A rack and a system

Abstract

A rack (10) for storing an item (2), the rack (10) comprising: an aisle (20), having an aisle rail (22), being a rail extending along the aisle (20); and a plurality of rows (30), each row (30) having a respective entrance (35) at the aisle (20) and a respective row rail (32), being a rail extending along the row (30); wherein the rack (10) is configured to allow transport of the item (2) in the rack (10) by an aisle cart (40) and a row cart (60), wherein the aisle cart (40) travels on the aisle rail (22) and transports the row cart (60) and the item (2) to the entrance (35) of a designated row (30) and the row cart (60) travels on the row rail (32) and transports the item (2) from the aisle cart (40) to a storage position (16) in the designated row (30); wherein each row rail (32) comprises an upper horizontal surface (82) for supporting the item (2) and a lower horizontal surface (81) for a wheel (66) of the row cart (60) to travel on, wherein both the upper (82) and lower (81) horizontal surfaces comprise an inner side (82i, 81i), facing a center axis of the row (30), and an outer side (82o, 81o), facing away from the center axis of the row (30); wherein the outer side (81o) of the lower horizontal surface (81) is connected to the inner side (82i) of the upper horizontal surface (82) by a side surface (183), the inner side (82i) of the upper horizontal surface (82) being further away from the center axis of the row (30) than the outer side (81o) of lower horizontal surface (81).

Description

[0001] A RACK AND A SYSTEM

[0002] TECHNICAL FIELD

[0003] The present inventive concept relates, in general, to storage of items in a rack.

[0004] BACKGROUND

[0005] Automated storage systems are often used in warehouses and distribution facilities. Such a system may comprise a rack, wherein automated vehicles transport items to and from their storage positions in the rack. The rack often comprises several stories, wherein each story comprises aisles and rows. For each aisle, there are generally a plurality of rows extending from the aisle, wherein the items are stored in the rows.

[0006] There are many types of automated vehicles that can be used to transport items within the rack. In some cases, aisle carts and row carts are used. The aisle cart transports the row cart and the item to the entrance of a row. The row cart then leaves the aisle cart and carries the item into the row and places the item at the storage position in the row.

[0007] SUMMARY

[0008] It is an objective of the present inventive concept to enable fast transport of an item in a rack, by an aisle cart and a row cart. It is a further objective to prevent congestion in the rack. It is a further objective to enable a simple and / or low cost aisle cart. It is a further objective to enable a simple and / or low cost row cart. It is a further objective to enable a simple and / or low cost rack.

[0009] These and other objectives of the inventive concept are at least partly met by the invention as defined in the independent claims. Preferred embodiments are set out in the dependent claims.

[0010] According to a first aspect there is provided a rack for storing an item, the rack comprising: an aisle, having an aisle rail, being a rail extending along the aisle; and a plurality of rows, each row having a respective entrance at the aisle and a respective row rail, being a rail extending along the row; wherein the rack is configured to allow transport of the item in the rack by an aisle cart and a row cart, wherein the aisle cart travels on the aisle rail and transports the row cart and the item to the entrance of a designated row and the row cart travels on the row rail and transports the item from the aisle cart to a storage position in the designated row; wherein each row rail comprises an upper horizontal surface for supporting the item and a lower horizontal surface for a wheel of the row cart to travel on, wherein both the upper and lower horizontal surfaces comprise an inner side, facing a center axis of the row, and an outer side, facing away from the center axis of the row; wherein the outer side of the lower horizontal surface is connected to the inner side of the upper horizontal surface by a side surface, the inner side of the upper horizontal surface being further away from the center axis of the row than the outer side of lower horizontal surface.

[0011] The item may be a pallet, with or without goods. Alternatively, the item may be any form of goods, crate or box.

[0012] The aisle may extend in a first direction. Each row may extend in a second direction from its respective entrance at the aisle. The first direction, in which the aisle extends, may be perpendicular to the second direction, in which the rows extend. There may be rows extending from the aisle both on the left and right side of the aisle.

[0013] The designated row may be any one of the plurality of rows in which the item is intended to be stored.

[0014] The rack may further comprise at least one loading position where the aisle cart may collect the item. The aisle cart may approach the loading position and collect the item by pulling the item onto the aisle cart, e.g. by using a belt conveyor of the aisle cart. The loading position may be a position at the edge of the rack. The loading position may be an elevator configured to transport the item to a designated story of the rack. The loading position may be a buffer conveyor, e.g. a buffer conveyor at a designated story of the rack, where items are waiting for further transport to their respective designated storage position. Thus, the aisle cart and row cart may be configured to move the item from the loading position, via the aisle and the designated row, to the storage position, or vice versa. The aisle comprises an aisle rail, being a rail extending along the aisle. The aisle may comprise a pair of aisle rails, e.g. a left rail for a left pair of wheels of the aisle cart to run on and a right rail for the right pair of wheels of the aisle cart to run on.

[0015] Each row comprises a row rail, being a rail extending along the row. Each row may comprise a pair of row rails, e.g. a left rail for a left pair of wheels of the row cart to run on and a right rail for the right pair of wheels of the row cart to run on.

[0016] The aisle cart may comprise a set of support wheels, e.g. four support wheels, e.g. a left pair of support wheels and a right pair of support wheels. One or more of the support wheels may be driven by a motor, e.g. a motor comprised in the aisle cart to propel the aisle cart along the aisle rail.

[0017] The row cart may comprise a wheel, e.g. a set of wheels, e.g. four wheels, e.g. a left pair of wheels and a right pair of wheels. One or more of the wheels of the row cart may be driven by a motor, e.g. a motor comprised in the row cart to propel the aisle cart along the row rail.

[0018] The aisle cart may comprise a platform, being configured to support the support wheel of the row cart while the aisle cart transports the row cart. When the aisle cart transports the row cart and the item along the aisle, the row cart may stand on the platform of the aisle cart. When the aisle cart transports the row cart and the item along the aisle, the item may stand on the belt conveyor.

[0019] The row cart may comprise a lifting device. Before the row cart transfers the item into the designated row, the row cart may lift the item using the lifting device. Thus, the item may be lifted up from the belt conveyor of the aisle cart. The lifting device may be configured to lift the item by lowering the support wheels of the row cart, e.g. lowering the support wheels of the row cart relative to the chassis of the row cart. In other words, a separation between the support wheels of the row cart and the chassis of the row cart may be increased to lift the item.

