GB2478815A

GB2478815A - Storage crate incorporating a weighing device

Info

Publication number: GB2478815A
Application number: GB201101947A
Authority: GB
Inventors: Andrew Carr; Terry Green; David Cornish
Original assignee: CONSORTIA PRODUCTS Ltd
Current assignee: CONSORTIA PRODUCTS Ltd
Priority date: 2010-03-16
Filing date: 2011-02-04
Publication date: 2011-09-21
Anticipated expiration: 2031-02-04
Also published as: GB2478815B; GB201004468D0; GB201101947D0; WO2011113871A1

Abstract

A storage crate incorporating a weighing device for weighing contents disposed in the storage cavity in order to warn the user of the likely effort needed to lift the crate. The weighing device comprises a vertically movable plate member disposed above and spaced from the base of the crate and forms a movable lowermost wall or floor of the storage cavity. The plate member extending over at least a majority of the inner surface of the base and has a plurality of springs disposed beneath it, biasing the movable plate member upwardly away from base. A weight indicator connected to or integral with the movable plate member and extending below it. There is also an opening in one of the sidewalls located along a line of vertical movement of the weight indicator so that when the plate member moves vertically under a load, the weight indicator is viewable through the opening from an exterior side of the crate.

Description

Storage Crate Incorporating a Weighing Device The present invention relates to a storage crate incorporating a weighing device.

In the UK and Europe, office and commercial relocation companies use plastic crates to transport papers, filing and personal effects from building to building or internally within the same building. Such crates typically have an integral interlocking lid. Accordingly, after the crate has been packed with contents and the lid has been closed, the user has no idea of the precise nature of the contents, in particular the weight of the contents. Before lifting the crate, the user therefore does not know whether the crate will be heavy or light in weight, and this lack of information can (and does) lead to injuries if the user lifts an overpacked or unexpectedly heavy crate.

From a health and safety perspective, a crate showing an approximate weight would provide an insurance to the employer that their staff would not be at risk of injury when moving or transporting the crates.

The state of the art includes a number of different prior proposals for containers incorporating a built-in weighing scale.

US-A-7,161,097 discloses a container with a built-in scale. The container is typically a suitcase although it may comprise a stackable bin or a tub. A scale is mounted on the planar bottom of the container, It is disclosed that the scale can be any conventional weighing mechanism which utilises mechanical sensing mechanisms, levers, springs and multiple moving parts as part of their design or alternatively an electronic means to provide a digital read-out, for example incorporating a sensing device such as a transducer load cell assembly, a piezoelectric sensor or an electromechanical actuator.

US-A-7, 151,231 discloses a combined suitcase and weighing scale in which a weight determining mechanism is disposed in a cavity within the suitcase and incorporating a mechanism for electronically displaying the weight of the item.

US-A-2005/0217903 discloses a luggage device with a built-in load determination component comprising a spring in a mechanical scale, a strain gauge or a load cell for measuring weight in the luggage. The preferred embodiment incorporates an electronic load determination means.

US-A-2005/0217904 discloses a container such as luggage or a shipping crate, with a built-in weighing device for displaying the weight of the container. The weighing device comprises a plurality of weight sensors which are attached to the bottom of the luggage device and act as legs when the luggage device is standing upright. The sensors are connected electrically to an electrical display screen.

Despite this large number of prior proposals of containers incorporating built-in weighing scales, none of them is particularly suitable for providing a storage crate incorporating a weighing device which not only has low manufacturing costs, for incorporation into a new storage crate or alternatively retrofitting into a storage crate, and which has the required durability and reliability when subjected to robust handling and varied ambient conditions in use. Furthermore, electronic devices suffer from the problem that battery life is limited and storage crates are sometimes required to be stored for very long periods of time. Also, it is desirable to have a weighing device which can reliably provide a continuous indication of the weight of the contents of the storage crate.

Yet further, it is desirable that the weighing device adds minimal additional cost to the manufacturing cost of the crate, Still further, it is desirable that the weighing device does not affect the ability of the crates to be stacked together when empty so as to take up minimal storage volume The present invention aims at least partially to overcome these problems of the known containers incorporating a built-in scale.

