AU690013B2 - Braking system for shopping trolleys - Google Patents

Description

TITLE BRAKING SYSTEM FOR SHOPPING TROLLEYS FIELD OF THE INVENTION This invention relates to a braking system for shopping trolleys. It is primarily concerned with the braking of shopping trolleys travelling on ramp escalators. The invention will be described by way of example with reference to the braking of shopping trolleys travelling on ramp escalators. However, it should be appreciated that this is given by way of example only and that the invention may be used to advantage in other circumstances.

BACKGROUND ART

In most shopping centres, travel between floors involves the use of an escalator. The traditional escalators use a moving staircase to transport people from one level to the next. For obvious reasons this type of escalator is not practical for use with shopping trolleys. Therefore, most new shopping centres are employing ramp escalators.

Ramp escalators have an inclined moving ground surface made up of a series of steel panels which are hinged to each other. The panels have an array of parallel longitudinal grooves extending along the panel in the direction of travel. Metal combs which mate with the longitudinal grooves are located at each end of the ramp escalator. The combs prevents debris from entering the internal structure of the ramp escalator.

Such ramp escalators are satisfactory for conveying people but are not satisfactory for wheeled vehicles such as shopping trolleys. When a person with a shopping trolley travels on the ramp escalator the trolley needs to be securely held to prevent it from experiencing unwanted movement. For this reason some trolleys are provided with a braking mechanism.

One type of braking mechanism which has not achieved commercial success is a handle bar brake which is not dissimilar to the brakes found on bicycles. These brakes are however expensive and the connecting wires tend to fray and snag.

A type of trolley wheel brake which has achieved a measure of commercial success has a metal strut bolted to the trolley wheel axle. The strut has a downward extending portion which terminates in a brake shoe. The brake shoe is fairly small, this being necessary to minimise the brake and strut being tripped over, kicked or scraped against. The brake shoe is spaced above the rim of the wheel such that when the wheel rolls along a level ground surface, the brake shoe does not engage with the ground. The wheel itself is formed from a pair of spaced apart discs defining a channel therebetween. The discs pass into the longitudinal grooves on the ramp escalator and as the grooves are fairly deep, the discs move into the grooves which in turn causes the brake shoe to contact the top of the escalator, thereby braking the trolley wheel.

In practice, an average shopping trolley weights 28kg when empty, and can weigh over 100kg when loaded, and often additionally contains children. In practice, it is found that the brake shoe is not sufficiently large enough and cannot function effectively to stabilise the trolley. The trolley therefore still slides or moves down the inclined ramp escalator, and as the wheels are formed from pairs of spaced apart relatively thin walled discs, the trolley is also susceptible to tipping.

The channel between the spaced apart discs is sized such that the base wall of the channel does not contact the ramp escalator, as damage to the channel may result if this is allowed to occur.

Another type of known braking system also employs a pair of spaced apart end discs and an intermediate brake member which has a polygonal shape, the shape typically being octagonal. The intermediate member is clamped or otherwise fastened between the end discs and thus rotates with the wheel. While the polygonal member does present level braking surfaces, because it rotates, there is also a high probability that a corner of the intermediate member, rather than a level portion will engage with the ramp escalator, the corner of course having a much smaller braking surface. This can cause the shopping trolley to suddenly move backward or forward which is extremely undesirable.

Another disadvantage with current trolley wheels which may or may not have brakes is that the wheels are mostly of the caster wheel type. The caster wheel has an inverted U-shaped bracket which supports an axle on which the wheel rotates. The top of the U-shaped bracket has a socket or a pin which allows the arrangement to be swivably attached to the shopping trolley or other article. Under rough handling conditions, for instance when a trolley is pushed into a gutter or hit by a vehicle, it is common for the swivel pin to bend. This in turn causes the entire wheel to adopt an inclined angle rather than a vertical position. When such a damaged wheel goes on a ramp escalator, the spaced apart discs do not pass into the longitudinal grooves on the escalator and thus the trolley is not properly braked.

Because of the possibility of wheel damage, shopping trolleys need to be inspected regularly, and typically six month inspections are held. A further disadvantage with existing trolleys having braked wheels is that the assemblies are rather complex to assemble and disassemble. OBJECT OF THE INVENTION

It is therefore an object of this invention to provided a shopping trolley braking system that may overcome the above disadvantages or provide the consumer with a useful or commercial choice. In one form, the invention resides in a combined wheel and brake assembly for a shopping trolley, the wheel comprising a pair of spaced apart rotatable circular end discs, and an intermediate brake member positioned between the end discs, the brake member having a generally horizontal brake contact area which is spaced inwardly from the rims of the end discs by a distance which allows the wheel to rotate freely over a smooth ground surface but which will engage with the surface of a ramp conveyor when the end discs pass into the longitudinal grooves of the conveyor, the brake member being fixed against rotation relative to the end discs.

