WO2008113116A1

WO2008113116A1 - Trolley with a guide wheel

Info

Publication number: WO2008113116A1
Application number: PCT/AU2008/000373
Authority: WO
Inventors: Graham Dull
Original assignee: Inautec Pty Limited
Priority date: 2007-03-16
Filing date: 2008-03-14
Publication date: 2008-09-25

Abstract

The present invention relates broadly to a trolley (10) comprising trolley framework (12) having four pairs of castor wheel assemblies (14A) to (14D). Each of the pair of castor wheel assemblies such as (14A) includes a swivel castor assembly (16) and a castor assembly (18) of a fixed directional orientation. The swivel castor assembly (16) includes a castor wheel (28) rotationally mounted to a castor support bracket (30). The castor (28) rotates about a rotational axis provided by axle bolt (32). The swivel castor assembly (16) also comprises a swivel shaft (34) about which a castor support bracket (30) together with the castor wheel (28) moves in a swivelling motion. The swivel shaft (34) is connected to a tilting element (36) which is operatively coupled to the trolley framework (12).

Description

TROLLEY WITH A GUIDE WHEEL

FIELD OF THE INVENTION

The present invention relates broadly to a trolley and relates particularly, although not exclusively, to a swivel castor assembly for a trolley.

BACKGROUND OF THE INVENTION

Trolleys with castor wheels are generally heavy and unwieldy to steer and are particularly difficult to control when they are loaded. Manoeuvring a trolley utilizing the hand rail provided at the rear of the trolley is no easy task, and involves a certain degree of dexterity and strength from the arm, waist and back of the user-

Users often find themselves in circumstances where they need to change the direction of travel of the trolley frequently such as when manoeuvring a shopping trolley along an aisle in a supermarket. The same applies to trolley beds in hospitals and serving trolleys in restaurants and bars. When turning a trolley from standstill, the user effectively acts as the pivot about which the trolley is moved. As the front castor wheels are relatively distant from the user, a significant torsional force from the waist and lower back of the user is required in order to turn the trolley from standstill or to swing it around from the direction it is pointing. The force required for this is substantially increased when the trolley is loaded. As a result, lower back injuries and muscle strain are relatively common. The resulting muscle pain and discomfort may not be immediate, but may become apparent hours or days after trolley usage,

In severe cases, muscle injuries resulting from trolley usage may exacerbate existing muscle or spine injury and in some cases, can be debilitating. Another awkward situation in which users quite frequently find themselves is when pushing a trolley across a sloping or uneven surface. Ivlαre specifically, it is not uncommon for a trolley to stall or for the ussr to lose control of the trolley when the front castor wheels of the trolley are driven into a bump. Trolleys are also inherently susceptible to turning down a sloping surface. In either instance, the user is forced to exert a significant effort in order to maintain the trolley on track. In the latter instance in particular, the user must exert a constant torsional force from their back region to prevent the trolley from turning from the direction of travel while traversing the sloping surface, which again subjects the user to increased risk of back and muscle injury. The castor wheels of shopping trolleys are also notorious for swivelling from side to side when being pushed ovsr rough surfaces such as often found on footpaths and in supermarket car parks, which besides being an annoyance, impacts deleteriously on the control the user has on the trolley.

Patents and patent applications EP424234 {Gυrtel Etienne Mobilor), JP10166807 (Naπshin KK), EPQ370716 (Herok RJK), WO9325398 {Lloyd Gerald), and GB2389084 (Moye Cyril) describe castors designed to address these problems. The castors described by these patents and patent applications each have a component in frictional contact with the wheel which urges a lock into engagement upon rotation of the wheel in a forward direction, and out of engagement upon rotation in a reverse direction. The lock prevents the castor swivelling. The castor when locked provides directional control to the trolley. As the trolley is moved in another direction the castor is unlocked and free to swivel in which case the castor does not restrict free manoeuvrability of the trolley.

Although the castors in each of these patents can be locked and unlocked they have considerable operational limitations. When the castors' swivel is locked and the locked castors are guiding the trolley a considerable and variable side pressure is applied to the lock. The unlocking force applied to the lock of each of these castors is not necessarily adequate to provide Immediate and consistent unlocking in normal operational situations. Each of these castors also has the disadvantage in that there is a frictional component contacting the wheel at all times which creates friction and wear to the associated castor components. If the said frictional contact is substantially minimized in forward travel so as to reduce wear it is generally also the case that the minimized frictional contact is insufficient to initiate unlocking and therefore cannot reliably and immediately unlock the castor in all operational situations.

