GB2298619A

GB2298619A - Trolley with lead screw length adjustment of all legs simultaneously

Info

Publication number: GB2298619A
Application number: GB9504628A
Authority: GB
Inventors: Christopher Lloyd-Lucas
Original assignee: Paraid Ltd
Current assignee: Paraid Ltd
Priority date: 1995-03-08
Filing date: 1995-03-08
Publication date: 1996-09-11
Anticipated expiration: 2015-03-08
Also published as: GB2298619B; GB9504628D0

Description

Title: Trolley Description of Invention The invention relates to a trolley, and in particular to one which is height adjustable and comprises a support structure and legs moveable relative to the support structure.

Trolleys according to the invention may be designed for a wide range of uses. However, the principal use envisaged is that of a trolley for stretchers or incubators which can be loaded into ambulance vehicles. Therefore, the invention will be described in terms of a trolley adapted and constructed for such use, although it is more widely applicable. In such use the legs are moveable relative to the support structure in that they are collapsible or foldable, either to lower the support structure adjacent to the ground or during loading into the ambulance vehicle.

For a trolley bearing a stretcher or incubator to be loaded into an ambulance vehicle, it is necessary for the support structure of the trolley on which the load is supported to be at an appropriate height for the loading platform of the vehicle. Since ambulances are manufactured by a wide range of companies the loading height of the vehicles can vary considerably. Therefore, in order to be able to load a trolley onto a wide range of vehicles it is necessary for the trolley to incorporate height adjustment. In many prior art trolleys, such adjustment is only made on the front legs of the trolley i.e. those legs which approach the ambulance first. Therefore, as the trolley is wheeled towards the ambulance the support structure of the trolley bearing the structure or incubator is not horizontal.Clearly, this is far from ideal and in some circumstances has serious disadvantages.

Some prior art trolleys do provide height adjustment of both sets of legs but tend to suffer from three significant disadvantages. Firstly, the two sets of legs are adjusted separately, thus it can still he difficult to maintain the support structure horizontal. Secondly, considerable physical effort may be required in order to achieve the height adjustment. Thirdly, in many cases, the adjustment cannot be carried out whilst the trolley is bearing a load on its support structure.

It is an object of the invention to provide a trolley which overcomes or mitigates the above identified problems.

According to a first aspect of the invention there is provided a trolley comprising a support structure, a plurality of legs moveable relative to the support structure, actuating means for adjusting the legs and thus the height of the support structure from the ground, and wherein the actuating means is constructed and arranged such that all legs can be adjusted simultaneously.

Preferably the actuating means is operable when the support structure is supporting a load. This provides the advantage that the height adjustment can be carried out with a stretcher and patient, or an incubator already loaded on the trolley.

Preferably the plurality of moveable legs comprises first and second pairs of collapsible legs. Preferably the legs may be telescopic and the height of the support structure is adjusted by means of retracting or extending the legs.

In a preferred embodiment, the actuating means comprises, within each of the telescopic legs, leadscrews.

Preferably, the actuating means further comprises a plurality of gearboxes and a plurality of interconnecting shafts such that rotation of a single spindle of one gearbox operates the whole actuating means.

Preferably the trolley further comprises a plurality of ground engaging wheels attached to the support structure such that when the plurality of moveable legs are moved relative to the support structure the weight of the trolley is supported on a ground engaging wheels. Preferably the ground engaging wheels comprise spring loaded wheel assemblies.

Preferably locking means are provided which prevent moving of the legs relative to the support structure until at least some of the weight of the trolley is taken on at least one of the ground engaging wheels.

According to a second aspect of the invention, there is provided a trolley comprising a support structure, a plurality of legs moveable relative to the support structure, a plurality of ground engaging wheels, and locking means which prevents moving of the moveable legs until weight is taken by at least one of the ground engaging wheels.

Preferably the plurality of moveable legs comprises first and second pairs of collapsible legs. Preferably the plurality of ground engaging wheels comprise first and second pairs of spring loaded wheel assemblies.

Preferably, the first pair of collapsible legs has associated therewith a first pair of spring loaded wheel assemblies and a first locking mechanism and the second pair of collapsible legs has associated therewith a second pair of spring loaded wheel assemblies and a second locking mechanism.

