FIELD OF THE INVENTION

T he present invention relates to a locking mechanism lor preventing swivelling of rear castor wheels of a shopping trolley.

BACKGROUND OF THE INVENTION

Conventional shopping trolleys have four castor wheels which are free to swivel in any direction. This provides good manoeuvrability in most circumstances, however, when operating on sloping or uneven ground, trolleys with such wheels follow a path of least resistance, which can make thern difficult to control. Although locking the rear wheels of a trolley against swivelling may solve, such problems, a plurality of sucla trolleys which are interen gaged into a train would be difficult to martoeuver or control if the rear wheels of each trolley were locked.

Examples of the invention seek to solve, or at least ameliorate, one or more disadvantages of previou s shopping trolleys.

SUMMARY OF THE INVENTION

According to the present invention there is provided a locking mechanism for preventing swivelling out of a forward/rear alignment condition the rear castor wheels of a shopping trolley having a rear flap which is movable from a rest position to a raised position upon engagement of the rear of the trolley' by another trolley, the mechanism being releasable upon a rear portion of the trolley being engaged by another trolley and including;

a trigger operable as the rcar flap returns to the rest position;

a lock operatively coupled to each rear castor wheel; and an actuation member extending from the trigger to the lock for operating the iock to prevent swivelling of the rear castor wheels on operation of the trigger.

According to a preferred embodiment of the invention, the trigger is a pivotable member fixed to a frame of the trolley and configured to engage and be moved by the rear flap as it moves to the rest position. A respective trigger may be provided tor each lock and is engaged by a lower portion of the flap as it moves to the rest position.

Preferably, each lock includes a locking bolt configured to be received in a aperture formed in a flange on a respective castor wheel, the locking bolt preventing swivelling of the castor wheel when received in the aperture. Preferably, the mechanism further includes a compression spring between the actuation member and the locking bolt, whereby movement of the actuation member causes the spring to compress if the castor wheel is not orientated so that the locking bolt can be received in the aperture, the spring driving the bolt into the aperture during subsequent swivelling of the caster wheels into a substantially fore-aft condition.

Preferably, the mechanism is configured to lock the rear wheels in a straight ahead condition. Preferably, the locking bolt is mounted at least partially in a, lower portion of a cylinder, the cylinder having the compression member mounted therein and above the locking bolt and the actuation member extending into the cylinder to compress the compression member. Preferably, the cylinder extends from the trigger to the lock. Preferably, the locking bolt is urged from a locking condition via a return spring. BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will be further described, by way of non-limiting example only, with reference to the accompanying drawings in which:

Figure 1 is a side elevation of a shopping trolley having a locking mechanism of one embodiment of the invention fitted thereto: Figure 2a is a partial side view of an upper portion of the mechanism prior to operation of a trigger;

Figure 2b is another partial side view of the upper portion pf the mechanism, showing the trigger in an operated state;

Figure 3 is a rear end view of the upper portion shown in Figure 2;

Figure 4 is a partial side view or a lower portion of the mechanism in an unlocked state:

Figure 5 is a partial side view of the mechanism of Figure 4 in a locked state;

Figure 6 is another partial side view of the mechanism of Figure 4 where the trigger is actuated but the lock is in an unlocked state because the castor wheel is not in the straight ahead condition;

Figure 7 is another partial side view of the mechanism, shoving an alternative actuation member;

Figure 8 is a partial side of a rear portion of the trolley;

Figure 9 is a side view of a stopper for retaining a rear flap in place: and

Figure 10 is an underneath view showing a pair of stoppers fitted to the trolley.

DETAILED DESCRIPTION With reference to Figures 2 to 6, there is shown a locking mechanism 10. The locking mechanism 10 is configured for preventing swivelling of rear castor wheels of a shopping trolley 12. The mechanism 10 is also configured to be releasable upon a rear of trolley 12 being engaged by another trolley. The mechanism 30 includes a trigger 14, a lock 16 operatively coupled to each rear castor wheel 1 8, and an actuation member 20 in the form of a rod. Rear caster wheels 18 are of the type having a fork 24 which is rotatably fixed to frame 26 of trollfcy 12 to allow the wheels to swivel in use. The trigger 14 is operable via engagement by a rear flap 22 of the trolley 12 which is movable from a rest position, as illustrated in Figure 1, to a raised position upon engagement of a rear of the trolley 12 by another trolley. During engagement of the rear of the trolley 12, a second trolley is brought behind the trolley 12, or alternatively the trolley 12 is brought in front of the second trolley, and they are urged together so that a forward portion of the second trolley moves into the load carrying area of the trolley 12. Such engagement is performed so that a plurality of trolleys can be interengaged to form a train for collection and transportation of the trolleys.