Another disadvantage Is that small amounts of deformation and wear of the wheel and the frictional component can substantially alter the necessary operational characteristics of the unit and render it unreliable or useless. A further disadvantage is that relatively small amounts of dirt, debris, gum, oil or other liquid can easily impede the operation of the unit and render it unreliable or useless. While small amounts of contamination detrimental to thθ castor's operation may be picked up in almost any environment this state of affairs is increased significantly for trolleys which are used in generally contaminated conditions suoh as supermarket trolleys which are used in surroundings such as shopping centers, car parks and out-of-doors in all weather conditions and trolleys used in industrial and warehousing situations.

Furthermore, the castor of Patent WO9325398 (Lloyd Gerald) enables an operator to unlock the castor swivel by a sideways movement of the trolley. This arrangement has the disadvantage that the castor may be unintentionally unlocked during normal operation. The castors may, for example, be unlocked when a trolley is manoeuvred across a slope or steered under load. When using this castor an operator cannot be sure that the swivel will remain locked in all operational situations and allow the guidance wheel to perform appropriately.

Patent JP55156702 (Morita) describes a castor that has considerable disadvantages. A component of the castor that is in frictional contact with the wheel rotates. The rotating component is also in frictional contact with a slide which locks and unlocks the swivel, Because of the frictional contact and relative movement between the rotating component and the sliding component it is almost impossible for them to remain synchronized. Patent GB2106378 (Morita) also describes a castor which has a component in Motional contact with the wheel. The component brakes the wheel when It rotates in a reverse direction. The braking action of the component pivots a sub-bracket to which the wheel is mounted. This pivotal movement unlocks the swivel. This approach has considerable disadvantages including the number and complexity of the components.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a swivel castor assembly for a trolley, said castor assembly comprising: a castor wheel rotationally mounted to a castor support bracKet; a swivel shaft pivotally coupled to the castor support bracket for swivelling of the support bracket and the wheel about the shaft; and a tilting element connected to the swivel shaft and operatively coupled to the trolley for tilling movement of said shaft for lifting or lowering of the trolley.

According to a another aspect of the invention there j$ provided a trolley comprising: trolley framework; a swivel castor assembly mounted to the framework and comprising: a castor wheel rotationally mounted to a castor support bracket; a swivel shaft pivotally coupled to the castor support bracket for swivelling of the support bracket and the wheel about the shaft; a tilting element connected to the swivel shaft and operatively coupled to the framework for tilting movement of said shaft; and at least on© castor of a fixed directional orientation being connected to tha trolley framework or the tilting element adjacent the swivel castor assembly whereby the tilting movement of the swivel shaft lifts or lowers the fixed castor.

Preferably the tilting element includes a tilt bracket fixed to the swivel shaft for tilting in a substantially vertical plane about a predetermined range of angles. More preferably the swivel shaft is tilted from between about 0° to less than 10* in the vertical tiit plane.

Preferably the trolley also comprises tilt restraining means connected to the swivel shaft or the tilt bracket and being arranged to abut the trolley framework to limit tilting between extreme tilt positions. More preferably the tilt restraining means includes one or more first restraining members each connected to the swivel shaft or the tilt bracket and configured to abut the framework at tilt angles of around 0° and les$ than 10* whilst permitting tilting between these angles. Even more preferably the tilt restraining means includes one or more second restraining members each connected to the swivel shaft or the first restraining members and being arranged to substantially prevent lateral tilting of the swivel shaft whilst permitting its tilting in the vertical tilt plane. Preferably the tilt bracket includes swivel restraining means connected to the swivel shaft or the tilt restraining means and being arranged to abut the trolley framework to limit swivelling of the swivel shaft. More preferably said swivel restraining means limits swivelling of the shaft to less than about 5*. Even more preferably the second restraining member Is also configured to function as the swivel restraining means.

Preferably the swivel castor assembly includes biasing means being operatively coupled to the tilt bracket and arranged to urge the swivel shaft toward an upright position. More preferably the biasing means includes a torsion bar or spring. Even more preferably the torsion bar or spring is biased at a preset force which determines the vertical load taken by the swivel castor assembly. According to a further aspect of the invention there is provided a swivel castor assembly for a trolley, said castor assembly comprising; a castor wheel rotationally mounted about a rotational axis to a castor support bracket; a swivel shaft pivotally coupled to the castor support bracket for swivelling of the support bracket and the wheel about a swivel axis of the shaft which is tilted relative to the trolley, the rotational axis of the castor wheel being offset from the swivel axis of the shaft whereby swivelling of the castor wheel lifts or lowers the trolley.

