GB2637034A

GB2637034A - Bearing replacement system and method

Info

Publication number: GB2637034A
Application number: GB2400169.5A
Authority: GB
Inventors: Fredrik Jonathan Nilsson Måns; Humphrey Ben; Grahn Anton; Söder Alfred; Hällje Arvid
Original assignee: Ocado Innovation Ltd
Current assignee: Ocado Innovation Ltd
Priority date: 2024-01-05
Filing date: 2024-01-05
Publication date: 2025-07-09
Also published as: GB202400169D0; WO2025146430A1

Abstract

A load handling device (30, Fig 2) for lifting and lowering storage containers (10) in a tracked framework structure (Fig 1), on which device (30) may move and within which containers (10) are stacked (12). Device wheels (320) are direction-changeable and comprise a drive assembly (500) having a rotatable shaft (610) allowing wheel engagement with the tracks and/or the lifting / lowering of the containers via a gripping device. A bearing 720 supports shaft (610) and a bearing mount (700) to allow press / snap fit engagement with bearing so to apply a radial force thereto. A user engageable snap-fit cover 670 releasably engages with bearing mount (700) to prevent bearing axial movement. Other components shown include bearing mount access hole 680 and split bearing halves 660a, 660b.

Description

Bearing replacement system and method

Technical Field

The present invention relates to a system and method for replacing bearings, such as those used in a load-handling device.

Background

Some commercial and industrial activities require systems that enable the storage and retrieval of a large number of different products. For example, W02015/185628A2 (Ocado) describes a storage and fulfilment system in which stacks of storage containers are arranged within a grid storage structure. The containers are accessed from above by load-handling devices operative on rails or tracks located on the top of the grid storage structure. The load-handling devices are further described in, for example, Within the storage and fulfilment system, it is important that the load-handling devices can be easily maintained. It is against this background that the present invention has been devised.

Summary

In a first aspect, there is a load-handling device for lifting and moving storage containers stacked in a grid framework structure comprising: a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicularly to the first set of rails or tracks in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be stacked between and be guided by the uprights in a vertical direction through the plurality of grid spaces, the load-handling device comprising: a body or skeleton mounted on a first set of wheels being arranged to engage with the first set of parallel tracks and a second set of wheels being arranged to engage with the second set of parallel tracks; a drive assembly comprising a shaft configured to rotate to drive the first or second sets of wheels to move the load-handling device along the first or second set of parallel rails respectively, or a direction-change assembly comprising a shaft either configured to rotate or along which the direction change assembly moves to raise or lower the first set of wheels, and/or lower or raise the second set of wheels with respect to the body or skeleton to engage and disengage the wheels with the parallel tracks, or a container-lifting assembly comprising a shaft configured to rotate to raise or lower a gripping device in the vertical direction; a bearing to support the shaft; a bearing mount configured to provide a press-fit engagement with the bearing to apply a radial force to the bearing; and a user-engagable snap-fit cover configured to releasably engage with the bearing mount to prevent axial movement of the bearing. This means the bearing can be accessed in minimum time with no tools when maintaining the load-handling device.

Operational downtime of the load-handing device due to bearing maintenance can be significantly reduced. Additionally, the bearing cannot move axially with respect to the bearing mount due to the presence of the user-engagable snap-fit cover.

The bearing mount may comprise at least one access hole to facilitate removal of the bearing in a first axial direction away from the bearing mount. The bearing may comprise a collar that covers an opening of the access hole. This means a force can be directly applied to the bearing to remove the bearing from the bearing mount. Increasing the ease of removing an existing bearing held firmly in place can again reduce the operational downtime of the load-handling device.

The bearing may comprise a split bearing. This means the bearing can be removed directly from the shaft. Again, this helps reduce operational downtime since any other components on the shaft need not be removed to access a worn bearing to replace with a new bearing.

