ROLLING OR SKIDDING PLATFORM LADDER
A rolling or skidding platform ladder 1 is provided that has a platform ladder part 3 and an undercarriage part 5. The undercarriage part 5 carries ground engaging parts 21 to enable rolling or skidding of the ladder 1. The platform ladder part 3 has legs 7/9 which are raisable with the platform ladder part 3 to elevate the bottom of the legs 7/9 spaced from the ground when the platform ladder 1 is to be rolled or skidded. The undercarriage part 5 comprises a lever arm 29 that is pivoted thereto in a see-saw manner so as to extend generally parallel with the ground. One end of the lever arm 29 is for co-operating with the ladder part 3 to raise at least two legs of the ladder part 3 relative to the undercarriage part 5 so that the rolling ladder 1 can then be rolled or skidded without the at least two raised legs engaging the ground.
This application is based on and claims the benefit of the filing dates of Australian application no. 2006905878 filed 23 Oct. 2006 and U.S. application No. 60/868589 filed 5 Dec. 2006, the contents of which are incorporated herein by reference in the entirety.
FIELD OF THE INVENTIONThis invention relates to a rolling or skidding platform ladder (hereinafter referred to as “rolling ladder”), and relates particularly but not exclusively to a rolling ladder manufactured from aluminium.
BACKGROUND ARTHitherto, rolling platform ladders have been known. One particular form of rolling platform ladder has a mechanism at the base of the ladder which allows the ladder part to be elevated relative to an undercarriage part so that the rolling ladder can be rolled or skidded on the undercarriage without the legs of the ladder impeding the general rolling or skidding movement. Such ladders have use in warehouses or other establishments where products are stored in racks or on high shelves. The known rolling ladder has a parallelogram arrangement for connecting the ladder part with the undercarriage part. Thus, in order to raise or lower the ladder part relative to the undercarriage part, the parallelogram swings to either extend or collapse. Thus, in turn, causes a corresponding raising or lowering of the ladder part. A clip arrangement is provided to hold the ladder part in the raised position. When the ladder is to be stood upon, the clip is unclipped so it releases its hold on the parallelogram arrangement, and the ladder moves downwardly so that the legs thereof engage with the ground. The mechanism is complicated and often subject to unintended collapsing operation when the platform ladder is pushed with extreme force in order to move the platform ladder.
OBJECT AND STATEMENTS OF THE INVENTIONThere is a need for an alternative platform ladder.
Therefore, according to a first broad aspect of the present invention there is provided a rolling or skidding platform ladder (hereinafter referred as rolling ladder) comprising a platform ladder part and an undercarriage part, said undercarriage part carrying ground engaging parts to engaging with the ground during rolling or skidding of the rolling platform ladder,
said platform ladder part having legs for engaging with the ground when the ladder is to be climbed upon, said legs being raisable with the platform ladder part from the undercarriage part to elevate the bottom of the legs spaced from the ground when the platform ladder is to be rolled or skidded,
said undercarriage part comprising a lever arm pivoted thereto by a pivot in a see-saw manner so as to extend generally parallel with the ground, one end of the lever arm being for co-operating with the ladder part to raise at least two legs of the ladder part relative to the under carriage part when the opposite end of the lever arm is moved in a direction downwardly, so said rolling ladder can then be rolled or skidded without the at least two raised legs of the ladder part engaging the ground.
The raised legs of the ladder part can be moved to engage the ground by a person standing on the ladder part using their weight to cause the lever arm to swing and the opposite end of the lever arm to be raised by swinging in a direction upwardly.
The undercarriage part is generally of rectangular shape in plan view and is at a lowermost part of the ladder part, and extends between sides of the ladder part and front and rear legs of the ladder part, and directly above generally horizontally extending leg braces of the legs of the ladder part which are adjacent the ends of the legs of the ladder that engage the ground and which interconnect front and rear legs of the ladder part,
said undercarriage part carrying vertically downwardly extending pins fixed thereto which penetrate apertures associated with the leg braces, said pins carrying respective ground engaging wheels or skids at their ends closest to the ground.
