WHEEL LOCKING MECHANISM

Abstract

A wheel locking mechanism, suitable for locking a wheel of a pushchair, the mechanism comprising: a rotatable member, adapted to be mounted on the hub of a wheel, whereby the rotatable member is co-rotatable with, and by rotation of, the wheel, said rotatable member comprising a locking surface, and a non-rotatable member, comprising a locking pin adapted to selectively cooperate with the locking surface of the rotatable member, whereby the relative positions of the rotatable and non-rotatable members are lockable. Also disclosed is a pushchair comprising a chassis having a rear axle, at each end of which a wheel is mountable, wherein each end of the rear axle is provided with such a wheel locking mechanism.

Claims

1-42. (canceled)

43. A wheel locking mechanism, suitable for locking a wheel of a pushchair, the mechanism comprising: a rotatable member, adapted to be mounted on the hub of a wheel, whereby the rotatable member is co-rotatable with, and by rotation of, the wheel, said rotatable member comprising a locking surface, and a non-rotatable member, comprising a locking pin adapted to selectively cooperate with the locking surface of the rotatable member, whereby the relative positions of the rotatable and non-rotatable members are lockable.

44. A wheel locking mechanism as claimed in claim 43, wherein the rotatable member further comprises a locking actuator and a locking release.

45. A wheel locking mechanism as claimed in claim 44, wherein the locking pin is pivotally mounted with respect to both the locking actuator and the locking release.

46. A wheel locking mechanism as claimed in claim 45, wherein the locking pin is slidably mounted with respect to both the locking actuator and the locking release.

47. A wheel locking mechanism as claimed in claim 46, wherein the locking pin is resiliently mounted with respect to both the locking actuator and the locking release.

48. A wheel locking mechanism as claimed in claim 45, wherein the locking actuator is selectively movable to cause the locking pin to pivot into cooperation with the locking surface of the rotatable member.

49. A wheel locking mechanism as claimed in claim 43, wherein the locking surface is a toothed surface, and wherein the locking pin is caused to immediately lock into a recess between two adjacent teeth on the toothed surface.

50. A wheel locking mechanism as claimed in claim 43, wherein the locking surface is a toothed surface, and wherein the locking pin is caused to pivot into a primed position in contact with the toothed surface, prior to being urged into a recess between two adjacent teeth on the toothed surface.

51. A wheel locking mechanism as claimed in claim 43, wherein the locking release is movable to cause the locking pin to pivot out of cooperation with the locking surface of the rotatable member, whereby the relative positions of the rotatable and non-rotatable members are unlockable.

52. A wheel locking mechanism as claimed in claim 43, wherein the non-rotatable member comprises a semi-rotatable portion and a non-rotatable housing, wherein the semi-rotatable portion is mounted on, and is semi-rotatable with respect to, the non-rotatable housing.

53. A wheel locking mechanism as claimed in claim 52, wherein the semi-rotatable portion is resiliently mounted on the non-rotatable housing.

54. A wheel locking mechanism as claimed in claim 53, wherein a first helical spring connects the semi-rotatable portion to the non-rotatable housing.

55. A wheel locking mechanism as claimed in claim 52, wherein the locking pin is mounted in, and is non-rotatable with respect to, the non-rotatable housing.

56. A wheel locking mechanism as claimed in claim 52, wherein the semi-rotatable portion includes a ramped surface, adapted to face into the non-rotatable housing, wherein the ramped surface extends in the direction of rotation of the semi-rotatable portion.

57. A wheel locking mechanism as claimed in claim 56, wherein the locking pin is pivotally mounted with respect to the ramped surface.

58. A wheel locking mechanism as claimed in claim 57, wherein the locking pin is slidably mounted with respect to the ramped surface.

59. A wheel locking mechanism as claimed in claim 58, wherein the locking pin is resiliently mounted with respect to the ramped surface.

60. A wheel locking mechanism as claimed in claim 58, wherein the locking pin is pivotally mounted with respect to a first end of a movable bar.

61. A wheel locking mechanism as claimed in claim 60, wherein a second end of the movable bar is in sliding contact with the ramped surface of the semi-rotatable portion, whereby the locking pin is slidable towards and away from the semi-rotatable portion.

