Patent ID: 12240516

FIG.1shows a wheeled carrier in the form of a dolly10, which comprises a body12providing a platform14for supporting a load. The dolly10further includes wheel assemblies in the form of four casters16. The casters16are arranged in two pairs: a first pair16A at one end of the body12, and a second pair16B at the opposite end of the body12.

The first pair of casters16A are connected to a brake operating arrangement18comprising a shaft20extending between the casters16. A respective cam member22is provided at each of the opposite ends of the shaft20. Each of the cam members22is secured on the shaft20by frictional engagement therewith.

Referring toFIG.7, the cam member22has alternating force applying regions26and release regions24. Each force applying region26has a radially outwardly facing force applying surface30, and each release region24has a radially outwardly facing release surface28. The force applying regions and surfaces26,30, and the release regions and surfaces24,28are described in more detail below.

In the embodiment shown, the cam member22has three force applying regions26and three release regions24. The force applying regions26and the release regions24alternate relative to each other. It will be appreciated that the cam member could have any other suitable number of alternating force applying regions26and release regions24, such as four or five.

Each caster16comprises a holding arrangement32, in the form of a frame, and a wheel34rotatably held by the holding arrangement32. Each caster16includes a brake mechanism36comprising a braking member38, a transmission element40, and a brake release spring41. The combination of the brake operating arrangement18and the brake mechanism36is referred to herein as a brake assembly.

The braking member38is movable between a braking position, in which the braking member38engages the wheel34, and a non-braking position in which the braking member38is spaced from the wheel34. The brake release spring41is arranged between the holding arrangement32and the braking member38to urge the braking member38to the non-braking position.

The transmission element40extends from the braking member38. A force can be applied by the cam member22to the transmission element40in the direction of the braking member38.

The force is applied when the cam member22moves to a force applying condition in which one of the force applying surfaces30engages the transmission element40. The force so applied is transmitted by the transmission element40to the braking member38to move the braking member38to the braking position.

The cam member22can be moved to a release condition. In the release condition, one of the release surface28engages the transmission element40, thereby allowing the transmission element40to move towards the shaft20, and the braking member38to move to the non-braking position.

Each cam member22and the shaft20are rotatable about an axis of rotation X extending longitudinally through the shaft20. The force applying surfaces30are a greater distance from the axis of rotation X than the release surfaces28.

The brake mechanism36further includes a drive member44in the form of a lever which, in the embodiment shown, comprises a foot pedal. The drive member44may float on the shaft20, without engagement therewith other than by means of a ratchet mechanism46discussed below. Alternatively, the drive member44is rotatably mounted on the shaft20by suitable bearings, thereby enabling the drive member44to rotate about the bearings. Each bearing may be similar to the bush forming the reaction member62discussed below.

The drive member44is connected to the shaft20by a ratchet mechanism46. The drive member44can be pressed in the direction indicated by the arrow A inFIG.3, so that it rotates in a drive direction from its position shown inFIG.3to its position shown inFIG.5. The movement of the drive member44in the drive direction is indicated by the arrow A inFIG.3. This downward movement of the drive member44is transmitted by the ratchet mechanism46to the shaft20, thereby rotating the shaft20.

The drive member44is also rotatable in a return direction from the position shown inFIG.5to the position shown inFIG.6(which shows the same position of drive member44asFIG.3). The movement of the drive member44in the return direction is indicated by the arrow B inFIG.5.

The ratchet mechanism46comprises a cylindrical propelling member48fixedly attached to the drive member44. The shaft20extends through an aperture in the propelling member48, the aperture being large enough to allow rotation of the propelling member48relative to the shaft20. Thus, the propelling member48rotates with the drive member44around the shaft20when the drive member44rotates in the drive and return directions.

The ratchet mechanism46also includes a propelled member50attached to the shaft20. The propelled member50is attached to the shaft20so that the propelled member50can move linearly along the shaft20. The propelled member50is rotatably fixed to the shaft20so that the shaft20is rotated when the propelled member50rotates.

The ability of the propelled member50to rotate the shaft20is effected by providing the shaft20with a hexagonal end profile, and by providing the propelled member50with a correspondingly shaped and sized hexagonal aperture through which the shaft20extends.

Each of the propelling and propelled members48,50is rotatable about the axis of rotation X.

Referring toFIG.4, the propelling and propelled members48,50have respective main portions52. Teeth54are arranged on each of the main portions52around the axis of rotation X.

The teeth54of each of the propelling and propelled members48,50are directed towards each other so that they mesh to allow the propelling member48to propel the propelled member50.

Each tooth54of the plurality of teeth54is asymmetric, having an axially extending drive surface56. The drive surface56extends parallel to the axis of rotation X. Each of tooth54also includes a return surface58sloping relative to the drive surface56.

When the drive member44is moved in the return direction, the teeth54of the propelling member48slide along the return surfaces58of the teeth54of the propelled member50.

