LEVEL LAD

DISPOSITIF A NIVEAU REGLABLE POUR MONTANTS D'ECHELLE

English 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.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
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.

Description

CA 02274330 1999-06-03
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.

Representative Drawing