GB2092077A - Guide system for patient- supporting platforms - Google Patents

Abstract

The system enables the transfer of hospital patients generally horizontally between patient- supporting units and comprises a system of wheels 17 and pairs of tracks 19 which can allow slight misalignment of the patient- supporting units. The wheels 17 are arranged with their axles at an angle oblique to the horizontal and the track comprises a first surface portion which engages with a rim of the wheels of one row to restrain sideways movement and a second surface portion which extends over a side of such wheels, the said surface portions of the two tracks cooperating to provide lateral guidance for the wheels and to prevent vertical separation of the wheels and tracks during a transfer operation. <IMAGE>

Description

SPECIFICATION Guide system for patient-supporting platforms The present invention relates to a guide system for enabling the transfer of hospital patients on patient-supporting platforms generally horizontally between patient-supporting units.

It is known to equip a hospital trolley with a separate patient-supporting platform or stretcher unit and provide a guidance system which permits the transfer of the platform from one trolley to another without lifting the patient. This may be needed in transferring the patient from a general purpose trolley to one in use in a sterile area or to a special purpose trolley or other type of patientsupporting unit such as an operating table.

It is known in various types of hospital equipment to use patient-supporting platforms provided with vertical rollers. However, these are not generally suitable for a transfer system of the type envisaged because of the danger inherent of the type envisaged because of the danger inherent in displacing the platform during the transfer operation.

In British Patent 1 498 949 there is described a hospital trolley equipped with transverse tubular members which are engageable with transverse rods attached to the patient-supporting platform together with a mechanism for linking two trolleys together in correct alignment for transfer. This sytem works very well in ensuring a smooth transfer without any danger of displacement of the platform but suffers from the considerable disadvantage that the two patient-supporting units are required to be positioned so that the tubular members are at precisely the same vertical level. Without this, transfer is impossible. This can be a very considerable disadvantage where e.g. a trolley and an operating table are not at exactly the same heights or where there is a step or uneven slope where it is desired to effect transfer.

This can be a very considerable disadvantage in many hospitals. Also the system requires careful manipulation of Ihe tubular members and rods.

The present invention is aimed at overcoming these problems. In accordance with the invention there is provided a guide system for enabling the transfer of hospital patients on patient-supporting platforms generally horizontally between patientsupporting units, comprising cooperating components respectively on the platform and on each support unit, one of the components comprising wheels arranged in two parallel rows, the other of the components comprising a track for each row of wheels wherein the wheels are arranged with their axles (in use) at an angle oblique to the horizontal and that the track comprises a first surface portion which is engageable (in use) with a rim portion of the wheels of one row to restrain sideways movement and a second surface portion which extends (in use) over a side of such wheels, the said surface portions of the two tracks cooperating to provide lateral guidance for the wheels and to prevent vertical separation of the wheels and tracks during a transfer operation.

Preferably the axles of the wheels of the two respective rows subtend equal and opposite angles to the vertical.

Preferably each track comprises a horizontal portion, a vertical portion, and an oblique portion, arranged in use so that a peripheral edge surface of each wheel engages the vertical and horizontal portions, the oblique portion extending generally parallel to and spaced from a side surface of the wheel.

However it would also be possible and within the scope of the invention to utilise a track in which the horizontal and vertical portions are replaced wholly or in part by an oblique surface portion generally at right angles to the wheels.

Normally the wheels will be attached to the platform and the tracks to the patient-supporting units, but the reverse is possible. Furthermore in the preferred embodiment the two rows of wheels are arranged so that the wheels of respective rows are splayed outwardly in a direction towards the tracks. Again however the reverse situation is possible.

Two embodiments will be described, in one of which the guiding means lie longitudinally along the platform and support unit and in the other of which the guiding means lie laterally along the platform and support unit. In the latter system, as will become apparent, it is desirable that there are at least three wheels in each row.

The preferred system includes means for coupling two support units together in a fixed relative coupling position for the transfer of a platform between the units, in which coupling position the corresponding tracks of each support unit are in alignment.

There is preferably included a platform restraint on the support unit which is automatically disengageable by operation of the coupling means.

Other preferred features of the invention will be found set out in the subsidiary claims.

The guide system according to the invention provides a number of advantages.

Firstly, the use of wheels, which may be provided with resilient tyres, provides a generally smoother transfer operation which can be important for seriously ill patients. The smoothness is greater, the greater the diameter of the wheels. However the use of large diameter wheels arranged vertically leads to a very thick, cumbersome platform. By arranging the wheels obliquely to the vertical it is possible to provide large diameter wheels within an acceptable vertical thickness.

