WO2000010502A1

WO2000010502A1 - Walking aid

Info

Publication number: WO2000010502A1
Application number: PCT/GB1999/002496
Authority: WO
Inventors: Thomas Francis Mcgrath
Original assignee: Thomas Francis Mcgrath
Priority date: 1998-08-25
Filing date: 1999-07-30
Publication date: 2000-03-02
Also published as: AU5179399A; GB9818404D0

Abstract

A walking aid comprises a shaft and a foot assembly, in which the foot assembly comprises in combination a sleeve member and a foot member adapted for relative axial sliding movement and including resilient movement-restraint means, the sleeve member being adapted for attachment to the shaft and including grip means for inhibiting or preventing removal from the shaft once attached thereto. The resilience may be adjustable and the foot member is preferably free to swivel within the sleeve member. The assembly may also be used as a castor, for use for example in shopping trolleys.

Description

WALKING AID

This invention relates to walking aids with resiliently-mounted feet, intended to alleviate problems experienced by users of conventional walking aids arising from shock loading transferred to the muscles of the hands, wrists, arms and shoulders; and to other apparatus incorporating resiliently-mounted feet or castors.

Physiotherapists have evidence to prove that the muscles of the shoulder in particular and the muscles of the hands, wrists and arms are stressed when using normal walking aids. Persons who have sustained several tears of the muscles of the shoulder experience difficulty when using a rigid, uncushioned walking stick, crutch or Zimmer frame. Similarly, persons who have osteo- arthritis or rheumatoid arthritis experience problems when using rigid support aids. Those who have hip and knee arthritis and have rotator cuff regeneration or tears in the shoulder are also uncomfortable with rigid walking aids.

In order to alleviate such problems, walking aids with shock-absorbing feet have been proposed. One such device is described in GB-A-2318510, in which the foot member slides telescopically over an upper sleeve, a spring providing for resilience in the sliding movement. However, in order to provide selective resilience according to the weight of the user, it is necessary to change the spring for another one of different spring rate. Additionally, although prior art shock-absorbing feet can be retro-fitted to existing walking aids, there is a tendency for the feet to work loose and even to become detached from the shaft of the walking aid in use.

It is an object of the present invention to provide a walking aid with a resiliently-mounted foot and which does not suffer from the disadvantages of the prior art.

According to one aspect of the present invention, a walking aid comprises a shaft and a foot assembly, in which the foot assembly comprises in combination a sleeve member and a foot member adapted for relative axial sliding movement and including resilient movement-restraint means, the sleeve member being adapted for attachment to the shaft and including grip means for inhibiting or preventing removal from the shaft once attached thereto. and including grip means for inhibiting or preventing removal from the shaft once attached thereto.

The shaft may be the or a leg of a crutch or walking frame or may be attached to the lower end of such a leg, which includes tubular legs.

In another aspect, the invention provides a foot assembly suitable for attachment to the shaft of a tubular walking aid or a tubular leg of a walking aid, the foot assembly comprising in combination a sleeve member and a foot member adapted for relative axial sliding movement and including resilient movement-restraint means, the sleeve member including grip means for inhibiting or preventing removal from the tubular leg once attached thereto.

The resilient movement-restraint means is preferably adjustable to suit the weight or the needs of the user according to the nature and severity of the disability suffered from. The resilient means may comprise a helical compression spring and adjustment thereof may be provided by pre-loading means on the spring, preferably accessible to the user without removing the sleeve from within the shaft. The spring may be made from spring steel, optionally coated with for example zinc or cadmium and referred to as "music wire", or stainless steel.

Preferably, the foot member comprises a base element to which a conventional rubber or plastics ferrule or shoe is attached, the base element being connected to a neck member which is journalled in the sleeve member with a compression spring therebetween, the neck member being provided at its upper or distal end with a screw thread to receive a retaining and resilience-adjustment nut.