One embodiment of a trolley according to the invention will now be described, by way of example only, with reference to the accompanying drawings in which: FIGURE 1 is an illustrative side view of a trolley according to the invention; FIGURE 2 is an illustrative plan view of the trolley of figure 1; FIGURE 3 is a schematic part sectional view of the actuating means of the trolley of figure 1; FIGURE 4 is a schematic partly sectional view in the direction of arrow X of figure 3, and, FIGURES 5 and 6 are schematic partly sectional views of the leg collapse release mechanism.

Referring now to figures 1 to 4, a trolley 1(), a support structure 11 and first and second pairs of collapsible second legs 12,13. The support structure 11 comprises a generally rectangular frame 14 with cross braces 15,16,17. The first pair of collapsible legs 12 comprise right and left telescopic legs 18 each comprising an upper portion 18a and a lower portion 18h. The lower portions 18b of the legs 18 are of reduced diameter compared with the upper portions 18a and can be withdrawn into the upper portions 18a or extended from the upper portions 18a in order to adjust the length of the legs 18. The upper portions 18a of the legs 18 each bear a three-spindle gearbox 19, by means of which they are pivotally connected to brackets 20 on the frame 14.The lower portions 18b of the legs 18 bear braked and clampable castoring wheels 21, which when clamped become non-castoring and when braked cannot rotate. The first pair of collapsible legs 12 further comprise bracing stays 22 (which are omitted from figure 2 for clarity) which fold when the legs 12 are collapsed.

The second pair of collapsible legs 13 are similarly constructed. They comprise right and left telescopic legs 23 each comprising an upper portion 23a and a lower portion 23b of reduced diameter. The telescopic legs 23 are each connected to a three-spindle gearbox 24 at their upper ends, and are pivotally connected thereby to cross brace 16 of the support structure 11 by means of brackets 25. The lower portions 23h of the legs 23 bear braked castoring wheels 26 which when braked cannot rotate, but are not clampable. The second pair of collapsible legs 13 further comprises bracing stays 27 (which are omitted from figure 2 for clarity) which fold when the legs 13 are collapsed.

The bracing stays 22,27, brace the upper portions 18 ,23E, of the telescopic legs 18,23, to the support frame 11 to which they are connected by means of brackets 28,29, respectively. All the brackets 22,25,28,29, are rigidly fixed to the support structure 11 and are not slidable or otherwise moveable with respect to the support structure 11.

The trolley 1() further comprises first and second pairs of ground engaging wheels in the form of spring loaded wheel assemblies 30,31, located adjacent the front of the trolley and between the first and second pairs of collapsible legs 12,13, respectively. Such spring loaded wheel assemblies are often referred to as jockey wheel assemblies. Front and rear handles 32,33, are provided for manoeuvring of the trolley 1().

The trolley 10 further comprises actuating means 34 of which the four three-spindle gearboxes 19,24, form a part. Each of the four gearboxes 19,24, is arranged such that a first spindle A is located within the respective telescopic leg 18,23, and is there attached to a leadscrew 35. Second and third spindles B,C, are arranged in a horizontal plane with the second spindle B directed inwardly of the frame 14 and the third spindle C directed outwardly of the frame 14. Each third spindle C has attached to it an engagement means 36 to which a crank handle 37 may be attached.

The actuating means 34 further comprises an additional two, threespindle gearboxes 38,39, located between the gearboxes 19, associated with the front legs 12 and between the gearboxes 24 associated with the rear legs 13 respectively. The additional gearboxes 38,39, are arranged with their three spindles in a horizontal plane with first and second spindles D,E, directed laterally and third spindle F directed longitudinally of the frame 14. The third spindles F of the gearboxes 38,39, are interconnected by means of a central shaft 40. The first and second spindles of the gearbox 38 are connected to the first spindles of gearboxes 19 by means of front intermediate shafts 41. Similarly, the first and second shafts of gearbox 39 are connected to the first shafts of the gearboxes 24 by means of rear intermediate shafts 42.

The actuating means 34 further comprises four captive nuts 43, each located adjacent the upper end of the lower portion 18b 23b of a telescopic leg 18,23.

The actuating means 34 operates as follows. The crank handle 37 is located on the engagement means 36 of the appropriate gearbox 19,24. The choice of engagement means 36 to which the crank handle 37 is attached is purely a matter of convenience. As an example, operation of the actuating means 34 will be described with the crank handle 37 attached, as illustrated in figure 2, to the front right gearbox 19. Rotation of the crank handle 37 rotates the lead screw 35 in the right front telescopic leg 18 which, depending on the direction of rotation of the crank handle 37, retracts or extends the lower portion 18b of the leg. The same rotation of the crank handle 37 also operates, via the second spindle B, front intermediate shaft 41 which in turn operates the first spindle of gearbox 38.

