to be fixedly attached in a recess in the bottom surface <NUM> of the base member <NUM>. On the bottom side of the mount member <NUM> a carrier member <NUM> is rotatably mounted via a bearing <NUM> so that the carrier member <NUM> may rotate about the amount member <NUM> about a steering axis <NUM>. In the present embodiment the carrier member <NUM> may rotate and not just pivot relative to the mount member <NUM>. However, for the present invention it would suffice when just a pivot movement within a limited angular range would be possible for the carrier member <NUM>.

The carrier member <NUM> comprises a coupling section <NUM> which when looking at the crosssection parallel to the steering axis <NUM> essentially extends perpendicularly to the steering axis <NUM> and is rotatably coupled to the mount member <NUM>. Attached to the coupling section <NUM> are arm sections <NUM>, which extend away from the mount member <NUM>, the arm sections <NUM> having a distal end <NUM> at which arm members <NUM> are pivotably mounted via a bolt member <NUM> so that the arm members <NUM> may pivot relative to the arm sections <NUM> and hence the carrier member <NUM> about a pivot axis <NUM> extending perpendicularly to the steering axis <NUM>. The pivot axis <NUM> also extends in parallel to the common support plane <NUM>. The carrier member <NUM> and the arm members <NUM> form a carrier assembly which is rotatable relative to the mount member <NUM> and which rotatably supports the wheel member <NUM>.

Whereas a first end of the arm members <NUM> is pivotably coupled to the arm sections <NUM> and hence the carrier member <NUM>, a second end of the arm members <NUM> opposite the first end carries the wheel member <NUM> wherein in this preferred embodiment the wheel member <NUM> comprises a first wheel <NUM> and a second wheel <NUM> which are supported by a shaft member <NUM> that defines the rotational axis <NUM> about which the wheels <NUM>, <NUM> and hence the wheel member <NUM> may rotate. As can be seen in <FIG> the rotational axis <NUM> and the pivot axis <NUM> are parallel to each other.

Moreover, as can be taken from <FIG>, the projection of the rotation axis <NUM> on the common support plane <NUM> is spaced from the point where the steering axis <NUM> intersects the common support plane <NUM>. Hence, when seen in the support plane <NUM> the rotation axis <NUM> and the steering axis <NUM> are at a distance from each other or spaced apart, and the wheels <NUM>, <NUM> are eccentrically mounted with respect to the steering axis <NUM>. Such arrangement has the advantage that when the cargo support <NUM> is maneuvered along a certain predetermined direction the wheel members <NUM> will align themselves with this direction.

Finally, as shown in <FIG> the wheel assembly <NUM> comprises a biasing member in the form of a ring member <NUM>, which in this preferred embodiment is circular and formed of steel. The ring member <NUM> is supported on the one hand by the bolt member <NUM> and the shaft member <NUM> and on the other hand by the coupling section <NUM>. Further, the ring member <NUM> is arranged between the first and second wheels <NUM>, <NUM> in the gap formed between them. the ring member <NUM> extends in a plane perpendicular to the pivot axis (<NUM>),.

So, the ring member <NUM> is arranged between the carrier member <NUM> and the arm member <NUM> and supported on the arm member <NUM> at a point spaced from the pivot axis <NUM> and on the carrier member <NUM> such that when the arm member <NUM> pivots towards the mount member <NUM>, the ring member <NUM> is elastically deformed.

When the ring member <NUM> is in the un-deformed state as shown in <FIG>, the wheels <NUM>, <NUM> are in an extended position and extend beyond the common support plane <NUM>, as can be seen in <FIG>. However, when a sufficiently high force acts on the wheels <NUM>, <NUM> pushing them towards the coupling section <NUM> and the mount member <NUM>, the ring member <NUM> will elastically be deformed and the arm members <NUM> pivot towards the coupling section <NUM> so that the wheels <NUM>, <NUM> are retracted from the support plane <NUM> towards the support surface <NUM> and they do not extend beyond the support plane <NUM> but are received in the recesses in the base member <NUM> and assume a retracted position. However, when the wheels <NUM>, <NUM> are in this retracted position, the ring member <NUM> acts as a biasing member which applies a biasing force to the wheels <NUM>, <NUM> which forces them towards the extended position.

