GB2366258A

GB2366258A - Trolley having independently braked rear wheels

Info

Publication number: GB2366258A
Application number: GB0120388A
Authority: GB
Inventors: David Leslie Hooker
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-08-22
Filing date: 2001-08-21
Publication date: 2002-03-06
Anticipated expiration: 2021-08-21
Also published as: GB2366258B; GB0120388D0

Abstract

A trolley includes at least one swivably mounted front wheel and two wheels mounted on opposite sides of the trolley at a rear end. Braking means independently brake each of the rear wheels and are controlled by levers which are positioned adjacent and in front of a handle which spans the width of the trolley.

Description

<Desc/Clms Page number 1> 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 front wheels, or all the wheels are pivotally mounted as castors so that the user can push them round corners. 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. GB Patent 2200083 discloses a trolley which can be steered by braking the rear wheels so that by selectively braking one wheel the trolley can be effectively steered. However this construction has not been successfully used as, in practice the braking levers have been difficult to fit and it has not proved possible to retrofit such an arrangement to existing trolleys.

We have now devised an improved carrier which is easier to steer and control and which can be constructed by modifying existing trolleys.

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 the front wheels being swivably mounted and there being two wheels mounted on substantially opposite sides of the carrier at the rear of the carrier and a handle mounted across the width of the trolley, there being a braking means which can independently brake each of the rear most wheels, which braking means being controlled by levers positioned adjacent and in front of the handle.

The terms front and rear being in the front and rear in relation to the intended direction of movement of the trolley and the term wheels includes castors etc.

A trolley which is widely used, particularly in airports, has brakes on its rear wheels which are operated by a bar located adjacent the handle by which the trolley is pushed and which brakes both rear wheels. This enables users to stop the trolley running away from the user for example when going down ramps etc. by pulling on the bar. The present invention also provides a method of adapting such a trolley by dividing the bar which operates the brakes so that it forms two separate bars which are separate levers each of which brakes a different wheel. In practice the attachment of the bar on the trolley may not be robust enough when the bar is divided, as each half of the bar has only one point of attachment to the trolley and preferably there is a reinforced bush attached to the trolley to which the bar or lever connects and which holds the lever in position.

As well as being applicable to baggage trolleys the present invention can be applied to any type of trolley such as shopping trolleys etc.

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 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.

The trolleys used in the present invention can have three four, five or more wheels. The braking means is preferably progressive so that the degree of braking can be independently controlled on each of the wheels separately.

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 commonly used in bicycles. Or a "seesaw" lever which engages on the outside surface of the tyre to brake by friction. The brake can be 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 or by rods connecting the levers to the brakes.

If 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 corner, 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.

Preferably there is an adjuster to compensate for wear so that the braking efficiency can be maintained, for example 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.

When there is a rod connection between the brake lever and the brake the preferred adjuster is an automatic adjuster which comprises a rod positioned between the brake and the brake lever, which rod is in two sections one of which screws into the other so that the overall length of the rod can be varied, one section of the rod is fixed to the body and the other section of the rod is rotatable and is fixed in position when the brake is correctly adjusted, there being a means whereby, when the brake wears the rotatable section becomes unfixed and there is a spring which then rotates the rotatable section to increase the overall length of the rod until the rotatable section brings the brake back into adjustment.

The preferred spring is a torsion spring located around the rod and the number of working turns created by the torsion spring equals the number of turns required to be made to the rotatable rod to bring the brake back into correct adjustment.

Preferably 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. 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 or a cam shape connected to or made as part of a turn knob which will lift the two aforementioned brake levers to engage the brakes when the knob is turned with the ends of the brake levers close together but not touching for this situation. This can be incorporated in the braking means of the invention or can be an independent system.

Preferably the trolley such as an airport luggage trolley incorporates an automatic braking system to lock the brakes in the on position.

The brake is held on when the trolley is stationary, preferably by a spring means which acts on the braking mechanism to hold the brake in the on position. Preferably the push bar is pivoted and, when a user pushes the trolley the push bar moves to release the spring means and release the brake. When the user stops pushing the push bar the spring means acts to cause the brake to engage. The automatic brake mechanism can act on one or both brakes.

The automatic brake can act on both or either of the braked wheels.