This causes rotation of the second and third spindles E,F, of the gearbox 38 and thus operation of the other intermediate shaft 41 and the central shaft 40 respectively. Operation of the other front intermediate shaft 41 causes operation of the left front gearbox 19 via its second spindle B and thus operation of the lead screw 35 in the left front leg 18. Operation of the central shaft 40 causes operation of the gearbox 39 via its third spindle F and thus operation of the two rear intermediate shafts 42 via the first and second spindles D,E, of the gearbox 39. Rotation of the two rear intermediate shafts 42 causes operation of the two rear gearboxes 24 via their second spindles B and thus rotation of the first spindles A and of the lead screws 35 in the rear legs 24.Therefore, rotation of the crank handle 37 causes operation of all four lead screws 35 and simultaneous extension or retraction of the four lower leg portions 18b,23b.

The actuating means 34 described provides a very significant advantage in that the second and third spindles B,C of the gearboxes 19,24 also provide the pivots for the folding of the legs 18,23, and therefore there is no complex alteration of geometry as the legs 18,23, fold.

It should be noted that since the actuating means 34 may be operated by use of the crank handle 37 with any of the four engagement means 36, only one of the gearboxes 19,24 need be fitted with an engagement means. Fitting of more than one engagement means simply provides a choice of operating point.

In order for the actuating means 34 to operate as described, the gearboxes 38,39, must provide a 1:1 ratio. However, the gearboxes 19,24, may have any appropriate ratio e.g. 3:1 which provides an acceptable rate of work when winding the crank handle 37 with a load on the support structure 11.

Suitable gearboxes are Bevel Gearboxes type Bl supplied by Hinchcliffe Precision Components Limited. However, any other appropriate gearboxes may be used.

The actuating means 34 as described above provides a significant advantage in that no locking mechanism is required to maintain the desired trolley height even when a load is supported on the support structure 11.

However, a locking mechanism may be provided if required.

Referring now also to figures 5 and G, a further feature of the trolley 10 will now be described. In order to prevent the collapsing of the first and second pairs of collapsible legs 12,13, when the weight of the trolley 10 is not supported on the jockey wheel assemblies 30,31 two locking mechanisms are provided. The first locking mechanism is associated with the first pair of jockey wheel assemblies 30 and prevents collapsing of the first pair of collapsible legs 12 until the first pair of jockey wheel assemblies 30 have moved onto the loading platform of, for example, an ambulance thereby taking some of the weight of the trolley 10.Likewise, the second locking mechanism is associated with the second pair of jockey wheel assemblies 31 and prevents collapsing of the second pair of collapsible legs 13 until the second pair of jockey wheel assemblies 31 is also on the loading platform and has taken part of the weight of the trolley 10. The two locking mechanisms operate in identical manner and therefore only the first locking mechanism will he described in detail with reference to figures 5 and 6.

The front jockey wheel assemblies 30 each comprise a yoke 50 in which an axle 51 of the respective wheel is located. The yoke 50 is attached to the rectangular frame 14 by means of a post 52 within which is located a pin 53 biased by a spring 54. Within the frame 14 a release rod 55 is located which is operated by means of a pull knob 56 located towards the rear of the frame 14.

The rod 55 is biased to the position shown in Figure 5 by spring 60 located between washers 61 and 62.

At the end of the rod 55 distant from the knob 56, the rod 55 is attached to a first pivoting lever 57, by means of a pin 55a through an elongate slot 57a. The first pivoting lever 57 is in turn connected to a second pivoting lever 58 which is also attached at its distant end to the frame 14 and at its mid point to the pin 53.

Adjacent the end of the rod 55 by the knob 56 the rod 55 is attached to formation 59 in the upper end of bracing stay 22, by means of a pin 55b through an oval hole 59a.