According to yet another aspect of the invention there is provided a trolley comprising: trolley framework; a swivel castor assembly mounted to the framework and comprising: a castor wheel rotationally mounted about a rotational axis to a castor support bracket; a swivel shaft pivαtally coupled to the castor support bracket for swivelling of the support bracket and the wheel about a swivel axis of the shaft which is tilted relative to the trolley, the rotational axis of the castor wheel being offset from the swivel axis of the shaft; at least one castor of a fixed directional orientation being connected to the trolley framework adjacent the swivel castor assembly whereby swivelling of the castor wheel lifts or lowers the fixed castor.

Preferably the tilt angle of the swivel shaft relative to the trolley is less than about 10°. More preferably the offset of the rotational axis of the castor wheel when measured as a ratio of the right angle sides of an imaginary right angle triangle (with a hypotenuse formed by a line connecting a tilt axis and the rotational axis) is less than about 1/3 (where the smaller length side is adjacent thθ rotational axis).

Preferably the swivel castor assembly is configured whereby rotation of the castor wheel in opposite directions effects swivelling of the support bracket for the lifting or lowering motion, respectively. More preferably movement in a reverse direction provides the lifting motion whereas movement in a. forward direction provides the lowering motion. Awarding to yet a further aspect of the invention there is provided a trolley comprising: trolley framework being generally elongate; a rocker bracket coupled transverse to the framework for rocking about a transverse rocking axis; and a pair of laterally spaced castor assemblies each including a castor wheel rotatioπally mounted about a rotational axis to a castor support bracket mounted to the rocker bracket with the respective rotational axe$ being longitudinally separated for Improved contact of the castor wheels with an uneven surface.

Preferably one of the pair of castor assemblies is of a fixed directional orientation whereas the other of the castor assemblies is a swivel castor assembly. More preferably the swivel castor assembly has its rotational axis offset from a swivel axis of its swivel shaft whereby movement of the castor wheel in one general direction swivels the support bracket to provide the longitudinal separation. Evgn more preferably the fixed castor assembly is oriented so that its rotational axis is offset in said one general direction.

Preferably the trolley includes rocker restraining means connected to the rocker bracket and being arranged to abut the trolley framework to limit rocking between extreme positions. More preferably the rocker restraining means includes one or more rocker restraining members each connected to the rocker bracket and configured to abut the framework at angles of around 0^D and less than 10° whilst permitting rocking between these angles.

Preferably the trolley is configured wherein Swivelling of the swivel castor assembly in one direction rocks the rocker bracket in one direction to lift the fixed castor assembly whereas swivelling of the swivel castor assembly in an opposite direction rocks the rocker bracket in an opposite direction to lower the fixed castor assembly.

Preferably the trolley also comprises a further castor assembly attached to the rocker bracket

Generally the fixed castor is in the form of a guide wheel. BRIEF DESCRIPTION OF THE FIGURES

In order to achieve a better understanding of the nature of the present invention a preferred embodiment of a swivel castor assembly and a trolley will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a perspective view of part of a trolley including a swivel castor assembly according to one embodiment of the invention;

Figures 2A and 2B are side elevational views of the trolley of figure 1 moving in one direction; Figures 3A and 3B are perspective views of one of the swivel castor assemblies together with a fixed castor or guide wheel shown moving in opposite directions, respectively;

Figure 4 is an exploded view of the swivel castor assembly together with the fixed castor of iigures 3A and 3B;

Figures 5A and 5B are side βlβvational views of another embodiment of a swivel castor assembly together with a fixed castor moving in opposite directions, respectively;

Figure 6 is an exploded view of the swivel castor assembly and fixed castor of figures 5A and 6B;

Figures 7A to 7C are various views of part of the swivel castor assembly and fixed castor of figure 6; Figures 8A to 8C are elsvational views of a further embodiment of a swivel castor assembly together with a fixed castor shown moving in various directions;

Figure 9 is an exploded view of the swivel castor assembly and fixed castor of figures 8A to SC;

Figures 10A and IOB are side slsvational views of yet another embodiment of a swivel castor assembly together with a fixed castor shown moving in opposite directions, respectively;

Figure 11 is an end view of the swivel castor assembly and the f ixed castor of figures 10A and 10B; and

Figure 12 is an exploded perspective view of the swivel castor assembly and fixed castor of figure

11 -

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in figure 1 there is part of a trolley 10 comprising trolley framework 12 being generally rectangular and having four (4) pairs of castor whaβl assemblies 14A to 14D at or adjacent each of its corners. Each of the pair of castor wheel assemblies such as 14A includes a swivel castor assembly 16 and a castor assembly 18 of a fixed directional onβntation.

The trolley framework 12 comprises a pair of side rails 2OA and 2OB interconnected at opposing ends with a front and rear frame member 22 and 24, respectively. The front and rear members 22 and 24 are each at opposing ends welded or otherwise connected to the side rails 2QA and 2OB. The front and rear members 22 and 24 are each elongate and fabricated of a U-section member which is cranked at its opposing ends.