62. A wheel locking mechanism as claimed in claim 60, wherein the locking pin is slidable towards and away from both the locking actuator and the locking release.

63. A wheel locking mechanism as claimed in claim 60, wherein the locking pin is resiliently mounted with respect to the first end of the movable bar.

64. A wheel locking mechanism as claimed in claim 63, wherein a second helical spring connects the locking pin to the first end of the movable bar.

65. A wheel locking mechanism as claimed in claim 56, wherein the locking release is resiliently mounted with respect to, and movable with, the locking actuator.

66. A wheel locking mechanism as claimed in claim 65, wherein a third helical spring is provided to resiliently mount the locking release with respect to the locking actuator.

67. A pushchair comprising a chassis having a rear axle, at each end of which a wheel is mountable, wherein each end of the rear axle is provided with a wheel locking mechanism according to claim 43.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The present invention will now be more particularly described, by way of non-limiting example only, with reference to and as shown in the accompanying drawings (not to scale) in which:

[0046] FIGS. 1A to 1C are partial perspective views of a wheel locking mechanism according to the invention in situ on the frame or chassis of a pushchair (only a portion of the frame or chassis being shown);

[0047] FIGS. 2A to 2C are partial exploded views of the wheel locking mechanism shown in FIGS. 1A to 1C;

[0048] FIG. 3 is a perspective view, shown partially cut-away, of the wheel locking mechanism shown in FIGS. 1C and 2C;

[0049] FIGS. 4A to 4C are side views of part of the wheel locking mechanism shown in FIGS. 2A to 2C;

[0050] FIGS. 5A to 5C are, partial perspective views of the wheel locking mechanism shown in FIGS. 2A to 2C;

[0051] FIGS. 6A and 6B are end views of the wheel locking mechanism shown in FIGS. 2A to 2C;

[0052] FIGS. 7A and 7B are further end views, along with partial cross-sectional views along lines A-A and B-B respectively, of the wheel locking mechanism shown in FIG. 2C;

[0053] FIG. 8 is a perspective view of a pushchair according to the invention incorporating a a wheel locking mechanism according to FIGS. 1A to 1C and a further wheel locking mechanism;

[0054] FIG. 9 is a perspective view of a part of the pushchair shown in. FIG. 8;

[0055] FIG. 10 is detail of the part of the pushchair shown in FIG. 9; and

[0056] FIG. 11 is a perspective view, shown partially cut-away, of the further wheel locking mechanism shown in FIGS. 8, 9 and 10.

DESCRIPTION OF EMBODIMENTS

[0057] FIGS. 1A to 1C show a wheel locking mechanism 10 provided on one end of a rear axle 11 of a pushchair. The rear axle 11 includes a right-angled portion 12 at both of its ends (although only one such end is shown in FIGS. 1A to 1C), in this embodiment, the wheel locking mechanism 10 is formed integrally (at least in part) with the right-angled portion 12 of the rear axle 11, but of course the wheel locking mechanism 10 could instead be connected to the right-angled portion 12 of the rear axle 11. Also shown mounted to the right-angled portion 12 of the rear axle 11 is a wheel 13, having spokes 14 extending axially from a central hub (hidden from view).

[0058] As shown in more detail in at least FIGS. 2A to 2C, the wheel locking mechanism 10 comprises a rotatable member 20 that is adapted to be mounted on/to the hub of the wheel 13, such that the rotatable member 20 is co-rotatable with, and by rotation of, the wheel 13. In other words, when the rotatable member is mounted on the hub of the wheel 13, as the Wheel is caused to rotate, the rotatable member will also be caused to rotate, but without any specific action needing to be taken in relation to the rotatable member 20; its rotation is caused solely by rotation of the wheel 13.

[0059] The rotatable member 20 is in the form of an annular member having a two opposed annular surfaces (forming first and second faces), and inner and outer peripheral surfaces there between; on the inner peripheral surface of the annular member, a locking surface 21 is provided. The locking surface 21 is in the form of a toothed surface having a plurality of cog-like teeth 21a between adjacent ones of which recesses 21b are provided. One of the opposed annular surfaces of the rotatable member 20—the surface that will face the hub of the wheel 13 to which the rotatable member 20 is mounted—is provided with a number of lugs 27 for mounting the rotatable member 20 to the wheel hub. Alternatively, the rotatable member 20 can be formed as an integral part of the hub of the wheel 13.