The grip means may comprise a resiliently-compressible element associated with the sleeve member for force-fitting within the shaft, whereby the sleeve member is retained within the shaft by friction forces acting between the resiliently-compressible member and the internal wall of the shaft. Preferably, however, the grip means comprises an element adapted to permit the sleeve member to be slidingly inserted within the shaft but which expands radially to assume a jamming position on attempted withdrawal thereof. Such an arrangement may be provided by for example a rubber or plastics O ring or a snap-ring, which may be made from metal, carried in an annular groove formed in the external surface of the sleeve member, the groove having a sloping or chamfered wall which urges the ring to expand to jam against the shaft wall on relative movement between the sleeve member and shaft in a direction of movement whereby the sloping or chamfered wall is the trailing or rear wall.

When using walking aids according to the invention, the user experiences more sure-footed ground contact than with rigid devices, even on slippery surfaces, the light spring force ensuring a more stable initial contact and the full load being gradually applied as the spring compresses. There is thus less of a tendency for the foot to slip or skid away when placed on the ground at an angle to the vertical. Furthermore, the sleeve member is desirably free to rotate axially about the foot member; such freedom of rotation not only promotes even wear and hence a considerably extended life to the ground-contacting ferrule but also manifestly improves user comfort and convenience, in that any twisting motion as between the user and the walking aid is more readily accommodated by the walking aid.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, of which:-

Figures 1 and 2 show respectively a sleeve member and foot member of one embodiment of a walking aid,

Figure 3 shows in partial elevation and partial longitudinal section a sleeve member and foot member incorporating variants of the embodiment of Figures 1 and 2, assembled together with a compression spring; and

Figures 4 and 5 show the embodiment of Figure 3 inserted in a shaft respectively in the fully-expanded and fully-compressed conditions. Referring first to Figures 1 and 2, the sleeve member 10 is cylindrical in cross section and has an enlarged-diameter lower end flange 11 defining an annular shoulder 12. The sleeve member has a through-bore 13 which has an enlarged-diameter part 14 at the lower end. The external wall carries a pair of annular grooves 15, 16. The foot member 20 is a cylindrical bar having a lower end 21 of maximum diameter and formed with an axial cavity 22, a first intermediate zone 23 of reduced diameter, a second intermediate zone 24 of further reduced diameter and defining a shoulder 25 and a screw-threaded upper end 26. The diameter of first intermediate zone 23 is such that it will slide within the enlarged-diameter bore 14 of the sleeve member and the diameter of second intermediate zone 24 is such that it will slide within the reduced-diameter bore 13 of the sleeve member. A compression spring can be accommodated in the annular gap between the second intermediate zone 24 of the foot member and the enlarged-diameter bore 14 of the sleeve member, as illustrated in and described with reference to Figure 3. The spring may have a free length of between 25 and 40 mm, for example 32 mm, with up to ten active coils, for example seven coils, and may be made from music wire or stainless steel of diameter 0.75 to 2.0 mm, for example 1.6 or 1.8 mm. The grooves 15, 16 are for accommodating O rings or snap rings.

With reference to Figure 3, the foot member 20 is shown slidingly inserted in sleeve member 10 with a compression spring 31 carried in annular gap 32 between the members. A washer 33 and nut 34, preferably of the self-locking type, are inserted over and on the screw-threaded end 26 of the foot member. A diametral hole 35 formed through the walls of the cavity 22 can accommodate a screwdriver or other suitable tool to restrain the foot member from turning as the locknut is tightened. A conventional rubber shoe 36 is applied over the lower end 21 of the foot member. O rings 37, 38 are contained in the annular grooves.

The variants of Figure 3 are firstly bushes 39, 40 which are carried in corresponding additional bore zones of the sleeve member and are intended to assist sliding movement of the foot member within the sleeve member; the bushes may be formed from nylon, p.t.f.e., or other suitable material. Secondly, the lower annular groove 16 of the sleeve member is formed with a 20° chamfer 41 to the upper wall, whereby the O ring or slip ring 38 contained in the groove is constrained by friction against the inner wall of the shaft, on any attempt being made to withdraw the assembly from within the shaft, to travel up the chamfered surface to expand the ring into jamming relationship with the shaft, thereby preventing or at least inhibiting removal of the assembly from the shaft.