Accordingly, the present invention provides a storage crate having a base and a plurality of sidewalls extending upwardly from the base to define a storage cavity, and a weighing device for weighing contents disposed in the storage cavity, the weighing device comprising a vertically movable plate member disposed above and spaced from the base and forming a movable lowermost wall of the storage cavity, the plate member extending over at least a majority of the inner surface of the base, a plurality of springs disposed beneath the movable plate member and biasing the movable plate member upwardly away from base at least when a load is disposed on the plate member, a weight indicator connected to or integral with the movable plate member and extending downwardly therefrom, an opening in one of the sidewalls located along a line of vertical movement of the weight indicator when the plate member moves vertically under a load disposed thereon so that the weight indicator is viewable through the opening from an exterior side of the crate.

The storage crate may further comprise a weight indicating display adjacent to the opening, wherein the weight indicator and the weight indicating display cooperate to indicate a weight of the load related to the vertical position of the vertically movable plate member.

Optionally, the display is adapted to indicate successive weight bands. The display may be a colour coded display with different colours indicating respective weight bands.

Typically, a surface of the weight indicator viewable through the opening has at least one marking thereon, the marking being configured to indicate a different weight based on the vertical position of the marking relative to the of the opening. The marking may comprise a mark inclined to the horizontal at an acute angle. The mark may comprise a lower zone having an upper inclined edge and an adjacent upper zone having a lower inclined edge. Typically, vertical movement of the upper and lower inclined edges due to vertical movement of the weight indicator causes horizontal movement of the upper and lower inclined edges along the opening.

Preferably the marking is adapted to indicate successive weight bands. The marking may be colour coded with different colours indicating respective weight bands.

Optionally, one weight band indicates a safe load and another weight band indicates a dangerous load. Further optionally, at least one further weight band indicates a take-care load between the safe load and the dangerous load.

Typically, the weight indicator is shaped so as to vary in at least one of shape and dimensions in a vertical direction therealong so that the at least one of shape and dimensions viewable through the opening indicates a different weight based on the vertical position of the weight indicator relative to the opening.

In one embodiment, the another part comprises the base.

Optionally, upper ends of the springs are fitted to an underside of the plate member and lower ends of the springs are fitted to an inner surface of the base.

In another embodiment, the another part comprises a lower plate member disposed between the base and the movable plate member, the plurality of springs being fitted to and between opposed surfaces of the lower plate member and the movable plate member.

The storage crate may further comprise a plurality of tension elements connected between the movable plate member and the another part to hold the movable plate member at an upper position when in the unloaded state.

Preferably, when the movable plate member is at an upper position when in the unloaded state, the storage crate is stackable in a nested configuration with an identical storage crate, and the bottom of the upper nested crate is spaced from the movable plate member of the lower nested crate.

Optionally, the opening is a horizontally oriented slot.

Typically, the weighing device includes a numerical scale to indicate the weight of a load on the movable plate member.

The preferred embodiments of the present invention can provide a storage crate incorporating a built-in weighing device which can overcome the problems of the known devices summarised above.

The weight detection system has low manufacturing costs, for incorporation into a new storage crate or alternatively retrofitting into an existing storage crate. The weight detection system has a high degree of durability and reliability when subjected to robust handling and varied ambient conditions in use.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic perspective view of a storage crate in accordance with a first embodiment of the present invention; Figure 2 is a schematic side view on line A-A of the inside of the storage crate of Figure 1; Figure 3 is a schematic plan view on line B-B of the inside of the storage crate of Figure 1; Figures 4(a), (b) and (c) illustrate the weight indicator indicating different loads within the storage crate of Figure 1, and Figure (d) indicates the unloaded state; Figure 5 illustrates an alternative weight indicator and opening combination; Figure 6 illustrates a further alternative weight indicator and opening combination; Figure 7 illustrates a nested stack of three of the empty storage crates of Figure 1; Figure 8 is a schematic plan view of a storage crate in accordance with a second embodiment of the present invention; Figure 9 is a schematic part-sectional view on line A-A of the storage crate of Figure 8; Figure 10 is an enlarged schematic part-sectional view on line B-B of the storage crate of Figure 8; Figure 11 is an enlarged schematic part-sectional view on line C-C of the storage crate of Figure 8; Figure 12 is a schematic part-sectional view on line D-D of the storage crate of Figure 9; Figure 13 is an exploded perspective view of the underside of the movable plate and spring assembly of the storage crate of Figure 8.

