CA2274330A1

CA2274330A1 - Level lad

Info

Publication number: CA2274330A1
Application number: CA 2274330
Authority: CA
Inventors: James Boyd Batten
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-06-03
Filing date: 1999-06-03
Publication date: 2000-12-03

Abstract

In a device to make adjustable the relative length of the side-rails of a ladder, to facilitate use on non-level supporting surfaces, a lockable, releasable, longitudinally slidable leg is attached to a side-rail by one or more bracket arrangements which freely embrace the sliding leg and provide a mounting base for attaching a lever hawing an eccentric cam that can optionally bind the sliding leg between that cam and the side-rail of a ladder. When the lever is moved to force the eccentric cam against the slidable leg until the eccentric is very slightly past it's point of highest compression, it is located in this position in it's arc around the lever fulcrum because being past the point of highest compression it tends to move on, away from that point towards a point of lower compression but is prevented from doing so because the lever handle has contacted the slidable leg also. To release this compressed locking action the operator applies force on the lever in the opposite direction to force the eccentric back past the point of highest compression and on to release the compression as desired. In this invention the strength of the operator is greatly augmented by the mechanical advantage of the lever when the lever is manipulated by simple movements in a single plane. This device is adaptable for use on many ladder designs as the bracket arrangements may be attached to side-rails of a ladder without interfering with operation of normal extension ladders while the brackets array be sized to fit smaller side-rails and may be expanded to fit larger ladder side-rails on installation by inserting appropriate spacer shims and washers between bracket parts and lever assemblies. The sliding leg may be made from material of sufficient size and strength and may be shaped so one end view would reveal a simple capital letter "L" form to allow convenient slidability along side-rails of various widths. This invention may be manufactured, installed and used without complicated machinery and highly skilled labour.

Description

Level-Lad I have re-designed the ladder leg length adjusting device in view of the e~: i sti ng patents.
I believe this new system will avoid impinging on the ef.isting patents both in Canada and the ~J.S. for these reasons:
1. This system can easily be added to e>:isting ladders as well as to ladders in the Mfg. process as the attachment brackets are conducive to a limited amount of suing through bending and/or the u=a of spacers or shims. It can bc.sold as a separate ~~'.1T;
. The operation does not require tightening of threaded parts and c~,n be operateo' with one hand with a single LEVER movement;
_. It is sa-~er because if lever is not held gravity returns it t;~war-~~s t he 1 oc~::i s,g posi t i on where i t i s desi gned to engage the Sliding leg a;,d r-c~Il the cam toward the loc~:ing position with increasing friction if load is appiisd to the OVER-CENTER GAM.
4. Adjustment of the leg length will ideal?y consist of placing the ladder in position for use, raising tl-,e lever with one hand from a standing position, allowing the weight of the ladder or the ~aei gh t of the e,. tendi ng 1 eg to detcrmi ne the e;: tensi on di=tance for the leg and depr~~ssing ~~r allowing the locking lever to fall towards tha locking position.

Claims

1. A manually operable device for adjusting the relative length of the lower ends of rung supporting side-rails of a ladder to allow easy stabilisation, in position for climbing, of a ladder used on sloping or uneven supporting surfaces. This device comprises an optionally slidable leg mounted on an optionally shortened lower ladder side-rail, one or more sets of sizably adjustable two part brackets adaptable to embrace freely the slidable leg to attach it to the side-rail of a ladder, and a manually operated levered cam-lock mounted on a bracket to lock in any position within the range of travel, or optionally unlock, the slidable leg which slides between the levered cam and the side-rail of the ladder.

2. A device as defined in claim 1, in which the slidable leg has a capital letter "L" shapes when viewed from one ends to allow installation on any ladder having a conventional side-rail of any common width. This leg has sufficient length and is capable of being slid outwards and inwards optionally to allow the desired range of adjustment of the relative length of the lower ends of the rung supporting side-rails of a ladder.

3. A device as defined in claim 1, the levered cam-lock is the locking means. The cam-lock is comprised of an eccentric which is an integral part of a lever fabricated so that operation of the lever causes the eccentric to move in an arc around the fixed fulcrum of the lever. The levered eccentric or "cam" is adapted to attach to the snide-rail by means of adjustably sizable two-part brackets which are mounted on the ladder siderails and which freely embrace the slidable leg.

4. A device as defined in claim 3, in which the process for making the levered cam-lock consists of bending appropriately sized metal flat-bar around pre-shaped forms to create a shoulder or eccentric in an oval like part circle a formed at about the middle of the flat-bar but at one end of the forming levered cam-lock. Both ends of the flat-bar, coming together at the opposite end of the levered cam-lock from the eccentric, have a cylinder of metal tubing pressed over them to form a handle of appropriate length, leverage and strength. A shorter length of flat-bare that has an inverted capital letter "U" shaped loop formed near one end, provides a means of attaching the completed levered cam-loch:
to the two-part mounting bracket. The position of the fulcrum of the lever is established when the shorter flat-bar with the "U"
shaped loop is fastened to the upper surface of the levered cam-lock with the "U" inverted. The levered cam is attached to the two part bracket, that also freely embraces the slidable leg, by a hinge-pin inserted through holes in the mounting surfaces of the bracket and through the aperture created by the inverted "U"

shaped flat-bar fastened to the levered eccentric so that the finished and installed levered cam-lock is between the two-part bracket surfaces with the eccentric of the cam-lock toward the slidable leg.

5. A device as defined in claim 1, in which a two-packet bracket assembly is designed to mount a slidable leg by freely embracing that leg while holding the leg in place against the side-rail of a ladder and allowing the levered cam-lock to be mounted so as to allow it to optionally lock the slidable leg in any position. The forms of both bracket parts may be pressed into pre- dimensioned "off the shelf" metal flat-bar into a pre-established form in a forming receptacle. The bracket assembly is made in two-parts to function with the capital letter "L" shape of the slidable leg, to allow the leg length adjusting device to be mounted on ladder side-rails of different dimensions. The two-part bracket assembly is mounted on the side-rail so that it does not obstruct the free movement of extending or retracting the sections of an extension ladder.

6. A device as defined in claim 1, permitting this device full function for ground or other ladder supporting surfaces sloping in all lateral directions, includes optional shortening of the ladder side-rail on which the slidable leg lengthening device is mounted and or optional lengthening of the side-rail which is not adjustable by the addition of a section of "U" shaped channel.
Above described lengthening and/or shortening permits the ladder side-rail made adjustable in length to be retracted to be shorter as well as to be extended longer than the ladder side-rail that is not adjustable as to it's length.