[0020] The row cart may run on the lower horizontal surface of the row rail. For example, a left pair of wheels of the row cart may run on the lower horizontal surface of a left row rail and a right pair of wheels of the row cart may run on the lower horizontal surface of a right row rail. The row cart may keep the item lifted while running on the lower horizontal surface of the respective left and right row rail. Thus, the item may be lifted above the upper horizontal surface of the row rail. The row cart may place the item at the storage position in the designated row by lowering the item using the lifting device. The lifting device may be configured to lower the item by raising the wheels of the row cart, e.g. raising the wheels of the row cart relative to the chassis of the row cart. In other words, a separation between the support wheels of the row cart and the chassis of the row cart may be reduced to lower the item. Thus, the item may be placed on the upper horizontal surface of the row rail, e.g. placed on the upper horizontal surface of the respective left and right row rail.

[0021] The row cart may normally enter a row by leaving the aisle cart at the entrance of said row and driving into said row. Similarly, the row cart may normally leave a row by driving onto the aisle cart at the entrance of said row. However, it is a realization that there may be situations where the row cart enters or leaves a row in other ways. For example, there may be situations where it is advantageous to lift the row cart into or out of the row. To further exemplify, the row cart may be lifted into or out of the row manually by service staff or by a machine (e.g. forklift), e.g. for the purpose of maintenance.

[0022] It is a realization that lifting the row cart into or out of the row is facilitated by the inner side of the upper horizontal surface of the row rail being further away from the center axis of the row than the outer side of lower horizontal surface of the row rail. The center axis of the row may be an axis in the second direction, in the center of the row. Accordingly, the upper horizontal surface of the row rail may cause little or no obstruction to the row cart as it is being lifted onto or off the lower horizontal surface of the row rail.

[0023] As the outer side of the lower horizontal surface is connected to the inner side of the upper horizontal surface by a side surface, the row cart may slide on the side surface towards the lower horizontal surface when being lifted into the row. Thus, the side surface may guide the row cart to a correct position. Accordingly, the precision requirements for the person or machine (e.g. forklift) lifting the row cart into the row is relaxed. This may in turn facilitate the row cart being lifted into the row quickly.

[0024] It is a further realization that congestion in the rack may be avoided by providing an alternative way for the row cart (with or without load) to enter or leave the row, in addition to entering / leaving the row from the aisle. This is facilitated by a row wherein the row cart easily can be lifted into or out of the row. To further exemplify, the row cart may be lifted into or out of the row, e.g. at a far end of the row. The far end being an end of the row opposite to the entrance of the row. The row cart may be lifted into or out of the row by e.g. a forklift or an elevator at the far end of the row. Thus, several row carts may simultaneously work in separate rows associated with the same aisle. If all row carts are dependent on the same aisle cart, congestion may arise. In such a situation the aisle cart and / or the aisle may not be able to service the row carts fast enough. Thus, row carts may need to wait for the aisle cart. However, if an alternative way for the row cart to enter or leave the rows is provided, congestion may be avoided.

[0025] It should be understood that each row rail of a pair of row rails may comprise an upper horizontal surface being further away from the center axis of the row than the outer side of lower horizontal surface of the row rail. Alternatively, only one row rail of a pair of row rails may comprise an upper horizontal surface being further away from the center axis of the row than the outer side of lower horizontal surface of the row rail.

[0026] The rack may be configured such that, for each row of the rack, the side surface of the row rail comprises a flat inclined surface, the inclined surface being inclined outwardly from the outer side of the lower horizontal surface towards the inner side of the upper horizontal surface. Thus, the row cart may easily slide on the flat inclined surface when being lifted into the row.

[0027] The upper and lower horizontal surfaces and the side surface of the row rail may be surfaces of one single metal sheet. When using a single metal sheet, joints may be avoided. Thus, a row cart may easily slide from one surface to another when being lifted into the row, without being caught and / or scratched by such joints. Further, easy and / or cheap manufacturing of the row rail is facilitated. The upper and lower horizontal surfaces and the side surface of the row rail may be created by pressing the single metal sheet, e.g. pressing in one single movement.

[0028] As discussed before, the rack may be configured such that, for at least one row of the rack, a far end of the row is arranged to allow the row cart being: received by the row cart being lowered onto the row rail; and / or collected by the row cart being lifted off the row rail; the far end of the row being an end of the row opposite to the entrance of the row.

[0029] As an example, the far end of the row may be arranged at a forklift aisle. The forklift aisle may be an aisle adjacent to the rack wherein an forklift may move. As another example, the far end of the row may be arranged at a stacker crane. As another example, the far end of the row may be arranged at an elevator.

[0030] The rack may comprise horizontal support elements, supporting the row rails. For example, the row rails of a pair of row rails may rest on horizontal support elements. Said horizontal support elements may connect the row rails of the pair of row rails. A row configured to allow a row cart being received or collected at the far end may be free from horizontal support elements connecting the row rails of the pair of row rails, within a distance of at least 0.5 m, or at least 1 m from the outermost point of the row rails. Thus, a row cart supported from below by e.g. the fork of a forklift may be lifted into the row without the fork being obstructed by a horizontal support element.

[0031] When the row cart is transported by the aisle cart, the row cart may stand in a confined space as it may be desirable to make the aisle cart compact. As mentioned, a wheel of the row cart may stand on a platform of the aisle cart. The platform may be connected to a side surface which may be vertical or less inclined than the side surface of the row rail, e.g. in order to make the aisle cart compact. In the following a bridge rail will be discussed, the bridge rail may act as an adaptor between the platform and the row rail. The bridge rail and the row rail may be separate pieces, e.g. different sections, and will in the following mainly be discussed as such. Alternatively, the bridge rail and the row rail may be one single piece, e.g. shaped out of the same metal sheet.

[0032] The rack may comprise a bridge rail arranged at the entrance of at least one row of the rack, the bridge rail forming a bridge for the row cart to travel across, between the aisle cart and the row rail, wherein the bridge rail comprises a horizontal surface for the wheel of the row cart to travel on.

[0033] The horizontal surface of the bridge rail may have a first and second end, wherein the horizontal surface of the bridge rail is wider at the first end than at the second end, the first end being closer to the aisle than the second end. Thus, a wheel of a row cart may be guided from a broad platform of the aisle cart, to a narrower lower horizontal surface of the row rail, by the bridge rail.