In another form the invention resides in a braking system for a shopping trolley comprising a wheel, the wheel having two transversely spaced circumferentially extending flanges; and a brake member, the brake member being spaced between said flanges and having a brake contact area; wherein the length of the brake contact area is at least as long as the radius of the wheel.

The brake system may be used on shopping trolleys that travel on ramp escalators.

The wheel may enable the shopping trolley to move freely on a flat solid ground surface. A shopping trolley wheel mounting may be used to mount the wheel for rotation. The discs may be constructed from any material, with preferred materials being hard and wear resistant. The wheel may be constructed of plastics material. Suitable plastics materials include most engineering plastics, such as polyurethane.

The wheel may be manufactured so that it is integrally formed. Alternatively, the wheel may be constructed through the use of two discs. These discs may be identically shaped and sandwiched together to form the wheel. The discs may each have a circumferentially extending flange or rim. The circumferentially extending flange or rim may be of a size that enables them to readily locate within longitudinal grooves on the ramp escalator.

An inner axial projection may extend from one side of the circumferentially extending flange. An outer axial projection may extend from the opposite side of the circumferentially extending flange. The outer axial projection may be used to space the circumferentially extending flange from the wheel mounting. The outer axial projection may be substantially smaller than the inner axial projection. The inner axial projection may have a axial groove located in its face to form a corresponding node which is of similar size, shape and orientation to the outer axial projection. Each disc may have a hole positioned through its centre adapt to receive an axle. The discs may be sandwiched together so that the inner axial projections contact each other, forming a wheel with transversely spaced circumferentially extending flanges.

The brake member may use frictional force to prevent movement of the shopping trolley on the ramp escalator. The brake contact area may be spaced radially inward from the rim of the discs. The brake member may be constructed from a material that is both hard wearing and provides sufficient slip resistance. Suitably plastics materials are used such as polyurethane. The brake member can be easily replaced and cheap to produce .

The brake member may be constructed so that it is one piece. The brake member may have a hole extending through it . This hole may be used to locate the brake member between the circumferentially extending flanges of the wheel. The brake member may be symmetrical. The brake member may have more than one brake contact area. The brake member may be of any geometrical shape such as a generally square shape. The brake member may be able to be held in its desired orientation by the shopping trolley mounting member which may be of an inverted U-shaped configuration. The brake member may be held by the top of the shopping trolley mounting member. Part of the brake member may be used as protection for the wheel. Typically, the brake member has a forward portion that is positioned forward of the wheel when the shopping trolley is a forward motion is used as protection. This part of brake member may extend outwardly from the circumferentially extending flanges, acting as a form of bumper bar. This may reduce the incidence of misalignment of the wheels caused by damage to the wheel. BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will be described with reference to the accompanying drawings in which

Figure 1 is a side view of a braking system attached to a shopping trolley wheel mounting.

Figure 2 is a front view of a braking system attached to a shopping trolley wheel mounting.

Figure 3 is a side view of a wheel disc. Figure 4 is an end view of the disc of Figure 3.

Figure 5 is a side view of a brake member.

BEST MODE

Figures 1 and 2 show a caster shopping trolley wheel mounting 10 to which a combined wheel and brake assembly 11 has been attached. The shopping trolley mounting 10 has an inverted U-shape and has a fork with two downwardly forwardly spaced apart tines 12. Located between the tines 12 is assembly 11. The assembly comprises a brake member 14 and a wheel formed from two spaced apart discs 16,17.

Referring to Figures 3 and 4 it can be seen that the wheel includes two circular end discs 16,17 constructed of a hard, wear resistant, engineering plastic. The discs 16 have a diameter of 125mm. Each disc 16 has a circumferentially extending flange or rim of a width smaller than the longitudinal grooves located on the ramp escalator.

An outer axial projection 18 is centrally located on one side of each disc 16,17. The outer axial projection 18 is circular. The outer axial projection 18 has a diameter of 45mm and a width of 5mm. An inner axial projection 19 is centrally located on the other side of each disc. The inner axial projection 19 is circular. The inner axial projection 19 has a diameter of 75mm and a width of 10mm. An axial groove 20 is located in the face of the inner axial projection 19. The axial groove 20 has a radial spacing of 10mm and a depth of 5mm. A corresponding node 21 is encompassed by this axial groove 20 and has the same size, shape and orientation as the outer axial projection 18. A hole 22 is centrally located in the disc with a diameter of 12mm. The hole 22 is able to receive an axle 23. To form a wheel 13, the two discs 16,17 are sandwiched together so that the inner axial projections 19 and corresponding nodes 20 are in contact. An axle is passed through the holes 22 in both discs 16,17. The axle is then mounted to the shopping trolley wheel mount through fasteners. No steel bearings are needed as the plastic components can be lubricated from time to time or are self-lubricating. However, should a bearing assembly be specifically required, sealed bearing assembles can be press-fitted around the axle and it will be necessary to have larger holes through the discs to fit the bearing assembly. The outer axial projections 18 space the discs 16,17 from the tines 13 of the shopping trolley wheel mounting 10. The outer axial projections 18 and corresponding nodes 21 form a large diameter solid shaft which extends through the wheel 15 making a stronger, more effective wheel that is difficult to misalign.