The invention is particularly applicable to the carriers or trolleys used in airports where relatively small wheeled carriers are used to provide large carrying capacity. The invention is described in the accompanying drawings in which Fig. 1 is a view of a trolley braking handle altered to that of one embodiment of the invention Fig. 2 is a view of a trolley braking handle altered to that of a different embodiment of the invention Fig 3 is a view of the self adjusting brake adjuster which can be part of the invention Fig. 4 shows a view of the brake handle with the automatic brake mechanism Fig. 5 shows a cut away view of an improved brake Fig. 6 shows a schematic view of an improved brake arm Fig. 7 shows a schematic view of an engagement and disengagement assembly for an automatic brake and Fig. 8 shows a schematic view of a brake release mechanism Referring to Fig. 1 a brake handle for a typical airport trolley (1) operates by being pulled upwards in the direction of the arrow to brake the rear wheels of the trolley. The section (1 a) is removed to form two levers (1c) and (1d). In order to provide adequate support for the levers (1c) and (1 d) and to prevent wobble of the levers (1c)

and (1 d) the bushes (A) are removed and replaced with new bushes which are a close fit within the ring (2) on the brake handle (1) and are of a length to provide adequate support. The retaining pin and circlip (B) are replaced with a Nyloc retaining nut and bolt. The bolt having enough smooth unthreaded length to offer a good bearing support. Ferrules are added to the end of each arm at (4) and (5). The adjustable screw (6) presses on the existing rod which operates the brakes.

Referring to fig. 2 the existing thin support plate (10) is replaced with bush (2) which provides accurate support for the arm.

In use, to adapt an airport trolley the handle (1) has the section (la) removed and ferrules placed over cut ends at (4) and (5). The fixing of the handle to the trolley is replaced with such a reinforced fitting to prevent excessive wobble. By pulling on each lever (1c) and (1d) separately either of the rear wheels can be braked independently without making other changes to the trolley. Thus it is easy and simple to convert existing trolleys to steerable trolleys.

A self adjusting brake mechanism of fig. 3 consists of body (20) having round ends, or is shaped to fit inside the rear down leg of a baggage or any other braked trolley, two threaded holes (not shown) are produced in body to suit trolley construction for setting the unit in the leg, the lower end (21) of male threaded shaft (28) has a cup or similar which is not shown to locate brake unit push rod, also not shown.

The upper end (22) of female threaded shaft (23) has a cup or similar (not shown) to locate upper push rod (not shown) which interfaces with the brake lever. There is upper tension pin (24) which fits tightly into shaft (23) and there is a slot (25) through body to accept tension pin (24). The collar (26) accepts one end of torsion spring (27) which fits over end of shaft (23) and is secured by 2 cone-point grub screws positioned at 90 degrees (only one shown) to lock shaft and collar together.

The torsion spring (27) is wound up clockwise when set and unwinds anticlockwise when released, turning lower male threaded shaft (28). The lower male threaded shaft (28) has lower tension pin (29) fitted into it and there is release slot (30) for lower tension pin (29) to locate into and spanner flats (31) for setting unit.

The unit is set by turning lower shaft (28) clockwise a predetermined number of turns (about 3) via spanner flats (31) and entering lower tension pin (29) into its slot (30). In doing this the two shafts (23) and (28) are slid upwards in the body. Via the standard adjustment screw at the trolley pull arm, the brake is set so that there is no "play" between the upper push rod, this brake adjuster unit and the lower push rod adjoining the brake assembly. The brake adjuster unit is now set in position in the trolley leg by tightening two screws in threaded holes in the unit body .

As the brake is operated and wears, the pull arm moves closer to the trolley handle, at a point where the pull arm nears the handle and normally the brake requires adjustment, lower tension pin (29) is released from its slot (30) because the two shafts (23) and (28) have been pushed downward through the unit body which has been set inside the trolley leg. This releases the torsion spring (27) which unwinds lower shaft (28) approximately 3 turns to reset the brake to near the original setting. The option of further adjustment can then be made if necessary by using the existing setting screw at the pull arm as currently employed.

Referring to fig. 4 which shows an automatic brake on mechanism, push bar (41) of a trolley is connected to the trolley at (42). Brake arm (43) is connected to trolley at strengthened pivot (44), flip bar (45) is connected by a tongue which is connected and retained at (44). There is drop bar (46), the position of which is adjustable by locknut (47). The flip bar (45) can be flipped up to give access to locknut (47) to adjust the brake when setting up. There is arm (48) connected to bar (41), which arm is acted on by tension spring (49) to hold the bar (41) away from the trolley when at rest.