Referring to Figures 1 to 4, a storage crate 10 in accordance with a first embodiment of the present invention is schematically illustrated. The storage crate 10 has a base 12 and a plurality of sidewalls 14, 16, 18, 20 extending upwardly from the base 12 to define a storage cavity 22. Typically, the storage crate 10 has a rectangular shape, with a rectangular base and rectangular sidewalls. The storage crate 10 is typically composed of plastic, and is typically injection moulded. The storage crate 10 further comprises a lid 24 for covering the storage cavity 22. The lid 24 comprises first and second interlocking lid members 26, 28 each hingedly attached to an upper edge 30, 32 of a respective one of two opposed sidewalls 14, 18. The storage crates 10 are structured so as to be stackable, when full and when the lid 24 closes the top of the storage crate 10, one on top of another, with the base 12 of an upper storage crate 10 mating with the lid 24 of a lower storage crate 10. The storage crates 10 are also structured so as to be stackable, when empty and when the lid members 26, 28 are folded back against the respective sidewafls 14, 18, by nesting one on top of another, with the base 12 of an upper storage crate 10 spaced above the base 12 of a lower storage crate 10.

In accordance with the present invention, a weighing device 34 is provided for weighing any contents disposed in the storage cavity 22. The weighing device 34 is disposed above the base 12 of the storage crate 10. The weighing device 34 comprises a movable plate 36, which is a movable floor, which is planar and has a peripheral edge 38 shaped so as to fit within the storage cavity 22 defined by the sidewalls 14, 16, 18, 20 of the storage crate 10. The movable plate 36 is spaced a particular distance, in the unloaded state, above the base 12 and is held at the particular distance by helical springs 42 located between the movable plate 36 and the base 12. The upper and lower ends 44, 46 of the helical springs 42 are respectively fitted, for example by an interference fit, to the opposed surfaces of the movable plate 36 and the base 12. Typically, there are at least four, e.g. five compression springs 42, four located inwardly of a respective corner of the storage crate 10 and one, if present, centrally located in the storage crate 10.

In the unloaded state the springs 42 are substantially unbiased and the movable plate 36 is held parallel to the base 12. In the loaded state, the movable plate 36 is urged downwardly by the load and the springs 42 are in compression and bias the vertically movable plate 36 upwardly away from the base 12 against the load.

A weight indicator element 50 is connected to or integral with the movable plate member and extends downwardly therefrom. The weight indicator element 50 does not extend above the movable plate 36 and so does not interfere with the contents of the cavity 22 when loaded into the crate 10. Typically, the weight indicator element comprises a plate of plastic material. An opening 52 in one of the sidewalls 18 is located along a line of vertical movement of the weight indicator element 50 when the movable plate 36 moves vertically under a load disposed thereon. In this embodiment the opening 52 is an elongate horizontal slot. The weight indicator element 50 is viewable through the opening 52 from an exterior side of the crate 10. The opening 52 may be covered by a transparent window (not shown), for example of a plastic material.

A surface 54 of the weight indicator element 50 viewable through the opening 52 has at least one marking 56 thereon. The marking may be printed. The marking 56 is configured to indicate a different weight based on the vertical position of the marking 56 relative to the opening 52. The marking 56 comprises a mark 58, and in particular the mark 58 comprises a lower zone 60 having an upper inclined edge 62 inclined to the horizontal at an acute angle and an adjacent upper zone 64 having a lower inclined edge 66 coincident with the upper inclined edge 62. The upper zone 64 indicates successive weight bands 68, 70, 72, and is colour coded with different colours indicating respective weight bands, whereas the lower zone 60 is plain.

Optionally, the lower zone 60 could be omitted, and the lower edge of the weight indicator element may be inclined to the horizontal.

Vertical movement of the upper and lower inclined edges 62, 66 due to vertical movement of the weight indicator element 50 causes horizontal movement of the upper and lower inclined edges 62, 66 along the elongate opening 52. This indicates the weight of the load to a user looking at the opening 52 from the exterior of the storage crate 10.

A weight indicating display 70 is adjacent to the opening 52, for example surrounding the opening 52. Like the weight indicator element 50, the display 70 indicates successive weight bands, and is colour coded with different colours indicating respective weight bands. Three weight bands A (light), B (medium) and C (heavy) are shown. The weight indicator element 50 and the weight indicating display 70 cooperate to indicate a weight of the load related to the vertical position of the vertically movable plate 36.

