GB2339409A - Trolley - Google Patents

Description

1233 Final Improved carrier 2nd filing.doc 13-Jun-99 11:24 2339409

Improved Carrier The present invention relates to a system for controlling the direction of movement of trolleys and the like, particularly trolleys for carrying objects.

Trolleys such as those used in shops, aircraft terminals etc can be moved around by being pushed by the user. In order to enable the trolley to turn, the frontwheels, or all the wheels are pivotally mounted as castors so that the user can push them round comers. In order that they will tend to go in a straight line, unless specifically pushed laterally, the front wheels at least are mounted as castors so that they will naturally run straight and return to the straight position. Some trolleys have a brake which is operated by means of a bar pulled by hand, which locks the back wheels so that the trolley can be parked or stopped if it is moving out of control, this is most commonly installed in the trolleys used at airport terminals etc, However the problems involved in trying to control such trolleys are well known, particularly when the trolleys are laden, the difficulty is caused by the fact that there is no means of turning the front wheels and they are free to swivel in any direction.

We have now devised an improved carrier which is easier to steer and control.

According to the invention there is provided a wheel mounted carrier which has at least three spaced apart wheels so that the carrier can be pushed along on the wheels, at least two of the wheels being swivably mounted on substantially opposite sides of the carrier and the wheels at the front of the carrier in the intended direction of motion incorporating an independent braking means whereby each of the swivably mounted wheels can be independently braked when the trolley is moving.

Preferably the swivably mounted wheels are mounted as castors so that, in the absence of extraneous forces, they will tend to run in a straight line. In most 253 Final Improved carrier 2nd filing.doc 13-Jun-99 11:24 2 commonly used carriers there are four wheels mounted in a substantially rectangular or square configuration, the front two being closer together than the rear two, allowing trolley nesting in lines, and such commonly used arrangements can be used in the present invention, the front wheels, back wheels or all the wheels can be swivably mounted.

In one embodiment the front wheels are swivably mounted and each of the front wheels incorporates an independent braking means. The braking means is preferably progressive so that the degree of braking can be independently controlled on each of the wheels separately. In another embodiment all four wheels are swivably mounted and able to be braked independently.

Any conventional braking means can be used, for example there can be a brake pad which can be engaged with the wheels so that the wheel is braked by friction as is is commonly used in bicycles. Or a "seesaw" lever which engages on the outside surface of the tyre to brake by friction. The brake is preferably cable operated e.g.

using a Bowden cable, by means of a lever attached to or adjacent that part of the carrier which is being pushed by the user, so that in use the levers are close to hand.

As the wheels to be braked can swivel, the braking means should be able to operate effectively whatever the orientation of the wheels.

In use, the carrier is pushed along by the user and, when it is desired to move off a straight line e.g. to go round a comer, the wheel or wheels on the inner side of the turn is braked, which causes it or them to run slower and thus the carrier is automatically and controllably turned. The greater the degree of braking the tighter the turn. The swivably mounted wheels on both sides of the carrier can be braked and, providing one wheel is braked more than the other, the carrier will turn either left or right as chosen.

253 Final Improved carrier 2nd filing.doc 13-Jun-99 11:24 3 Preferably where the brakes are operated via a Bowden cable, there will be a cable adjuster to automatically take up cable stretch and wear of the braking material.

Preferably there is brake wear indicator which shows the degree of wear on the brakes so that it can be easily seen when they need adjustment or replacing.

Preferably there is a means which can operate to lock the brakes in the on position when the carrier is parked, e.g. a ratchet means. This can be incorporated in the braking means of the invention or can be an independent system. 10 The invention is particularly applicable to the carriers or trolleys used in supermarkets and in airports where relatively small wheeled carriers are used to provide large carrying capacity.

