A common problem for major food retailers is loss of trolleys, whether by theft or due to unauthorised use of the trolleys in transporting goods away from the retail outlet. Trolleys are commonly stored in a car park or outside the front of the retail outlet so that customers arriving at the retail outlet can easily take a trolley to be wheeled around the retail space. After having finished shopping the customer typically uses the trolley to transfer the bought goods to a waiting vehicle in the car park. The trolley is then left in the car park in areas designated for trolleys, or persons are employed to return the discarded trolleys to their original positions ready for use by another person. Customers may be encouraged to return the trolleys to a particular area by the use of coin operated locking mechanisms which only release a trolley after a coin has been entered into the locking mechanism, and only return the coin when the trolley

has been attached to another trolley.

Another method for encouraging the return of trolleys is the use of a key card operated locking mechanism to replace the coin operated mechanism. The key card must be purchased from the retail outlet. It is then inserted into a trolley mounted receptacle in order to release the trolley. The card is only removable for the customer to retain when the trolley is engaged with another trolley. This has the advantage of removing the need for the trolley to retain a coin, which renders the trolley locking mechanism liable to vandalism.

Nevertheless retail outlets suffer significant losses of trolleys, estimated to be as much as 10% of an outlet's collection per year. This represents a significant financial loss. Retailers may have to employ collection agents to tour around the retailer outlet's local area in order to retrieve abandoned trolleys.

There is therefore a requirement for means to hinder the removal of a trolley from a retail outlet's property. One method which has been developed is to provide one or'more wheels of the trolley with a braking mechanism.

US-A-5,194,844 discloses a mechanism which is remote operated, and activated when the trolley passes a marker such as underground cabling. The cabling

may be located around the perimeter of a retail outlet, so that the brake is activated as soon as the trolley enters an unauthorised area. This prevents wheeled movement of the trolley an therefore discourages further movement of the trolley.

US-A-5,598,144 discloses a braking mechanism which involves the use of a drum brake with expanding callipers. The brake is activated on passing a marker by the callipers being urged onto a drum inside surface, as in conventional drum braking.

GB 2 347 493 A discloses a trolley security system provided with one or more reflective targets which are secured to a trolley. The targets are for reflecting a signal back to a signal-detecting device.

WO 00/16271 is concerned with a system for encouraging customers to return shopping trolleys by a reward mechanism which awards points/credits to a customer's loyalty or reward card as and when a trolley is returned to a pre- determined location. The invention includes a processing circuit which is capable of providing a customer-identification code in association with return of the trolley.

WO 99/59112 concerns a trolley-monitoring system in which each trolley is

provided with an identifier. Readers for reading identification tags are distributed around the store and allow monitoring of the location of individual trolleys and the provision of marketing data and monitoring of theft.

US 5,881,846 concerns a castor wheel with an external braking member. The braking member is held in a non-braking position by a locking member engaging an aperture in the braking member. A solenoid or motor releases the locking-member and the braking-member moves into contact with the ground under the influence of a biassing spring. Once in contact with the ground, continued rotation of the wheel causes the braking member to move under the wheel and lift the wheel from contact with the ground.

Various applications disclose braking mechanisms which interact with the ground walkways of an escalator or travelator. For example EP-A-0 775 598 discloses a trolley wheel which has a side-mounted brake-shoe and two discs which define the wheel. Each disc has a grooved tyre which mates with a grooved floor plate. When the wheel goes over the floor plate, engagement of the tyres in the plate reduces the axle height of the wheel thereby bring a brake into engagement with the ground.

EP-A-0633151 discloses a flanged wheel which has a brake disposed between

the flanges. When the wheel is driven over a grooved walkway the flanges drop into the grooves bringing the brake into engagement with the walkway.

The walkway appears to drive a part of the brake into engagement with the fixed part of the trolley to effect brake activation.

W092/15476 discloses an arrangement in which a trolley castor has a braking device which comprises a ground-engaging member normally held in an inoperative position by a blocking member. The ground-engaging member is an eccentrically axled disc which when released by the blocking member rotates into engagement with the ground. Continued forward movement causes further rotation of the ground-engaging member causing the trolley wheel to be lifted from the ground.

EP-A-0532472 discloses a trolley brake consisting of a probe which when dipped into a grooved floor plate causes braking of the trolley. The disclosure particularly relates to a magnet used for activation either of the probe or for release of the probe.

EP-B-0275959 concerns a castor equipped with braking means. The braking means consists of a pedal activated lever which operates to lift the castor wheel from the ground when the pedal is depressed. A key feature of the invention is

a lever which pivots about a fixed floor stand.