The undercarriage part has the lever arm positioned generally midway between the two sides of the ladder part, and adjacent thereto a further lever arm pivoted to the undercarriage part by a further pivot, said pivot being at a front of the ladder part and said further pivot being at a rear of the ladder part, said further lever arm being also pivoted in a see-saw manner to said undercarriage part so as to extend generally parallel to the ground, one end of the further lever arm being for co-operating with the ladder part to raise the other two legs of the ladder part relative to the under carriage part when the opposite end of the further lever arm is moved in a direction downwardly.
In order that the invention can be more clearly ascertained an example of an embodiment will now be described with reference to the accompanying drawings wherein:
Referring to all the figures generally, it can be seen that the rolling or skidding platform ladder 1 (hereinafter referred to as a “rolling ladder”), comprises a platform ladder part 3 and an undercarriage part 5. The ladder part 3 has front legs 7, rear legs 9, and leg braces 11. The leg braces 11 extend generally horizontally adjacent the ends of the legs 7, 9 that engage the ground. These braces 11 interconnect the front legs 7 with the rear legs 9 of the ladder part 3. The undercarriage part 5 has a generally rectangular configuration as shown in
The undercarriage part 5 is made from elongate metal such as aluminium tube of rectangular transverse cross section and has ground engaging parts 21 for engaging with the ground during rolling or skidding of the rolling platform ladder. In this example, the ground engaging part 21 comprise four vertically downwardly extending steel pins 23 that penetrate respective apertures (not shown) in the leg braces 11. The pins 23 are best shown in
The undercarriage part 5 has a lever arm 29 pivoted thereto by a pivot pin 31 that passes through an upstanding post 33 at a forward end 35. The pivot pin 31 supports the lever arm 29 in a generally horizontally disposed condition and so the lever arm 29 can swing in a see-saw fashion about the pivot pin 31.
It should be noted that as the lever arms 29/39 move in a direction downwardly (as shown in
It should be appreciated that the raising and/or lowering of the ladder part 3 is effected by operation of the lever arms 29/39 and/or by a person standing on the ladder part 3. This provides enhanced safety relative to the prior platform ladders where the undercarriage part is carried by a parallelogram mechanism and wherein the raising and/or lowering of the ladder part relative to the undercarriage part is effected by swinging of the parallelogram. In such cases, the mere pushing of the ladder can effect an unintended dislodgement of the ladder part being maintained in a position where the legs do not contact the ground.
Modifications may be made to the invention as would be apparent to persons skilled in the art of producing rolling ladders or other sheet metal like products. For example, whilst the rolling ladder 1 has been described as being made from aluminium, it may be made from other metals such as mild steel. Aluminium is preferable because of its lightness. Whilst the lever arms 29/39 have been shown so that their free ends are within the confines of the front legs 7 and rear legs 9, it may be possible to cause them to extend across the front legs 7 and/or rear legs 9 so that a person may engage their foot therewith from either the front of the ladder, or the rear of the ladder. In addition, whilst the lever arms 29 and 39 are shown positioned generally midway between the left and right hand sides of the ladder, they may be positioned to one side or the other. Further, whilst the lever arms 29 and 39 are shown to engage with the ladder part by the use of pressing bars 37 and 47, there may be a physical link connection directly with the front legs 7 and the rear legs 9 such as by pins locating in arcuate shaped slots that generally follow the path of swinging of the ends of the lever arms 29 and 39 at the ends that engage with the ladder part. Further, the lever arms 29/39, may be suitably shaped and positioned to engage with the ladder part 3 directly without the use of the pressing bars 37/47. The pressing bars 37/47 however, distribute forces to the ladder part 3 over a greater surface area than if they were not provided.
In the examples shown, the ground engaging parts 21 are provided with castor wheels 65 to permit rolling movement of the platform ladder. Alternatively, the ground engaging part 21 may be provided with skid feet.
These and other modifications may be made without departing from the ambit of the invention the nature of which is to be determined from the foregoing description.
It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.
In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
Claims
1. A rolling or skidding platform ladder (hereinafter referred as rolling ladder) comprising a platform ladder part and an undercarriage part, said undercarriage part carrying ground engaging parts to engaging with the ground during rolling or skidding of the rolling platform ladder,
- said platform ladder part having legs for engaging with the ground when the ladder is to be climbed upon, said legs being raisable with the platform ladder part from the undercarriage part to elevate the bottom of the legs spaced from the ground when the platform ladder is to be rolled or skidded,
- said undercarriage part comprising a lever arm pivoted thereto by a pivot in a see-saw manner so as to extend generally parallel with the ground, one end of the lever arm being for co-operating with the ladder part to raise at least two legs of the ladder part relative to the under carriage part when the opposite end of the lever arm is moved in a direction downwardly, so said rolling ladder can then be rolled or skidded without the at least two raised legs of the ladder part engaging the ground.