The display 70 may be a colour coded display with different colours indicating respective weight bands 74, 76, 78. For example, one weight band 74, optionally coloured green, indicates a safe load and another weight band 78 optionally coloured red, indicates a dangerous load. At least one further intermediate weight band 76, optionally coloured yellow or orange, indicates a take-care load between the safe load and the dangerous load. Such a "traffic-light" indication system is easy to see and comprehend, even under low levels of ambient light. Although not illustrated, the display 70 may optionally incorporate a numerical scale of measured load, for example in kilograms and/or pounds, and/or icons representative of the load band, for example indicating how many persons are required safely to lift the loaded storage crate 10.

When the storage crate 10 is loaded, the weight of the contents pushes the movable plate 36 downwardly against the bias of the compression springs 42 and the spring force and spring rate are such that the load is spread equally over the surface of the movable plate 36 so that when depressed under the load the movable plate 36 remains substantially horizontal and parallel to the base 12. Such downward urging of the movable plate 36 causes the weight indicator element 50 to move downwardly which correspondingly causes the upper and lower inclined edges 62, 66 to move horizontally along the opening 50. The movement of the colour coded upper zone 64 on the weight indicator element relative to the colour coded display 70 around the opening 52 enhances the visibility of the indicated weight. However, the display may be omitted.

Figures 4 (a), (b) and (c) illustrate the weight indicator element 50 and opening 52 showing three different loads, the weight indicator respectively indicating light, medium and heavy loads, within the storage crate 10. In the loaded state the upper zone 64 is visible through the opening 52. Figure (d) indicates the unloaded state and the lower zone 60 is visible through the opening 52.

Figure 5 illustrates an alternative weight indicator and opening combination. The weight indicator element 80 mounted on the movable plate 36 is rectangular and has three vertically arranged warning markings 82, 84, 86. Progressive loading of the movable plate 36 causes the warning markings 82, 84, 86 to be progressively and sequentially displayed through the opening 88 in sidewall 18.

Figure 6 illustrates a further alternative weight indicator and opening combination. The weight indicator element 88 mounted on the movable plate 36 is triangular and progressively increases in width from the bottom point 90 to the top edge 92 which is fitted to the movable plate 36. The sidewall 18 has three horizontally arranged warning markings 94, 96, 98 adjacent to the opening 100. Progressive loading of the movable plate 36 causes an increasing width of the weight indicator element 88 to be progressively displayed through the opening 88 in sidewall 18 adjacent to the markings 94, 96, 98.

Typically, a maximum vertical distance for moving the movable plate 36 between its unloaded and fully loaded conditions is about 54mm. In the unloaded state, the movable plate 36 is spaced a distance from the base 12 that is less than the spacing between the storage crate bases 12 when they are nested together. This means that the storage crates can be efficiently nested together, as shown in Figure 7.

In a modification of the first embodiment, the weighing device comprises an upper movable plate and a lower non-moving plate which rests on the base. The upper plate is spaced a particular distance, in the unloaded state, above the lower plate and is held at the particular distance by the combination of helical compression springs located between the plates and tension elements in the form of flexible restraining wires which are fitted between upper and lower clamps respectively provided on the opposed surfaces of the upper and lower plates. A corresponding number of restraining wires may be provided, each associated with the respective compressive spring.

Referring to Figures 8 to 13, a storage crate 110 in accordance with a second embodiment of the present invention is schematically illustrated. The storage crate 110 has a structure similar to that of the first embodiment, and includes a base 112 and a plurality of sidewalls 114, 116, 118, 120 extending upwardly from the base 112 to define a storage cavity 122.

The weighing device 134 comprises a movable plate 136, which is a movable floor, which is planar and has a peripheral edge 138 shaped so as to fit within the storage cavity 122.

The storage crate 110 is modified as compared to the first embodiment by providing a plurality of inwardly directed stop members 124, each located on the inside surface of a sidewall 114, 116, 118, 120 and located a particular distance upwardly from the base 112 corresponding to the desired location of the movable plate 136 in an unloaded state. The stop members 124 are arranged in a mutually spaced configuration extending peripherally around the inside of the storage crate 110. For example, two stop members 124 may be located on each of the two opposed end walls 116,120 of the storage crate as illustrated.