Thus in the preferred case wheels are 1 5 cm diameter are used within an overall platform thickness of only 8.3 cm.

Secondly by reducing the height of the platform and wheels it is easier to ensure locking or restraining of the platform when positioned on a patient-supporting unit.

Thirdly, possibly the most important feature is that the oblique disposition of the wheels allows a much smoother negotiation of inequalities of height between the patient-supporting units. Thus when a wheel engages a step in the track system there is no immediate lifting of the platform but rather a smooth raising over a considerable horizontal distance as the step progressively engages successive parts of the side edge of the rim.

Finally the provision of the wheels at an oblique angle enables an edge surface of the rim of the wheel to engage a vertical guide surface so that there is no friction introduced in lateral guidance such as would take place if a side surface of the wheel engaged an abutment.

Embodiments of the invention are hereafter described with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the upper parts of two hospital trolleys prior to transfer of a patient-supporting platform from the left hand trolley to the right hand trolley, Figure 2 is an enlarged elevational view partly in section of one of the wheels and its corresponding track, Figure 3 is a diagrammatic view corresponding to Figure 1 illustrating the operation of the coupling means, Figure 4 is a perspective view corresponding generally to Figure 1 of a second embodiment utilising laterally extending tracks, Figures 5 and 6 are eievational views partly in section further illustrating the coupling means in the embodiment of Figure 4 in two positions, and Figures 7 and 8 are perspective views of the coupling means of Figures 5 and 6 illustrating further details.

Turning to Figure 1 there are shown two hospital trolleys 10 and 11 arranged for the longitudinal transfer of a patient-supporting platform 12 which is shown in the normal position on trolley 10. Only the upper parts of the trolleys are shown since the trolleys may be otherwise conventional with sideguards generally indicated at 13 and if desired a tilting mechanism.

The platform 12 comprises a mattress 14 attached to a base frame 1 5 provided with a handle 1 6 which is normally detachable so that a smaller handle 1 7 may be optionally provided.

A platform 12 is provided with four wheels 17, only one of which is clearly visible. These are situated generally in respective corners of the platform 12. They are arranged obliquely to the horizontal and in two longitudinal rows, so that the wheel at the near lefthand end of the platform 12 will be parallel to that indicated at 17 and the wheels of the opposite row will be splayed oppositely as indicated by the wheel supporting brackets 18, 18'. The wheels 1 7 run along extruded metal tracks 1 9 which run longitudinally along the trolleys 10, 11 adjacent respective sides.

The associations of the wheels and tracks are best viewed in Figure 2 where it can be seen that each wheel 1 7 comprises a tyre 20 of rubber or other resilient material on a hub which is not generally shown but is provided with a ballbearing 21 so that the wheel unit may be clamped adjacent the bearing between two limbs 22, 23 of a bracket 24 which extends at an oblique angle, preferably 450 from the framework 1 5 to which it is welded. The wheel therefore extends at 450 to the vertical and horizontal in the preferred case.

The extruded track 1 9 includes a horizontal track portion 25 which engages the lower corner of the rim of the tyre 20, a vertical track portion 26 which engages the upper corner of the rim of the tyre 20 for lateral guidance and an oblique track portion 27 which extends at least partly over the side of the wheel near the rim. It will be apparent from Figure 1 that the view shown in Figure 2 will correspond to the position of the wheel at the bracket 18' of Figure 1 viewed from the right hand end. The wheel 17 so marked in Figure 1 will be splayed oppositely and the associated track 1 9 will be the mirror image of that shown in Figure 2.

In other words the tracks face inwardly and the portions 27 extend inwardly so that when the platform is in the position shown at 1 2 in Figure 1 it cannot be removed vertically from the trolley 10 by reason of the overhanging track portions 27.

It will be evident that no frictional resistance results from the engagement of the vertical surfaces 26 with the wheel since the engagement is at a rim portion of the wheel rather than a side surface. This allows smooth running and lateral guidance. It will be evident that an oblique track surface could if desired be formed against the obliquely situated lower surface of the tyre 20.

However, this would require greater precision in the construction of the components, notably the tracks and could lead to certain difficulties in transferring from one trolley to another when there is a misalignment of height. The engagement of the wheel at edge portions of the rim is greatly advantageous from this point of view.

The trolleys in Figure 1 are designed to be coupled end to end as shown in Figures 1 and'3, which should be considered together for understanding of the coupling mechanism in use in this embodiment.