The bearing mount may comprise a housing, the housing comprising an opening in which the bearing is located, and at least one snap-fit element to engage with the snap-fit cover to prevent movement of the bearing in a first axial direction. A projection may be within the opening to prevent movement of the bearing in a second axial direction opposite the first axial direction. This prevents the bearing moving axially with respect to the bearing mount.

The opening may comprise crush ribs to apply a compressive or radial force to the bearing. At least one of the crush ribs may comprises a snap-fit element. This holds the bearing in place axially whilst applying a radial force on the bearing. This also ensures that the bearing cannot move axially with respect to the bearing mount.

The body or skeleton, or the drive assembly, or the direction-change assembly, or the container-lifting assembly may comprise the bearing mount. This means the bearing can be accessed anywhere on the load-handling device. This means that the bearings used for any given function can be easily accessed and replaced. Certain bearings may wear more frequently due to the function they support in the load-handling device. Being able to access the bearings used on one function allows that function alone to be maintained at a given time.

The cover may be substantially U-shaped, or substantially V-shaped, or substantially half 0-shaped to engage the bearing mount in a radial direction. The cover comprises two user-engaged cantilever snap-fit elements opposite each other to facilitate removal of the cover in a radial direction. This means the cover can be directly removed from the shaft by a user. Again, this helps reduce operational downtime since any other components on the shaft need not be removed to access a worn bearing to replace with a new bearing.

The cover is substantially 0-shaped to engage the bearing mount in an axial direction.

The bearing mount may comprise a plurality of projections arranged in an annular shape to contact an outer surface or race of the bearing, and either a slot or projection, and the cover comprises a plurality of steps arranged in an annular shape, two user-engagable cantilever snap-fit elements on opposite sides of the cover configured to engage respective snap fit elements in the bearing mount in a radial direction, and the other of the slot or projection such that the slot and projection rotationally interact to move the cover in the axial direction to engage the edges of the steps with respective projections to apply radial pressure to the bearing when the snap-fit elements snap in place in the bearing mount. The bearing mount may comprise a plurality of projections arranged in an annular shape to contact an outer surface or race of the bearing, and the cover comprises a plurality of snap-fit cantilever elements arranged in an annular shape configured to engage corresponding elements in the bearing mount in an axial direction such that the snap-fit elements engage with respective projections to apply radial pressure to the bearing when the snap-fit cantilever elements snap in place in the bearing mount. This means the axial engagement of the cover can apply a radial force to the bearing. The bearing is thus secured in place by engaging the cover with the bearing mount.

The bearing may comprise a plain bearing, or slide bearing, or glide bearing.

In a second aspect, there is a method of installing a bearing in and/or removing a bearing from the load-handling device of the first aspect, the method comprising: press-fitting the bearing into the bearing mount; and snap-fitting the user-engagable snap-fit cover into the bearing mount; and/or removing the snap-fit cover from the bearing mount; and removing the bearing from the bearing mount.

The method may further comprise using the at least one access hole to release the bearing from its press-fit in the bearing mount.

Brief Description of Drawings

The present invention is described with reference to one or more exemplary embodiments as depicted in the accompanying drawings, wherein: Figure 1 shows an automated storage and retrieval system that uses load-handling devices; Figure 2 shows a single load-handling device with container-lifting means in a lowered configuration; Figures 3A-C show a direction-change assembly that can be used to raise and lower first and seconds sets of wheels of a load-handling device; Figures 4 shows a container-lifting assembly used in a load-handling device; Figure 5 shows a drive assembly used in a load-handling device; Figures 6A-C show a first bearing mount; Figure 7 shows a second bearing mount; Figure 8 shows a third bearing mount; and Figure 9 shows how the second bearing mount can be used on a drive shaft.

Detailed Description

Automated storage and retrieval system W02015/185628A (Ocado), hereby incorporated by reference, describes a known automated storage and retrieval system in which stacks of containers are arranged within a grid framework structure. The containers are accessed by one or more load-handling devices, otherwise known as "bots", operative on tracks located on the top of the grid framework structure. A system of this type is illustrated schematically in Figure 1.