To move away, the bar (41) is pushed down slightly to lift arm (48) which lifts set screw (50) and which is set in arm (48) to bear on flip bar (45), which then releases the brake through drop bar (46). When a user ceases to push on (41) the tension spring (49) causes arm (48) to act on flip bar (45) and drop bar (46) to engage brake. To apply the brake when the trolley is being pushed the user pulls on brake arm (43) which acts on drop bar (46) to apply the brake and to enable the trolley to be steered by the braking.

In an alternative arrangement which gives easier setting up, the head (51) is replaced by a flat bottomed head and there is a radial cam in space M set between the bottom of head and top of drop bar (46). A sprung ball bearing is housed in a housing which surrounds the cam and fits at the top of the drop bar (46) and locates in one of a number of ball shaped indentations set in a circle on the side of the cam, allowing the cam to be "clicked" in fine angular increments in either radial direction for setting the cam precisely.

A preferred brake arrangement and wheel/castor is shown in fig. 5 which needs less force compared with presently used brakes. A castor tyre (52) which rotates in direction shown is braked by raised brake rim (53). A cone with face shown in profile at (54), contacts the wheel to brake the wheel, but before the elastic limit of the tyre is reached and the material permanently deforms, the cone face (55) also interfaces with the tyre by way of the braking process and stops the raised rim digging further into the tyre. The correct balance of rim size to cone face allows less pressure by the braking mechanism for a given braking effect.

A preferred brake lever arrangement is shown in fig. 6 which gives easier setting and better action than with presently used brakes by replacing the traditional grub screw and lock nut version. This is particularly of advantage as part of the automatic brake variant. A brake arm (50) pivots about brake arm pivot point (51),a cam (53) with a

clenchlock (52) or similar stiffened nut welded to it, fits against inside face of arm (54). Cap screw (56) fits through arm (54) and cam (53) and is secured via stiffened nut (52). The stiffened nut (52), welded to cam (53) allows the cam to be turned by cap screw (56) and set in relation to drop bar (55) to remove "play" from the brake linkage instead of the traditional grub screw and locknut. When the setting has been completed, brake arm (50) can be pulled thereby tightening cam (53) against drop bar (55) to stop cam turning and screw (56) can be finally tightened to lock assembly in set position. An alternative cam can be a moulded version in nylon including a "stiffened" thread.

The automatic brake holds the brake on when the trolley is in the stationary position. This can cause difficulties when trolleys are stacked in lines or need to be moved around by service personnel.

A preferred method of disengaging the automatic brake mechanism is shown in fig. 7. A cranked rod bears through mechanism side plates at (a) in fig. 4. Details of this are shown in fig. 7 where the cranked rod is itemised as (60). Fitted to the crank is tension spring (61) which activates the automatic brake. When the crank is down the spring is tensioned; when the crank is up the spring is not tensioned and the automatic brake will not come on. Bush (64) fits on cranked rod (60) and bush (64) is a press fit in one mechanism side plate. Alternatively the bush is split, made of nylon and keyed to match the plate. The other end of the cranked rod bears in the other mechanism side plate. Tension pin (63) fits in a hole passing through the cranked rod which is on the same axis as the crank. Pin (63) is kept in a slot in bush (64) by compressing spring (66). To engage or disengage the automatic brake, the socket key (67) is fitted to hexagon head (68), pushed in and turned half a circle in either direction to rotate the crank either up or down, thereby engaging or disengaging the automatic brake. Referring to Fig. 8 this mechanism applies to any trolley which comes under the commonly used term of;"brake on". That is a trolley with the parking brake fixed on

when the trolley is unattended. To release the brake the bar used for pushing the trolley along is first pushed down or up. This new improved version of the release action affords an overall improvement to brake-steering a trolley as well.

Referring to Fig 8 Two Bowden cables L & M are fixed to trolley pushing bar boss A at point B so that they run either side of the boss. The ends of cables L & M are fixed in block C or by any other joining method with a third Bowden cable D. Cable D runs around pulley wheel E and is fixed into end of plunger F which is sprung downward by compression spring G. Plunger F acts upon brake lever arm H and the force created by spring G is increased by leverage onto adjustment cam J which presses on drop bar K to apply pressure to a brake button or pad acting upon the castor wheel.

In its free state, trolley pushing bar A can swing radially about its pivot boss. Therefore by the action of compression spring G keeping the brake on and the 3 Bowden cables L M & D linked to the trolley pushing bar boss A, the trolley pushing bar will radially centralise itself within it's swing range. So when trolley pushing bar A is pushed downwards, cable L tightens against tension pulley p and pulls cable D to lift plunger F and release the brake. Similarly when trolley pushing bar A is lifted upwards, cable M tightens against tension pulley R and pulls cable D to lift plunger F and release the brake 3.