Figure 5 shows the brake member 14. The brake member 14 is a unitary piece of moulded polyurethane having weight-reducing voids therein. Located adjacent the middle of the brake member 14 is a large locating hole 24 which extends through the brake member 14. The locating hole 24 is of slightly larger diameter than the diameter of the inner axial projection 19. The brake member is roughly symmetrical and has a braking contact area 25 which is large, flat and rectangular in shape. The brake contact area 25 has a length of 90mm and a width of 20mm, and extends outwardly from the discs to form a protruding rearward portion. The brake member 14 is located, through the use of the locating hole 24, on the inner axial projections 19 of the disc 16. The brake member 14 is held in the correct orientation by the top of the shopping trolley wheel mounting 10 through extending lugs 31 which pass into the mounting 10 to prevent rotation of the brake member. Although Figure 5 illustrates two lugs, further lugs or other types of projections may be provided to firmly hold the brake member against rotation. The brake member 14 is correctly orientated when the brake contact area 25 to be used does not interfere with the movement of the shopping trolley on a flat ground surface. The brake contact area 14 to be used is substantially horizontal with the ground surface and spaced radially inwardly from the circumference of the wheel 14. The member 14 substantially fills the space between discs 16,17 to support the discs against dents and damage.

In the embodiment, the brake member 14 also operates as a bumper bar for the wheel 15. The brake member has a forward portion 30 which extends outwardly from the rim of the wheel 15. This portion is located in front of the wheel 15 when the shopping trolley is in a forward motion. Any object that the shopping trolley hits, such as a wall or gutter, contacts the brake member not the wheel. Therefore, the wheel is less likely to become misaligned.

The brake system operates when travelling on a ramp escalator. The circumferentially extending flanges or rims 16,17 locate within the longitudinal slots of the belt of the ramp escalator. The brake contact area 14 contacts the belt of the ramp escalator. The large surface area of the brake contact area creates a large friction force between the brake contact area and ramp escalator belt preventing shopping trolley movement . The brake member is designed to substantially fill the gap between discs 16,17 thereby protecting the discs as much as possible from being bent or otherwise damaged. Of course, at the lower portion of the discs, the brake member is spaced inwardly to present the brake contact area 25.

A further advantage with this arrangement is that the wheel and brake assembly comprises only three components being the two wheel discs and the single central polyurethane brake member. The wheel assembly can therefore be readily removed and opened for repair, cleaning or replacement.

It should be appreciated that various modifications may be made to the embodiment described without departing from the spirit and scope of the invention as claimed.

Claims (9)

CLAIMS :

1. A combined wheel and brake assembly for a shopping trolley, the wheel comprising a pair of spaced apart rotatable circular end discs, and an intermediate brake member positioned between the end discs, the brake member having a generally horizontal brake contact area which is spaced inwardly from the rims of the end discs by a distance which allows the wheel to rotate freely over a smooth ground surface but which will engage with the surface of a ramp conveyor when the end discs pass into the longitudinal grooves of the conveyor, the brake member being fixed against rotation relative to the end discs.

2. The assembly of claim 1, wherein the brake contact area has a length which is at least as long as the radius of the wheel.

3. The assembly of claim 2, wherein the brake contact area has a width which is slightly less than the width between the end discs such that the brake contact area substantially fills the spacing between the discs.

4. The assembly of claim 2, wherein the brake member has a rearward portion which extends past the rims of the discs and generally behind the wheel, the portion having a lower surface which forms part of the brake contact area.

5. The assembly of claim 2, wherein the brake member has a forward portion which extends past the rims of the discs and generally in front of the wheel to form a bumper to reduce damage to the assembly.

6. The assembly of claim l, wherein the brake member substantially fills the area between the end discs to reduce denting of the rims of the discs except around the portion of the disc which contacts the ground surface where the brake member is spaced inwardly relative to the rims of the discs.

7. The assembly of claim 2, wherein the discs are mounted to a single horizontal axle, ends of the axle being supported by an inverted U-shaped bracket, the brake member being secured against rotation by the bracket.

8. The assembly of claim 2, wherein the braking member is formed from a single piece of plastics which can readily be removed and replaced.

9. The assembly of claim 7, comprising a caster wheel.

10 An article containing at least one wheel assembly as claimed in claim 1.