As shown in Figures 1, stackable containers 10, also known as "bins" or "totes", are stacked on top of one another to form stacks 12. The stacks 12 are arranged in a grid framework structure 14. The grid framework structure 14 is made up of a plurality of storage columns or grid columns. Each grid in the grid framework structure has at least one grid column to store a stack of containers. Each bin 10 typically holds a plurality of product items (not shown).

The grid framework structure 14 comprises a plurality of upright members 16 that support horizontal members 18, 20. A first set of parallel horizontal grid members 18 is arranged perpendicularly to a second set of parallel horizontal members 20 in a grid pattern to form a horizontal grid structure 15 supported by the upright members 16. The members 16, 18, 20 are typically manufactured from metal. The bins 10 are stacked between the members 16, 18, 20 of the grid framework structure 14, so that the grid framework structure 14 guards against horizontal movement of the stacks 12 of bins 10 and guides the vertical movement of the bins 10.

The top level of the grid framework structure 14 comprises a grid or grid structure 15, including rails 22 arranged in a grid pattern across the top of the stacks 12. The rails or tracks 22 guide a plurality of load-handling devices 30. A first set 22a of parallel rails 22 guide movement of the robotic load-handling devices 30 in a first direction (e.g. an X-direction) across the top of the grid framework structure 14. A second set 22b of parallel rails 22, arranged perpendicular to the first set 22a, guide movement of the load-handling devices 30 in a second direction (e.g. a Y-direction), perpendicular to the first direction. In this way, the rails 22 allow the robotic load-handling devices 30 to move laterally in two dimensions in the horizontal X-Y plane. A load-handling device 30 can be moved into position above any of the stacks 12.

A known form of load-handling device 30 shown in Figure 2 is described in W02015/019055 (Ocado), hereby incorporated by reference. The load-handling device 30 comprises a vehicle 32, which is arranged to travel on the rails 22 of the frame structure 14. A first set of wheels 34, consisting of a pair of wheels 34 on the front of the vehicle 32 and a pair of wheels 34 on the back of the vehicle 32, is arranged to engage with two adjacent rails of the first set 22a of rails 22. Similarly, a second set of wheels 36, consisting of a pair of wheels 36 on each side of the vehicle 32, is arranged to engage with two adjacent rails of the second set 22b of rails 22. Each set of wheels 34, 36 can be lifted and lowered, by way of a direction-change assembly (an example of which is shown in Figures 3A-C), so that either the first set of wheels 34 or the second set of wheels 36 is engaged with the respective set of rails 22a, 22b at any one time. For example, when the first set of wheels 34 is engaged with the first set of rails 22a and the second set of wheels 36 is lifted clear from the rails 22, the first set of wheels 34 can be driven, by way of a drive assembly (an example of which is shown in Figure 5) housed in the vehicle 32, to move the load-handling device 30 in the X-direction. To achieve movement in the Y-direction, the first set of wheels 34 is lifted clear of the rails 22, and the second set of wheels 36 is lowered into engagement with the second set 22b of rails 22. The drive assembly can then be used to drive the second set of wheels 36 to move the load-handling device 30 in the Y direction.

The load-handling device 30 is equipped with a container-lifting device or assembly, e.g. a crane mechanism, to lift a storage container from above. The lifting device comprises a winch tether or cable 38 wound on a spool or reel and a gripper device 39. The lifting device shown in Figure 2 (a further example is shown in Figure 4) comprises a set of four lifting tethers 38 extending in a vertical direction. The tethers 38 are connected at or near the respective four corners of the gripper device 39, e.g. a lifting frame, for releasable connection to a storage container 10. The gripper device 39 is configured to releasably grip the top of a storage container 10 to lift it from a stack of containers in a storage system of the type shown in Figure 1.

