GB2424215A

GB2424215A - Power-assisted stretcher

Info

Publication number: GB2424215A
Application number: GB0505447A
Authority: GB
Inventors: Robert Williamson; David Whyman
Original assignee: Ferno UK Ltd
Current assignee: Ferno UK Ltd
Priority date: 2005-03-17
Filing date: 2005-03-17
Publication date: 2006-09-20
Also published as: GB0505447D0; EP1702600A1; ATE417587T1; EP1702600B1; DE602006004233D1

Abstract

A trolley includes driven wheels 8 and castor wheels 6a,6b,6c and 6d. The driven wheels 8 may be moved to a position clear of the ground or to a position in which they contact the ground with the adjacent castor wheels 6c and 6d being raised off the ground. Movement between these two positions is effected by pivoting a sub-frame 16 to which the driven wheels 8 and the castor wheels 6c and 6d are connected. During this movement the region of the trolley above the driven wheel is first lowered and then raised slightly such that the end elevation of the support for a patient remains the same.

Description

STRETCHERS

The present invention relates to a stretcher and a method of operating a stretcher. Herein any reference to a stretcher includes a stretcher trolley.

Stretchers are presently manoeuvred manually by an operator who exerts the forces required to direct and move the stretcher about hospital ward, between wards, between ambulances and between ambulances and incidents. During the course of manoeuvring the stretcher the operator has to exert a considerable force in order to control the stretcher. The effect can be bad for the back of the operator. The force is increased when manoeuvring the stretcher up steep inclines or ramps, such as an ambulance ramp or hospital ramp. Furthermore, the wheels of the stretcher are mounted on swivels, which, particularly if the ramp tilts to one side (such as may occur when the vehicle is not parked on level ground), as the operator pushes the stretcher up it can run off the stretcher. In addition the stretcher can run off course when going up or down hill or on a slope. Alternatively, the stretcher can run away down hill if on a steep hill or if the operator slips and loses grip. All of these problems are accentuated when the patient on the stretcher is particularly heavy.

It is an object of the present invention to attempt to overcome at least some of the above or other disadvantages.

According to one aspect of the present invention a stretcher trolley arrangement includes at least three non- driven wheels and at least one driven wheel, the driven wheel being moveable relative to at least one of the non- driven wheels between a driving position in which the driven wheel is in contact with the ground and a non- driving position in which the driven wheel is spaced from the ground.

According to a further aspect of the present invention a method of operating a stretcher arrangement that includes at least three non-driven wheels and at least one driven wheel comprises moving at least one of the wheels between a driving position in which the driven wheel is in contact with the ground and a non-driving position in which the driven wheel is spaced from the ground.

Further features of the present invention are defined in the claims.

The drive means may include, although by no means be limited to, linear lead-screw actuators, hydraulic actuators, or electro-hydraulic actuators.

The present invention includes any combination of the herein referred to features or limitations.

The present invention can be carried into practice in various ways but several embodiments will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a side perspective view of a stretcher trolley 2 showing the patient support 4, castor wheels 6a, 6b, 6c and 6d, a driven wheel 8 and a main frame 10; Figures 2 and 3 are a side perspective and rear perspective view of the rear trolley end region 12 showing the rear castor wheels 6b and 6c and the driven wheels 8 connected to a sub frame 16. The sub frame 16 is assembled to the main frame 10 at a fixed pivot point 20 to enable it to rotate about a first axis; Figure 4 is a side view of a first transition position 22 showing the rear castor wheels 6c and 6d in contact with the surface 24 and the driven wheels 8 free from the surface 24 such that the stretcher trolley 2 is solely supported by castor wheels.

Figure 5 is a side perspective view of a mid transition position 28 showing the driven wheels 8 and all castor wheels in contact with the surface 24; Figure 6 is a side perspective view of a second transition position 30 showing the driven wheels 8 in contact with the surface 24 with the rear castor wheels clear from the surface 24 such that the trolley is solely supported by the front castor wheels 6a and 6b and the driven wheels 8; and Figures 7 and 8 show side views in the two transition positions effected by pulling a lever 31 down.