As best shown in figures 3A/3B and figure 4 the swivel castor assembly 16 includes a castor wheel 28 rotationally mounted to a castor support bracket 30. The castor 28 rotates about a rotational axis provided by axle bolt 32. The swivel castor assembly 18 also comprises a swivel shaft 34 about which the castor support bracket 30 together with the castor wheel 28 moves in a swivelling motion. The swivel shaft 34 is in this example in the form of a swivel bolt connected to a tilting element 36 which is operatively coupled to the frame member 22.

As best shown in figure 4, the tilting element 36 is in the form of tilt bracket fixed to the swivel bolt 34 for tilting movement together with the castor support bracket 30 and its associated castor wheel 2B. The tilt bracket 36 is a U-shaped bracket having a pair of opposing tilt shafts such as 38. The tilt shafts such as 38 are joumallβd in opposing locating holes 40 and 42 of the front frame member 22 and a corresponding elbow-shaped mounting bracket 44. The mounting bracket 44 is secured by one or more bolts such as 46 to an underside of the frame member 22. The tilt bracket 36 includes tilt restraining means in the form of opposing pairs of restraining members or stops such as 48A and 48B. The tilt stops such as 48A/B are arranged to limit tilting of the tilt bracket 36 together with the swivel shaft 34 and associated components, generally being limited to less than 10^a or typically in a range of between CP to 8^fl in a substantially vertical plane. The tilt stops such as 48A/B are configured to abut the frame member 22 and the elbow-shaped mount 44 to limit tilting of the tilt bracket 36 together with the swivel bolt 34,

The swivel castor assembly 16 also includes biasing means in the form of torsion spring 50 operatively coupled to the tilt bracket 36 and the frame member 22 together with the elbow support 44- The torsion spring 50 includes a U-shaped intermediate portion 52 and a pair of C-shaped wing elements such as 54, The intermediate portion 52 includes a pair of laterally spaced coils designed to locate about inwardly directed protrusions such as 58 of the tilt bracket 36. The

C-shaped wing elements such as 54 engage the framework 12 whereby the tilt bracket 36 and the associated castor support bracket 30 is urged in this example in a generally clockwise direction.

The fixed castor assembly 18 includes a fixed castor support bracket 60 (of a similar construction to the swivel castor support bracket 30) to which castor wheel 62 is rotatably mounted about a rotational axis defined by another rotational shaft or axle bolt 64. The fixed castor support bracket 60 Is firmly secured to the framework 12 via anchoring bolt 66 alongside the swivel castor assembly 16. The anchoring bolt 66 is in this example fixed to the front frame member 22 and the associated castor wheel 62 is oriented generally parallel to the side rail member such as 2OA and when in contact with the ground serves as a guidance wheel.

Figures 3A and 3B best illustrate operation of the swivel castor assembly such as 16 with movement of the trolley in a forward and rearward direction, respectively. In the forward direction of figure 3A the castor wheels £8 and 62 of the respective swivsl castor assembly 16 and the fixed castor assembly 18 are In contact with the ground. The tilt bracket 36 is rotated in a clockwise direction under the influence of the castor wheel 28 and with the assistance of the torsion spring 50 maintains contact with the ground. In this direction of forward travel the swivel shaft or bolt 34 is tilted at around 8^a to the vertical and has the effect of placing the castor wheel 28 at about the same level as the other castor wheel 62. As best shown in figures 2A and 2B the other pair oi θ

swivel castor 16D and fixed castor 18D assemblies are similarly oriented and contacting the ground in this direction of forward travel.

As shown in figure 3B, reversal Of the trolley 10 provides tilting of the tilt bracket 36 in a generally clockwise direction lifting the fixed castor or guide wheel 62 clear of the ground. As shown in figure 2B the rearward of the swivel castor assemblies such as 16C is configured to provide lifting of the adjacent guide wheel 18C on movement of the trolley in the forward direction. In this embodiment the rearward swivel castor assemblies such as 16C via their respective tilt restraining means are prevented from tilting clockwise but permitted to tilt anti-clockwise for lowering of the guide wheel such as 62C on reversal of the trolley 10. The swivel castor assembly 16C is arranged so that movement of the trolley 10 in the forward direction disposes the swivel castor wheel 2BC lower than its adjacent fixed castor wheel 62C with the swivel shaft or bolt 34C oriented upright. On the other hand, reversal of the trolley 10 reorients the swivel castor assembly 16C for tilting of thθ swivel shaft 34C and tilt bracket 36C in a generally anti-clockwise direction for lowering of the adjacent fixed castor wheel 62C into contact with the ground.