To remove a bin 10 from the top of a stack 12, the load-handling device 30 is first moved in the X-and Y-directions to position the gripper device 39 above the stack 12. The gripper device 39 is then lowered vertically in the Z-direction to engage with the bin 10 on the top of the stack 12. The gripper device 39 grips the bin 10, and is then pulled upwards by the cables 38, with the bin 10 attached. At the top of its vertical travel, the bin 10 is held above the rails 22 accommodated within the vehicle body (or skeleton) 32. In this way, the load-handling device 30 can be moved to a different position in the X-Y plane, carrying the bin 10 along with it, to transport the bin 10 to another location. On reaching the target location (e.g. another stack 12, an access point in the storage system, or a conveyor belt) the bin or container 10 can be lowered from the container receiving portion and released from the grabber device 39.

Operating principles of a load-handling device Direction-change assemblies are described in W02021175922A1 (Ocado) and W02023025882A1 (Ocado), both of which are incorporated by reference. Figures 3A-C show a direction-change assembly 300, which has a wheel chassis 310 including wheels 320, which in this example, is one pair of a set of wheels (i.e. 36 or 34) that can move in either the X or Y direction. The wheel chassis is supported by vertical shafts 330. A cam 340 is connected to the wheel chassis. The cam has a slot 350 that through which a follower 360 is held in place by a travelling part 370. As shown by Figure 3A-C, due to the interaction of the follower with the slot, as the travelling member moves along horizontal shaft 380, the wheel chassis lowers to bring the wheels 320 into contact with tracks 395. It will be appreciated that this process can be reversed to lift the wheels up off the ground, and that only one wheel chassis need be capable of vertical movement to effect direction change. This is one example, but it will be appreciated that, in general, the direction-change assembly moves along shafts to effect direction change. Effecting movement of the direction-change assembly may also involve rotating a shaft such as one that supports a belt arrangement to move the travelling part in this example. Typically, bearings are used to support rotation of shafts or movement along shafts when effecting direction change.

An example container-lifting assembly (further described in W02023083913A1 (Ocado) and incorporated by reference) is shown in Figure 4. A lifting assembly 400 has four spools 410, 420, 430, and 440 to wind and unwind respective tethers 38. Spools 410 and 420 are on drive shaft 450, whereas spools 430 and 440 are on drive shaft 460. Drive shafts 450 and 460, when driven by a motor via pulley arrangement 470, are configured to rotate in opposite directions when raising and or lowering gripping device 480.

Rotation of the spools involves rotation of shafts, such as drive shafts 450, 460, and rotatable shafts to which the pulleys of the pulley arrangement are fixed. This is one example, but it will be appreciated that, in general, the container-lifting assembly rotates shafts to effect a raising or lowering of the gripping device. Typically, bearings are used to support the rotation of the shafts when effecting a raising or lowering of the gripping device.

An example drive assembly 500 for one pair 510 of a set of wheels is shown in Figure 5. The drive assembly comprises a drive belt for engaging with the pair of wheels. A drive belt 520 is guided by a first pulley 530 and a second pulley 540 mounted on the load-handling device, and two tensioning wheel arrangements 550. Each of the wheels, first pulley, second pulley, and tensioning wheels, all involve rotation of shafts, such as an axle to which a wheel is connected, or rotatable shafts to which respective pulleys and tensioning wheels are fixed. This is one example, but it will be appreciated that, in general, the drive assembly rotates shafts to effect movement of the load-handling device in the X or Y directions. Typically, bearings are used to support the rotation of the shafts when effecting movement of the load-handling device in the X or Y directions.

It will now be appreciated that the load-handling device 30 has three systems, each of which involves the use of a significant number of bearings: the direction-change assembly; the container-lifting assembly; and the drive assembly. Bearings will of course wear over time and require replacement. Making the bearing replacement process easier and quicker is helpful.