[0034] The horizontal surface of the bridge rail may comprise an edge, being an edge facing the aisle, wherein an angle of the edge deviates from 90°, the angle of the edge being an angle between the edge and the center axis of the row. Similarly, the platform of the aisle cart may comprise an edge, wherein an angle of the edge of the platform deviates from 90°. The platform of the aisle cart may be displaceable and the aisle cart may be configured to, at the entrance of the designated row, displace the platform such that a gap between the edge of the platform and the edge of the bridge rail is reduced. Thus, when the wheel of the row cart rolls across said gap, the wheel may not roll in a direction perpendicular to the edges and may thereby be prevented from dropping into the gap.

[0035] The bridge rail may comprise a side surface, wherein an angle between the side surface of the bridge rail and the horizontal surface of the bridge rail is smaller in a first cross-section of the bridge rail than in a second cross section of the bridge rail, the first and second cross-sections being cross-sections perpendicular to the center axis of the row, the first crosssection being closer to the aisle than the second cross-section. Thus, the side surface of the bridge rail may form a gradual transition from a side surface connected to the platform of the aisle cart, to the side surface of the row rail (between the upper and lower horizontal surfaces of the row rail).

[0036] As mentioned, the bridge rail and the row rail may be separate pieces. Thus, the row rail may be produced in a number of long sections which may be connected to form most of the row rail. The bridge rail may then be a short section of the row rail which acts as an adaptor for easing the transfer of the row cart from the aisle cart into the row.

[0037] The rack may further comprise a row rail supporting bracket, being a bracket supporting one of the row rails of the rack, wherein the row rail supporting bracket comprises a first plate arranged horizontally and supporting a back side of a lower metal sheet of the row rail, wherein a front side of the lower metal sheet of the row rail is the lower horizontal surface of the row rail; and a second plate supporting a back side of a side metal sheet, wherein a front side of the side metal sheet is the side surface of the row rail.

[0038] Such a supporting bracket may provide stable support to the row rail.

[0039] The rack may comprise at least one fastener, the at least one fastener fastening the second plate of the row rail supporting bracket to the side metal sheet of the row rail; and / or the at least one fastener fastening a third plate of the row rail supporting bracket to a protruding metal sheet, being a metal sheet protruding from the inner side of the lower horizontal surface or from the outer side of the upper horizontal surface. By fastening to the side metal sheet of the row rail or to the protruding metal sheet of the row rail, it is possible to avoid fastening to the lower horizontal surface of the row rail. Thus, it is possible to avoid obstructing the wheel of the row cart.

[0040] The at least one fastener may comprise a bolt, a screw, or a rivet.

[0041] By using such a fastener, welding may be avoided. This saves time when assembling the rack. Accordingly a time efficient and / or cost efficient assembly is facilitated.

[0042] According to a second aspect there is provided a system comprising the rack of the first aspect and a row cart, the row cart being a cart configured to travel on the row rail and transport the item from the aisle cart to the storage position in the designated row, the row cart comprising at least one support wheel, being a wheel arranged to roll on the lower horizontal surface of the row rail and to support the row cart when the aisle cart travels on the row rail, wherein the row cart comprises at least one guide member, being a member configured to guide the row cart onto the row rail by engaging the side surface of the row rail.

[0043] The system may have the same or similar advantages as the advantages described in the discussion above, relating to the rack. The guide member may further guide the row cart onto the row rail. Thereby, the body of the row cart may not need to engage the row rail. Thus, damages to the body of the row cart may be avoided. Further, the guide member enables the row cart to enter the row quickly and / or travel in the row quickly.

[0044] The guide member may comprise a downwards rolling guide wheel, being a wheel configured to roll downwards along the side surface of the row rail when the row cart is lowered onto the row rail. Such a downwards rolling guide wheel enables the row cart to enter the row quickly when being lifted onto the row rail. The downwards rolling guide wheel may be arranged to roll around an axis parallel with the center axis of the row.

[0045] The guide member may comprise a forwards rolling guide wheel, being a wheel configured to roll forwards along the side surface of the row rail when the row cart enters the row rail from the aisle cart. Such a forwards rolling guide wheel enables the row cart to enter the row quickly when entering the row from the aisle cart. Similarly, such a forwards rolling guide wheel enables the row cart to travel fast in the row. The forwards rolling guide wheel may be arranged to roll around a vertical axis. The guide member may be arranged between a front of the row cart and the support wheel of the row cart that is nearest to the front of the row cart. Thus, the forwards rolling guide wheel may engage the side surface of the row rail before the support wheel of the row cart engages the lower horizontal surface of the row rail. This further enables the row cart to enter the row quickly when entering the row from the aisle cart.

[0046] BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The above, as well as additional objects, features and advantages of the present inventive concept, will be better understood through the following illustrative and non-limiting detailed description, with reference to the appended drawings. In the drawings like reference numerals will be used for like elements unless stated otherwise.

[0048] Fig. 1 illustrates a system for storing an item.

[0049] Fig. 2a-c illustrate an aisle cart, a row cart, aisle rail, and row rail.

[0050] Fig. 3 illustrates an aisle cart, a row cart, aisle rail, and row rail.

[0051] Fig. 4 illustrates an aisle cart.

[0052] Fig. 5 illustrates an aisle cart.

[0053] Fig. 6a-c illustrate an aisle cart, a row cart, and aisle rail,

[0054] Fig. 7 illustrates an aisle rail and a guide member.

[0055] Fig. 8 illustrates an aisle cart and aisle rail.

[0056] Fig. 9a-b illustrate an aisle rail.

[0057] Fig. 10 illustrates a row cart and row rail.

[0058] Fig. 11 illustrates a row rail.

[0059] Fig. 12 illustrates a bridge rail.

[0060] Fig. 13 illustrates an aisle cart, a row cart, aisle rail, and row rail.

[0061] Fig. 14 illustrates a row rail.

[0062] Fig. 15 illustrates a bridge rail, a row rail, and a platform.

[0063] DETAILED DESCRIPTION

[0064] In cooperation with attached drawings, the technical contents and detailed description of the present invention are described thereinafter according to a preferable embodiment, being not used to limit the claimed scope. This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0065] Fig. 1 illustrates a system 1 for storing an item 2. The system comprises a rack 10, the rack 10 comprises an aisle 20 and a plurality of rows 30. The illustrated rack 10 comprises three stories, each story comprising an aisle 20 and a plurality of rows 30. The aisle 20 extends in a first direction 11 and each row 30 extend in a second direction 12. In the figure, the first direction is the X direction and the second direction is the Y direction. It should be understood that the directions may be denoted differently. For example, in the FEM (European materials handling federation) standard, the direction in which the aisle extends (the first direction 11 ) is referred to as the X direction and the direction in which the rows extends (the second direction 12) is referred to as the Z direction, while the vertical direction is referred to as the Y direction.