This embodiment of the tilt bracket such as 36 tilts through around 8° for lifting or lowering of the fixed castor around 6mm. However, it will be appreciated that by re-engineering the swivel castor assembly 16, for example, varying the position of the tilt restraining means, the angular displacement and extent of lifting or lowering of the guide wheel such as 62 may be varied.

Figures 5 to 7 illustrate a variant of the preceding embodiment of this invention. For ease of reference and in order to avoid repetition the same reference numerals have been used for the same components of this other embodiment. As shown in figure 6 the swivel castor assembly 16 is similarly biased to the preceding embodiment hut with a torsion bar 70 instead of the torsion spring 50 of the previous embodiment. The fixed castor wheel assembly 18 is effectively th© same as the previous embodiment but also provides an anchor point for a distal arm portion 72 of the torsion bar 70, The tilting element of this embodiment Is In the form oi tilt plate 76 which the swivel shaft 34 is secured via nut 78. Furthermore, unlike the previous embodiment, the swivel shaft or bolt 34 passes through an oversized aperture 80 provided in thθ trolley frame 12 to accommodate limited tifting movement of the swivel shaft 34.

The tilt plate 76 has upwardly turned and laterally directed wing elements 78A and 78B designed to abut an underside of the trolley frame 12 to prevent sideways tilting of the swivel shaft 34 and the associated castor components including the castor support bracket 30. The tilt plate 76 also includes a pair of opposing and longitudinally oriented restraining or stop members 8OA and 8OB. The stop members 8OA and 8OB are effectively equivalent to the stops such as 48A and 48B of the previous embodiment and configured to abut an underside of the trolley frame 12 to limit tilting of the swivel shaft 34 within the tilt plane. As bast shown in figures 5A and 5B a rearward of the tilt, stops 8OA abuts the trolley f rame 12 with forward movement of the trolley 10, whereas a forward of the tilt stops 8OB abuts the trolley frame 12 on reversal of the direction of travel of the trolley 10. As with the previous embodiment, movement In the forward direction permits anti-clockwise tilting of the swivel shaft 34 for lowering of the guide wheel 62 into contact with the ground, whereas reversal of the trolley 10 reorients the swivel castor wheel 28 tilting the swivel shaft 34 in a clockwise direction for lifting of the guide Wheel 62 clear of the ground.

The torsion bar 70 is bent in a C-shape at each of its proximal 69 and distal 72 ends. The tilt plate 76 includes a series of slots 82A and 82B for hooked engagement pf the proximal end 69 of the torsion bar 70- The distal end 72 of the torsion bar 70 is hooked about the anchor bolt 66 of the guide wheel assembly 1 β. In this embodiment the torsion bar 70 is designed to urge the swivel shaft 34 in a generally clockwise direction maintaining contact of the forward swivel castor 16 and fixed castor 1 B assemblies with the ground during forward motion. The rearward swivel castor such as 16B and fixed castor 18B assemblies are reconfigured so that the torsion bar 7OB urges the tilt plate 76B in an anti-clockwise direction for contact of the swivel castor 28B and fixed castor 62B wheels on reversal of the trolley 10. It will be appreciated that the tilt plate 76B and in particular the tilt plate stops 8OA and 8OB is reconfigured for positioning of the swivel shaft 34B in the upright position on forward travel, whereas tilting of the shaft 34B is permitted on reversing of the trolley 10. Figures 8 and 9 show a further embodiment of a swivel castor assembly together with a fixed castor. Like components of this further embodiment vt$ a vis the previous embodiments have been designated with the same reference numerals. However, in this embodiment the swivel castor assembly 16 does not include a tilting element as with the previous two (2) embodiments. Rather, in this further embodiment the swivel castor assembly 16 has the swivel shaft 34 fixed to the trolley frame 12 at a predetermined tilt angle, typically less than about 10^≥. The rotational axis of the castor wheel 28 Is offset from the axis of the swivel shaft 34 so that on swivelling of ihe castor wheel 28 the trolley frame 12 or adjacent fixed or guidance wheel 62 is lifted or lowered relative to thθ ground.