Figures 6A-C show different views of a first bearing mount. Figure 6A shows a wheel chassis 600 that moves up and down shafts 610 (shown in dashed lines for simplicity), similar to what is shown in Figures 3A-C. A bearing housed by 620 supports the shafts. 620 is shown in more detail in Figure 6B where a bearing mount 640 provides a press-fit (or interference fit) with bearing 660a, b. This applies a radial force to the bearing. In the example shown, the press fit is achieved by sizing an opening 650 according to the size of the bearing. Additionally, crush ribs within the opening may be used for this purpose. The crush ribs may include one or more snap-fit elements.

The radial force provided by the press-fit should be sufficient to resist substantial axial forces applied to the bearing. Nonetheless, an extra measure to prevent axial movement ensures that the bearing is held in place within the mount. In this context, preventing axial movement of the bearing refers to preventing axial movement of the bearing with respect to the bearing mount. Of course, the bearing and bearing mount can move axially as a whole. A user-engagable snap-fit cover 670 releasably engages with the bearing mount to prevent axial movement of the bearing. In general, the user engagement of the snap-fit cover of the described invention is preferably implemented directly by hand, as in this example, but indirect engagement is also possible. As best shown in Figure 6C, the cover, in this example, has opposing user-engagable cantilever snap-fit elements 691 that engage with corresponding elements (not shown) in openings 690 in the bearing mount. The cover may also have guide elements 693 to facilitate alignment with corresponding recesses in the bearing mount, which means the top of the cover is flush with the top of the bearing mount. When engaged with the bearing mount, a portion of the cover contacts the outer region of the bearing (shown in dashed-line), and thus prevents axial movement of the bearing. Accordingly, the cover has a U-shaped, or half 0-shaped, or V-shaped configuration where generally opposing arms engage an outer region of the bearing. Due to this configuration, the cover can engage the bearing mount in a radial direction (i.e. the cover engages the bearing mount in a direction perpendicular to the axis of the shaft). Due to the user-engagable snap-fit cover, a user can easily and quickly access the bearing without using any tools.

As shown in Figure 6B, the bearing mount can also have at least one access hole 680 between the outside of the bearing mount through to the opening 650. The location of an opening of the access hole within the opening 650 can be located to be near an edge or surface of the bearing to allow contact with the bearing. When the user engagable snap-fit cover has been removed, a user can access the bearing (optionally with an appropriate tool, such as a screwdriver) to apply a force to overcome the radial force holding the bearing in place and remove the bearing in an axial direction.

The cover will prevent axial movement in a first direction (e.g. upwards). Additionally, axial movement can be prevented in a second direction opposite the first direction (i.e. downwards).

In the example shown, the bearing has a collar 665 to hold the bearing and prevent axial movement in the second direction (i.e. downwards). That is, the collar engages with a corresponding projection in the bearing mount to prevent downwards axial movement of the bearing. When access holes are used with this arrangement, the location of the opening of the access hole within the opening 650 is below the collar. Appling a force to the collar via the access hole moves the bearing axially (i.e. upwards). The bearing is thus prevented moving in both axial directions due to the cover and the collar engaging with the bearing mount.

The bearing does not necessarily require a collar. For example, the opening may instead or additionally have a projection (not shown) to engage with the end of the bearing (with or without a collar), farthest from the cover, to prevent axial movement in the second direction. When access holes are used with this arrangement, the location of the opening of the access hole within the opening may be located near the projection so that a force can be applied to an edge or surface of the bearing.

The bearing shown in Figure 6B is a split bearing that has two halves, 660a and 660b.

This allows the bearing to be removed without having to remove any other parts that may be located on the shaft. It will be appreciated that any type of bearing may be used including a plain bearing, a slide bearing, a glide bearing, or a rolling element bearing. Irrespective of the bearing type used, it can be a complete bearing or split into any number of sections/parts. Whilst Figures 6A-C show the bearing used is in respect of the direction-change mechanism sliding about a shaft, the same arrangement can be used to support the rotation of a shaft as described in respect of Figures 3-5.

