IMPROVEMENTS IN INTERNESTING TROLLEY SYSTEMS This invention relates to internesting trolley systems and more particularly but not exclusively to supermarket trolleys. There is a well known and annoying problem with supermarket trolleys in that they are extremely difficult to steer and this problem is exacerbated with increasing load. The main reason for the difficulty in steering is that all four wheels are swivel castor type which makes it difficult to steer round corners or across slopes because of the tendency of the trolley to move sideways. If either front or back wheels were non-swivelling types and the other wheels were swivelling types the steering and control would be substantially improved. The reason that the trolleys are designed with four 360° castoring wheels is purely for marshalling of groups of trolleys nested one within another. When such groups are nested it would be virtually impossible to steer the group if many of the wheels along the length of the group were non-swivelling types. One way of overcoming this problem is to incorporate in each trolley a mechanism which causes two of the swivelling wheels, either the front or the rear wheels, to lock in a forward position once the trolley is laden with say 201bs of goods. This can be done by means of a dog clutch and spring. Although this system can be made to work the cost of the mechanism involved is significant, the mechanism can be unreliable particularly with extended use

and lack of'maintenance and the trolley still does not steer properly un _t il a particular weight of goods actuates the mechanism.

The presen _t invention has various aspects one of which is concerned with improving the marshalling capability of trolleys be they the conventional type having all wheels of the swivel castor type or trolleys having mixed swivel castor and non castoring wheels and another aspect of which is concerned with the provision of a simple and reliable solution to the problem of providing a trolley that can be steered accurately.

According to one aspect of the invention there is provided an in _t ernesting trolley system, in which each trolley has at least three wheels and means co-operable with an adjacent nested trolley to enable at least one of the wheels of the trolley, or its adjacent nested trolley, to be raised from the ground.

According to another aspect of the invention there is provided an internesting trolley system in which each trolley has a _t least three wheels and in which when a row of trolleys are nested for movement en block one or more wheels of each of the trolleys are caused to be raised clear of the σrounα.

According to a third aspect of the invention there is provide _d a _t rolley for an internesting trolley system, the trolley having at least three wheels, at least one wheel being provided towards one end and at least two towards the other end of the trolley, wherein means is provided whereby when one trolley is nested with another similar trolley at least one of the wheels of one of the trolleys is raised from the ground

According to a fourth aspect of the invention there is provided an internesting trolley system in which each trolley has both swivel castored and non-swivelling wheels and means co-operable with an adjacent nested trolley to enable the non-swivelling wheels of the trolley, or its adjacent nested trolley, to be raised from the ground.

According to a fifth aspect of the invention there is provided an internesting trolley system each trolley comprising swivel castored and non-swivelling wheels in which when a row of trolleys are nested for movement en block, the or most of the non-swivelling wheels are caused to be raised clear of the ground.

According to a sixth aspect of the invention there is provided a trolley for an internesting trolley system, the trolley having at least three wheels, at least one wheel being provided towards one end and at least two towards the other end of the trolley, in which either said at least one or said at least two wheels are swivel castored type and the other of said at least one or said at least two wheels are non-swivelling type, wherein means is provided whereby when one trolley is nested with another similar trolley the non- swivelling type wheel(s) of one of the trolleys are raised from the ground.

The invention which I call, and intend to market, under the Trade Mark PIGGY BACK TROLLEY has arisen from an appreciation that it is possible to marshall groups of nested trolleys having some wheels which are swivel castored and some wheels which are non-swivelling provided that when the trolleys are nested one within another the non- swivelling wheels are raised clear of the ground. Apart from overcoming the previously mentioned problem relating to steering of individual trolleys the system has another significant advantage in that when the trolleys are nested for marshalling less wheels are in contact with the ground and accordingly the group is easier to move due to significantly reduced friction between wheels and axles and reduced rolling friction of wheels against ground undulations and obstructions. The cost of trolleys are also significantly reduced as the cost of swivel castor wheels is significantly more than non-swivelling wheels. The invention is also applicable to conventional trolleys in which all wheels are of swivel castor type as it provides the previously mentioned advantages resulting from

the fact that when marshalling there is a very significant reduction of the number of wheels in contact with the ground.

The invention is applicable to three, four or more than four wheel trolleys. The swivel castor wheel(s) may be towards the front with the non-swivelled wheel(s) towards the back of the trolley or vice versa.

The invention also enables existing trolley systems to be converted to the improved system at extremely low cost.

In order that the invention and its various other preferred features may be understood more easily, some embodiments thereof will now be described, by way of example only, with reference to the schematic outline drawings, all of which relate to supermarket trolleys, in which:-

Figure 1 is a side view of a first embodiment of trolley constructed in accordance with the invention.