[0060] The wheel locking mechanism 10 further comprises a non-rotatable member 22 (shown in FIGS. 1A to 1C but omitted in part, for clarity, from FIGS. 2A to 2C). The non-rotatable member 22 includes a locking pin 23 adapted to selectively cooperate with the locking surface 21 of the rotatable member, such that the relative positions of the rotatable and non-rotatable members 20, 22 are lockable. A more detailed description of this relationship will be given below.

[0061] The non-rotatable member 22 includes a semi-rotatable portion 22a, which is resiliently mounted on, and is semi-rotatable with respect to, a non-rotatable housing 22b. By “semi-rotatable” it is meant that the rotation of the semi-rotatable portion. 22a is limited, i.e. it is not freely rotatable through 360°. Indeed, the semi-rotatable portion 22a may only be rotated through an angle that is less than 180°, and more typically less than 90°. A first helical spring 60 (shown in FIGS. 6A and 6B, and 7A and 7B connects the semi-rotatable portion 22a to the non-rotatable housing 22b, but of course any other suitably resilient means having a restorative action for connecting the semi-rotatable portion 22a to the non-rotatable housing 22b could instead be used. Further detail as to the action of the first helical spring 60 will be described below.

[0062] The semi-rotatable portion 22a of the non-rotatable member 22 comprises a locking actuator 24, in the form of a foot pedal, and also houses a locking release 25, comprising a foot button 26. Each of the foot pedal 24 and foot button 26 are adapted to be depressed by a user of the mechanism 10, i.e. a person in control of the pushchair. As is clearly seen from the figures, both the foot pedal 24 and the foot button 26 are external of the semi-rotatable portion 22a of the non-rotatable member 22, so as to be accessible for depressing by a user.

[0063] The semi-rotatable portion 22a includes a ramped surface 28 which joins a lower land 28a to an upper land 28b, and which is adapted to face into the non-rotatable housing 22b. Together, the ramped surface 28 and the lower and upper lands 28a, 28b extend in the direction of rotation of the semi-rotatable portion 22a. The lower land 28a is located a further distance away from the non-rotatable housing 22b than the upper land 28b.

[0064] The locking pin 23 is mounted in, and is non-rotatable with respect to, the non-rotatable housing 22b of the non-rotatable member 22, i.e. the angular position of the locking pin 23 with respect to the plane of the non-rotatable housing 22b is fixed. The locking pin 23 is, however, pivotally mounted with respect to both the locking actuator 24 and the locking release 25; selective movement of the locking actuator 24 causes the locking pin 23 to pivot into cooperation with the locking surface 21 of the rotatable member 20 such that the relative positions of the rotatable and non-rotatable members 20, 22 are lockable, whilst subsequent movement of the locking release 25 causes the locking pin 23 to pivot out of cooperation with the locking surface 21 of the rotatable member 20, such that the relative positions of the rotatable and non-rotatable members 20, 22 are unlockable.

[0065] Because the locking surface 21 is a toothed surface, the locking pin 23 is caused to either (1) immediately lock into a recess 21b between two adjacent teeth 21a on the toothed surface such a locked configuration being shown in FIGS. 2C and 3, or (2) pivot into a primed position in contact with the toothed surface such a primed configuration is shown in FIG. 2B, prior to being urged into a recess 21b between two adjacent teeth 21a on the toothed surface. Such urging may be achieved, in part, by a slight nudge of the pushchair in either a forward or backward direction to provide the further amount of rotation required to cause the locking pin 23 to align with a recess 21b and lock into position therein.

[0066] As shown in more detail in FIGS. 4A to 4C and FIGS. 5A to 5C (noting that the configurations in FIGS. 4A to 4C are the same as those in. FIGS. 5A to 5C respectively), the locking pin 23 is pivotally mounted about a pivot 30 to a first end 31a of a movable bar 31 via a connection piece 32 in which the pivot 30 is located. Connection piece 32 includes a hinged portion 32a which connects connection piece 32 to the first end 31a of the movable bar 31, and allows connection piece 32 to flex between the position shown in FIGS. 4A and 5A and the position shown in positions 4B, 5B, 4C and 5C. The extent of movement by flexing between these two positions is controlled by the provision of a pin 34 on the locking pin 23, which pin 34 slidably cooperates with an elongate, slightly curved, aperture 35 in the connection piece 32.