Thus, the position of the wheels <NUM>, <NUM> may be altered between an extended position and a retracted position against the biasing force of the biasing member in the form of the ring member <NUM>, the biasing force mainly acting along the steering axis <NUM>.

The ring member <NUM> is dimensioned in such a manner that the biasing force it applies to the wheel member <NUM> and the wheels <NUM>, <NUM> in the direction of the steering axis <NUM> towards the extended position has such a magnitude that it exceeds the maximum gravitational force by <NUM> % at most which acts on the wheel member <NUM> and forces it towards the retracted position when all the wheel members <NUM> of the cargo support <NUM> are placed on the floor surface <NUM> and one or more cargo elements are placed on the support surface <NUM> having the maximum allowable weight of the one or more cargo elements for the cargo support. It is preferred when the biasing member in the form of the ring member <NUM> is configured such that the biasing force it applies exceeds the maximum gravitational force by <NUM> % at most, more preferably by just <NUM> % at most. With such preferred configuration the wheel assembly <NUM> is even more sensitive to situations where the applied forces exceed the limit at which the floor <NUM> on which the cargo support <NUM> is currently resting, may be damaged.

Thus, when the support surface <NUM> of the embodiment of the cargo support <NUM> carries a cargo element having the maximum allowable weight for the cargo support <NUM>, the wheel members <NUM> will still be in the extended position and project beyond the common support plane <NUM>, so that the cargo support <NUM> can be maneuvered over a floor surface <NUM> with the wheels <NUM>, <NUM> rolling over the surface <NUM>. However, when the embodiment of the cargo support <NUM> is subjected to additional forces, e.g., during landing, which act also parallel to the steering axis <NUM> and which add up to the already mentioned gravitational forces, the biasing force of the ring member <NUM> is exceeded, so that the wheel members <NUM> will move from the extended position to the retracted position, and the support sections <NUM> on the bottom surface <NUM> of the base member <NUM> will come into contact with the floor surface <NUM>, as it is shown in <FIG>. Thus, the entire cargo support <NUM> is then no longer supported by the wheel members <NUM> only but by the support sections <NUM>, so that high point loads to which the floor surface <NUM> will be subjected at the positions of the wheels <NUM>, <NUM>, are avoided. Instead, the entire load due to the cargo unit <NUM> is then transferred to the floor surface <NUM> via the support sections <NUM> having a much larger contact surface.

<FIG> and <FIG> show an alternative configuration of the wheel assembly <NUM> to be mounted in the bottom surface <NUM> of the base member <NUM>. However, this second alternative does not essentially differ from the first alternative shown in <FIG>. It also comprises a mount member <NUM> which is adapted to be fixedly mounted on the base member <NUM>. Rotatably coupled to the mount member <NUM> about a steering axis <NUM> is a carrier member <NUM> comprising a coupling section <NUM> and arm sections <NUM>, the coupling section <NUM> extending essentially perpendicularly to the steering axis <NUM> and the arm sections <NUM> extending away from the mount member <NUM> and having a distal end spaced from the coupling section <NUM> along the steering axis <NUM>.

At the distal end of the arm sections <NUM> arm members <NUM> are pivotably supported about a pivot axis <NUM> via bolt members <NUM>. Hence, also in this case the first end of the arm members <NUM> is supported at the distal end of the arm sections <NUM> by means of bolt members <NUM>, and the second end of the arm members <NUM> carries shaft members <NUM> which define a rotational axis for first and second wheels <NUM>, <NUM> which are supported on the shaft members <NUM> and which form a wheel member <NUM>. As can further be taken from the left part of <FIG>, the rotational axis <NUM> is spaced from the steering axis <NUM> when seen in the support plane <NUM>, so that also in this alternative the rotational axis <NUM> is eccentrically arranged relative to the steering axis <NUM>.