[0066] Each row 30 comprises an entrance 35 and a far end 39. The entrance 35 of the row 30 being at the aisle 20 and the far end 39 being at the opposite end of the row 30.

[0067] In Fig. 1 , for clarity, the item 2 is not illustrated. However, the item 2 may be a pallet 3, with or without goods 4. Alternatively, the item 2 may be any form of goods 4, crate or box. The rack 10 of Fig. 1 is suitable to store items 2 in the form of pallets 3, with or without goods 4.

[0068] The system 1 further comprises an aisle cart 40, and a row cart 60. The aisle cart 40 and row cart 60 are configured to transport the item 2 to a storage position 16 in a designated row 30, e.g. from a loading position 14 to the storage position 16. The storage position 16 may be any position along the designated row 30. The designated row 30 may be any row 30 of the plurality of rows 30.

[0069] In the following, the top story of the rack 10 in Fig. 1 will be discussed as an illustrative example. The top story of the rack 10 comprises an aisle 20 and a plurality of rows 30. The aisle 20 extends in the X direction, starting at a loading position 14 at the at the edge of the rack 10. A plurality of rows 30 extend to the left (in the positive Y direction) and to the right (in the negative Y direction) of the aisle 20. Each row 30 has an entrance 35 at the aisle 20. In Fig. 1 , an aisle cart 40 is seen in the aisle 20 of the top story of the rack 10. A row cart 60 is seen in the first row 30 to the right of the top story of the rack 10. As mentioned, the storage position 16 may be any position along the designated row 30, e.g. a position furthest from the entrance 35 of the row 30 which is free to accept the item 2. A storage position 16 is indicated in the last row 30 to the left of the aisle 20 of the top story of the rack 10 in Fig. 1. Since said row 30 is empty in the figure, the storage position may be at the far end 39 of said row 30.

[0070] The far end 39 of the rows 30 may be arranged to allow the row cart 60 being: received by the row cart 60 being lowered onto the row rail 32; and / or collected by the row cart 60 being lifted off the row rail 32.

[0071] For example, the far end 39 may be open, such that a fork lift or an elevator may deliver the row cart at the far end of the row rail 32. Thus, row carts 32 (e.g. empty row carts 32) may be delivered into (or retrieved from) the rack 10 without having to take the path through the aisle 20. Thus, congestion in the rack 10 may be avoided.

[0072] Further, as illustrated in Fig. 1 , a row 30 may, at the far end 39, be free from horizontal support elements connecting the row rails of the pair of row rails, within a distance from the outermost point of the row rails. This is for example seen at the marked storage position 16. The distance may be 0.5 m or 1 m. Alternatively, the distance may be equal or larger than the length of the row cart (not shown). Thus, a row cart supported from below by e.g. the fork of a forklift may be lifted into the row without the fork being obstructed by a horizontal support element.

[0073] Figs 2a-c illustrate the aisle cart 40 arriving at a designated row 30 and the row cart 60 moving into the designated row 30. Again, for clarity, the item 2 is not illustrated.

[0074] The illustrated aisle 20 comprises a rail 22 (henceforth called aisle rail 22). In the illustrations, the aisle rail 22 is in the form of a hollow beam 50. As illustrated, there may be a pair of aisle rails 22. The aisle cart 40 may comprise a wheel 46 (also called support wheel 46 of the aisle cart 40) for rolling on the aisle rail 22. The aisle cart 40 may comprise two pairs of support wheels 46.

[0075] In Figs 2a-c, there is one row 30 to the left of the aisle 20 and one row 30 to the right of the aisle 20, with a respective entrance 35 at the aisle 20. Each illustrated row 30 comprises a rail 32 (henceforth called row rail 32). As illustrated, each row 30 may comprise a pair of row rails 32. The row cart 60 may comprise a wheel 66 (also called support wheel 66 of the row cart 60) for rolling on the row rail 32. The row cart 60 may comprise two pairs of support wheels 66.

[0076] The illustrated aisle cart 40 comprises a platform 42. The platform 42 is best seen in Fig. 2b and Fig. 2c, and in the insets of Fig. 2a and Fig. 2b. The illustrated platform 42 is configured to support the at least one wheel 66 of the row cart 60 while the aisle cart 40 transports the row cart 60, the platform 42 being displaceable relative to the at least one wheel 46 of the aisle cart 40. As illustrated, the aisle cart 40 may further comprise a belt conveyor 52 for pulling the item 2 onto the aisle cart 40 and supporting the item 2 while the aisle cart 40 transports the item 2, the belt conveyor 52 being attached to the platform 42 and configured to be displaced relative to the at least one wheel 46 of the aisle cart 40 together with the platform 42.

[0077] When the aisle cart 40 transports the row cart 60 and the item 2 along the aisle 20, the row cart 60 may stand on the platform 42 under the item 2. When the aisle cart 40 transports the row cart 60 and the item 2 along the aisle 20, the item 2 may stand on the belt conveyor 52. However, the aisle cart 40 does not necessarily need to comprise a belt conveyor 52. For example, when the aisle cart 40 transports the row cart 60 and the item 2 along the aisle 20, the item 2 may stand on the row cart 60, or on a support surface of the aisle cart 40, instead of on the belt conveyor 52.

[0078] The row cart 60 and the item 2 may be transported along the aisle 20 using the aisle cart 40. The aisle cart 40 may be stopped at the entrance 35 of the designated row 30, this is illustrated in Fig. 2a. The platform 42 may then be displaced, relative to the at least one wheel 46 of the aisle cart 40, in the second direction 12 such that a gap 36 between the platform 42 and the entrance 35 of the designated row 30 is reduced.

[0079] Fig. 2a illustrates a gap 36 between the platform 42 and the entrance 35 of the designated row 30.

[0080] Fig. 2b illustrates the platform 42 of the aisle cart 40 being displaced towards the entrance 35 of the designated row. In the figure, the row cart 60 is not displaced for reasons of clarity, such that the platform 42 is visible. In reality, the row cart 60 standing on the platform 42 would be displaced together with the platform 42. Fig. 2b further shows the gap 36 between the platform 42 and the rolling surface 81 (a.k.a. lower horizontal surface 81) of the row rail 32 being closed. The row cart 60 may then move into the designated row 30 by rolling from the platform 42, across the gap 36, and onto the rolling surface 81 of the row rail 32. This is illustrated in Fig. 2c. Part of the row rail 32 has been cut away for illustrative purposes, such that a wheel 66 of the row cart 60 can be seen rolling on the rolling surface 81 of the row rail 32.