[0067] A second end 31b of the movable bar 31 is in sliding contact with the ramped surface 28 of the semi-rotatable portion 22a, such that the locking pin 23 is slidable towards and away from the semi-rotatable portion 22a. In particular, the second end 31b is slidable from a position on the lower land 28a (as shown in FIGS. 4A and 5A) via the ramped surface 28 to the upper land 28b (as shown in FIGS. 4B and 5B, and 4C and 5C). The locking pin 23 is thus both pivotally mounted and slidably mounted with respect to the ramped surface 28, and furthermore is slidable towards and away from both the locking actuator and the locking release. The importance of this relationship will be described in more detail below.

[0068] The locking pin 23 is also resiliently mounted with respect to the ramped surface 28, and in particular is resiliently mounted and connected, by means of a second helical spring 33, to the first end 31a of the movable bar 31 via the hinged portion 32a of the connection piece 32.

[0069] In FIGS. 4A and 5A, the locking pin 23 is not in contact with the toothed locking surface 21 of the rotatable member 20, the second end 31b of the movable bar 31 is located on the lower land 28a of the ramped surface 28, and the second helical spring 33 is in a relaxed position, such that the connection piece 32 is in a relaxed position with the hinged portion thereof 32a being un-flexed and the pin 34 being located at the right-hand extremity of the elongate aperture 35. In this configuration, the relative positions of the rotatable and non-rotatable members 20, 22 are unlocked such that the wheel 13 is free to rotate.

[0070] In FIGS. 4B and 5B, the locking pin 23 is in contact with the toothed locking surface 21 of the rotatable member 20—in particular with a tooth 21a thereof, the second end 31b of the movable bar 31 is located on the upper land 28b of the ramped surface 28, and the second helical spring 33 is in a first compressed position, such that the connection piece 32 is in a flexed position with the hinged portion thereof 32a being flexed and the pin 34 being located somewhere in the middle of, and towards the left-hand extremity of, the elongate aperture 35.

[0071] Clearly, sliding movement of the second end 31b of the movable bar 31 from the lower land 28a to the upper land 28b causes both compression of the helical spring 33 and flexing of the hinged portion 32a of the connection piece 32, which in turn causes the locking pin 23 to pivot into a primed position about pivot 30, thus bringing it into contact with the tooth 21a of the locking surface 21. This configuration is non-essential in achieving locking of the relative positions of the rotatable and non-rotatable members 20, 22, however, it is an intermediate configuration that may be adopted when a user seeks to park or engage the brake of the pushchair, prior to achievement of the configuration shown in FIGS. 4C and 5C.

[0072] Turning to FIGS. 4C and 5C, the locking pin 23 is locked into a recess 21b between two adjacent teeth 21a on the toothed locking surface 21 of the rotatable member 20, the second end 31b of the movable bar 31 is located on the upper land 28b of the ramped surface 28 (in the same position as shown in FIGS. 4B and 5B), and the second helical spring 33 is in a second compressed position (being less compressed than the first compression position shown in FIGS. 4B and 5B; some compression in the second helical spring 33 being released on pivoting of the locking pin 23 into the recess 21b), such that the connection piece 32 is in a flexed position with the hinged portion thereof 32a being flexed (in the same position as shown in FIGS. 4B and 5B) and the pin 34 again being located at the right-hand extremity of the elongate aperture 35.