A feature of this design is that it not only releases the brake by moving the trolley pushing bar in either an up or down direction, but it also creates a powerful braking action at the brake mechanism, yet still affords a ligbl action at the trolley pushing bar for release by the use of suitable leverage forces built into the design. This feature applies to any other linking method such as a chain, or ball links etc.

The brake on, brake-steering mechanism shown in Fig 8 can be significantly simplified in a production environment by the removal of :-

Roller tensioner - P and R.

In the case of a loop of chain to replace Bowden cables Land M, the tension sprockets in place of rollers P and R can be removed Block C with its retaining screw and ball bearing. Replaced by a loop connection in cable D to the aforementioned chain Cam J and its screw and nut Adjustment method after the removal of above components The end of plunger F which presses on arm H to have a screw adjuster added by tapping a thread in the end of plunger F (a little room can be created here compared with drawing Fig 8).

Improvement to Brake Steering Pull Arms, Known as a "Wobble Arms" The brake steering pull arms is and 1d in Fig 1, or as shown as arm H in Fig 8, can be altered as follows to offer a more "user friendly" function. The two arms can be joined by means of a coil spring so that either lc or id can still be pulled in the normal way without infringing on the other and the whole unit encased in a suitable plastic/rubber etc material so the unit becomes appropriately pliable over its length. The word "TURN" or other suitable word to be displayed on the central part. Alternatively a mix of materials to allow the arm, over it length to flex so that either end can be pulled to operate the brake-steer action at either castor without affecting the other.

Claims

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 the front wheels being swivably mounted and there being two wheels mounted on substantially opposite sides of the carrier at the rear of the carrier and a handle mounted across the width of the trolley, there being a braking means which can independently brake each of the rear most wheels, which braking means being controlled by levers positioned adjacent and in front of the handle.
2. A carrier as claimed in claim 1 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 1 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.
5. A carrier as claimed in claim 3 or 4 in which the braking means is progressive so that the degree of braking can be independently controlled on each of the wheels separately.
6. A carrier as claimed in any one of claims 3 to 5 in which the braking means is cable, hydraulic or any other linkage method operated 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.

<Desc/Clms Page number 13>
7. 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.
8 A carrier as claimed in any one of the preceding claims in which the levers are formed by removing a central part of a bar which is positioned across the width of the trolley, which bar operates brakes acting on the rear wheels.
9. A carrier as claimed in any one of the preceding claims in which there is an automatic brake adjuster which comprises a rod positioned between the brake and the brake lever, which rod is in two sections one of which screws into the other so that the overall length of the rod can be varied, one section of the rod is fixed to the body of the trolley and the other section of the rod is rotatable and is fixed in position when the brake is correctly adjusted, there being a means whereby, when the brake wears the rotatable section becomes unfixed and there is a spring which then rotates the rotatable section to increase the overall length of the rod until the rotatable section brings the brake back into adjustment.
10. A carrier as claimed in claim 9 in which the spring is a torsion spring located around the rod and the number of working turns created by the torsion spring equals the number of turns required to be made to the rotatable rod to bring the brake back into correct adjustment.
11. A carrier as claimed in any one of the preceding claims in which the braking means on at least one of the braked wheels can be held in the on position when the carrier is stationary.
12. A carrier as claimed in claim 11 in which there is a spring means which automatically urges a brake into contact with a wheel when the carrier is stationary.

<Desc/Clms Page number 14>
13. A carrier as claimed in claim 12 or 13 in which pressure on the handle causes the braking means to be released.
14. A carrier as claimed in 12 or 13 in which the brake lever is adjusted in relation to the brake linkage by means of a cam attached to the brake lever with a stiffened nut at its pivot centre and a cap screw for setting the "play" in the brake whereby rotating the cam via the cap screw simplifies the adjustment operation by replacing the traditional grub screw and lock nut.
15. A carrier as claimed in 12 or 13 in which the automatic brake can be disconnected from use with a special key which turns a cranked rod onto which is hooked a tension spring; when the rod is rotated through half a circle in either direction to tension or release the spring thereby engaging or disengaging the automatic brake.
16. A method of converting a trolley which has a bar which is positioned across the width of the trolley and which bar operates brakes acting on the rear wheels of the trolley which method comprises removing a central part of the bar to form two levers each of which operates independent brakes on different wheels.
17. A method as claimed in claim 16 in which the levers are pivotally attached to the trolley through reinforced mountings.
18. A carrier as hereinbefore described with reference to the accompanying drawings.