As shown in Figures 1 and 2, the patient support 4 is mounted on a first support 32, which extends upwardly from the front of the main fame 10, and a second support 34, which extends upwardly from the rear of the main frame 10 -n so that the patient support 4 is held mainly flat or horizontal.

The lower end of the second, rear support 34 is fixed to an upwardly extending arm lOa of the main frame 10. The upper end region of the second, rear support 34 is connected by a first group of co-operating parts 36 to the patient support 4.

The lower end region of the first, front support 32 is attached to a piston of a first linear actuator 38 by a second group of co-operating parts 40. The upper end region of the first support 32 is connected by a third group of co-operating parts 42 to the patient support 4.

The lower end of the actuator 38 is fixed to an upwardly extending arm lOb of the main frame 10. The configuration of the patient support 4, the first support 32, the second support 34, the first linear actuator 38, and the three groups of co-operating parts 36 and 42 is such that the first linear actuator may be driven to extend or contract a piston 38a of the linear actuator in order to incline or decline the angle of the patient support 4. When inclined, the patient support 4 may, for instance, be raised up to 15 to drain fluid from the legs of a patient on the support 4 with pivot occurring about the parts 36.

The first linear actuator 38 may be controlled by an operator controlling a two-position or multi-position switch, such as a rocker switch, which may be positioned at the rear of the trolley. A battery 56 mounted on the main frame 10 is able to power the actuator 38 in order to extend or contract the piston 38a using any well known method. fl

The main frame 10 provides the housing for the two front castor wheels 6a and 6b. The castor wheels 6a and 6b are aligned substantially in the same plane and at the first trolley end region and are spaced apart laterally across the stretcher, generally being positioned on the widest portion of the main frame 10. The front castor wheels are able to rotate about a horizontal axis and can swivel about a vertical axis on a stub shaft 47, offset from the horizontal axis.

The rear castor wheels 6c and 6d are able to rotate in the same way as the front castor wheels and, in addition.

As shown in relation to figures 2 and 3, a sub frame comprising of two side rails 50 and two cross rails 52 is pivotally mounted at points 20 on the main frame 10 at the rear end such that the sub frame 16 is able to pivot about a horizontal axis.

A rear castor wheels 6c and 6d are located on the rearward projecting end region of the sub frame 16. The castor wheel sub axles 48 of the rear castor wheels pivot with the sub frame about the pivot points 20.

The driven wheels 8 are mounted on axles 54 that project from a forward region of the sub frame, spaced from the pivot points 20 of the sub frame. The battery 56 powers a motor 58 mounted on the axle 54 or the sub frame 16 in order to drive the axle 54 and subsequently the wheels 8 in any well known manner. For instance, the motor may impart a drive via an induction force being applied to a magnet fast with the axles 54. fl

A second actuator 60 controls the movement of the sub frame 16 about the pivot points 20. The second actuator is rotatably fixed at the upper end to the upwardly extending arm lOa just forward of that arm. The lower end of the actuator 60 is pivotally connected to the axle 54 of the sub frame 6 such that when the piston 66 of the second actuator 60 is extended or contracted the point at which the actuator 60 is located on the sub frame 16 moves up or down through a circumferential path by rotating about the pivot points 20.

The battery 56 powers the actuator 60 to extend or contract a piston 66 of the actuator. A two-position switch, such as a rocker switch, which may be positioned at the rear end of the trolley and controlled by an operator, may control the extension or contraction of the actuator 60.

It should be clear from figure 4, 5 and 6 that extending the piston 66 of the actuator 60 effects a movement between the first, mid and second transition positions. of the surface 24. In the second transition position the co- operating parts of the actuator resist any rotational movement of the sub frame 16. During the transition between the first position 22 and the second position 30 the patient support 4 only marginally. It can be seen that as the rear of the trolley is being moved between the position showing in Figures 7 and 8 the castor wheels are moved down, initially, to cause a slight lowering of the pivot points 20 about the contact of the driven wheels with the ground until the castors contact the ground.

Then the pivot points 20 are raised slightly about the -n contact point of the castors with the ground. Accordingly the inclination change of the patient support 4 is minimal and the support is at substantially the same inclination regardless of the positions shown in Figure 7 and 8.