With reference to Figures 4 and 5, the assembly of Figure 3 is shown inserted in the lower end 42 of a tubular walking stick or crutch shaft, with the bottom of the shaft abutting against the shoulder 12 of the sleeve member. Figure 4 illustrates the extended condition with no loading on the foot member, whereby the compression spring 31 urges the foot member to the maximum extent below the sleeve member, as determined by the washer 33 and nut 34 engaging the upper end of the sleeve member. Figure 5 illustrates the maximum compressed condition under axial loading on the foot member, whereby adjacent coils of the spring 31 are urged into contiguous relationship.

It will be appreciated that the nut can be adjusted to pre-load the spring to adjust the resilience thereof; such adjustment may be carried out either with the foot assembly in place within the shaft, by using a suitable socket spanner and extension bar, or after manually removing the foot assembly by twisting and pulling against the jamming effect. If necessary, the spring can be exchanged for another spring of different rate; again, this can be done in situ by removing the nut, whereupon the foot member and spring can be withdrawn from within the sleeve member.

Where the locking ring is an O ring, the desired spring strength for the user may conveniently be pre-set by initially rolling the lower O ring 38 out of groove 16 and down the sleeve member until it abuts shoulder 12. The assembly may then be inserted in the shaft to test whether the spring strength is correct and if necessary withdrawn for adjustment without bringing into effect the jamming action of the assembly within the shaft. When the spring strength is correct, the O ring is then rolled back into groove 16 and the assembly re-inserted in the shaft, where it will be retained by virtue of the jamming effect between the O ring and the interior surface of the shaft. The O ring 37 in the upper groove 15 provides ordinary resilient sealing between the sleeve and foot members and allows insertion and withdrawal with friction but does not provide any jamming or locking effect.

It will be appreciated that although a foot assembly as herein described is suitable and primarily intended for attachment to a walking aid, it would be equally suitable for attachment to other apparatus requiring a resiliently-mounted foot, including trolley apparatus such as pushchairs and shopping trolleys the castors of which may benefit from the provision of a resiliently-mounted wheel. In such an embodiment, the forks of the castor could be attached to or integrally formed with the cylindrical bar of the foot member.

Claims

1. A walking aid comprising a shaft and a foot assembly, in which the foot assembly comprises in combination a sleeve member and a foot member adapted for relative axial sliding movement and including resilient movement-restraint means, the sleeve member being adapted for attachment to the shaft and including grip means for inhibiting or preventing removal from the shaft once attached thereto.

2. A walking aid according to claim 1, in which the resilient movement-restraint means is adjustable.

3. A walking aid according to claim 1 or claim 2, in which the foot member comprises a base element to which a rubber or plastics shoe is attached, the base element being connected to a neck member which is journalled in the sleeve member with a compression spring therebetween, the neck member being provided at its upper or distal end with a screw thread to receive a retaining and resilience-adjustment nut.

4. A walking aid according to any preceding claim, in which the grip means comprise a resiliently-compressible element associated with the sleeve member for force-fitting within the shaft, whereby the sleeve member is retained within the shaft by friction forces acting between the resiliently-compressible member and the internal wall of the shaft.

5. A walking aid according to claim 4, in which the grip means comprises an element adapted to permit the sleeve member to be slidingly inserted within the shaft but which expands radially to assume a jamming position on attempted withdrawal thereof.

6. A walking aid according to claim 5, in which the grip element comprises a rubber or plastics O ring or a snap-ring, carried in an annular groove formed in the external surface of the sleeve member, the groove having a sloping or chamfered wall which urges the ring to expand to jam against the shaft wall on relative movement between

^Γûáthe sleeve member and shaft in a direction of movement whereby the sloping or chamfered wall is the trailing or rear wall.