Figures 7A and 7B show a second bearing mount 700. A bearing mount 710 provides a press-fit (or interference fit) with bearing 720. The cover is generally 0-shaped, but may be closed if the bearing can be accessed via a shaft from the other side of the bearing mount. In general, the press-fit may be applied by sizing opening 740 appropriate to the bearing, or the introduction of crush ribs for example. The crush ribs may have one or more snap-fit elements. In this respect, the main difference from the second bearing mount is that a user-engagable snap-fit cover 730 engages with the mount in an axial direction.

However, Figures 7A and 7B show optional features that may be used to effect the press-fit as the cover engages with the mount. In particular, an opening 740 of the bearing mount has a plurality of projections 760 arranged in an annular shape. The projections can pivot in a radial direction to engage with an outer surface or race of the bearing. In this example, as shown, this is achieved by narrowing each projection at the point at which the projection connects to the bearing mount. To act against these projections, there are a plurality of steps 770 in the inner surface of the cover. The edges of these steps contact respective projections to urge the projections radially inwards when the cover engages with the bearing mount. In the example shown, two user-engagable cantilever snap-fit elements engage with the mount radially as the edges contact the projections. Further, an optional complimentary projection 780a and slot 780b in the opening of the mount and outer surface of the cover engage in a thread or screw like manner to hold the cover in place. The cover in general can be configured to apply radial pressure to the bearing whilst also preventing axial movement in the first direction. Similar to the first bearing mount, a projection 795 may be used prevent movement in the second axial direction. Although not shown, access holes may be included to assist removing the bearing as described in respect of the first bearing mount. Additionally, holes 790 in respective tabs can be used to insert a tool, such as a screwdriver shaft, for rotational advantage.

It will be appreciated that any type of bearing may be used in the second bearing mount including a plain bearing, a slide bearing, a glide bearing, or a rolling element bearing.

Irrespective of the bearing type used, it can be a complete bearing or split into any number of sections/parts. Further, the bearing can support both rotation of a shaft or movement along a shaft.

Figure 8 shows a third bearing mount 800 similar in operation to the second bearing mount 700. A bearing mount 810 provides a press-fit (or interference fit) with bearing 820. The cover is generally 0-shaped, but may be closed if the bearing can be accessed via a shaft from the other side of the bearing mount. In general, the press-fit may be applied by sizing opening 840 appropriate to the bearing, or the introduction of crush ribs for example. The crush ribs may have one or more snap-fit elements. In this respect, the main difference from the first bearing mount is that a user-engagable snap-fit cover 830 engages with the mount in an axial direction.

Again, Figure 8 shows optional features that may be used to effect the press-fit as the cover engages with the mount. An opening 815 of the bearing mount has a plurality of projections 850 arranged in an annular shape. The projections can pivot in a radial direction to engage with an outer surface or race of the bearing. In this example, as shown, this is achieved by narrowing each projection at the point at which the projection connects to the bearing mount. To act against these projections, there are a plurality of snap fit elements 860 on the outer surface of the cover. The snap fit elements contact respective projections to urge the projections radially inwards when the cover engages with the bearing mount. In the example shown, there are eight snap-fit cantilever projections, four of which are user-engagable. Similar to the first and second bearing mounts, a projection 825 may be used to prevent movement in the second axial direction. Although not shown, access holes may be included to assist removing the bearing as described in respect of the first bearing mount.

It will be appreciated that any type of bearing may be used in the third bearing mount including a plain bearing, a slide bearing, a glide bearing, or a rolling element bearing.