As can be taken from <FIG> and <FIG>, both the bolt members <NUM> and the shaft members <NUM> each carry a bracket <NUM>, <NUM>, and the ring member <NUM> which also in this alternative acts as a biasing member is supported in the brackets <NUM>, <NUM>. Thus, in this embodiment the ring member <NUM>, which is also arranged between the wheels <NUM>, <NUM>, is not directly supported on the bolt members <NUM> and the shaft members <NUM> but carried by additional brackets <NUM>, <NUM> so that the bolt members <NUM> and the shaft members <NUM> only indirectly carry the ring member <NUM>.

In this second alternative the ring member <NUM> is also dimensioned such that the biasing force it applies to the wheels <NUM>, <NUM> in the direction of the steering axis <NUM> towards the extended position has such a magnitude that it exceeds that force by X % at most which acts on the wheel member <NUM> and forces it towards the retracted position when all the wheel members <NUM> of the cargo support <NUM> are placed on the floor surface <NUM> and cargo elements having the maximum allowable weight are placed on the support surface <NUM>. Therefore, when using this second alternative of a wheel assembly <NUM> in the cargo support <NUM> the same behavior as described above will be achieved, i.e., when in addition to the gravitational forces further inertia forces act in the direction of the steering axis <NUM>, the wheel members <NUM> will be pushed towards the retracted position against the biasing force applied by the ring member, and the support sections <NUM> will get into contact with the floor surface so as to reduce the point loads.

Finally, <FIG> shows a further alternative of a wheel assembly <NUM> to be coupled with the base member <NUM> of the cargo unit <NUM> of the present invention.

It also comprises a mount member <NUM> which is adapted to be fixedly mounted on the base member <NUM>. A carrier member <NUM> comprising a coupling section <NUM> and arm sections <NUM> is rotatably coupled to the mount member <NUM> about a steering axis <NUM> via a bearing <NUM>. The coupling section <NUM> extends essentially perpendicularly to the steering axis <NUM> and the arm sections <NUM> project away from the mount member <NUM> and have a distal end spaced from the coupling section <NUM> along the steering axis <NUM>. On the distal ends of the arm sections <NUM> arm members <NUM> are pivotably supported about a pivot axis <NUM> via bolt members <NUM>. So, also in this third alternative the first end of the arm members <NUM> is supported at the distal end of the arm sections <NUM> by means of bolt members <NUM>, and the second end of the arm members <NUM> carries a shaft member <NUM> which defines a rotational axis <NUM> for first and second wheels <NUM>, <NUM> which are supported on the shaft member <NUM> and which form a wheel member <NUM>.

As can further be taken from <FIG>, the rotational axis <NUM> is spaced from the steering axis <NUM> when seen in the support plane <NUM>, so that also in this third alternative the rotational axis <NUM> is eccentrically arranged relative to the steering axis <NUM>.

In this third alternative of a wheel assembly <NUM> a gas spring <NUM> is employed as a biasing member rather than a ring member, the gas spring <NUM> being arranged between the distal end of the arm member and <NUM> and the arm section <NUM>. In particular, the gas spring <NUM> is coupled to the distal end of the arm member <NUM> via the shaft member <NUM>, which also carries one end of the gas spring <NUM>. Thus, it is also possible to use linearly acting biasing members for applying the biasing force onto the wheel members <NUM>.

In particular, also in this third alternative the biasing member in the form of the gas spring <NUM> is dimensioned such that the biasing force it applies to the wheels <NUM>, <NUM> in the direction of the steering axis <NUM> towards the extended position has such a magnitude that it exceeds that force by X % at most which acts on the wheel member <NUM> and forces it towards the retracted position when all the wheel members <NUM> of the cargo support <NUM> are placed on the floor surface <NUM> and cargo elements having the maximum allowable weight are placed on the support surface <NUM>.

Therefore, when using also this third alternative of a wheel assembly <NUM> in the cargo support <NUM> the same behavior as described above will be achieved, i.e., when in addition to the gravitational forces further inertia forces act in the direction of the steering axis <NUM>, the wheel members <NUM> will be pushed towards the retracted position against the biasing force applied by the ring member, and the support sections <NUM> will get into contact with the floor surface so as to reduce the point loads.