[0081] In Fig. 2c, the row cart 60 is not carrying an item 2. This is for illustrative purposes. However, the row cart 60 may carry an item 2, e.g. resting on-top of the row cart 60. Thus, the row cart 60 may transfer the item 2 into the designated row, when the at least one wheel 66 of the row cart 60 crosses the reduced gap 36.

[0082] Before the row cart 60 transfers the item 2 into the designated row 30, the row cart 60 may lift the item using a lifting device 62. The lifting device 62 may be a raisable platform, e.g. part of the chassis of the row cart 60. Thus, the item 2 may be lifted up, e.g. from the belt conveyor 52, of the aisle cart 60. The lifting device 62 may be configured to lift the item 2 by lowering the wheels 66 of the row cart 60, e.g. lowering the wheels 66 of the row cart 60 relative to the chassis of the row cart 60. In other words, a separation between the wheels 66 of the row cart 60 and the chassis of the row cart 60 may be increased to lift the item 2.

[0083] After the row cart 60 has transferred the item 2 into the designated row 30, the row cart 60 may transport the item 2 along the designated row 30. The row cart 60 may then place the item 2 at the storage position 16 in the designated row 30.

[0084] The inset of Fig. 2a and the inset of Fig. 2b show a top view of the aisle cart 40 at the entrance 35 of the designated row 30 before and after displacing the platform 42, respectively. Thus, the insets of Fig. 2a Fig. 2b illustrate the gap 36 being reduced. The gap 36 in the inset of Fig. 2a may be 85 mm. The gap 36 in the inset of Fig. 2b may be 5 mm.

[0085] The insets of Fig. 2a and Fig. 2b illustrate the gap 36 extending between a first edge 43 of the platform 42 and a first edge 33 of the row rail 32. Further, the insets of Fig. 2a and Fig. 2b illustrate that the first edge 33 of the rail 32 may be arranged at an angle to the second direction 12 and that the first edge 43 of the platform 42 may be arranged at an angle to the second direction 12. The system 1 may be configured such that both the angle of the first edge 33 of the rail 32 and the angle of the first edge 43 of the platform 42 are larger or smaller than 90°, as illustrated. The angle of the first edge 33 of the rail 32 may have an absolute value in the range 10°-80°, e.g. 30°-60°. The angle of the first edge 43 of the platform 42 may have an absolute value in the range 10°-80°, e.g. 30°-60°. The angle of the first edge 33 of the rail 32 may be the same as the angle of the first edge 43 of the platform 42, as illustrated.

[0086] The platform 42 may be displaceable both forwards and backwards. While Figs 2a-c illustrate the platform 42 being displaced towards a row 30 to the right of the aisle 20 (as compared to the first direction 11 ), Fig. 3 illustrate the platform 42 being displaced towards a row 30 to the left of the aisle 20 (as compared to the first direction 11 ).

[0087] Fig. 4 is a side view of an aisle cart 40 carrying an item 2 in the form of a pallet 3 with goods 4. In Fig. 4, the pallet 3 is standing on the belt conveyor 52. For illustrative purposes the row cart 60 is not shown. However, the row cart 60 may stand on the platform 42 of the aisle cart 40, underneath the pallet 3.

[0088] Fig. 13 shows an aisle cart 40 at a designated row 30, in this case the row 30 to the right of the aisle 20 (as compared to the first direction 11 ). In the figure, the platform 42 is displaced towards the designated row 30 and the row cart 60 is entering the designated row 30. The row cart 60 may (as in Fig. 13) enter the designated row 30 empty, when collecting an item 2, e.g. the item 2 closest to the aisle 20. Alternatively, the row cart 60 may enter the designated row 30 while carrying an item 2 to be stored in the designated row 30. Fig. 13 further illustrates items 2 in the form of pallets 3 with goods 4 stored both in the row 30 to the left of the aisle 20 and in the row 30 to the right of the aisle 20.

[0089] Fig. 5 shows an aisle cart 40 comprising a first 42’ and a second 42” platform, the first platform 42’ being configured to support a left side wheel of the row cart 60 and the second platform 42” being configured to support a right side wheel of the row cart 60. The first 42’ and second 42” platform are separated by an open space 148. As seen in the figure, both the first 42’ and second 42” platform are displaceable relative to the at least one wheel 46 of the aisle cart 40. In the figure, both the first 42’ and second 42” platform have been displaced in the negative Y direction, towards the viewer. A platform 42 of the aisle cart 40 may be displaced by displacement means 58. The first 42’ and second 42” platform may be displaceable by a common displacement means 58, as illustrated. Displacement means 58 may comprise a motor of any sort (e.g. a stepper motor) or an actuator (e.g. a linear actuator). Alternatively or additionally, the displacement means 58 may comprise a hydraulic actuator or pneumatic actuator.

[0090] Fig. 5 further shows that the belt conveyor 52 may be attached to the platform 42 and configured to be displaced relative to the at least one wheel 46 of the aisle cart 40 together with the platform 42. The illustrated aisle cart 40 further comprises a motor 54 for driving the belt conveyor 52. Part of the aisle cart 40 in Fig. 5 is removed for illustrative purposes, to show the motor 54. The motor 54 may be immovably attached to the chassis 56 of the aisle cart 40 such that the motor 54 is prevented from being displaced relative to the at least one wheel 46 of the aisle cart 40. The aisle cart 40 may be configured to: drive the belt conveyor 52 by the motor 54 while the platform 42 is displaced relative to the at least one wheel 46 of the aisle cart 40; or declutch the belt conveyor 52 from the motor 54 before or while the platform 42 is displaced relative to the at least one wheel 46 of the aisle cart 40.

[0091] In Fig. 5, the aisle cart 40 comprises blocking elements 47, each blocking element 47 being a movable element which: in a blocking position, blocks the row cart 60 from leaving the platform 42; and in an unblocking position, unblocks the row cart 60 from leaving the platform 42. In Fig. 5 there are two blocking elements 47 at each side of the aisle cart 40. Each illustrated blocking element 47 is a lever pivotably attached to the platform 42. The aisle cart 40 may be configured to move the blocking element 47 from the blocking position to the unblocking position such that the blocking element 47 arrives at the unblocking position after the platform 42 has started displacing relative to the at least one wheel 46 of the aisle cart 40. In Fig. 5, the first 42’ and second 42” platform have been displaced in the negative Y direction, towards the viewer.