[0073] If the optional intermediate configuration shown in FIGS. 4B and 5B is not adopted, the locking pin 23 can move from the position shown in FIGS. 4A and 5A directly to the configuration shown in FIGS. 4C and 5C. With such a mode of action, sliding movement of the second end 31b of the movable bar 31 from the lower land 28a to the upper land 28b via ramped surface 28 causes some compression of the helical spring 33 and flexing of the hinged portion 32a of the connection piece 32, which in turn causes the locking pin 23 to pivot about pivot 30 into a locked position in a recess 21b between two adjacent teeth 21a on the locking surface 21. In this configuration, the relative positions of the rotatable and non-rotatable members 20, 22 are locked and the wheel 13 is prevented from rotating, i.e. the pushchair is parked (the brake has been applied),

[0074] If the optional intermediate configuration shown in FIGS. 4B and 5B is adopted, the locking pin 23 can be urged from the position shown in FIGS. 4B and 5B to the configuration shown in FIGS. 4C and 5C. With such a mode of action, the urging is achieved, in part, by a slight nudge of the pushchair in either a forward or backward direction to provide the further amount of rotation required to cause the locking pin 23 to align with a recess 21b and lock into position therein. In doing so, the locking pin 23 is caused to pivot about pivot 30 into a locked position in a recess 21b between two adjacent teeth 21a on the locking surface 21 by the compressive force in the second helical spring 33, which is partially released and causes, in part, urging of the locking pin 23 from its primed position into its locked position. In this configuration, the relative positions of the rotatable and non-rotatable members 20, 22 are locked and the wheel 13 is prevented from rotating, i.e. the pushchair is parked (the brake has been applied).

To recap on the configurations shown thus far: [0075] FIGS. 1A, 2A, 4A and 5A show the wheel locking mechanism 10 in a configuration in which the wheel of the pushchair is unlocked, i.e. the pushchair is not parked and the brake is not applied (i.e. the foot pedal 24 has not been depressed); the wheel of the pushchair is able to rotate freely because the relative positions of the rotatable and non-rotatable members 20, 22 are unlocked because the locking pin 23 of the non-rotatable member 22 is not in contact with (i.e. is non-cooperative with) the locking surface 21 of the rotatable member 20. [0076] FIGS. 1B, 2B, 4B and 5B show the wheel locking mechanism 10 in an intermediate configuration in which the wheel of the pushchair is not yet locked, but is primed for being locked, i.e. the pushchair is not yet properly parked although the brake has been applied (i.e. the foot pedal 24 has been depressed, as indicated in FIG. 1B by arrow P causing semi-rotation of the semi-rotatable portion 20 and thus of the ramped surface 28 and the lower and upper lands 28a, 28b); the wheel of the pushchair is able to rotate to a small degree (by no more than the radial distance occupied by a tooth 21a) so as to achieve locking of the relative positions of the rotatable and non-rotatable members 20, 22 by urging of the locking pin 23 of the non-rotatable member 22 from its primed position in contact a tooth 21a of the locking surface 21 of the rotatable member 20 to a locking position in a recess 21b between two adjacent teeth 21a on the locking surface 21. [0077] FIGS. 1C, 2C, 3, 4C and 5C show the wheel locking mechanism 10 in a configuration in which the wheel of the pushchair is locked, i.e. the pushchair is parked and the brake has been applied (i.e. the foot pedal 24 has been depressed, as indicated in FIG. 1C by arrow P causing semi-rotation of the semi-rotatable portion 20 and thus of the ramped surface 28 and the lower and upper lands 28a, 28b) the wheel of the pushchair is prevented from rotating because the relative positions of the rotatable and non-rotatable members 20, 22 are locked because the locking pin 23 of the non-rotatable member 22 is locked into (i.e. is cooperative with) the locking surface 21 of the rotatable member 20.

[0078] In seeking to lock the wheel 13 of the pushchair, the configuration of the wheel locking mechanism may be caused to change directly from that shown in FIG. 1A, etc. to that shown in FIG. 1C, etc., or it may be cause to change from that shown in FIG. 1A, etc. to that shown in FIG. 1C via that shown in FIG. 1B, etc. As to whether the former “direct” change or the latter “indirect” change is adopted will depend on the relative positions of the rotatable and non-rotatable members 20, 22 at the point at which the foot pedal 24 is depressed, and whether or not the locking pin 23 of the non-rotatable member 22 is in alignment with a recess 21b in the toothed locking surface 23 of the rotatable member 20.

[0079] The mechanism by which the relative positions of the rotatable and non-rotatable members 20, 22 can be unlocked (from the configuration shown in FIGS. 1C, 2C, 3, 4C and 5C) will now be described.

