Land vehicles – Wheeled – Nesting vehicles
Reexamination Certificate
1997-10-27
2001-12-18
Swann, J. J. (Department: 3611)
Land vehicles
Wheeled
Nesting vehicles
C280S079110, C280SDIG004
Reexamination Certificate
active
06331009
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a control wheel assembly for a trolley and to a trolley fitted with such an assembly and particularly relates to control wheel assemblies for hand trolleys fitted with castors and includes, by way of example trolleys for the carriage or transport of goods in supermarkets, trolleys for the carriage or transport of baggage at airports, trolleys for the carriage or transport of goods in warehouses and offices, trolleys for the carriage or transport of patients or food or medicines or medical equipment in hospitals and perambulators or “prams”. As is well known, castors are provided on trolleys to enable the trolley to be propelled in any desired direction independent of the direction in which the trolley may be apparently orientated.
1. Background of the Invention
Trolleys of the above type have a base frame which is usually fitted with four castors to enable the trolley to be pushed in any direction and manoeuvred in sometimes confined spaces. Such trolleys are notoriously difficult to control and steer, particularly if any of the castors becomes worn, dirty or damaged or if the trolley is operated on a sloping, slippery or uneven surface.
2. Discussion of the Prior Art
A number of attempts have been made to overcome the problem of controlling such trolleys. European Patent application No. A2 0 352 647 Wanzl Metallwarenfabrik GmbH, discloses a stackable (nestable) shopping trolley having four guide castors at the comers of the frame of the trolley and having one (or more) support castors or wheels located under the centre of the frame. The support castors or wheels are spring biased to press onto the ground to prevent the trolley rolling sideways on an incline. The castors or wheels are hinged to move out of the way when the shopping trolley is nested with other similar trolleys. Australian Patent No. 589,046 (European 0 267 817) Ostosvaunuholto Oy, discloses a trolley having four castors and a fifth wheel (or pair of wheels) at about the centre of the frame of the trolley.
The trolley has a bottom frame having all wheels or castors attached to it in which: the bottom frame is substantially “M” shaped in plan view; the tour castors and the fifth wheel(s) are not coplanar such that e.g. the front or rear castors do not touch at the same time on a flat surface. The fifth wheel is thus not spring biased. The arrangement is designed to overcome the difficulty of steering trolleys which becomes greater as the load on the trolley becomes greater. Australian Patent Application No. 42540193, Lloyd discloses a five castor trolley in which the fifth “central” castor can be simply automatically locked against vertical axis rotation during use and unlocked when it is desired to move the trolley sideways. Australian Patent Application No. 51532/93 Feron Investments Limited, primarily discloses a trolley with castors in which the axes of the castors may be varied from the vertical in any one or more of the forward, rearward or sideways directions. The specification also discloses the possible use of a fifth castor which is only disclosed as being situated between the front castors.
Australian Patent No. 640,700 Lovie & Grantham, discloses a castor lockable about the vertical rotation axis similar to Lloyd above. Australian Patent No. 573,843, Kart Gard Internationale, Inc., discloses a shopping cart security device in which a fifth wheel drops and locks automatically when the trolley is pushed over a hump which makes the trolley difficult then to control. British Patent Application No. 2,052,399, Cheddar Valley Engineering Limited, discloses a nestable trolley with a “V” frame and a hinged rectangular base with two fixed wheels on the arms of the “V” at about the pivot between the base and the frame and two castors on the opposite ends of the base with a fifth castor at the point of the “V” of the frame. The two castors provide stability to the triangular configuration of the fixed “V” frame wheels and the fifth castor under load. U.S. Pat. No. 4,456,273, McKinnon, discloses a trolley frame of “M” plan configuration in which the two side arms of the frame can pivot to abut the middle arms of the “M” frame. McKinnon does not disclose a fifth wheel assembly. None of the above appear to have solved adequately the problem of controlling trolleys as there is still widespread use trolleys which merely have four castors and which, after a while become difficult to control and steer. Whilst the prior art discloses the use of a “fifth” wheel arrangement, none of the prior art discloses or suggests the use of a fifth fixed wheel assembly which includes bias means to bias the fifth wheel towards surface on which the trolley is travelling and damping means to control the effect of the bias means or a single bias and damping means combination.
BRIEF DISCLOSURE OF THE INVENTION
It has unexpectedly been found that the provision of a trolley control wheel assembly with a combination of damped bias means to a trolley allows excellent control of the trolley as compared to presently used trolleys without such an assembly. The control wheel assembly controls the direction of travel of the trolley over and above the influence of the castors. The control wheel assembly includes a fixed wheel means which includes a wheel which is able to rotate about it's hub axis but is not able to rotate about a vertical axis as can a castor.
The present invention therefore provides in one preferred form a trolley control wheel assembly adapted to be fitted to a trolley having a longitudinal axis of travel and an array of castors, which assembly includes a fixed wheel or wheels positioned at or near the load centre of the trolley or at or near the centre of the array and which includes a bias means and a damping means to provide controlled contact between the wheel or wheels and a surface on which the trolley is intended to travel. The present invention also provides in another preferred form a trolley having a longitudinal axis of travel and having an array of castors fitted thereto and a trolley control wheel assembly which includes a fixed wheel or wheels positioned at or near the load centre of the trolley or at or near the centre of the array and which includes a bias means and a damping means to provide controlled contact between the wheel or wheels and a surface on which the trolley is intended to travel. The present invention also further provides, in a trolley having a longitudinal axis of travel and having an array of castors on which the trolley can be moved from place to place in the general direction of the longitudinal axis of the trolley or otherwise, the improvements which comprises the provision of a control wheel assembly, which assembly includes a fixed wheel or wheels positioned at or near the load centre of the trolley or at or near the centre of the array and which includes a bias means and a damping means to provide controlled contact between the wheel or wheels and a surface on which the trolley is intended to travel. Preferably the load centre of the trolley and the centre of the array of castors coincide. The force exerted on the control wheel by the damped bias means is not so excessive as to lift any of the trolley castors off the travel surface when the trolley is unloaded. In other words, the force of the bias means must not exceed the weight of the empty trolley. Preferably, the force of the bias means is independent of the load on the trolley. Preferably the bias means and the damping means are jointly provided by a gas strut. Preferably the trolley has four castors preferably disposed at or near the corners of the trolley or disposed effectively at or near the corners of the trolley. Preferably the array of castors includes four castors. Preferably, in order to facilitate lateral manoeuvring of a trolley there is preferably provided a lifting means to lift the wheel of the control wheel assembly out of contact with the floor or other travel surface to enable the trolley to be more readily moved at right angles to the customary desired directio
Bottorff Christopher
Crowell & Moring LLP
Swann J. J.
Work Systems Technology Pty Ltd.
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