When the jockey wheel assemblies 30 are not supporting weight, the pin 53 and pivoting levers 57,58 are in the positions shown in solid lines in figure 6 and prevent the pulling of the knob 56 to the position shown in dashed lines in figure 5, because the pin 55a cannot slide along the elongate slot 57L and thus the rod 55 cannot be moved to the left as shown in the figures 5 and 6. When the jockey wheel assemblies 30 are supporting weight the pin 53 is pushed up within the post 52 against the bias of the spring 54, thus pivoting the second lever 58 and the first lever 57 into the positions shown in dashed lines in figure 6. The first lever 57 is then in line with the rod 55 and thus the pin 55a can slide along the elongate slot 57a permitting movement of the rod 55 to the left.Therefore, if the knob 56 is then pulled the rod 55 is free to move as shown in the dashed lines in figure 5 against the bias of spring 60. Such movement of the rod 55 rotates formation 59 at the upper end of bracing stay 22 and permits folding of that stay and thus collapsing of the legs 12.

The exact positioning of the front and rear jockey wheel assemblies 30,31, is carefully chosen to prevent the operator loading the trolley into the ambulance having to support any of the trolley weight at any point in the procedure. Thus once the front jockey wheels 30 have taken some of the weight and the first locking mechanism has permitted the collapse of the front legs 12 all the weight of the trolley 10 is safely supported by the front jockey wheel assemblies 30 and the rear legs 13. The position of the rear jockey wheel assemblies 31 is rearwards of the calculated centre-of-mass of the loaded trolley 10. Therefore when the second jockey wheel assemblies 31 take some of the weight of the trolley 10 all of the weight can, in general, be safely supported on the two sets of jockey wheel assemblies 30,31 without the trolley 10 tipping up.

It should be noted, however, that this cannot be guaranteed if the trolley is incorrectly loaded.

The locking mechanism described is an example only. Other locking mechanisms released by the taking of weight by the jockey wheel assemblies may also be constructed. In addition, other forms of ground engaging wheels may be used as appropriate for the application.

The trolley 10 has been described with one pair of braked and clampable castoring wheels 21 and one pair of braked castoring wheels 26.

However, any forms of wheel may be incorporated as appropriate for the intended use of the trolley 10.

The features disclosed in the foregoing description the following claims or the accompanying drawings. expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A trolley comprising a support structure, a plurality of legs moveable relative to the support structure, and actuating means for adjusting the legs and thus the height of the support structure from the ground, wherein the actuating means is constructed and arranged such that all legs are simultaneously adjustable.

2. A trolley according to claim 1 wherein the actuating means is operable when the support structure is supporting a load.

3. A trolley according to claim 1 or 2 wherein the plurality of moveable legs comprises first and second pairs of collapsible legs.

4. A trolley according to any preceding claim wherein the legs are telescopic and the height of the support structure is adjusted by means of retracting or extending the legs.

5. A trolley according to claim 4 wherein the actuating means comprises, within each of the telescopic legs, leadscrews.

6. A trolley according to claim 5 wherein the actuating means further comprises a plurality of gearboxes and a plurality of interconnecting shafts such that rotation of a single spindle of one gearbox operates the whole actuating means.

7. A trolley according to any preceding claims wherein the trolley further comprises a plurality of ground engaging wheels attached to the support structure such that when the plurality of moveable legs are moved relative to the support structure the weight of the trolley is supported on a ground engaging wheels.

8. A trolley according to claim 7 wherein the ground engaging wheels comprise spring loaded wheel assemblies.

9. A trolley according to claim 7 or 8 wherein locking means are provided which prevent moving of the legs relative to the support structure until at least some of the weight of the trolley is taken on at least one of the ground engaging wheels.

10. A trolley comprising a support structure, a plurality of legs moveable relative to the support structure, a plurality of ground engaging wheels, and locking means which prevents moving of the moveable legs until weight is taken by at least one of the ground engaging wheels.

11. A trolley according to claim 10 wherein the plurality of moveable legs comprises first and second pairs of collapsible legs.

12. A trolley according to claim 10 or 11 wherein the plurality of ground engaging wheels comprise first and second pairs of spring loaded wheel assemblies.

13. A trolley according to claim 12 wherein the first pair of collapsible legs has associated therewith a first pair of spring loaded wheel assemblies and a first locking mechanism and the second pair of collapsible legs has associated therewith a second pair of spring loaded wheel assemblies and a second locking mechanism.

14. A trolley substantially as hereinbefore described with reference to the accompanying drawings.

15. Any novel feature or novel combination of features as herein described and/or shown in the accompanying drawings.