EP-B-0373398 concerns a wheel for shopping trolleys. The castor has a running wheel and a sensor wheel. The sensor wheel is pressed against the floor by a compression spring and on insertion of the sensor wheel into longitudinal grooves of a moving conveyor belt/escalator step, the running wheel is stopped. The sensor wheel comprises a vertically movable hub and a "running annulus"capable of rotary movement on the hub by means of a rolling bearing. The invention is characterised in that the compression spring arrangement and rolling bearings are spaced laterally from one another. This is another patent application relating to engagement of a braking system with a grooved floor plate of the type seen on escalators or conveyor belts.

A disadvantage of all of these braking mechanisms is that the braking action is very sudden. This can be dangerous for the pusher of the trolley, who may be harmed by impact with the suddenly stopping trolley. This is particularly dangerous for pregnant women and the elderly or infirm. It is also alarming for a trolley user who may accidentally have wandered into an unauthorised area.

There is therefore a requirement for a trolley security system which allows for the restriction of trolley movement outside authorised areas, but which does not

suffer from the aforementioned problems.

According to the present invention there is provided a wheel assembly for a trolley comprising: a wheel or roller mounted for free rotation to permit travel of the trolley, a braking mechanism for applying a brake to prevent rotation of the wheel or roller, brake activation means comprising an actuator responsive to a remote activation signal, wherein the braking mechanism comprises spring means having an anchored end and a free end region, wherein operation of the actuator causes the free end region of the spring means to snag whereby continued rotation of the wheel or roller causes the spring means to load and gradually resist further rotation of the wheel or roller thereby to provide gradual braking.

By gradually loading a braking spring means, the trolley is not brought to an abrupt halt and the danger to the customer using the trolley is decreased.

Preferably the spring means comprises a helical spring, although other springs such as coil springs and tension and compression springs are within the scope of the invention.

In one embodiment, the said one end of the spring is anchored to a central hub

portion of the wheel from which the spring spirals outward to the free end. The spring therefore rotates with the wheel.

The free end of the spring means may be provided with a hook, the snagging of which provides a gradual loading of the spring.

A non-rotating second hub portion may be provided with a snagging arm, which arm is movable in response to the actuator from a rest position to a snagging position in which the arm is capable of engaging with the hook.

The actuator may comprise an electric motor and gear train which is adapted to rotate the snagging arm between its rest position and snagging position.

The actuator may further comprise a radio frequency signal receiver for receiving a remote actuation signal. Radio frequency provides a convenient remote transmission method, although other methods are within the scope of the invention.

The assembly is preferably provided with a self contained power supply, conveniently a battery.

The wheel may be comprised in a castor. Castors are the usual wheeled support for a retail trolley. Usually only one wheel assembly according to the present invention is required on any trolley, however more may be present if necessary.

According to another aspect of the invention there is provided a retail outlet goods transport security system, comprising a plurality of trolleys as hereinbefore described and one or more actuation signal generators providing an actuation signal capable of activating the brake mechanism of a trolley passing thereby.

The actuation signal generator may comprise floor or ground located actuation cabling. The cabling may provide a network delineating authorised and unauthorised areas for trolleys. For example, actuation cabling may be provided at car park vehicle or pedestrian exits.

Actuation signal generators may be provided at store exits which are not approached via cashier sites. In this way trolley progress may be halted if a customer attempts to exit without having passed through a checkout/cashier site.

According to yet another aspect of the invention wherein each trolley may be

provided with a unique identification signal generator, and wherein remote identification signal reading and logging means are provided, thereby permitting tracking of the movement of individual trolleys. Preferably, the unique signal identification generator is provided in a wheel assembly according to the present invention, although this aspect of the invention may find application in conventional prior art trolleys.

The remote signal reading and logging means may comprise cabling and a data processor communicating with the cabling for the logging of trolley identification signal data and cable location data, thereby to provide a logging of trolley movement past cable locations.

This allows for the tracking of the movement of trolleys through a store by the placing of suitable remote logging means at intervals throughout the store. This can provide valuable marketing information for enhancing the retail efficiency of the store. Another benefit is the possibility of providing an identification logger at the trolley storage sites, so that at the end of a trading day each trolley may be accounted for, and any missing trolleys individually identified.

In addition, when a trolley is damaged or requires servicing its condition and service history may be manually logged on the data processor with reference to

its identifier. This makes it much easier to track servicing and repair of trolleys, which is usually carried out by an outside agency and difficult to administer. Once a repair has been completed and the trolley returned it, its arrival in the trolley storage area may be automatically logged and its record updated to show repaired.