As best shown in figure 9 the swivel castor assembly 16 includes a pair of wedge-shaped tilt plates 84A and 84B each including a swivel shaft aperture 86A and 86B and on assembly being located either side of the end frame member such as 22 of the trolley frame 12. As best shown in figure 8C the wedge plates 84A and 84B are oriented generally parallel Io the side rails such as 2OA of the trolley frame 12 for permanent tilting of the swivel shaft 34 about a tilt plane which is also generally parallel to the side rail such as 2OA. In this example the forward of the swivel castor assemblies such as the swivel castor assembly 16 is titled or raked behind the forward direction of travel of the trolley 10. Furthermore, the rotational shaft 32 of the swivel castor assembly 16 is offset rearward of the swivel axis of the swivel shaft 34. When measured as a ratio of the right angle aides of an imaginary right angle triangle {with a hypotenuse formed by a line connecting a tilt axi$ and ths rotational axis) the offset is equal to about 1/3 (where the smaller length side is adjacent the rotational axis). The angle of tilt Of the swivel shaft 34 in conjunction with the degree of offset of the rotational axis ensures that in the forward travel direction both the castor wheel 28 and the fixed wheel 62 contact the ground, see figures 8A and 8C. As shown in figure 8B, on reversal of the trolley 10 ths castor support bracket 30 swivels about the swivel shaft 34 lifting the fixed castor guidance wheel 62 clear of the ground. That is, swivelling of the castor support bracket 30 and its associated components alone effects lifting or lowering of the guidance wheel 62. The extent to which the guidance wheel 62 moves vertically depends on the tilt angle and degree of offset of the rotational axis of the swivel castor 28. Figures 10 to 12 depict yet another embodiment of the invention with like numerals used to designate components corresponding to the previous embodiment. In this example the trolley includes a rocker bracket 90 to which both the castor support bracket 30 via the swivel shaft 34, and the guide wheel support bracket 60 are secured. The rocker bracket 90 is elongate and locates on an underside of either the front 22 or rear 24 end frame members. One end of the rocker bracket 90 is cranked and partly nested within the frame member such as 22. The cranked end of the rocker bracket 90 includes an anchor bolt hole 92 which receives the anchor bolt 66 for rigid securement of the guide wheel support bracket 60 for fixing orientation of the fixed castor or guide wheel 62. The cranked end of the rocker bracket 90 is sandwiched between a pair of looking nuts 94A and 94B. The frame member 22 includes an oversized hole 96 for receipt of the anchoring bolt 66 to accommodate tilting of the rocker bracket 90.

The rocker bracket 90 at an end opposite ths cranked end is rotatabiy coupled to the swivel castor support bracket 30 via the swivel shaft or bolt 34. The swivel shaft or bolt 34 passes through an oversized hole 98 formed in the end frame member 22 or 24 to accommodate its tilting movement. The swivel bolt 34 is rigidly fixed to the rocker bracket 90 via locking nut 100 which is located between the end member such as 22 and the rocker bracket 90. The swivel bolt 34 passes through a locating hole 102 formed in the rocker bracket 90, an underlying washer 104, and the inner race of a ball bearing (not shown) being integral to the swivel castor assembly 16 which permits swivelling of the castor support bracket 30.

As best shown in figure 12 the rocker bracket 90 includes an intermediate mounting element 106 being integral with tilt restraining means in the form of forward and rearward stop plates 108 and 110, respectively. As shown in figures 10A/10B, the rearward $toρ plate 110 is configured to abut a, corresponding rearward edge of the end member such as 22 of the trolley framework 12 on anticlockwise tilting of the rocker bracket 90, whereas clockwise tilting brings the forward stop plate 108 into contact with a forward edge of the end frame member 22. As shown in figure 10A, the trolley 10 of this embodiment is designed so that forward movement tilts the rocker bracket 90 together with the associated swivel castor assembly 16 and fixed castor 18 in a clockwise direction wharein both the swivel castor 28 and fixed castor 62 contact thό ground. On the other hand and as shown in figure 10B, reversal of the trolley 10 swivels the swivel castor wheel 28 in an opposite direction lifting the fixed castor or guidance wheel 62 clear of tha ground. In this embodiment the rocker bracket 90 spans substantially the full width of the rectangular trolley framework 12. In a similar manner to the embodiment of figures 8 and 9, trie extent of vertical movement of the fixed castor or guidance wheel 62 is determined by the tilt angle of the swivel shaft 34 together with the extent to which the rotational axis is offset from the swivel access. Furthermore, the forward and rearward stop plates 108 and 11 Q control the degree to which the rocker bracket 90 tilts.

According to another aspect of the invention the embodiment of figures 10 to 12 provides a pair of laterally spaced castor assemblies 16 and 18 mounted to the rocKer bracKet 90. The fixed castor wheel assembly 18 is (unlike the previous embodiments) oriented so its rotational axis is offset in the direction of forward travel while forward movement effects the swivelling of the swivel castor assembly 16 to offset its rotational axis away from the direction of travel. This means that forward movement of the trolley 10 longitudinally separates the rotational axes of the respective castor assemblies 16 and 18. This longftudinal separation of the rotational axis's improves contact of the corresponding castor wheals 28 and 62 with an uneven ground surface.