is The invention can be applied to existing carriers by attaching braking means to two oppositely mounted wheels and the invention covers such carriers having brakes attached and braking means adapted to be attached to carriers. The invention is described in the accompanying drawings in which 20 Fig. 1 is a view of a supermarket trolley incorporating the invention Fig. 2 is a view of a braking mechanism which can be part of the invention Fig 3 is a view of the cable adjuster which can be part of the invention Fig 4 is an exploded view of the parking brake and brake lever assembly which can 25 be used in the invention Figs. 5 to 8 show the effect of braking Referring to Fig. I a supermarket trolley shown generally at (1) has swivably mounted castor wheels (2a, 2b) at the front comers; 2a & 2b are swivel points. On 30 each of the wheels (2a, 2b) there is a brake operated by means of Bowden cables (4) 253 Final improved carrier 2nd filing.doc 13-Jun-99 11:24 4 (RH cable not shown) and controlled by lever (8a) for wheel (2b) and lever (8b) for wheel (2a). The trolley is pushed by the user pushing on handle (9). There are knobs (10) & (11) which can operate to cause the brake on either wheel to lock on for parking and a wear indicator line (7) on the tyre which indicates when the tyres are worn down to the limit by brake action. There is a baby carrier at (5). The brake levers are shrouded by guard covers fitted between handle (9) and the trolley fi-amework (not shown). A handle for the baby to hold is fitted between the guards (also not shown for clarity). The two front castors (2a) & (2b) are mounted on a rocker arm (12) which ensures that the braked wheels always remain firmly down on the ground if the surface is uneven and therefore the braking always remains controlled. There is a gap between the top face of the rocker arm and the trolley fi-amework (13) when standing on flat ground, so that, in the case of extreme movement, the rocker arm will come to a firm stop before the trolley can become unstable and topple over. 15 Referring to Fig. 2 a wheel (22) is attached to a housing with a swivable bearing at its top (23), the centre of the wheel bearing (14) is off-set from the vertical plane of the swivel bearing centre so as to generate a castor action when the unit moves. The castor is attached to the trolley through its swivel bearing by means of a hollow bolt (15). Through the hollow bolt runs a Bowden cable (16). A rectangular pivot plate (17) pivots via a rod (18) between the sides of the castor housing (19). The rod bears in a hole each side of the housing. The castor housing is shaped to accept the pivoting plate (17) At one end of the pivoting plate is a slotted countersunk hole to accept a ball nipple (20) on the end of the Bowden cable (16). The ball nipple will 25 slide radially in its seat allowing the castor to rotate fully without the cable twisting. The pivoting plate, when pulled up one end by the cable tips down at the other end and bears on the wheel (22) thus causing friction with the outside of the tyre and a braking action. A spring (not shown) fitted over the inner Bowden cable between the head of the hollow bolt (15) and the pivot plate (17) returns the pivot plate to the off 253 Final Improved carrier 2nd filing.doc 13-Jun-99 11:24 position when not in use. There is a radial line on the side of the tyre (21) which indicates the limit of brake wear.

Referring to Fig 3 the self adjusting unit is shown inside a tubular leg (5 1) of the trolley and positioned towards the horizontal for easy reading. The unit slides inside and can be fixed in place by two screws at the riser block (43). Parts of the unit can move lengthways along the fixed riser block. The movable parts are the shuttle (44) and the slip carriage (45). They are fixed together by the location key (46). Two Bowden cables are involved per brake. When fitted to the self adjusting unit, the two cables become functionally one cable. The long Bowden cable is fitted to the brake end, the short fitted to the brake lever. The other end of long Bowden cable (47) is fitted to the slip carriage (45) and the other end of the short Bowden cable (48) is fitted to the shuttle (44). There are slots (53) in the slip carriage base. Fig 3 shows how, as brake wear takes place, the brake lever requires to be pulled further and 15 moves the slip carriage in small increments further along the riser block (43). As the slip carriage moves, the riser insert (49), which remains stationary, lifts the location key (46) further up into its slot in the shuttle and out of the slot, shown at (53), until it no longer maintains the connection between the slip carriage (50) and the shuttle (44). A compression spring (not shown) fitted over the two inner cables in pocket B is then 20 released to push the shuttle along until the location key (46) drops down into the next slot under the influence of its small leaf spring (50). All adjustment is a continuation of this process. Thus, according to the number of slots and the predetermined distance between the slots, so can automatic adjustment be created to the inner cable where it can be functionally "shortened" precisely each time to counteract the wear 25 which has taken place on the brake. A conventional screw cable adjuster will be fitted next to the auto adjuster so that the required "play" needed in the cable can be adjusted in when the trolley brakes are set up initially. The design is such that virtually no adjustment will need to take place in the life of each brake.

253 Final Improved carrier 2nd filing.doc 13-Jun-99 11:24 6 Referring to Fig. 4 an exploded view of the parking brake co mponents are shown.