The coupling means of Figures 1 and 3 includes a latch engaging member 30 on trolley 10 and a corresponding member 30' on trolley 1 1. When the trolleys are correctly aligned, the two latch engaging members are offset on opposite sides of the common vertical plane lying centrally between and parallel to the aligned tracks. On the opposite side of this plane from member 30 is a latch member 31 (Figure 3) which engages with latch engaging member 30' of trolley 11. Similarly a corresponding latch member 31' on trolley 11 engages with latch engaging member 30 of trolley 10 in the coupling position i.e. when the trolleys are brought together by means of handles 32, 32'.

Each trolley is provided with a horizontal supporting framework formed essentially from longitudinal struts 33 joined at the ends by crosspieces 34 reinforced by angle members 35. The extruded metal track members are supported by the struts 33 and cross-members 34. The latch engaging members 30, 30' are attached to the angle members 35. The latch members 31, 31' are fixedly mounted to pivotally rotatable laterally extending rods 36, 36' which are attached to handles 37, 37' at each end, the rods 36 extending through brackets 38 fixed, for example by screwing or welding to struts 33. The latches 31, 31' may be spring biassed to their latched position or reliance may be placed on the weight of the handles 37, 37' to bias the latch members to this position. The ends of the struts 33 which may be of hollow box section, may be provided with resilient pads.

In the coupled position, the ends of the tracks will be spaced by approximately 2 to 3 mm. In this position, as more clearly indicated in Figure 3, the latch 31' engages over the forward reaching corner of latch engaging member 30 and likewise the latch member31 engages of the forward reaching corner of latch engaging member 30'. To assist in the sideways alignment of the trolleys, there is provided a pin 39 on trolley 10 substantially at the front edge of the frame which engages with latch engaging member 30' of trolley 11 and a similar pin 39' is provided on trolley 11 on the opposite side which engages with the left hand edge of latch engine member 30 of trolley 10. Outwardly facing oblique surfaces 40, 40' are provided on the latch engaging members 30, 30' respectively which are formed of bent steel rod.These oblique surfaces guide the pins 39, 39' to their final station in the coupled position of the trolleys, against the longitudinal outward side surfaces of the latch engaging members.

The latch engaging members 30, 30' are also provided with inwardly facing oblique surfaces 41, 41'. The purpose of these faces is to engage with an operating lever 42', 42 of a platform restraining member 43', 43. The platform retaining members 43, 43' comprise pivotable plates which in the normal position as shown in Figures 1 and 3 extend upwardly from the trolley framework in front of and behind the platform framework to prevent the platform rolling. They are biassed in this position by springs 44, 44'. The operating levers 42, 42' project from a lower corner of each retaining member at an oblique angle towards the side away from the corresponding latch engaging member 40, 40'.As the trolleys are brought to the coupling position the operating levers 42', 42 engage the oblique surfaces 41, 41' of the latch engaging members and are moved by these oblique surfaces so as to pivot the restraining members 43, 43' about pivot axes 45, 45' until they disengage from their respective platforms thus allowing the platform 12 to be rolled from trolley 10 to trolley 11.

The coupled trolleys may be disengaged by lifting two adjacent handles 37, 37' and using the handles 32 to move the trolleys apart.

In order to provide a further safeguard, pins 46 may be provided extending downwardly from the platform frameworks which would engage behind a cross strut 34 should by some chance á restraining member 43 be displaced on a separated trolley and the front wheels 1 7 slip off the end of the tracks 1 9. They will ensure that a platform cannot be inadvertently rolled off a trolley onto the floor.

The coupling mechanisms of Figures 1 and 3 are so designed that trolleys may be coupled head to head, toe to toe or head to toe. In case it is desired that trolleys should always be coupled in a head to toe position, additional guide means may be provided. These are shown in Figure 1 by the pair of welded projections 47 which are spaced to allow the insertion between them of a single projection 48 on trolley 11. In order to accommodate misalignment of height, these projections have an upward slant towards their ends.

It will be appreciated that in the trolleys of Figures 1 and 3 only four wheels are necessary to ensure that even during the transfer operation it is impossible to remove a platform at any stage by lifting vertically. The minimal gap between the aligned tracks ensure that as soon as the first platform wheel reaches the second trolley it is retained by the oblique track surfaces 27.