Now that several preferred embodiments of the present invention have been described in some detail, it will be apparent to those skilled in the art that the swivel castor assembly and trolley have at least the following advantages over the admitted prior art:

1. the swivel castor assembly provides automatic lifting or lowering of an associated fixed castor or guidance wheel on movement of the trolley in opposite directions; 2. the swivel castor assembly in combination with the fixed castor provides directional

"stability" in one direction, preferably a forward direction, whilst allowing the necessary manoeuvrability in an opposite direction;

3. the swivel castor assembly lends itself to retrofitting to existing trolleys;

4. the $wivel castor assembly has a reduced number of moving parts and for example is reliable in harsh environments;

5. the trolley with its longitudinally separated castor wheels has relatively good lateral stability on an uneven surface.

Those skilled in the art will appreciate that the Invention described herein is susceptible to variations and modifications other than those specifically described. For example, the biasing or tilt restraining means of the first two (2) embodiments may vary from that described provided the required lifting effect is achieved on swivelling of the swivel castor assembly. The swivel castor assembly and trolley can have a range of applications including but not limited to shopping trolleys, bed and cot trolleys, patient lifters, trolley carts and wagons, serving trolleys, warehouse trolleys and industrial trolleys. All such variations and modifications are to be considered within the scope of the present Invention the nature of which is to be determined from the foregoing descriptions.

It Js to t>δ understood that any acknowledgement of prior art in this patent specification is not to be taken as an admission that this prior art forms part of the common general knowledge.

Claims

1. A swivel castor assembly for a trolley, said castor assembly comprising: a castor wheel rotatϊonally mounted to a castor support bracket; a swivel shaft pivotal Iy coupled to the castor support bracket for swivelling of the support bracket and the wheel about the shaft; and a tilting element connected to the swivel shaft and operatively coupled to the trolley for tilting movement of said shaft for lifting or lowering of the trolley.

2. A swivel castor assembly as defined in claim 1 wherein the tilting element includes a tilt bracket fixed to the swivel shaft for tilting in a substantially vertical plane about a predetermined range of angles.

3. A swivel castor assembly as defined in claim 2 wherein the swivel shaft is tilted from between about 0° to less than 10° in the vertical tilt plane.

4. A swivel castor assembly as defined in either of claims 2 or 3 wherein the tilt bracket includes swivel restraining means connected to the swivel shaft to limit swivelling of the swivel shaft.

5. A swivel castor assembly as defined in claim 4 wherein said swivel restraining means limits swivelling of the shaft to less than about 5°.

6. A swivel castor assembly as defined in any one of claims 2 to 5 wherein the swivel castor assembly includes biasing means being operatively coupled to the tilt bracket and arranged to urge the swivel shaft toward an upright position.

7. A swivel castor assembly as defined in claim 6 wherein the biasing means includes a torsion bar or spring.

8. A swivel castor assembly as defined in claim 7 wherein the torsion bar or spring is biased at a preset force which determines the vertical load taken by the swivel castor assembly.

9. A trolley comprising: trolley framework; a swivel castor assembly mounted to the framework and comprising: a castor wheel rotationally mounted to a castor support bracket; a swivel shaft pivotally coupled to the castor support bracket for swivelling of the support bracket and the wheel about the shaft; a tilting element connected to the swivel shaft and operatively coupled to the framework for tilting movement of said shaft; and at least one castor of a fixed directional orientation being connected to the trolley framework or the tilting element adjacent the swivel castor assembly whereby the tilting movement of the swivel shaft lifts or lowers the fixed castor.

10. A trolley as defined in claim 9 where the tilting element includes a tilt bracket fixed to the swivel shaft for tilting in a substantially vertical plane about a predetermined range of angles.

11. A trolley as defined in claim 10 wherein the swivel shaft is tilted from between about 0° to less than 10° in the vertical tilt plane.

12. A trolley as defined in either of claims 10 or 11 also comprising tilt restraining means connected to the swivel shaft or the tilt bracket and being arranged to abut the trolley framework to limit tilting between extreme tilt positions.

13. A trolley as defined in claim 12 wherein the tilt restraining means includes one or more first restraining members each connected to the swivel shaft or the tilt bracket and configured to abut the framework at tilt angles of around 0° and less than 10° whilst permitting tilting between these angles.

14. A trolley as defined in claim 13 wherein the tilt restraining means includes one or more second restraining members each connected to the swivel shaft or the first restraining members and being arranged to substantially prevent lateral tilting of the swivel shaft whilst permitting its tilting in the vertical tilt plane.

15. A trolley as defined in claim 14 wherein the tilt bracket includes swivel restraining means connected to the tilt restraining means and being arranged to abut the trolley framework.

16. A trolley as defined in claim 15 wherein said swivel restraining means limits swivelling of the shaft to less than about 5°.