The inside edges 125 of the stop members 124 define an inner zone 126 having a shape corresponding to the shape of the upper surface of the movable plate 136, but dimensions smaller than those of the upper surface of the movable plate 136. Each stop member 124 has a downwardly directed stop surface 127. Therefore when the movable plate 136 is located beneath the stop members 124, the movable plate 136 is captive in a lowermost portion 128 of the storage crate 110 by the stop members 124, with an upper outer edge portion 129 of the movable plate 136 bearing upwardly against the downwardly directed stop surface 127.

An outer edge 130 of the movable plate 136 has at least one inwardly chamfered area 132 aligned with a respective stop member 124. The inside edges 125 are curved.

Accordingly, the movable plate 136 can be inserted into the lowermost portion 128 by pressing downwardly so that the chamfered areas 132 slide over the curved stop members 124 and the movable plate 136 is received and captured in the lowermost portion 128 by a snap-or relaxation-fit.

In such a position, the movable plate 136 can move upwardly and downwardly within the lowermost portion 128 dependent upon any load present on the movable plate 136. The stop members 124 define the maximum upper position of the movable plate 136 in the unloaded state.

As for the first embodiment, at least one weight indicator element 150 is connected to or integral with the movable plate member 136 and a surface 154 of the weight indicator element 150 is viewable through an opening 152 in a sidewall 114, 118 of the storage crate 110. In the illustrated embodiment there are two weight indicator elements 150 on opposite sides of the storage crate 110, but they may be located on opposite ends or on a side and an end, or only a single weight indicator element may be provided on any selected side or end of the storage crate 110. The or each weight indicator element 150 indicates a zero or safe load in the unloaded state.

Also as for the first embodiment, a plurality of helical springs 142 are located between the movable plate 136 and the base 112.

The upper ends 144 of the helical springs 142 are respectively fitted, for example by an interference fit, to the undersurface 146 of the movable plate 136. The undersurface 146 includes spring-receiving pockets 147, each including a circular cavity 160 at each spring location. The circular cavity 160 includes at its closed end 161 a circular central boss 162.

The inner circumference of the circular cavity 160 and the outer circumference of the central boss 162 respectively correspond to the outer and inner circumference of the helical springs 142. The upper end 144 of the respective helical spring 142 is received in the circular cavity 160 and fitted between the circular cavity 160 and the central boss 162 so as to be securely held on the movable plate 136. Typically, there are at least four, e.g. five compression springs 142, four located inwardly of a respective corner of the storage crate 110 and one, if present, centrally located in the storage crate 110.

In the unloaded state the springs 142 are substantially unbiased and the movable plate 136 is held parallel to the base 112 by the stop members 124. In the loaded state, the movable plate 136 is urged downwardly by the load and the springs 142 are in compression and bias the vertically movable plate 136 upwardly away from the base 112 against the load. The at least one weight indicator element 150 indicates the load state to a viewer of an external surface of the storage crate 110.

This embodiment provides the advantage of a reduced number of parts and a simple yet robust fitting of the movable plate securely within the storage crate.

It would be apparent to the skilled person that various modifications to the illustrated embodiments may be made within the scope of the invention. For example, different shapes and dimensions of the crate may be employed. The display may be varied, and the weight indicator may be located elsewhere on the crate.