Figure 2 is a rear view of the trolley of Figure 1, Figure 3 is a side view of two of the trolleys of Figures 1 and 2 approaching a nested position.

Figure 4 is a side view similar to Figure 3 but with the two trolleys nested.

Figure 5 is a side view of a second embodiment of trolley constructed in accordance with the invention, Figure 6 is a plan view of the trolley of Figure 5, Figure 7 is a side view of two of the trolleys of Figures 5 and 6 nested together.

Figure 8 is a side view of two nested trolleys of a third embodiment constructed in accordance with the invention.

Figure 9 is a plan view of the trolley of Figure 8,

Figure 10 is a side view of two nested trolleys of a fourth embodiment constructed in accordance with the invention, Figure 11 is a plan view of the trolley of Figure 10,

Figure 12 is a side view of two nested trolleys of a fifth embodiment constructed in accordance with the

invention, and

Figure 13 is a side view of two nested trolleys of a sixth embodiment constructed in accordance with the invention. In the drawings for simplicity a single basic design of trolley is described incorporating the features of the invention and common reference numerals are used for similar components throughout this specification.

Referring now to Figures 1 and 2 a supermarket trolley is shown which has a wire basket 1 mounted on a tubular supporting framework 2 having two swivel castored wheels 3 for steering purposes and two non-castored wheels 4. In this embodiment the swivel castored wheels 3 are mounted at the back of the framework and the non-swivelling wheels 4 at the front. Mounted towards the front of the framework there are a pair of ramps 5 inclined downwardly and extending rearwardly of the front wheels to a level lower than the front of the framework which serve to receive the front of the framework of a similar nesting trolley. The wire basket is of conventional construction having a hinged rear section which is raised when a similar trolley is nested therewith.

Referring now to Figure 3 there is illustrated two trolleys of the type illustrated in Figures 1 and 2 with one inserted partially within the other in the direction of _, nesting but not fully engaged. It will be seen that the left hand trolley which is being nested has the leading edge of its framework approaching the ramps 5 of the right hand receiving trolley. Further insertion of the trolley results in the leading edge of the framework riding up the ramps 5 until the lefthand trolley reaches the fully nested position illustrated in Figure 4.

As will be seen in Figure 4 this causes the front of the trolley to be raised such that the non-swivelling wheels of the nested lefthand trolley are raised from the ground. An optional stop 6 may be provided at the upper end of the ramps although this is probably not required as the nesting

insertion is normally restricted by the geometry of the trolley. A projection may be provided on the ramp which permits the leading edge of the framework of the nesting trolley to ride over it but which resists return of the nesting trolley thereby retaining the front of the nested trolley in the raised state until forcibly released by pulling the nested trolley backwardly. Such a projection could be shaped to provide easy on difficult return and could be sprung loaded such that it is retracted during upwardly sliding movement of the leading edge of the framework of the nesting trolley.

An alternative if less satisfactory arrangement is for the ramp 5 to be inclined downwardly and forwardly so that the nesting trolley causes the front wheels of the receiving trolley to be raised when the trolley is fully nested.

Referring now to Figures 5 & 6 there is illustrated a second embodiment of the invention which provides an extremely simple way of raising the front wheels of a nesting trolley. The basic trolley construction is similar to the construction of Figure 1 having two swivel castored wheels 3 at the back of the framework and the non-swivelling wheels 4 at the front of the framework. Instead of providing the ramps 5 on the framework a ramp 7 is fitted on the inside bottom of the basket towards the front. As can be seen this provides a ramp which is inclined upwardly in a direction towards the front of the basket. As can be seen from Figure 7, where one such trolley is nested with a similar trolley the leading edge of the bottom of the basket of the nesting trolley rides up the ramp and lifts the nesting trolley such that its front wheels are raised from the ground.

The concept of Figure 5 is particularly suitable for adapting existing trolleys in that the ramp can be a simple wedge which can be secured to the bottom of the trolley baskets by a simple clamp or a snap action retainer. The ramp could advantageously be made of a plastics material and

could have moulded in snap action retainers which co-operate with the wire mesh of the basket. Although a single ramp is shown which extends across the width of the basket it will be appreciated that the ramp need not be so wide. Furthermore, instead of employing a single ramp two similarly contoured narrow ramps could be employed spaced apart one to each side of the basket.

A stop and/or retaining projection could be provided on the or each of the ramps similar to those described for Figure 1.