According to a further aspect of the present invention there is provided an anti shop-lifting system, comprising a system hereinbefore described, wherein each trolley is provided with an electronic logging means capable of occupying at least two states, one state corresponding to"goods unpaid for"and the other corresponding to"goods paid for", wherein the logging means is provided with remote logging signal receiving means and transmission means for transmitting/receiving a"goods unpaid for"or"goods paid for"signal, and one or more checkout sites at which payment for goods is made, each checkout site being provided with a"goods paid for"signal generator, which signal is generated in response to a completed transaction and transmitted to the trolley remote logging receiving means to trigger a state change from"goods unpaid for"to"goods paid for", and wherein a"goods unpaid for"signal generation means is provided so that a trolley entering a retail space is provided with a "goods unpaid for"signal which alters the trolley state to"goods unpaid for".

Braking signal generation means are preferably provided at retail space exits/entrances, which generation means are provided with receiving means adapted remotely to detect a trolley state and generate an activation signal in response to the passage thereby of a trolley having a"goods unpaid for state".

In this way trolleys will become braked if a customer attempts to exit the shop or retail space without paying for goods.

According to yet another aspect of the invention remote braking system release means may be provided, comprising a release signal generator which on activation generates a brake activation return signal, which signal when received by the brake activation means of a wheel assembly causes the actuator to operate to release the snagged spring means free end and thereby release the brake mechanism.

Following is a description by way of example only and with reference to the accompanying drawings of a method of putting the present invention into effect.

In the drawings:- Figure 1 is a perspective view of a wheel hub portion forming part of a wheel assembly according to the present invention.

Figure 2 is a perspective view of an actuator used in the wheel assembly of the present invention.

Figure 3 is a perspective view of a spring mounting hub forming part of the wheel assembly of the present invention.

Figure 4 is a perspective view of the wheel hub of figure 1 showing the position of a helical braking spring.

Figure 5 shows the hub of figure 3 accommodated in a wheel moulding.

Figure 6 is a perspective view of a complete wheel assembly according to the present invention.

Figures 7 to 12 are third angle projection engineering drawings showing in more detail components generally shown in figures 1 to 6.

In figure 1 a hub member is shown as 10. The hub is formed with a central axle hole 11 for accommodating a fixed, non rotating castor axle (not shown).

The hole is formed with a key channel 9 for fixing the hub against rotation on the axle. The hub member is also formed with a rectangular plan cut-out for

accommodating a printed circuit board (PCB) 12 and associated electronic componentry. Another cut out is provided juxtaposed the PCB for accommodating a battery power supply 13 for the PCB.

Further cut outs are provided for accommodating an electric actuating motor 14 and associated gear train 15. The gear train 15 drives an actuation spindle 16 shown in figure 2. The spindle'carries at an upper end thereof a snagging arm 17. The snagging arm comprises a cylindrical base portion 18 and a generally planar tongue portion 19.

Figure 3 shows a spring mounting hub 20. An inside surface 21 of the mounting hub is generally planar. An annular collar 22 is formed on a central region of the inside surface. The collar is formed with an axle hole 23. The collar is provide with an L-section slot 24 for accommodating and anchoring a correspondingly shaped end region of an helical braking spring 26. The spring is formed at free end thereof with fold 27 which functions as a snagging hook.

The position of the spring 26 inside the assembled wheel is shown in figure 4, with the spring mounting hub removed for the sake of clarity. The hub member 10 is shown with the snagging arm tongue portion 17 in a snagging position engaged with the snagging hook 27.

Figure 5 shows a part assembled wheel. The hub 10 and spring 26 are shown accommodated in a generally cylindrical wheel moulding 30. In figure 6 the spring mounting hub 20 is shown attached to the wheel moulding 30 by means of six circumferential screws 29. Final assembly involves setting the wheel into a castor, and attaching the castor to a trolley.

The PCB carries a radio frequency (RF) receiver for receiving braking radio signals. A logic circuit is which identifies a braking signal when received, and then provides an actuation signal which starts the actuation motor 14. Such electronic and electrical hardware is commonplace so is not described in detail.

In figures 7 to 12 the components are numbered according to the description in the foregoing.

For use, the hub member 10 is fixed onto a castor axle. the wheel moulding 30 and attached spring mounting hub 20 are free to rotate. The helical spring rotates in a chamber formed between the hub member 10 and the spring mounting hub 20. When the actuation motor is activated, rotation of the motor rotates the snagging arm from a position in which the tongue portion is generally tangentially oriented on the circumference of hub 10, to a snagging position in which the arm stands proud and perpendicularly in a direction

parallel to the rotational axis of the wheel, as shown in figure 4. In this position relative rotation of the hub 10 and spring 26 in the wheel causes the tongue to engage the hook 27. Further rotation causes the helical spring to become loaded until the spring is fully loaded and/or the trolley is halted. The helical spring provides a gradual loading braking action which is safer to a customer than a conventionally braked trolley.