2. A rolling ladder as claimed in claim 1, wherein the raised legs of the ladder part can be moved to engage the ground by a person standing on the ladder part using their weight to cause the lever arm to swing and the opposite end of the lever arm to be raised by swinging in a direction upwardly.
3. A rolling ladder as claimed in claim 1, wherein the undercarriage part is generally of rectangular shape in plan view and is at a lowermost part of the ladder part, and extends between sides of the ladder part and front and rear legs of the ladder part, and directly above generally horizontally extending leg braces of the legs of the ladder part which are adjacent the ends of the legs of the ladder that engage the ground and which interconnect front and rear legs of the ladder part,
- said undercarriage part carrying vertically downwardly extending pins fixed thereto which penetrate apertures associated with the leg braces, said pins carrying respective ground engaging wheels or skids at their ends closest to the ground.
4. A rolling ladder as claimed in claim 1, wherein said undercarriage part has the lever arm positioned generally midway between the two sides of the ladder part, and adjacent thereto a further lever arm pivoted to the undercarriage part by a further pivot, said pivot being at a front of the ladder part and said further pivot being at a rear of the ladder part, said further lever arm being also pivoted in a see-saw manner to said undercarriage part so as to extend generally parallel to the ground, one end of the further lever arm being for co-operating with the ladder part to raise the other two legs of the ladder part relative to the under carriage part when the opposite end of the further lever arm is moved in a direction downwardly.
5. A rolling ladder as claimed in claim 4, wherein the opposite ends of the lever arm and further lever arm, are interconnected by a common pivot, so when one is moved downwardly or upwardly, it will cause the other to move in a corresponding direction.
6. A rolling ladder as claimed in claim 5, wherein the opposite ends of the lever arm and the further lever arm carry a person's foot engaging surface,
- said lever arm and said further lever arm being pivoted to each other generally midway between a front and a rear of the undercarriage part, whereby a user can place his foot within the ladder part between the front legs and rear legs and press either one of the foot engaging surfaces with his foot to cause both the lever arm and the further lever arm to move in a direction downwardly.
7. A rolling ladder as claimed in claim 3, wherein there are four vertically downwardly extending pins, each being positioned on the undercarriage part to be adjacent a respective one of four legs of the ladder part, so that there will be a wheel or a skid adjacent each of the four legs.
8. A rolling ladder as claimed in claim 6, wherein the lever arm and the further lever arm are pivoted to each other and to the front and rear of the undercarriage so that when the lever arms are moved to pass each other, during moving in a downward or upward direction, there will be a flexing of a front and a rear of the undercarriage part in a direction outwardly of the undercarriage part, said flexing providing a bias force to cause snap movement of the lever arm and further lever arm as the lever arm and further lever arm move to pass each other.
9. A rolling ladder as claimed in claim 8 wherein the undercarriage part is fabricated from elongate metal.
10. A rolling ladder as claimed in claim 1, wherein the ladder part carries a slidable sheet like member,
- said slidable sheet like member being supported in a generally horizontal plane by generally horizontal extending guide rails under the upper tread surface of the ladder part, and wherein the slidable sheet like member can slide along said rails so that one side thereof is positioned outwardly of the steps of the ladder, whereupon the one side can be swung downwardly to overlie one or more treads of the ladder and to act as a visual indicator that the rolling ladder is closed for use.
11. A rolling ladder as claimed in claim 10, wherein the slidable sheet like member has fingers extending from side edges thereof, said fingers being received in a channel in the guide rails and being at both ends of the slidable sheet like member, and such that when the slidable sheet like member is slid so that the one side thereof is positioned outwardly, the fingers remaining in the channels will act like a hinge to allow the slidable sheet like member to swing thereabout to overlie the one or more treads.
Type: Application
Filed: Oct 22, 2007
Publication Date: Apr 24, 2008
Inventors: Danny FROLIK (Rye), Scott Jacobsen (Sandringham)
Application Number: 11/876,265
International Classification: E04G 3/28 (20060101);