[0080] As described above, the semi-rotatable portion 22a of the non-rotatable member 22 houses a locking release 25, comprising a foot button 26, which is adapted to be depressed by a user of the mechanism 10, i.e. a person in control of the pushchair, as indicated by arrow B in FIGS. 1C and 7B. Furthermore, a first helical spring 60 connects the semi-rotatable portion 22a to the non-rotatable housing 22b, and provides a restorative action for between the rotational position of the semi-rotatable portion 22a in relation to the non-rotatable housing 22b.

[0081] FIGS. 6A and 6B, and 7A to 7B, provide further detail of the wheel locking mechanism 10 as contained within the non-rotatable member 22—in particular within the semi-rotatable portion 22a and the non-rotatable housing 22b thereof.

[0082] The locking release 25 is resiliently mounted by means of a third helical spring 40 to, and is movable with, the semi-rotatable portion 22a and the locking actuator 24. The locking release 25 is in the form of a flattened bar having the foot button 26 projecting from one end thereof (the third helical spring 40 being connected to the other end thereof) and through an aperture in the semi-rotatable portion 22a, such that the locking release 25 is housed substantially within the semi-rotatable portion 22a, whilst the foot button 26 is located externally of the semi-rotatable portion 22a.

[0083] FIG. 6A shows the wheel locking mechanism 10 in the configuration where the relative positions of the rotatable and non-rotatable members 20, 22 are unlocked, such that the wheel 13 is free to rotate; the locking actuator 24 is in a non-use position (i.e. rotated upwardly as compared to its use position) and the locking release 25 is in a primed position, whereby the first helical spring 60 (connecting the rotatable and non-rotatable members 20, 22) is relaxed and the third helical spring 40 (connecting one end of the locking release 25 to the semi-rotatable portion 22a) is compressed.

[0084] The flattened bar of the locking release 25 is provided in each of its long edges with a pair of notches 41 which are co-operable with a pair of elongate stops 42 (elongate in the direction into the page, as shown) provided in the non-rotatable housing 22b. The notches 41 are rotationally symmetrical about a pivot point in the flattened bar. Each elongate stop 42 fits snugly into a notch 41, as shown in FIG. 6A.

[0085] To maintain the third helical spring 40 under compression, such that the locking release 25 is in its primed position, each notch 41 of the locking release 25 is stopped against an elongate stop 42 of the non-rotatable housing 22b, and the first helical spring 60 is relaxed.

[0086] FIG. 6B shows the wheel locking mechanism 10 in the configuration where the relative positions of the rotatable and non-rotatable members 20, 22 are locked, such that the wheel 13 is prevented from rotating; the locking actuator 24 is in a use position (i.e. rotated downwardly as compared to its non-use position) and the locking release 25 is in a non-primed position, whereby the first helical spring 60 (connecting the rotatable and non-rotatable members 20, 22) is under tension and the third helical spring 40 (connecting one end of the locking release 25 to the semi-rotatable portion 22a) is relaxed.

[0087] Each notch 41 on the locking release 25 has been rotated out of cooperation with the pair of elongate stops 42 provided in the non-rotatable housing 22b by virtue of rotation of the locking actuator 24 into its use position. Once a critical point of rotation of the locking release 25 compared to the non-rotatable housing 22b is reached, the notches 41 disengage with the stops 42, thereby allowing the compression in the third helical spring 30 to be released, which forces the locking release 25, and in particular the foot button 26, upwardly out of the aperture in the semi-rotatable portion 22a. With the third helical spring 40 relaxed, the locking release 25 is in its non-primed position.

[0088] The non-rotatable housing 22b further comprises an abutment 43, shown in. FIGS. 6A and 7B, against which the locking release 25 abuts when in its non-primed position, as shown in FIGS. 6B and 7A (the abutment 43 being hidden from view in FIGS. 6B and 7A).

[0089] The wheel locking mechanism 10 is held in the configuration shown in FIGS. 6B and 7A by virtue of engagement of the locking pin 23 with a recess 21b of the locking surface 21 of the rotatable member 20; the locking pin 23 and its associated mechanism, along, with the rotatable member 20, are located behind the components shown in FIGS. 6A, 6B. 7A and 7B.

