Miscellaneous hardware (e.g. – bushing – carpet fastener – caster – Casters – Pintle retainers
Patent
1997-07-16
1999-08-31
Mah, Chuck Y.
Miscellaneous hardware (e.g., bushing, carpet fastener, caster,
Casters
Pintle retainers
16 35D, B60B 3300
Patent
active
059437359
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a shopping trolley, a castor for a shopping trolley and to a kit of parts for fitting to such a castor.
Shopping trolleys are well known for being difficult to steer. If either or both the castors at the rear of the trolley is or are provided with a device operable to provide steering assistance which comprises spring loading means operable to allow swivelling of the castor when it is not in line but which acts when the castor comes into line to resist swivelling out of line and which comprises a spring which acts continuously on a cam, the spring will be continuously under load which is undesirable and there will always be some friction in the system even when free swivelling is required. CH-A-607958, U.S. Pat. No. 4,246,677, U.S. Pat. No. 4,280,246, FR-A-2488190 and DE-A-3136203 disclose various forms of steering aids for castors which comprise some such form of continuously loaded spring arrangement.
An object of this invention is to provide an aid to steering a shopping trolley which is automatically operable in that it does not require any operating function by the shopper, which is capable of being fitted to existing castors without a need to modify the structure of the castor itself, and which does not suffer from the disadvantages referred to above.
According to one aspect of this invention there is provided a castor for a shopping trolley, comprising a swivel body, a fixing component by which the castor is to be fixed to the respective leg of the shopping trolley, and means operable to resist angular displacement of the swivel body relative to the fixed component from a substantially dead centre position, the means comprising a spring-loaded capture device which comprises means carried by the swivel body which define a capture recess and cam means mounted on the fixing component, the spring-loaded capture device being operable to capture the cam means in the capture recess in the substantially dead centre position, wherein the castor is for a rear wheel of the shopping trolley and the cam means comprise a cam having a lobe the spring-loaded capture device being operable to capture the lobe, in the recess in the substantially dead centre position, the spring loading being operable to allow engagement and disengagement of the lobe from the recess at either end of a limited range of angular movement which extends on either side of the dead centre position and to resist angular movement of the capture device relative to the cam when the lobe is engaged within the recess, there being a substantially friction free clearance around the cam and its lobe for a substantial part of the range of swivelling movement of the swivel body relative to the fixing component when the lobe is disengaged from the recess and the spring of the spring-loaded capture device is relaxed so that the swivel body is free for substantially friction free swivelling movement relative to the fixing component for the substantial part of its full range of swivelling movement.
Preferably the spring-loaded capture device is provided with at least two resiliently deflectable side members formed outwith the recess, each of said side members being adapted such that the lobe can engage therewith, so that when the lobe is so engaged with one of the side members, the angular movement of the capture device is resiliently resisted, the spring-loading being such that it is operable to allow engagement or disengagement of the lobe from the side member, the arrangement being such that the swivel body is free for substantially friction free swivelling movement relative to the fixing component when the lobe is disengaged from both the recess and the side members.
Preferably the capture device comprises a closed generally rectangular figure which extends around the cam, each side of the closed generally rectangular figure comprising a resilient slat, a respective one of which has an arcuate portion which forms the recess, with the resilient side members being placed on the sides adjacent said respective one and symmetrically
REFERENCES:
patent: 4212093 (1980-07-01), Lombard
patent: 4399587 (1983-08-01), Penifaure
patent: 5727285 (1998-03-01), Goman
Walker Doris Jessie
Walker Phillip Stuart
Walker Stuart Charles
Browning Clifford W.
Flexello Limited
Mah Chuck Y.
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