Turning to the embodiment of Figures 4 to 8 there are shown the upper portions of two trolleys 50, 51 ready for coupling in a position side to side rather than end to end as in Figures 1 to 3. In this case tracks similar to those shown in Figures 1 to 3 are provided running along the width of each trolley, at each end, the tracks and wheels being otherwise as indicated notably in Figure 2. As far as the tracks and wheels are concerned, the only notable difference is that each row of wheels is provided with at least three wheels to ensure against vertical separation of a platform from either trolley during a transfer operation, since the tracks in this embodiment are further separated in the coupling position. Attention will therefore be directed in Figures 4 to 8 to the coupling means utilised in this embodiment.The coupling means comprises pairs of cooperating pivotable bridge members 53, 54, the members 53 being in male relationship with respect to female members 54.

Each trolley as shown in Figure 4 has female members on the lefthand side as shown in that Figure and male members on the righthand side.

In the coupled position as shown in Figures 5 and 8 a pair of members 53, 54 interengages between two associated tracks so as to define a track bridging surface for the wheels. In the uncoupled position or disengaged position, the bridge members extend vertically upwards each blocking an end of a track. This position is shown in Figures 6 and 7. The tracks in this embodiment are also indicated at 1 9.

Each bridge member 53, 54 is formed as a right angle bracket and comprises a first limb 53a, 54a which defines a bridge surface and a second limb 53b, 54b at right angles thereto. The limbs 53a, 54a are enlarged towards their respective bases in opposite directions so as to form a lap joint in the coupled position as best seen in Figures 5 and 8 and the thickened portions are provided.with slots 53c, 54c which extend lengthwise of each respective limb and receive pins 55, 56 on respective trolleys which extend horizontally and longitudinally parallel to the side surfaces of the respective trolleys between angle brackets 57, 58.

In the disengaged, uncoupled position of Figures 6 and 7 each member 53, 54 extends with the respective limb 53a, 54a upright so that the pin 55, 56 is at the end of the slot removed from limb 53b 54b. The engagement of the lower part of the respective limb 53a, 54b, below the pin, with the side of the respective trolley, prevents inadvertent movement towards the position of Figures 5 and 8 and the members are stressed in this position by springs 59, 60 which extend between spigots 61 and further spigots on their adjacent brackets 57, 58, on each side of each member 53, 54.

The corners between limbs 53a and 53b and likewise between 54a and 54b are rounded as shown so that to bring the bridge members to the position of Figures 6 and 8 the members are lifted until the pins 55, 56 engage the opposite ends of the slot when the members are free to pivot over into the alternate position where they are again stressed by the springs 59, 60.

Each male bridge member 53 is provided with a projection o2 which projects outwardly as shown in Figure 6 and which in the coupled position engages within an aperture 63 in the corresponding female member 54. The engagement between projections 62 and aperture 63 is relatively loose so that the coupling can provide sufficient tolerance for a fairly extensive difference in level between the two tracks of the respective trolleys. If desired the female members 54 may be provided with similar projections 62' to assist in lifting these but to prevent mis-coupling of two trolleys head to toe, these may be provided with knobs 64 to prevent their passage through apertures 6.3 on other trolleys.

It will be appreciated from Figures 5 and 8 that in the coupled position the upper surface of the member 53 provides most of the bridge surface and rests in the step in a member 54, the thickened portion of which provides the remainder of the bridge surface.

Thus the bridge members fulfil three functions, they provide a smooth continuous bridge between the tracks of coupled trolleys or other patientsupporting units, they provide secure coupling of two such trolleys or other units together during transfer, and in the uncoupled position they act as platform restraining members to prevent unwanted movement of a platform of the trolley or other unit.

Although the specification has been described with reference to a guide system for enabling transfer of a patient-supporting platform between two trolleys, the trolleys or one of them may be replaced by another type of patient-supporting unit such as an operating table or a space-bridging framework which may be provided with a longitudinal or lateral track system. Many modifications are avaiiable. For example although the different types of coupling units for lateral and longitudinal transfer are differently described, they may if desired be alternated. Thus it is theoretically possible for the lateral coupling system to be used at the ends of trolleys rather than at the sides. The longitudinal coupling system is less desirably used on the sides of trolleys because of the projecting latch engaging members which would take up a lot of lateral space.

Although only two wheels have been advocated for each row in the longitudinal system, obviously more wheels may be utilised but in that case there may be more difficulty in accommodating misalignment of levels. Likewise in the lateral system three wheels are advocated in each row, the third wheel being central. This ensures that two wheels are always engaged by one track while one end wheel is on a bridge surface. There is sufficient play provided in the overhanging track portion 29 to allow some sideways tilting of a platform when there is a misalignment of level.