An example of how the second bearing mount can support the rotation of shaft is shown in Figure 9. Although Figure 9 depicts the second bearing mount, both the first and third bearing mounts could be used in a similar way. Figure 9 shows a driveshaft system 900 that could be used to drive one set of wheels used to effect either X or Y movement of the load-handling device. A drive shaft 910 is supported by two bearings 720. The bearings are housed in two mounts 710 (only one of which is shown) that engage with respective covers 730.

A method of installing and/or removing a bearing comprises press-fitting the bearing into the bearing mount, and snap-fitting the user-engagable snap-fit cover into the bearing mount, and/or removing the snap-fit cover from the bearing mount, and removing the bearing from the bearing mount. An access hole may be used to remove the bearing.

It will be appreciated that the bearing mounts can be used with any device and have wider uses than a load-handling device.

1. An assembly to support a shaft, the assembly comprising: a bearing to support the shaft; a bearing mount configured to provide a press-fit engagement with the bearing to apply a radial force to the bearing; and a user-engagable snap-fit cover configured to releasably engage with the bearing mount to prevent axial movement of the bearing.

2. The assembly of embodiment 1, wherein the bearing mount comprises at least one access hole to facilitate removal of the bearing in a first axial direction away from the bearing mount.

3. The assembly of embodiment 2, wherein the bearing comprises a collar or surface that covers an opening of the access hole.

4. The assembly of embodiment 3, wherein the bearing comprises a split bearing.

5. The assembly of any preceding embodiment, wherein the bearing mount comprises a housing, the housing comprising: an opening in which the bearing is located; and at least one snap-fit element to engage with the snap-fit cover to prevent movement of the bearing in a first axial direction.

6. The assembly of embodiment 5, further comprising a projection within the opening to prevent movement of the bearing in a second axial direction opposite the first axial direction.

7. The assembly of embodiment 5, wherein the opening comprises crush ribs to apply a compressive or radial force to the bearing.

8. The assembly of embodiment 7, wherein at least one of the crush ribs comprises a snap-fit element.

9. The assembly of any preceding embodiment, wherein the cover is substantially U-shaped, or substantially V-shaped, or substantially half 0-shaped to engage the bearing mount in a radial direction.

10. The assembly of embodiment 9, wherein the cover comprises two user-engaged cantilever snap-fit elements opposite each other to facilitate removal of the cover in a radial direction.

11. The assembly of embodiments 1 to 8, wherein the cover is substantially 0-shaped to engage the bearing mount in an axial direction.

12. The assembly of embodiment 11, wherein the bearing mount comprises: a plurality of projections arranged in an annular shape to contact an outer surface or race of the bearing; and either a slot or projection; and the cover comprises: a plurality of steps arranged in an annular shape; two user-engagable cantilever snap-fit elements on opposite sides of the cover configured to engage respective snap fit elements in the bearing mount in a radial direction; and the other of the slot or projection such that the slot and projection rotationally interact to move the cover in the axial direction to engage the edges of the steps with respective projections to apply radial pressure to the bearing when the snap-fit elements snap in place in the bearing mount.

13. The assembly of embodiment 11, wherein the bearing mount comprises: a plurality of projections arranged in an annular shape to contact an outer surface or race of the bearing; and the cover comprises: a plurality of snap-fit cantilever elements arranged in an annular shape configured to engage corresponding elements in the bearing mount in an axial direction such that the snap-fit elements engage with respective projections to apply radial pressure to the bearing when the snap-fit cantilever elements snap in place in the bearing mount.

14. The assembly of any preceding embodiment, wherein the bearing comprises a plain bearing, or slide bearing, or glide bearing.