7. A walking aid according to any preceding claim, in which the foot member is free to rotate axially within the sleeve member.

8. A walking aid according to claim 1, in which the sleeve member is cylindrical in cross section and has an enlarged-diameter lower end flange defining an annular shoulder, the sleeve member having a through-bore which has an enlarged-diameter part at the lower end and carrying a pair of external annular grooves, and in which the foot member is a cylindrical bar having a lower end of maximum diameter and formed with an axial cavity, a first intermediate zone of reduced diameter, a second intermediate zone of further reduced diameter and defining a shoulder and a screw-threaded upper end, the diameter of first intermediate zone being such that it will slide within the enlarged-diameter bore of the sleeve member and the diameter of second intermediate zone being such that it will slide within the reduced-diameter bore of the sleeve member, a compression spring being accommodated in the annular gap between the second intermediate zone of the foot member and the enlarged-diameter bore of the sleeve member, the grooves accommodating O rings or snap rings.

9. A walking aid according to claim 8, in which bushes are carried in corresponding additional bore zones of the sleeve member and assist sliding movement of the foot member within the sleeve member.

10. A walking aid according to claim 8 or claim 9, in which the lower annular groove of the sleeve member is formed with a chamfer to the upper wall, whereby the O ring or slip ring contained in the groove is constrained by friction against the inner wall of the shaft, on any attempt being made to withdraw the assembly from within the shaft, to travel up the chamfered surface to expand the ring into jamming relationship with the shaft, thereby preventing or at least inhibiting removal of the assembly from the shaft.

11. A foot assembly for attachment to the shaft of a tubular walking aid or a tubular leg of a walking aid, the foot assembly comprising in combination a sleeve member and a foot member adapted for relative axial sliding movement and including resilient movement-restraint means, the sleeve member including grip means for inhibiting or preventing removal from the tubular leg once attached thereto.

12. Apparatus incorporating a foot assembly as claimed in claim 11.

13. Apparatus according to claim 12, in which the foot assembly comprises a castor.

14. Apparatus according to claim 13 comprising a trolley for goods or a person.

AMENDED CLAIMS

[received by the International Bureau on 17 December 1999 (17.12.99); new claims 15-20 added; remaining claims unchanged (2 pages)]

12. Apparatus incorporating a foot assembly as claimed in claim 11.

14. Apparatus according to claim 13 comprising a trolley for goods or a person.

15. A walking aid comprising a shaft and a foot assembly in which the foot assembly includes a ground-contacting ferrule and comprises relatively axially-slidable cylindrical sleeve and neck members and means for resiliently restraining sliding movement between said sleeve and neck members, said neck member being journalled in said sleeve member for relative axial rotation, whereby said ground-contacting ferrule is axially rotatable with respect to said shaft to accommodate twisting movement as between the user and the ground in use.

16. A walking aid according to claim 15, in which bushes are provided between said neck and sleeve members to assist relative sliding and rotational movement.

17. A walking aid according to claim 15 or claim 16 in which the resilient movement-restraint means is adjustable.

18. A walking aid according to any of claims 15 to 17, in which the resilient movement-restraint means comprises a compression spring.

19. A walking aid according to claim 18, in which the compression spring is disposed about the neck member and retained by a locknut which limits the relative sliding movement in the expansion direction of the compression spring by engagement with the sleeve member.

20. A foot assembly for attachment to the shaft of a walking aid, the foot assembly including a ground-contacting ferrule and comprising relatively axially-slidable cylindrical sleeve and neck members and means for resiliently restraining sliding movement between said sleeve and neck members, said neck member being journalled in said sleeve member for relative axial rotation, whereby said ground-contacting ferrule is axially rotatable with respect to said shaft to accommodate twisting movement as between the user and the ground in use.