Besides the scenario described with respect to <FIG> and <FIG>) other scenarios are also conceivable where the afore-mentioned configuration with wheel assemblies <NUM> having wheels members <NUM> that are forced towards an extended position via a biasing member that is chosen such that the force it applies exceeds the gravitational forces by only a small amount, prevents sections of a floor from being damaged by high point loads applied by the wheel members <NUM>. As it is shown in <FIG>) and <FIG>) the cargo support <NUM> may also be positioned above seat rails <NUM> in the floor <NUM> having locking members <NUM> inserted therein, wherein the cargo unit <NUM> is positioned such that the locking members <NUM> engage with recesses in the support section <NUM> of the cargo unit <NUM> and prevent the cargo unit <NUM> from being moved relative to the floor surface <NUM>. When in such case in addition to the gravitational forces due to the weight of cargo elements arranged on the support surface <NUM> further inertia forces act on the cargo support <NUM> in a direction parallel to the steering axis <NUM>, the wheel members <NUM> of the wheel assemblies <NUM> are pushed towards the retracted position since the biasing force generated by the biasing the members does not suffice anymore to keep the support sections <NUM> spaced from the seat rails <NUM>. Instead, the support sections <NUM> approach the seat rails <NUM> and get into contact with them. Hence, when large forces occur in such situation, a high point loads due to the wheel members <NUM> are avoided since the support sections <NUM> contact the seat rails <NUM>.

Finally, in <FIG>) another situation is shown in which with the cargo unit <NUM> of the present invention it can be avoided that high point loads are applied onto a floor surface <NUM> by the wheel members <NUM>. In this case some wheel members <NUM> of wheel assemblies <NUM> are positioned on a light strip <NUM> or seat rail <NUM>. However, due to the choice of the biasing force of the wheel assemblies <NUM> positioned on the rails, the respective wheel members <NUM> will be pushed towards the retracted position so that the other wheel members <NUM> will still contact the floor surface <NUM>.

Claim 1:
A movable cargo support (<NUM>) for being received in the cargo hold or passenger cabin of an aircraft comprising:
a base member (<NUM>) having a support surface (<NUM>) and a bottom surface (<NUM>) opposite the support surface (<NUM>),
wherein the support surface (<NUM>) is adapted to support one or more cargo elements,
wherein the bottom surface (<NUM>) comprises one or more support sections (<NUM>), which are adapted to support the base member (<NUM>) on a floor surface (<NUM>), and
wherein the one or more support sections (<NUM>) extend in a common support plane (<NUM>),
wherein the base member (<NUM>) comprises a plurality of wheel assemblies (<NUM>),
wherein each wheel assembly (<NUM>) comprises a wheel member (<NUM>) which may rest on a floor surface (<NUM>) and is rotatable about a rotation axis (<NUM>) that is parallel to the support plane (<NUM>), the wheel member (<NUM>) being movably mounted on the base member (<NUM>) such
- that it may pivot about a steering axis (<NUM>) of that wheel assembly (<NUM>) which steering axis (<NUM>) extends perpendicularly to the support plane (<NUM>) and
- that its position parallel to the steering axis (<NUM>) may be altered between an extended position and a retracted position,
wherein in the extended position the wheel member (<NUM>) protrudes beyond the support plane (<NUM>),
wherein in the retracted position the wheel member is retracted from the support plane (<NUM>) towards the support surface (Ziffer <NUM>), so that it does not extend beyond the support plane (<NUM>),
wherein each wheel assembly (<NUM>) comprises a biasing member (<NUM>, <NUM>) biasing the wheel member (<NUM>) towards the extended position with a biasing force acting in the direction of the steering axis (<NUM>), and
wherein the biasing member (<NUM>, <NUM>) is configured such that the biasing force is higher than the maximum gravitational force which acts on the wheel member (<NUM>) and forces it towards the retracted position when the wheel members (<NUM>) are placed on a horizontal floor surface (<NUM>) and one or more cargo elements are placed on the support surface (<NUM>) having the maximum allowable weight of the one or more cargo elements for the cargo support (<NUM>) and wherein the biasing force exceeds the maximum gravitational force by <NUM> % at most.