It is possible to lock the castors in a fixed rotational position about the stub axles. Thus, if the stub axles are locked in the position shown in Figure 8 when, or after the driven wheels only at the rear contact the ground, as in Figure 7, there is significant clearance for the trolley to negotiate small steps or ledges without the rear castor wheels contacting the step or ledge. In the locked position the tangent between the raised castor wheels and the driven wheels and the included angle to the horizontal may be more than 8 or more than 100 or in the region of 12 15 .

When the second trolley end region 12 is orientated in the second transition position, the stretcher can be moved by an operator at the rear of the trolley using a lever, which initiates and varies the speed of rotation of the drive shaft from the motor and the speed of travel of the trolley. Similarly, the lever can be moved in an opposite direction to initiate and vary the speed of reverse rotation of the axle 54. The motor may include a positive drive that prevents the axle 66 from being able to rotate faster than that set by the lever to prevent the runaway of the stretcher down inclines.

Furthermore, it will be appreciated that not all of the power to move the stretcher need be applied by the motor and an operator could assist in providing the necessary power. fl

Should the motor fail or should it be desired to manoeuvre the stretcher in a traditional manner using both sets of castor wheels 26 and 14 or the front castor wheels and the driven wheels. The actuator piston 66 may contract to initiate the transition to the first position 22.

Alternatively the actuator may relax such that all driven and non driven wheels contact the ground.

Should the battery fail the transition means may be effected manually as depicted by figures 7 and 8. A telescopic lever 31 held fast to the sub frame is extended from the sub frame 16 by any well-known means. The actuator piston 66 is unloaded such that the co-operating parts of the actuator 60 do not resist rotational movement of the sub frame 16. A downwards force exerted on the lever 31 by the hand or foot of an operator acts to rotate the sub frame 16 in to the first transition position. The actuator piston 66 may be re-locked in order to impart the necessary rotational movement of the sub frame 16 or the lever may be moved sideways to engage with a locking part of the main frame. Return movement and locking is a reverse of this operation.

The pistons may comprise linear actuators whereby a nut is axially fixed but rotated to drive the piston axially with regard to the rotation of the nut.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. fl

Claims

1. A stretcher arrangement including at least three non- driven wheels and at least one driven wheel, the driven wheel being movable relative to at least one of the non- driven wheels between a driving position in which the driven wheel is in contact with the ground and a non- driving position in which the driven wheel is spaced from the ground.

2. An arrangement as claimed in claim 1 in which at least one of the driven wheel or a non-driven wheel is movably mounted on the stretcher in order to effect the movement between the two positions.

3. An arrangement as claimed in claim 1 or 2 in which in the driving position at least one of the non-driven wheels is spaced from the ground.

4. An arrangement as claimed in any preceding claim in which the height of a patient support above the region of the driven wheel is substantially the same in both positions.

5. An arrangement as claimed in any preceding claim in which the height of a patient support above the driven wheel first decreases and then increases as movement occurs between the two positions.

6. An arrangement as claimed in any preceding claim in which, in the driving position at least one of the non- driven wheels is spaced from the ground and is spaced from the extent between the non-driven wheels in contact with the ground and the driven wheels.

7. An arrangement as claimed in claim 6 in which a non- driven wheel that is spaced from the ground is rotatable about its own wheel axis and a further axis spaced from that axis whereby the wheel can be moved about that further axis and locked in position about that further axis to move that non-driven wheel further from the ground.

8. An arrangement as claimed in claim 7 in which that further axis is an upwardly extending axis.

9. An arrangement as claimed in any preceding claim in which the driven wheel is pivotally mounted on the stretcher about an axis offset from that wheels rotational axis to effect the movement between the driven and nondriven positions.

10. An arrangement as claimed in any preceding claim in which at least one non-driven wheel is pivotally mounted on the stretcher about an axis offset from that wheels rotational axis to effect the movement between the positions.

11. An arrangement as claimed in claims 9 and 10 in which the driven wheel and the non-driven wheel are connected to a link that is pivotally mounted on the stretcher with, in the longitudinal extent of the stretcher, the pivot axis of the driven wheel being on one side of the pivotal mounting of the link on the stretcher and the pivot axis of the non-driven wheel is on the other side.