17. A trolley as defined in either of claims 15 or 16 wherein the second restraining member is also configured to function as the swivel restraining means.

18. A trolley as defined in claim 17 wherein the swivel castor assembly includes biasing means being operatively coupled to the tilt bracket and arranged to urge the swivel shaft toward an upright position.

19. A trolley as defined in claim 18 wherein the biasing means includes a torsion bar or spring.

20. A trolley as defined in claim 19 wherein the torsion bar or spring is biased at a preset force which determines the vertical load taken by the swivel castor assembly.

21. A swivel castor assembly for a trolley, said castor assembly comprising: a castor wheel rotationally mounted about a rotational axis to a castor support bracket; a swivel shaft pivotally coupled to the castor support bracket for swivelling of the support bracket and the wheel about a swivel axis of the shaft which is tilted relative to the trolley, the rotational axis of the castor wheel being offset from the swivel axis of the shaft whereby swivelling of the castor wheel lifts or lowers the trolley.

22. A swivel castor assembly as defined in claim 21 wherein the tilt angle of the swivel shaft relative to the trolley is less than about 10".

23. A swivel castor assembly as defined in either of claims 21 or 22 wherein the offset of the rotational axis of the castor wheel when measured as a ratio of the right angle sides of an imaginary right angle triangle (with a hypotenuse formed by a line connecting a tilt axis and the rotational axis) is less than about 1/3 (where the smaller length side is adjacent the rotational axis).

24. A swivel castor assembly as defined in any one of claims 21 to 23 wherein the swivel castor assembly is configured whereby rotation of the castor wheel in opposite directions effects swivelling of the support bracket for the lifting or lowering motion, respectively.

25. A swivel castor assembly as defined in claim 24 wherein movement in a reverse direction provides the lifting motion whereas movement in a forward direction provides the lowering motion.

26. A trolley comprising: trolley framework; a swivel castor assembly mounted to the framework and comprising: a castor wheel rotationally mounted about a rotational axis to a castor support bracket; a swivel shaft pivotally coupled to the castor support bracket for swivelling of the support bracket and the wheel about a swivel axis of the shaft which is tilted relative to the trolley, the rotational axis of the castor wheel being offset from the swivel axis of the shaft; at least one castor of a fixed directional orientation being connected to the trolley framework adjacent the swivel castor assembly whereby swivelling of the castor wheel lifts or lowers the fixed castor.

27. A trolley as defined in claim 26 wherein the tilt angle of the swivel shaft relative to the trolley is less than about 10°.

28. A trolley as defined in either of claims 26 or 27 wherein the offset of the rotational axis of the castor wheel when measured as a ratio of the right angle sides of an imaginary right angle triangle (with a hypotenuse formed by a line connecting a tilt axis and the rotational axis) is less than about 1/3 (where the smaller length side is adjacent the rotational axis).

29. A trolley comprising: trolley framework being generally elongate; a rocker bracket coupled transverse to the framework for rocking about a transverse rocking axis; and a pair of laterally spaced castor assemblies each including a castor wheel rotationally mounted about a rotational axis to a castor support bracket mounted to the rocker bracket with the respective rotational axes being longitudinally separated for improved contact of the castor wheels with an uneven surface.

30. A trolley as defined in claim 29 wherein one of the pair of castor assemblies is of a fixed directional orientation whereas the other of the castor assemblies is a swivel castor assembly.

31. A trolley as defined in claim 30 wherein the swivel castor assembly has its rotational axis offset from a swivel axis of its swivel shaft whereby movement of the castor wheel in one general direction swivels the support bracket to provide the longitudinal separation.

32. A trolley as defined In either of claims 31 or 32 wherein the fixed castor assembly is oriented so that its rotational axis is offset in said one general direction.

33. A trolley as defined in any one of claims 30 to 32 also comprising rocker restraining means connected to the rocker bracket and being arranged to abut the trolley framework to limit rocking between extreme positions.

34. A trolley as defined in claim 33 wherein the rocker restraining means includes one or more rocker restraining members each connected to the rocker bracket and configured to abut the framework at angles of around 0° and less than 10° whilst permitting rocking between these angles.

35. A trolley as defined in any one of claims 30 to 34 wherein the fixed castor is in the form of a guide wheel.

36. A trolley as defined in any one of claims 30 to 35 wherein swivelling of the swivel castor assembly in one direction rocks the rocker bracket in one direction to lift the fixed castor assembly whereas swivelling of the swivel castor assembly in an opposite direction rocks the rocker bracket in an opposite direction to lower the fixed castor assembly.

37. A trolley as defined in any one of claims 29 to 36 also comprising a further castor assembly attached to the rocker bracket