The trigger 14 is operable as the rear flap 22 returns to the rest position. Figure 2a illustrates the flap 22 in a position just prior to operating the trigger 14. Figure 2b illustrates the flap 22 after operating the trigger 14. In this regard, in a normal condition of use. i.e. when a user is using the trolley 12 for carrying goods, the rear flap 22 is in the rest position and the lock 16 on each wheel is in a locked state to prevent swivelling of the rear castor wheels 18, to thereby assist with steering of the trolley 12. The trigger 14 is a pivotable member fixed to a frame 26 of the trolley 12 and configured to engage and be moved by the rear flap 22 as it moves to the rest position. In the illustrated embodiment the trigger 14 is tfxed to the frame 26 via a split pin 30. Pivoting of the trigger 14 causes rod 20, which extends from the trigger 14 to the lock 16, to move downwardly for operating the lock 16 on operation of the trigger 14. Rod 20 is coupled to the trigger 14 via a socket 28.

In preferred embodiments, a lock 16 is provided οη each of the rear castor wheels 18, and a trigger 14 is provided on either side of the trolley 12 and generally above each lock 1 6. In alternative embodiments, a single trigger 14 may be provided for operating both locks 16. In further alternative embodiments, only a single lock 16 and trigger 14 pair may be provided for preventing swivelling of only one of the rear castor wheels 1 8.

As illustrated in Figure 4, each lock 16 includes a locking bolt 32 configured to be received in a correspondingly shaped aperture 34 formed in a flange 36 on ¾i respective castor wheel 1 8 to operate the lock 16. The locking bolt 32 prevents swivelling of the castor wheel 18 when received in the aperture 34, as illustrated in Figure 5. A compression member in the form of a compression spring 38 is provided between the actuation member 20 and the locking bolt 32, whereby movement of the actuation member 20. as illustrated in Figure 6, causes the spring 38 to compress if the castor wheel 18 is not orientated so that the locking bolt 32 can be received in the aperture 34. The spring 38 allows the castor wheel IS to swivel and only lock upon return to a desired condition, which is preferably a straight ahead condition. In use, this means that as a trolley 12 is removed from engagement with another trolley, the rear castor wheels 18 are free to swivel until they return a condition \M which the trolley is directed to travel straight ahead, at which point they become locked and ready for use. It will be appreciated by those skilled in the art that castor wheels used in shopping trolleys have a swivel axis with a small degree of rearward offset that causes them to swivel rearwardly when the trolley is pushed forwardiy. A return spring 42 is also provided to allow automatic disengagement of the lock 16 when the rear flap 22 is lifted, without requiring further external force. Depending on the strength of the springs 38 and 42, and the weight of the rear flap 22., a user may be required to apply a small amount of force to the rear flap 22 to ensure locking of the rear castor wheels 18.

As can be seen in Figure 4, the lacking bolt 32 is mounted at least partially in a lower portion of cylinder 40. Within the cylinder 40 is spring 38, acting between the locking bolt 32 and the rod 20, which also at least partially extends into the cyljhder, though it will be appreciated that other arrangements are also possible.

In the embodiments of Figures 4 to 6, the cylinder 38 is a small cylinder fixed to the frame 26 of the trolley 12 via body 44. In the alternative example illustrated in Figure 7, cylinder 138 extends from the trigger 14 to the lock 16. In such an embodiment, o-ring seals 46 are provided to seal opposite ends of the. cylinder 138.

Figures 8 and 10 illustrate the location of stopper 50 (refer Figure 9), Which is provided to retain the rear flap 22 in position during nonnal use. In this regard, stopper 50 is provided on an upper surface with a recess in which a lower portion of the rear flap 22 rests. The recess allows the rear flap 22 to be lightly held in position to prevent aecidentai release of lock 16 during normal use. As suggested by its profile, as shown in Figure 9, stopper 50 is configured to clip onto the trolley 12, with the opening being configured for receiving the frame and the narrow portion for engaging the mesh material of a floor of the basket.

The embodiments have been described by way of example only and modifications are possible within the scope of the invention disclosed.

REFERENCE NUMERAL LIST

10 Locking mechanism

10a Upper portion of locking mechanism

10b Lower portion of locking mechanism

12 Shopping trolley

14 Trigger

16 Lock

18 Rear Castor wheel

20 Actuation member

22 Rear flap

2Ί Castor wheel fork

26 Frame

28 Socket

30 Split pin

32 Locking Bolt

34 Aperture

36 Flange

38 Compression member

40 Cylinder

42 Return spring

44 Mounting body

46 O-ring seal

48 Rear floor frame

50 Stopper