12. An arrangement as claimed in any preceding claim in which the movement in at least one direction between the positions is effected by driving means.

13. An arrangement as claimed in claim 12 in which the drive means are arranged to hold the stretcher in at least one of the positions.

14. An arrangement as claimed in claim 13 in which the hold exerted in at least one of the positions is releasable.

15. An arrangement as claimed in any preceding claim in which the movement from at least one position to another is effect manually.

16. An arrangement as claimed in claim 15 in which the manual movement is effected by a telescopic arm.

17. An arrangement as claimed in claim 15 and 16 when dependent on claim 11 in which the link is constrained to move with the lever about the pivot axis of the link.

18. An arrangement as claimed in claim 17 in which the lever is movable to a locking condition to restrain pivotal movement of the link in at least one position.

19. An arrangement as claimed in any preceding claim including claim 12 in which the drive means includes an extendable and contractable member pivotally connected to the stretcher and the link at a location spaced from the pivotal mounting of the link to the stretcher. .fl

20. An arrangement as claimed in claim 18 in which the pivotal connection of the drive means to the link is coincident with the pivot axis of at least one of the driven wheel or a non-driven wheel.

21. An arrangement as claimed in any preceding claim in which the movement from the driving to the non-driving position is at least initially pivotal movement about the point of contact of the driven wheel with the ground.

22. An arrangement as claimed in any preceding claim in which the movement from the driving to the non-driving position is, at least towards the end of that movement, pivotal movement about the contact of at least one nondriven wheel.

23. An arrangement as claimed in any preceding claim in which the driven wheel is larger than the non-driven wheel.

24. An arrangement as claimed in Claim 23 in which the diameter of the driven wheel is more than twice the diameter of at least one non-driven wheel.

25. An arrangement as claimed in any preceding claim in which, when the wheel is driven in the driving position, the drive is arranged to be able to act as a brake should the stretcher be going down an incline.

26. An arrangement as claimed in any preceding claim including a battery arranged to power the drive wheel.

27. An arrangement as claimed in any preceding claim including a battery arranged to drive the movement between at least one of the positions.

28. A stretcher trolley arrangement as claimed in any preceding claim in which the angle of the axis of the driven wheel is fixed with respect to the longitudinal extent of the stretcher.

29. A stretcher as claimed in any preceding claim in which the axis of at least one non-driven wheel is able to move about an upwardly extending axis and may be selectively lockable in at least one position of the upwardly extending axis.

30. A stretcher as claimed in any preceding claim in which the driven wheel is located between non-driven wheels in the direction of longitudinal extent of the stretcher.

31. A stretcher as claimed in any preceding claim in which the non-driven wheel is located towards one end of the stretcher in the region of a support extending up from a lower region of the trolley to a support for a body.

32. A stretcher as claimed in Claim 31 in which the driven wheel is pivotally connected to the support.

33. A stretcher as claimed in Claim 31 or 32 in which the driven wheel and a non-driven wheel are located in the region of the support with each being either side of the support in the longitudinal extent of the trolley.

34. A stretcher arrangement substantially as herein described with reference to and as shown in any of the accompanying drawings.

35. A method of operating a stretcher arrangement that includes at least three non-driven wheels and at least one driven wheel comprising moving at least one of the wheels between a driving position in which the driven wheel is in contact with the ground and non-driving position in which the driven wheel is spaced from the ground.

36. A method as claimed in Claim 35 comprising moving the driven wheel and at least one non-driven wheel when moving between the positions.

37. A method as claimed in Claim 35 or 36 comprising causing at least one non-driven wheel to be clear of the ground in the driving position.

38. A method as claimed in Claim 37 comprising causing the non-driven wheel to be clear of the ground in the driving position at a location spaced from the longitudinal extent of the remaining wheels in contact with the ground.

39. A method as claimed in any of Claims 35 to 38 comprising causing a support for a patient located above the region of the driven wheel to move first downwardly and then upwardly when moving from the driving position to the non-driving position.

I

40. A method of operating a stretcher trolley substantially as herein described with reference to and as shown in any of the accompanying diagrams.

41. A method of operating a stretcher as claimed in any of Claims 35 to 40 when the stretcher is as claimed in any of Claims 1 to 34.