[0092] In Fig. 5 the blocking elements 47 at the end of the platforms 42’, 42” towards the viewer are in the unblocking position wherein the lever 47 has pivoted downwards (out of a slit 49). Thus, said blocking elements 47 are not blocking the travel path of the row cart.

[0093] In Fig. 5 the blocking elements 47 at the end of the platforms 42’, 42” away from the viewer are in the blocking position wherein the lever 47 has not pivoted downwards (out of a slit 49). Thus, said blocking elements 47 are blocking the travel path of the row cart. In other words, in Fig. 5, a row cart 60 may move out of the aisle cart 40 in the negative Y direction but not in the positive Y direction.

[0094] Figs 6a-c illustrate that the aisle cart 40 may comprise a guide member 110. Fig. 6a shows an aisle cart 40 on aisle rail 22 in the form of hollow beams 50. The support wheels 46 of the aisle cart 40 roll on the top surfaces 54t of the respective hollow beams 50 of the aisle rail 22. The illustrated aisle cart 40 comprises a guide member 110, being a member configured to guide the aisle cart 40 along the hollow beam 50 of the aisle rail 22 by engaging the rack 10. As illustrated, the aisle cart 40 may comprise several guide members 110. Fig. 6b and Fig. 6c show close-up views of the frontmost guide member 110 in Fig. 6a, as seen from different perspectives. The illustrated guide member 110 has three different means for engaging the rack 10, a first guide wheel 111 , a second guide wheel 112, and a protrusion 113. However, it should be understood that either one could be used on its own or in any combination with the others.

[0095] In Figs 6a-c, the guide member 110 comprises a first guide wheel 111 , being a wheel arranged to roll on a first side surface 51s of the hollow beam 50 and a second guide wheel 112, being a wheel arranged to roll on second side surface 52s of the hollow beam 50, the second side surface 52s of the hollow beam 50 being opposite to the first side surface 51s of the hollow beam 50. The first side surface 51s of the hollow beam 50 may be the outer side surface of the hollow beam while the second side surface 52s of the hollow beam 50 is the inner side surface of the hollow beam, as illustrated, or vice versa.

[0096] In Figs 6a-c, the guide member 110 comprises a protrusion 113 protruding in a direction of an axis 46A of the support wheel 46. The illustrated protrusion 113 is a plate.

[0097] Fig. 8 illustrates that the protrusion 113 may slide under a surface 10s of the rack 10 when the aisle cart 40 travels on the aisle rail 22. In Fig. 8 said surface 10s of the rack 10 is a bottom surface 70s of a ledge 70 extending in parallel with the hollow beam 50 of the aisle rail 22. Thus, the protrusion 113 is configured to engage a portion 17 of the rack (in this case the ledge 70) that extends in parallel with the hollow beam 50 of the aisle rail 22 of the rack 10.

[0098] The protrusion 113 may be arranged at a distance below the ledge 70, said distance may be 1-15 mm, e.g. 5 mm. The protrusion 113 may extend 20 mm under the ledge 70, in a horizontal direction perpendicular to the ledge. The protrusion 113 may extend 50 mm under the ledge 70, in a horizontal direction parallel to the ledge.

[0099] Fig. 7 illustrates a close-up view of the guide member 110 engaging the hollow beam 50 by the first 111 and second 112 guide wheel. A spacing between the first 111 and second 112 guide wheel may be larger than the width of the hollow beam 50, e.g. 2% larger than the width of the hollow beam 50.

[0100] Fig. 7 and Fig. 6c shows a connector 48 for connecting the chassis 56 of the aisle cart 40 to the protrusion 113 and to the first 111 and second 112 guide wheel. The connector 48 may e.g. comprise one or more bars or rods, e.g. made of steel.

[0101] Figs 9a-b illustrate that an aisle rail 22 may comprise a plurality of hollow beams 50. Fig. 9a and 9b are views of the same aisle rail 22, as seen from opposite sides.

[0102] Fig. 9a-b illustrate a section of an aisle rail 22 comprising a first 50’ and a second 50” hollow beam. The joint between the first 50’ and a second 50” hollow beam may be smooth.

[0103] In Fig. 9a-b, the first 50’ and the second 50” hollow beams are supported by a first 55 and second 56 plate, the first 55 and second 56 plate being arranged perpendicular to each other, the first plate 55 being in contact with a respective bottom surface 53b of the first 50’ and the second 50” hollow beams, the second plate 56 being in contact with a respective side surface 52s of the first 50’ and the second 50” hollow beams. Similar first 55 and second 56 plates are also seen in Fig. 6c.

[0104] Fig 10 illustrate a row cart 60 on row rail 32, in a cross-sectional view of the row rail 32. In other words, the row cart is standing in a row 30. A left and a right support wheel 66 of the row cart 60 are standing on respective row rails 32. The illustrated row rail 32 comprise a upper metal sheet 87 and a lower metal sheet 85, both being arranged horizontally. A side metal sheet 86 is arranged to connect the upper metal sheet 87 with the lower metal sheet 85. A protruding metal sheet 84 protrudes downwards from the lower metal sheet 85. In Fig. 10 an item 2, in the form of a pallet 3, is resting (i.e. supported) on the respective upper metal sheets 87 of the left and right row rail 32. Thus, the pallet 3 is stored on the row rail 32. The support wheels 66 of the row cart 60 are supported by the respective lower metal sheets 85 of the left and right row rail 32. The illustrated row cart 60 comprises a lifting device 62. In Fig. 10 the lifting device 62 is in a lowered position. Thus, the row cart may travel under the stored item 2. By raising the lifting device 62, the row cart 60 may lift the item 2 from the row rail 32.

[0105] The row cart 60 of Fig. 10 comprises guide members 120 configured to guide the row cart 60 onto the row rail 32 by engaging the side surface 183 of the row rail 32. In this case, the side surface 183 is a surface of the side metal sheet 86. The guide member 120 may be a guide wheel.

[0106] Fig 11 is a cross-sectional view of a row rail 32, corresponding to the left row rail 32 of Fig. 10. As described above, the illustrated row rail 32 comprises a upper metal sheet 87, a side metal sheet 86, a lower metal sheet 85, and a protruding metal sheet 84.