Claims

Claims 1. A load-handling device for lifting and moving storage containers stacked in a grid framework structure comprising: a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicularly to the first set of rails or tracks in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be stacked between and be guided by the uprights in a vertical direction through the plurality of grid spaces, the load-handling device comprising: a body or skeleton mounted on a first set of wheels being arranged to engage with the first set of parallel tracks and a second set of wheels being arranged to engage with the second set of parallel tracks; a drive assembly comprising a shaft configured to rotate to drive the first or second sets of wheels to move the load-handling device along the first or second set of parallel rails respectively, or a direction-change assembly comprising a shaft either configured to rotate or along which the direction change assembly moves to raise or lower the first set of wheels, and/or lower or raise the second set of wheels with respect to the body or skeleton to engage and disengage the wheels with the parallel tracks, or a container-lifting assembly comprising a shaft configured to rotate to raise or lower a gripping device in the vertical direction; a bearing to support the shaft; a bearing mount configured to provide a press-fit engagement with the bearing to apply a radial force to the bearing; and a user-engagable snap-fit cover configured to releasably engage with the bearing mount to prevent axial movement of the bearing.
2. The load-handling device of any preceding claim, wherein the bearing mount comprises at least one access hole to facilitate removal of the bearing in a first axial direction away from the bearing mount.
3. The load-handing device of claim 2, wherein the bearing comprises a collar or surface that covers an opening of the access hole.
4. The load-handling device of claim 3, wherein the bearing comprises a split bearing.
5. The load-handling device of any preceding claim, wherein the bearing mount comprises a housing, the housing comprising: an opening in which the bearing is located; and at least one snap-fit element to engage with the snap-fit cover to prevent movement of the bearing in a first axial direction.
6. The load-handling device of claim 5, further comprising a projection within the opening to prevent movement of the bearing in a second axial direction opposite the first axial direction.
7. The load-handling device of claim 5, wherein the opening comprises crush ribs to apply a compressive or radial force to the bearing.
8. The load-handling device of claim 7, wherein at least one of the crush ribs comprises a snap-fit element.
9. The load-handling device of any preceding claim, wherein the body or skeleton, or the drive assembly, or the direction-change assembly, or the container-lifting assembly comprises the bearing mount.
10. The load-handling device of any preceding claim, wherein the cover is substantially U-shaped, or substantially V-shaped, or substantially half 0-shaped to engage the bearing mount in a radial direction.
11. The load-handling device of claim 10, wherein the cover comprises two user-engaged cantilever snap-fit elements opposite each other to facilitate removal of the cover in a radial direction.
12. The load-handling device of claims 1 to 9, wherein the cover is substantially 0-shaped to engage the bearing mount in an axial direction.
13. The load-handling device of claim 12, wherein the bearing mount comprises: a plurality of projections arranged in an annular shape to contact an outer surface or race of the bearing; and either a slot or projection; and the cover comprises: a plurality of steps arranged in an annular shape; two user-engagable cantilever snap-fit elements on opposite sides of the cover configured to engage respective snap fit elements in the bearing mount in a radial direction; and the other of the slot or projection such that the slot and projection rotationally interact to move the cover in the axial direction to engage the edges of the steps with respective projections to apply radial pressure to the bearing when the snap-fit elements snap in place in the bearing mount.
14. The load-handling device of claim 12, wherein the bearing mount comprises: a plurality of projections arranged in an annular shape to contact an outer surface or race of the bearing; and the cover comprises: a plurality of snap-fit cantilever elements arranged in an annular shape configured to engage corresponding elements in the bearing mount in an axial direction such that the snap-fit elements engage with respective projections to apply radial pressure to the bearing when the snap-fit cantilever elements snap in place in the bearing mount.
15. The load-handling device of any preceding claim, wherein the bearing comprises a plain bearing, or slide bearing, or glide bearing. 30
16. A method of installing a bearing in and/or removing a bearing from the load-handling device of any preceding claim, the method comprising: press-fitting the bearing into the bearing mount; and snap-fitting the user-engagable snap-fit cover into the bearing mount; and/or removing the snap-fit cover from the bearing mount; and removing the bearing from the bearing mount.
17. The method of claim 16 when dependent on claim 2, the method further comprising using the at least once access hole to release the bearing from its press-fit in the bearing mount.