[0090] It is therefore clear to see that actuation of the locking actuator 24 to cause it to move from its non-use position to its use position causes the locking release 25 to move from its primed position to its non-primed position. In particular, actuation of the locking actuator 24 causes the locking release 25 to move out of contact with the elongate stops 42, thereby releasing compression in the third helical spring. Further particularly, actuation of the locking actuator 24 causes rotation of the semi-rotatable portion 22a and the ramped surface 28 thereof, whereby the locking pin 23 is caused to cooperate with the locking surface 21 of the rotatable member 20.

[0091] In reverse, release of the locking release 25 by actuation of the foot button 26 causes the locking release 25 to move out of contact with the abutment 43, thereby releasing tension in the first helical spring 60 connecting the semi-rotatable portion 22a to the non-rotatable housing 22b. The restorative force of the first helical spring 60 causes rotation of the semi-rotatable portion 22a from its use position to its non-use position, which causes rotation of the locking release 25 to a position in which the notches 41 therein reengage with the elongate stops 42 on the non-rotatable housing 22b, thus (re)compressing the third helical spring 40. In addition, release of the locking release 25 causes rotation of the ramped surface 28 of the semi-rotatable portion 22a such that the locking pin 23 is caused to be non-cooperative with the locking surface 21, i.e. the locking pin 23 is caused to pivot out of cooperation with the locking surface 21 or the rotatable member 20.

[0092] For the avoidance of any doubt, although it is clear from the above description and the accompanying drawings, rotation of the semi-rotatable portion 22a caused by release of the locking release 25 is in an opposite rotational direction to the rotation caused by actuation of the locking actuator 24.

[0093] Turning to FIG. 8, there is shown a pushchair 80 comprising a chassis 81 having a rear axle 11, at each end of which a wheel 13 is mounted. At a first end 11a of the rear axle 11, a wheel locking mechanism 10 is provided; at a second end 11b of the rear axle 11, a further wheel locking mechanism 100 is provided. This configuration is shown in more detail in FIGS. 9 and 10.

[0094] The wheel locking mechanism 10 is as hereinbefore described. The further wheel locking mechanism 100 is similar in construction to, and provides the same locking and unlocking function as, the wheel locking mechanism 10, however, clearly there are differences. It is these differences that will be described in more detail below (with reference numerals increased by 100 being used for the same components are as used for the wheel locking mechanism 10).

[0095] The further wheel locking mechanism 100 includes a semi-rotatable portion 122a (part of the non-rotatable member 122) however it does not include a locking actuator and does not house a locking release. Instead, a linking cable 82 is provided linking the semi-rotatable portion 22a of the wheel locking mechanism 10 with the semi-rotatable portion 122a of the further wheel locking mechanism 100, such that the action and consequences of actuation of the locking actuator 24 and locking release 25 of the wheel locking mechanism 10 are transmitted by the linking cable 82 and replicated in the wheel locking mechanism 100.

[0096] FIG. 11 shows that the locking pin 123 is mounted in, and is non-rotatable with respect to, the non-rotatable housing 122b of the non-rotatable member 122, i.e. the angular position of the locking pin 123 with respect to the plane of the non-rotatable housing 122b is fixed. Selective movement of the locking actuator 24 of the wheel locking mechanism 10, view the linking cable 82, causes the locking pin 123 to pivot into cooperation with the locking surface 121 of the rotatable member 120 such that the relative positions of the rotatable and non-rotatable members 120, 122 are lockable, whilst subsequent movement of the locking release 25 of the wheel locking mechanism 10, via the linking cable 82, causes the locking pin 123 to pivot out of cooperation with the locking surface 121 of the rotatable member 120, such that the relative positions of the rotatable and non-rotatable members 120, 122 are unlockable.

[0097] Because the locking surface 121 is a toothed surface, the locking pin 123 is caused to either (1) immediately lock into a recess 121b between two adjacent teeth 121a on the toothed surface, or (2) pivot into a primed position in contact with the toothed surface, prior to being urged into a recess 121b between two adjacent teeth 121a on the toothed surface. Such urging may be achieved, in part, by a slight nudge of the pushchair in either a forward or backward direction to provide the further amount of rotation required to cause the locking pin 123 to align with a recess 121b and lock into position therein.