[0107] The illustrated row rail 32 comprises an upper horizontal surface 82 for supporting the item 2, the upper horizontal surface 82 being a surface of the illustrated upper metal sheet 87.

[0108] The illustrated row rail 32 comprises a lower horizontal surface 81 for a wheel 66 of the row cart 60 to travel on, the lower horizontal surface 81 being a surface of the illustrated lower metal sheet 85.

[0109] In the figure, the upper horizontal surface 82 comprise an outer side 82o and an inner side 82i. Similarly, the lower horizontal surface 81 comprise an outer side 81 o and an inner side 81 i.

[0110] The illustrated row rail 32 comprises a side surface 183, the side surface 183 being a surface of the side metal sheet 86. The illustrated side surface 183 is a flat inclined surface 83.

[0111] In Fig. 11 , the outer side 81 o of the lower horizontal surface 81 is connected to the inner side 82i of the upper horizontal surface 82 by the side surface 183. Further, in Fig. 11 , the inner side 82 i of the upper horizontal surface 82 is further away from the center axis of the row 30 than the outer side 81 o of lower horizontal surface 81 .

[0112] In Fig. 11 , the upper metal sheet 87, the side metal sheet 86, the lower metal sheet 85, and the protruding metal sheet 84 form a single metal sheet.

[0113] Fig. 11 further illustrates a row rail supporting bracket 130.

[0114] The illustrated row rail supporting bracket 130 comprises a first plate 131 arranged horizontally and supporting a back side 85b of a lower metal sheet 85 of the row rail 32.

[0115] The illustrated row rail supporting bracket 130 further comprises a second plate 132 supporting a back side 86b of the side metal sheet 86.

[0116] The illustrated row rail supporting bracket 130 further comprises a third plate 133. The third plate 133 may be fastened to the protruding metal sheet 84 by a fastener (not shown), e.g. a fastener in the form of a bolt, a screw, or a rivet.

[0117] Fig. 14 is a perspective view of a row rail 32 similar to the row rails 32 of Figs 10 and 11.

[0118] The illustrated row rail 32 comprises an upper horizontal surface 82 for supporting the item 2, the upper horizontal surface 82 being a surface of the illustrated upper metal sheet 87.

[0119] The illustrated row rail 32 comprises a lower horizontal surface 81 for a wheel 66 of the row cart 60 to travel on, the lower horizontal surface 81 being a surface of the illustrated lower metal sheet 85.

[0120] The illustrated row rail 32 comprises a side surface 183, the side surface 183 being a surface of the side metal sheet 86. The illustrated side surface 183 is a flat inclined surface 83.

[0121] The illustrated row rail 32 further comprises a protruding metal sheet 84.

[0122] Fig 12 is a close-up view of the row rail 32 at the entrance 35 of the row 30. As illustrated, the row rail 32 may comprise a bridge rail 90 forming a bridge for the row cart 60 to travel across. The bridge rail 90 may be part of the row rail 32. Thus, the row cart 60 may travel across the bridge rail 90 onto a further section of the row rail 32. Thus, the row rail 32 may be produced in a number of long sections which may be connected to form most of the row rail 32. The bridge rail 90 may then be a short section of the row rail 32 which acts as an adaptor for easing the transfer of the row cart 60 from the aisle cart 40 into the row 30.

[0123] The illustrated bridge rail 90 comprises a horizontal surface 81 for the wheel 66 of the row cart 60 to travel on. The illustrated bridge rail 90 has a first end 95 close to the aisle 20 and a second end 96 further away from the aisle.

[0124] The horizontal surface 81 of the illustrated bridge rail 90 may be wider at the first end 95 than at the second end 96.

[0125] The horizontal surface 81 of the illustrated bridge rail 90 comprises an edge 33 facing the aisle 20, wherein an angle of the edge 33 deviates from 90°.

[0126] The illustrated bridge rail 90 comprises a side surface 183. An angle between the side surface 183 of the bridge rail 90 and the horizontal surface 81 of the bridge rail 90 may be smaller in a first cross-section of the bridge rail 90 than in a second cross section of the bridge rail 90. The first cross-section of the bridge rail 90 may be at the first end 95. The second cross-section of the bridge rail 90 may be at the second end 96.

[0127] Fig. 15a-e illustrate a row rail 32 and a platform 42 of an aisle cart 40. For clarity, the rest of the aisle cart 40 is not shown. The row rail 32 comprising a bridge rail 90 for the row cart 60 to travel across. Fig. 15a is a perspective view. Fig. 15b is a cross-sectional view of the platform 42. Fig. 15c is a cross-sectional view of the bridge rail 90 at a first end 95 close to the aisle 20. Fig. 15d is a cross-sectional view of the bridge rail 90 at a second end 96 close to the aisle 20 further away from the aisle 20. Fig. 15e is a cross-sectional view of the row rail 32 at a section adjacent to the bridge rail 90.

[0128] In the Fig. 15e cross-sectional view of the row rail 32, the row rail 32 comprises an upper horizontal surface 82, for supporting the item 2, and a lower horizontal surface 81 , for a wheel 66 of the row cart 60 to travel on. The inner side of the upper horizontal surface 82 is further away from the center axis of the row 30 than the outer side of lower horizontal surface 81 . The upper horizontal surface 82 and the lower horizontal surface 81 are connected by a side surface 183, which is inclined.

[0129] In the Fig. 15b cross-sectional view of the platform 42, the platform 42 is connected to a side surface 283 which is in the illustration is vertical.

[0130] In the Fig. 15c-d cross-sectional views of the bridge rail 90, it is seen that the bridge rail 90 may act as an adaptor between the platform 42 and the further section of the row rail 32. In the cross-sectional view of the bridge rail 90 at the first end 95, Fig. 15c, the cross-section of the bridge rail 90 is similar to the cross-section of the platform 42 and the side surface 283 connected to the platform 42, seen in Fig. 15b. Further, in the cross-sectional view of the bridge rail 90 at the second end 96, Fig. 15d, the cross-section of the bridge rail 90 is similar to the cross-section of the further section of the row rail 32 in Fig. 15e. Thus, the horizontal surface 81 of the bridge rail 90 is wider at the first end 95 than at the second end 96. Further, an angle between the side surface 183 of the bridge rail 90 and the horizontal surface 81 of the bridge rail 90 is smaller at the cross-section at the first end 95 than at the second end 96. As seen in the figures, the angle (with respect to the direction of the row 30) of the first edge 33 of the bridge rail 90 and the angle (with respect to the direction of the row 30) of the first edge 43 of the platform 42 may both differ from 90°. Said angles may e.g. be the same. In the above the inventive concept has mainly been described with reference to a limited number of examples. However, as is readily appreciated by a person skilled in the art, other examples than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended claims.