The construction illustrated in Figures 8 and 9 relates to trolleys which have the swivel castored wheels 3 at the front and non-swivelling wheels at the back. In this construction a ramp is formed by a simple wedge 8 similar to the wedge 7 of Figure 5. However in this case the wedge 8 is fitted transversely on the top and towards the rear of the basket in such a position that when a trolley is nested with a similar trolley the top rail of the receiving trolley rides up the ramp such that its rear wheels are raised fro t he ground as illustrated in Figure 10. Again this construction is particularly suitable for adapting existing trolleys in that the ramp can be a simple wedge which can be secured to the upper side edges of the trolley basket by clamping or by a snap action retainer. The ramp could advantageously be made of plastics material and could have moulded in snap action retainers which co-operate with the upper edge of the basket. Although a single ramp is shown which extends across the width of the basket it will be appreciated that individual narrow ramps may be fitted one to each side of the basket thereby avoiding interference with access to the basket. A stop and/or retaining projection could be provided in the or each of the ramps similar to those described for Figure 1.

The construction of Figures 10 & 11 relates to trolleys which have swivel castored wheels 3 at the front and non-swivelling wheels at the back. In this construction the trolley is provided with a bar or roller 9 externally at

the back of the basket which extends transversely of the basket near to the top. The bar or roller serves to ride on the upwardly inclined top of the basket of a similar nesting trolley such that when fully nested the rear wheels of the receiving trolley are raised above the ground. Again this construction is particularly suitable for adapting existing trolleys as the bar or roller can be secured to the rear of the basket by clamping or snap action retainer which co¬ operates with the basket. The bar or roller could be made of plastics and the bar or the shaft for the roller could have moulded in snap action retainers. Instead of having a bar or roller which extends right across the back of the trolley it will be appreciated that a short projection or a narrow roller may be provided one to each side of the rear of the trolley which ride on the upwardly inclined top of the basket of a similar nesting trolley.

The construction of Figure 12 relates to trolleys which have swivel castored wheels 3 at the front and non- castored wheels 4 at the back. In this construction the supporting framework 2 is provided at the back on each side with a ramp 10 which is inclined downwardly in a forward direction from a position about the level of the wheel to a position near to the ground. The ramps are designed to act like a scoop in that when a nesting trolley is inserted into a receiving trolley the rear wheels of the receiving trolley ride up the ramp and are thereby raised from the ground. A stop 11 which provides an easy on facility but which resists return of the wheels may be provided to avoid the raised wheels from riding down off the ramp purely under the action of gravity. A single ramp may be employed which extends transversly.

An arrangement similar to Figure 12 can be provided for trolleys having front wheels which are non swivelling in which case a ramp such as 10 can be arranged to raise the wheels of receiving trolley when another trolley is nested A disadvantage of each of the constructions of Figures 8 to 12 is that they are really only suitable for

application- where relatively small groups of nested trolleys are to be moved. This is because as each additional trolley is nested each of the previous trolleys is being raised so that the weight to be lifted is progressively increased. For large groups the constructions of Figures 1 to 7 are therefore preferred.

The constructions of Figure 13 relates to trolleys which have swivel castor wheels 3 at the front and non swivelling wheels 4 at the back. In this construction the supporting framework 2 is provided at the back on each side with an arcuate wheel rest 12 which extends backwardly from near the bottom of the framework and just clear of the ground. In this construction, when one trolley is nested with a similar trolley it is lifted manually and its rear wheels are located in the wheel rest so that they are retained in a position raised from the ground.

It will be appreciated that there are numerous ways of arranging for non-swivelled wheels of nested trolleys to be raised from the ground and only a few examples have been described, however all such constructions are considered to fall within the scope of this invention.

Whilst the embodiments described relate to trolleys having both swivel castor and non swivelled wheels, the same principle can be applied to existing conventional trolleys where all wheels are swivel castored. In such an application the significant reduction of the number of wheels in contact with the ground when marshalling leads to the significant advantages for marshalling which have been previously mentioned. Such a construction and system is considered to fall within the scope of this invention.

Although the specific embodiments described are supermarket trolleys it will be appreciated that the invention is also applicable to other types of trolleys which are designed for nesting one with another for example pallet or platform type trolleys. Such trolleys are considered to fall within the scope of this invention.

Whilst the specific embodiments described relate to

four wheeled trolleys the invention is also applicable to three wheeled trolleys having a single swivel castored wheel at the front or back and two non-swivelling wheels at the back or front respectively. It is also applicable to trolleys having more than four wheels where there are mixed swivelling and non-swivelling wheels. Such trolleys are also considered to fall within the scope of this invention.