They are part of the brake lever assembly mounted at each end of the handle. The brake lever assembly for braking the trolley and the parking brake function are all in one unit and comprise plunger (54) and an upper spring (59) which locates under S shoulder (55), there is a tension pin (60) fitted after assembly and locates in its slot under block (64) when the plunger is up. The upper spring (59) is stronger, the lower compression spring (57) is weaker and underside of the hole (56) is counter bored to accept the lower spring. There are fine ratchet teeth under ratchet block (63) and the brake lever (62) has fine radial ratchet teeth at (58). The hole (61) accepts the tube handle and the side A can be extended enabling the frame tube to connect in a hole. Push the plunger (54) down and twist it to lock and, once the brake lever (62) has been pulled up, the brake will be held on thereafter until release is required. Twist and turn the plunger (54) to release. This operation is produced by the use of simple 15 radial ratchet components sprung together by the intervention of the plunger which Fig. 4 shows clearly. Referring to fig. I to operate the trolley a user pushes the trolley in the normal way and when they want to turn left they will pull on the lever (8a) as they start their turn, 20 which will cause the brake at (2b) and (in the case of another embodiment, 2c also) to slow the wheel down and cause the trolley to swing radially about (2b) and thus turn left. To turn right the lever (8b) is operated. The greater the pressure applied to the levers (8a) or (8b) the more braking there is and the tighter the turn. By applying varying braking pressures to the wheels the trolley can be easily steered and 25 controlled. Front wheel braking has advantages over rear wheel braking in that a far larger angle of turn is automatically achieved. This is illustrated in figs. 5 to 8 of the drawings, in fig. 5 braking of rear wheel (3 1) will cause the trolley (30) to slow in a straight line 30 with no turning, as the centrally mounted rear wheel (3 1) will have no bias to turn.

2S3 Final Improved carrier 2nd filing.doc 13-Jun-99 11:24 7 In fig. 6 there is a typical four wheel trolley (33), which is braked by rear wheels (34a) and (34b); as shown in fig. 7, when rear wheel (34a) is braked this causes the trolley to turn by about 26' and the trolley will continue to move in this orientation "crabwise" until it stops or until the shopper pushes the trolley handle to increase the angle of turn. The same applies in the opposite direction when the other wheel (34b) is braked. However as the vast majority of turns into aisles in supermarkets require a larger angle of turn than this, the shopper cannot rely on the forward motion of the trolley coupled also with the braking to turn the trolley any further but will have to push the trolley round the comer.

In fig. 8 a trolley has its front wheels (36a) and (36b) braked and braking of either of these wheels will bring about a large angle of turn which can cause the trolley to turn through almost 180' if required, as is shown in fig. 8 where wheel (36a) is braked. Wheel (36a) is the pivot point of the turn. This gives the shopper much more manoeuvrability and, by pulling on the chosen brake lever the required degree of turn can be achieved by harnessing forward momentum or movement of the trolley alone, with no other steering means e.g. by pushing at an angle on the trolley handle required. Thus front wheel braking is much superior to rear wheel braking.

In addition to the steering advantages there is a large increase in braking efficiency when the front wheels are applied compared with rear wheel braking and less danger of skidding etc.

2.53'Final Improved carrier 2nd filing.doc 13-Jun-99 11:24 8

Claims (10)

Claims

1. A wheel mounted carrier which has at least three spaced apart wheels so that the carrier can be pushed along on the wheels, at least two of the wheels being swivably mounted on substantially opposite sides of the carrier and the wheels at the front of the carrier in the intended direction of motion incorporating an independent braking means whereby each of the swivably mounted wheels can be independently braked when the trolley is moving.

2. A carrier as claimed in claim I in which the swivably mounted wheels are mounted as castors so that, in the absence of extraneous forces, they will tend to run in a straight line.

3. A carrier as claimed in claim I or 2 in which there are four wheels mounted in a substantially rectangular or square configuration.

4. A carrier as claimed in claim 3 in which the front two wheels are closer together than the rear two wheels. 20

5. A carrier as claimed in claim 3 or 4 in which all four wheels are swivably mounted and the two front wheels are mounted on a rocker arm and each of the two front wheels incorporates an independent braking means. 25

6. A carrier as claimed in claim 3, 4 or 5 in which the braking means is progressive so that the degree of braking can be independently controlled on each of the wheels separately.

7. A carrier as claimed in any one of claims 3 to 6 in which the braking means is 30 cable, hydraulic or any other linkage method operated by means of a lever attached to 2..93'Final Improved carrier 2nd filing.doc 13-Jun-99 11:24 9 or adjacent that part of the carrier which is being pushed by the user, so that in use the levers are close to hand.

8. A carrier as claimed in any one of the preceding claims in which there is a brake wear indicator which shows the degree of wear on the brakes so that it can be easily seen when they need adjustment or replacing.

9. A carrier as claimed in any one of the preceding claims in which there is a means which can operate to lock the brakes in the on position when the carrier is parked.

10. A carrier as hereinbefore described %kith reference to the accompanying drawings.

10. A carrier as claimed in any one of claims 3 to 9 in which the brakes are operated by Bowden cables in conjunction with a brake auto adjuster which automatically takes up brake wear and cable stretch.

11. A carrier as claimed in claim 10 in which the Bowden cable is routed through the tubular frame work.