Claims

CLAIMS1 . A rack (10) for storing an item (2), the rack (10) comprising: an aisle (20), having an aisle rail (22), being a rail extending along the aisle (20); and a plurality of rows (30), each row (30) having a respective entrance (35) at the aisle (20) and a respective row rail (32), being a rail extending along the row (30); wherein the rack (10) is configured to allow transport of the item (2) in the rack (10) by an aisle cart (40) and a row cart (60), wherein the aisle cart (40) travels on the aisle rail (22) and transports the row cart (60) and the item (2) to the entrance (35) of a designated row (30) and the row cart (60) travels on the row rail (32) and transports the item (2) from the aisle cart (40) to a storage position (16) in the designated row (30); wherein each row rail (32) comprises an upper horizontal surface (82) for supporting the item (2) and a lower horizontal surface (81 ) for a wheel (66) of the row cart (60) to travel on, wherein both the upper (82) and lower (81 ) horizontal surfaces comprise an inner side (82i, 81 i), facing a center axis of the row (30), and an outer side (82o, 81 o), facing away from the center axis of the row (30); wherein the outer side (81 o) of the lower horizontal surface (81 ) is connected to the inner side (82 i) of the upper horizontal surface (82) by a side surface (183), the inner side (82i) of the upper horizontal surface (82) being further away from the center axis of the row (30) than the outer side (81 o) of lower horizontal surface (81 ).

2. The rack (10) according to claim 1 , wherein, for each row (30) of the rack (10), the side surface (183) of the row rail (32) comprise a flat inclined surface (83), the inclined surface (83) being inclined outwardly from the outer side (81 o) of the lower horizontal surface (81 ) towards the inner side (82 i) of the upper horizontal surface (82).

3. The rack (10) according to claim 1 or 2, wherein the upper (82) and lower (81 ) horizontal surfaces and the side surface (183) of the row rail (32) are surfaces of one single metal sheet.

4. The rack (10) according to any one of the preceding claims, wherein, for at least one row (30) of the rack (10), a far end (39) of the row (30) is arranged to allow the row cart (60) being: received by the row cart (60) being lowered onto the row rail (32); and / or collected by the row cart (60) being lifted off the row rail (32); the far end (39) of the row (30) being an end of the row (30) opposite to the entrance (35) of the row (30).

5. The rack (10) according to any one of the preceding claims, wherein the rack (10) comprises a bridge rail (90) arranged at the entrance (35) of at least one row (30) of the rack (10), the bridge rail (90) forming a bridge for the row cart (60) to travel across, between the aisle cart (40) and the row rail (32), wherein the bridge rail (90) comprises a horizontal surface (81 ) for the wheel (66) of the row cart (60) to travel on, wherein i- the horizontal surface (81 ) of the bridge rail (90) has a first (95) and second (96) end, and wherein the horizontal surface (81 ) of the bridge rail (90) is wider at the first end (95) than at the second end (96), the first end (95) being closer to the aisle (20) than the second end (96); and / or ii- the horizontal surface (81 ) of the bridge rail (90) comprises an edge (33), being an edge (33) facing the aisle (20), wherein an angle of the edge (33) deviates from 90°, the angle of the edge (33) being an angle between the edge (33) and the center axis of the row (30); and / or iii- the bridge rail (90) comprises a side surface (183), wherein an angle between the side surface (183) of the bridge rail (90) and the horizontal surface (81 ) of the bridge rail (90) is smaller in a first cross-section of the bridge rail (90) than in a second cross section of the bridge rail (90), the first and second cross-sections being cross-sections perpendicular to the center axis of the row (30), the first cross-section being closer to the aisle (20) than the second cross-section.

6. The rack (10) according to claim 5, wherein the bridge rail (90) and the row rail (32) are separate pieces.

7. The rack (10) according to any one of the preceding claims, the rack (10) further comprising a row rail supporting bracket (130), being a bracket supporting one of the row rails of the rack (10), wherein the row railsupporting bracket (130) comprises a first plate (131 ) arranged horizontally and supporting a back side (85b) of a lower metal sheet (85) of the row rail (32), wherein a front side (85f) of the lower metal sheet (85) of the row rail (32) is the lower horizontal surface (81 ) of the row rail (32); and a second plate (132) supporting a back side (86b) of a side metal sheet (86), wherein a front side (86f) of the side metal sheet (86) is the side surface (183) of the row rail (32).

8. The rack (10) according to claim 7, wherein the rack (10) comprises at least one fastener, the at least one fastener fastening the second plate (132) of the row rail (32) supporting bracket to the side metal sheet (86) of the row rail (32); and / or the at least one fastener fastening a third plate (133) of the row rail supporting bracket (130) to a protruding metal sheet (84), being a metal sheet protruding from the inner side (81 i) of the lower horizontal surface (81 ) or from the outer side (82o) of the upper horizontal surface (82).

9. The rack (10) according to claim 8, wherein the at least one fastener comprise a bolt, a screw, or a rivet.

10. A system (1 ) comprising the rack (10) of any one of the preceding claims and a row cart (60), the row cart (60) being a cart configured to travel on the row rail (32) and transport the item (2) from the aisle cart (40) to the storage position (16) in the designated row (30), the row cart (60) comprising at least one support wheel (66), being a wheel (66) arranged to roll on the lower horizontal surface (81 ) of the row rail (32) and to support the row cart (60) when the row cart (60) travels on the row rail (32), wherein the row cart (60) comprises at least one guide member (120), being a member configured to guide the row cart (60) onto the row rail (32) by engaging the side surface (183) of the row rail (32).11 . The system (1 ) according to claim 10, wherein the guide member (120) comprises a downwards rolling guide wheel, being a wheel configured to rolldownwards along the side surface (183) of the row rail (32) when the row cart (60) is lowered onto the row rail (32).

12. The system (1 ) according to claim 10 or 11 , wherein the guide member (120) comprises a forwards rolling guide wheel, being a wheel configured to roll forwards along the side surface (183) of the row rail (32) when the row cart (60) enters the row rail (32) from the aisle cart (40).

13. The system (1 ) according to any one of claims 10-12, wherein the guide member (120) is arranged between a front of the row cart (60) and the support wheel (66) of the row cart (60) that is nearest to the front of the row cart (60).

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