Claims

Claims: 1. A storage crate having a base and a plurality of sidewalls extending upwardly from the base to define a storage cavity, and a weighing device for weighing contents disposed in the storage cavity, the weighing device comprising a vertically movable plate member disposed above and spaced from the base and forming a movable lowermost wall of the storage cavity, the plate member extending over at least a majority of the inner surface of the base, a plurality of springs disposed beneath the movable plate member and biasing the movable plate member upwardly away from base at least when a load is disposed on the plate member, a weight indicator connected to or integral with the movable plate member and extending downwardly therefrom, an opening in one of the sidewalls located along a line of vertical movement of the weight indicator when the plate member moves vertically under a load disposed thereon so that the weight indicator is viewable through the opening from an exterior side of the crate.
2. A storage crate according to claim 1, further comprising a weight indicating display adjacent to the opening, wherein the weight indicator and the weight indicating display cooperate to indicate a weight of the load related to the vertical position of the vertically movable plate member.
3, A storage crate according to claim 2, wherein the display is adapted to indicate successive weight bands.
4. A storage crate according to claim 3, wherein the display is a colour coded display with different colours indicating respective weight bands.
5. A storage crate according to any foregoing claim, wherein a surface of the weight indicator viewable through the opening has at least one marking thereon, the marking being configured to indicate a different weight based on the vertical position of the marking relative to the of the opening.
6. A storage crate according to claim 5, wherein the marking comprises a mark inclined to the horizontal at an acute angle.
7, A storage crate according to claim 6, wherein the mark comprises a lower zone having an upper inclined edge and an adjacent upper zone having a lower inclined edge.
8. A storage crate according to claim 7, wherein vertical movement of the upper and lower inclined edges due to vertical movement of the weight indicator causes horizontal movement of the upper and lower inclined edges along the opening.
9. A storage crate according to any one of claims 5 to 8, wherein the marking is adapted to indicate successive weight bands.
10. A storage crate according to claim 9 wherein the marking is colour coded with different colours indicating respective weight bands.
11. A storage crate according to any one of claims 3, 4, 9 or 10, wherein one weight band indicates a safe load and another weight band indicates a dangerous load.
12. A storage crate according to claim 11, wherein at least one further weight band indicates a take-care load between the safe load and the dangerous load.
13. A storage crate according to any foregoing claim, wherein the weight indicator is shaped so as to vary in at least one of shape and dimensions in a vertical direction therealong so that the at least one of shape and dimensions viewable through the opening indicates a different weight based on the vertical position of the weight indicator relative to the opening.
14. A storage crate according to any foregoing claim, wherein when the movable plate member is at an upper position when in the unloaded state, the storage crate is stackable in a nested configuration with an identical storage crate, and the bottom of the upper nested crate is spaced from the movable plate member of the lower nested crate.
15. A storage crate according to any foregoing claim, wherein the opening is a horizontally oriented slot.
16. A storage crate according to any foregoing claim, wherein the weighing device includes a numerical scale to indicate the weight of a load on the movable plate member.
17. A storage crate according to any foregoing claim, wherein the another part comprises the base.
18. A storage crate according to claim 17, wherein upper ends of the springs are fitted to an underside of the plate member and lower ends of the springs are fitted to an inner surface of the base.
19. A storage crate according to any one of claims 1 to 16, wherein the another part comprises a lower plate member disposed between the base and the movable plate member, the plurality of springs being fitted to and between opposed surfaces of the lower plate member and the movable plate member.
20. A storage crate according to any foregoing claim, further comprising a plurality of tension elements connected between the movable plate member and the another part to hold the movable plate member at an upper position when in the unloaded state.
21. A storage crate according to any one of claims 1 to 16, wherein at least one inwardly directed stop member is located on an inside surface of the plurality of sidewalls and located a particular distance upwardly from the base to define a maximum upper position of the movable plate member in the unloaded state.
22. A storage crate according to claim 21, wherein a plurality of the stop members are arranged in a mutually spaced configuration extending peripherally around the inside surface of the storage crate.
23. A storage crate according to claim 22, wherein two stop members are located on each of two opposed walls of the storage crate.
24. A storage crate according to any one of claims 21 to 23, wherein an inside edge of the or each stop member defines an inner zone having dimensions smaller than those of the upper surface of the movable plate member.
25, A storage crate according to claim 24, wherein the inside edge of the or each stop member is curved.
26. A storage crate according to claim 24 or claim 25, wherein the or each stop member has a downwardly directed stop surface, and the movable plate member is located beneath the or each stop member, the movable plate being captive in a lowermost portion of the storage crate by the or each stop members, with an upper outer edge portion of the movable plate bearing upwardly against the downwardly directed stop surface.
27. A storage crate according to claim 26, wherein an outer edge of the movable plate member has at least one inwardly chamfered area aligned with the or a respective stop member.
28. A storage crate according to claim 27, wherein the movable plate member is adapted to be inserted into the lowermost portion by pressing downwardly so that the at least one chamfered area slides over the at least one stop member and the movable plate member is received and captured in the lowermost portion by a snap-fit.
29. A storage crate according to any one of claims 1 to 16 or claims 21 to 28, wherein upper ends of the springs are respectively fitted to spring-receiving pockets on an undersurface of the movable plate member.
30. A storage crate according to claim 29, wherein the spring-receiving pocket includes a circular cavity at each spring location, the circular cavity including at a closed end a circular central boss, and the upper end of the respective spring is received in the circular cavity and fitted between the circular cavity and the central boss so as to be securely held on the movable plate member.