The ratchet mechanism46further includes an urging member60, in the form of a compression spring, in engagement with the propelled member50. A reaction member62in the form of a bush is provided on the shaft20adjacent the propelled member50. The reaction member62is secured on the shaft20by frictional engagement therewith.

The reaction member62is rotationally and linearly fixed to the shaft20, so that the reaction member62cannot move linearly along the shaft20, and rotates with the shaft20when the shaft20rotates.

The urging member60extends between the reaction member62and the propelled member50. Thus, the urging member60urges the propelled member50onto the propelling member48.

The urging member60can be attached to the propelled member50and the reaction member62. This attachment can be effected by means of projecting members each opposite end of the urging member60. The projecting members are received in respective holes in the propelled member50and the reaction member62. When the drive member44is pressed in the direction of the arrow A inFIG.3, the urging member60is resiliently twisted from an untwisted position to a twisted position. On releasing the drive member44, the urging member60returns to its untwisted position, thereby moving the drive member44in the return direction as indicated by the arrow B inFIG.5.

When the propelled member50is so urged, the teeth54on the main portion52of the propelling member48mesh with the teeth54on the main portion52of the propelled member50.

The meshing of the teeth54has the effect that rotation of the propelling member48by the drive member44causes the propelling member48to rotate the propelled member50.

Rotation of the propelled member50effects rotation of the shaft20in the same direction, thereby effecting rotation of the cam members22.

When the cam member22is in the release condition and the drive member44is in the position shown inFIG.3, the teeth54of the propelled member50are meshed with the teeth54of the propelling member48.

Rotation of the drive member44in the drive direction, shown by the arrow A inFIG.4, causes the propelling member48to rotate the propelled member50in the same direction as the arrow A, thereby rotating the cam member22in the same direction.

As a result, the cam member22rotates to the force applying position, pressing the transmission element40downwards. This moves the braking member38to the braking position in engagement with the wheel34.

The user may then lift his or her foot off the drive member44, to allow the resilient urging member60to rotate the drive member44in the return direction, shown by the arrow B inFIG.5.

The rotation of the drive member44in the return direction causes the teeth54of the propelling member48to move over the teeth54of the propelled member50, thereby urging the propelled member50along the shaft20in the direction of the arrow C. Thus, the urging element moves the drive member44to its resting position shown inFIG.6.

In order to move the braking member to the non-braking position, it is necessary to move the cam member22to the release condition. This is done by the user again pressing down on the drive member44, thereby rotating it in the drive direction.

Rotating the drive member44in the drive direction rotates the cam member22in the same direction, thereby moving the cam member22to the release condition so that the release region24engages the transmission element40.

When the cam member22is moved to the release condition, the transmission element40and the braking member38move upwardly, urged by the brake release spring41.

The user can then lift his or her foot off the drive member44, thereby allowing the drive member44to move back to its resting position so that the teeth54of the propelling member48slide along the return surfaces58of the propelled member50. The release condition of the cam member22and the resting position of the drive member44are shown inFIG.3.

There is thus described a dolly10with a brake operating arrangement18that can operate a brake mechanism36, moving it between braking and non-braking positions by pressing downwardly on the pedal. A ratchet mechanism46is provided to enable the aforesaid movement.

Various modifications can be made without departing from the scope of the invention.

A further brake operating arrangement118is shown inFIGS.8to10. The further brake arrangement118comprises many of the features of the brake arrangement18shown inFIGS.1to7. These features are designated inFIGS.8to10with the same reference numerals as the corresponding features inFIGS.1to7.

The further brake operating arrangement118differs from the brake operating arrangement18in that the reaction member62and the cam members22of the brake operating arrangement118is secured to the shaft20by means of a grub screw tightened against the shaft20through threaded apertures70,72in the reaction member62and the cam members22.

The further brake arrangement118additionally includes a locking member74to lock the drive member44in a central position on the shaft20. The drive member44is urged by the urging member60into engagement with the locking member74. The locking member74is secured to the shaft20by a grub screw which is screwed through a threaded aperture78into engagement with the shaft20.

The brake arrangement118further includes a return spring80to return the drive member44in the direction indicated by the arrow B inFIG.8. The return spring80extends around the shaft20, and has projections82,84at the opposite ends. The projection82is received by a suitable formation in the drive member44. The projection84is received by a suitable formation in the body12. Thus, after the drive member44has been depressed and released, the return spring80urges the drive member44in the direction indicated by the arrow B inFIG.8.

As the drive member44moves in the direction indicated by the arrow B, the interaction of the teeth54of the propelling member48and the propelled member50causes the propelled member50to be pushed in the direction indicated by the arrow C inFIG.8. This movement of the propelled member50compresses the spring60, as shown inFIG.8, thereby urging the drive member44against the locking member74. The return spring80also urges the teeth54of the propelled member50into meshing engagement with the teeth54of the propelling member48when the drive member44has fully returned in the direction indicated by the arrow B.