Although the embodiments show inwardly engaged vertical guide surfaces on the tracks with outwardly splayed wheels, inwardly splayed wheels may be utilised with outwardly facing vertical guide tracks and similarly, if desired, wheels may be provided on the trolleys or other patient supporting units rather than on the platforms. The preferred embodiment illustrated can provide for a difference in platform level or floor slope between two patient-supporting units.

Suitable wheels may be provided by Tente castors. These are provided with synthetic rubber tyres treated so as to be antistatic.

Although the wheels have been shown at 450 which is a convenient angle for providing horizontal and vertical engagement, the angle may be varied, particularly if oblique track surfaces are provided. A wheel angle to the vertical of between 35 and 550 is in general to be preferred.

Claims (22)

1. A guide system for enabling the transfer of hospital patients on patient-supporting platforms generally horizontally between patient-supporting units, comprising cooperating components respectively on the platform and on each support unit, one of the components comprising wheels arranged in two parallel rows, the other of the components comprising a track for each row of wheels wherein the wheels are arranged with their axles (in use) at an angle oblique to the horizontal and that the track comprises a first surface portion which is engageable (in use) with a rim portion of the wheels of one row to restrain sideways movement and a second surface portion which extends (in use) over a side of such wheels, the said surface portions of the two tracks cooperating to provide lateral guidance for the wheels and to prevent vertical separation of the wheels and tracks during a transfer operation.

2. A system according to claim 1 wherein the axles of the wheels of the two respective rows subtend equal and opposite angles to the vertical.

3. A system according to claim 1 or claim 2, wherein each track comprises a horizontal portion, a vertical portion, and an oblique portion, arranged in use so that a peripheral edge surface of each wheel engages the vertical and horizontal portiOns, the oblique portion extending generally parallel to and spaced from a side surface of the wheel.

4. A system according to any preceding claim wherein the two rows of wheels are arranged so that the wheels of respective rows are splayed outwardly in a direction towards the tracks.

5. A system according to any preceding claim wherein the wheels are attached to the platform.

6. A system according to any preceding claim wherein the guiding means is longitudinally along the platform and support unit.

7. A system according to any of claims 1 to 5 wherein the guiding means lie laterally along the platform and support unit, there being at least three wheels in each row.

8. A system according to any preceding claim wherein the wheels comprise ball or thrust bearings and rim portions of resilient material which extends at least partially over the side of the wheels.

9. A system according to any preceding claim including means for coupling two support units together in a fixed relative coupling position for the transfer of a platform between the units, in which coupling position the corresponding tracks of each support unit are in alignment.

10. A system according to claim 9 including a platform restraint on the support unit which is automatically disengageable by operation of the coupling means.

11. A system according to claim 10 wherein the coupling means comprises pairs of cooperating pivotable bridge members on respective support units interengageable between respective associated tracks and defining in the coupling position a track bridging surface for the wheels, said bridge members in their disengaged position each blocking an end of a track.

12. A system according to claim 11 wherein each bridge member comprises a first limb defining a bridge surface and a second limb at right angles thereto, the first limb bearing a longitudinally extending slot receiving a mounting pin.

13. A system according to claim 11 or claim 12 as dependent on claim 7 wherein the bridge members are attached to the support units, the bridge members of opposite sides being in male/female relationship.

14. A system according to claim 9 or claim 10 wherein said coupling means comprise a latch engaging member and a latch member off-set from a vertical plane centrally between the two tracks and so positioned that the latch of one unit to be coupled is engageable with the latch engaging member of the other in said fixed coupling position.

1 5. A system according to claim 1 4 wherein the coupling means includes a projection engageable with latch engaging member of a unit to be coupled to prevent relative sideways movement of the support units during the coupling operation.

1 6. A system according to claim 14 or 1 5 wherein the latch engaging member comprises a bar having two horizontal oblique surfaces joined at a latch engaging station.

17. A system according to claim 1 6 including a platform restraining member pivotally mounted so as to be movable between a platform engaging position and a platform releasing position and having an Operating lever engageable with one of said oblique surfaces for movement into the platform releasing position during the coupling operation.

18. A system according to any of claims 14 to 1 7 as dependent on claim 6 wherein the coupling means are positioned at end surfaces of the support units.

19. A system according to any of claims 14 to 1 8 including means for preventing head to head coupling of two support units.

20. A system according to claim 11 or claim 18 substantially as described herein with reference to the accompanying drawings.

21. A combination of a hospital trolley including a patient-supporting unit and a removable patient-supporting platform incorporating a system according to any preceding claim.

22. A hospital trolley having a pair of wheelsupporting tracks and forming part of the combination of claim 21.