Fire escape – ladder – or scaffold – Ladder – Supporting surface compensating means
Patent
1989-11-27
1991-02-19
Machado, Reinaldo P.
Fire escape, ladder, or scaffold
Ladder
Supporting surface compensating means
E06C 744
Patent
active
049935143
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a ladder levelling device.
According to the present invention a ladder levelling device is characterised by the combination of a carrier structure capable of attachment to a ladder and adapted releasably to receive the feet of the ladder in a sliding fit at spaced apart stations on the structure, said structure incorporating fixedly mounted first interconnect means extending substantially linearly between said stations, first and second adjustably mounted ground-engaging means, and articulated linkage means connected to the first and second ground-engaging means and including second linearly extending interconnect means for releasably interconnecting with said first interconnect means, said second interconnect means extending parallel to said first interconnect means, each of said interconnect means comprising interconnect elements capable of connecting the second interconnect means to the first interconnect means at a selected one of a plurality of locations along the length of the first interconnect means, wherein the linkage means is resiliently biassed against said interconnection being effected in the absence of ladder weight being applied to said carrier structure, whereby to permit by selective interconnection of the first and second interconnect means verticality of a ladder when the ground-engaging means are supported by an inclined surface, with rigidity between the ground-engaging means and the carrier structure provided by said interconnection of the first and second interconnect means.
The first and second interconnect means may each take the form of a toothed rack or one may take the form of a rack whilst the other may take the form of a member having at least one tooth which is interengageable with the rack. Alternatively, one may take the form of a member defining a series of sockets whilst the other is in the form of a member having at least one spigot. A still further alternative is for one to take the form of a member defining a series of spigots whilst the other is in the form of a member having at least one socket.
Preferably the linkage means includes a stop member which, in the absence of ladder weight, supports the second interconnect member.
Preferably said first interconnect means and said second interconnect means each extend generally horizontally when the device is in use, the first interconnect means being substantially at right angles to the length of the ladder.
Preferably said ground-engaging means comprises a pair of feet members each pivotally mounted on the lower portion of the carrier structure. Alternatively the ground-engaging means may comprise a pair of feet members each slidably mounted on the carrier structure.
Preferably the carrier structure is of box-like configuration dimensioned to receive the ladder feet in a sliding fit.
Preferably the carrier structure incorporates clamp means for clamping to the ladder. The clamp means may clamp to the ladder feet or to a ladder rung or tread.
An embodiment of the present invention will now be described by way of example with reference to the accompanying drawing, in which:
FIG. 1 is a front view of a device according to the present invention;
FIG. 2 is a rear pictorial view of the FIG. 1 device; and
FIGS. 3, 4 and 5 schematically illustrate alternative versions of ladder levelling devices.
As is shown in the drawings a ladder levelling device 10 comprises a box-like carrier structure 11 having a front panel 11a, side panels 11B and a truncated rear panel 11C, the side panels being braced by a bar 12 which forms a platform for supporting the feet of a ladder (not shown) in the regions where the bar 12 meets with the side panels 11B, the depth and spacing of the panels 11B of the structure 11 being dimensioned to receive the ladder feet in a sliding fit.
As is shown in FIG. 1 the structure 11 has an upper portion to which is affixed a toothed rack 14 the teeth of which extend horizontally and are downwardly presented. The lower portion of the structure 11 supports ground-engaging means in the form
REFERENCES:
patent: 1088167 (1914-02-01), Osterhoudt
patent: 1424934 (1922-08-01), Paterson
patent: 2971602 (1961-02-01), West
patent: 3199629 (1965-08-01), Fagaly
patent: 3233702 (1966-02-01), Feltrop
patent: 4243122 (1981-01-01), Coutts
patent: 4456095 (1984-06-01), Hodson
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