Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION:
ladder levelling device
NAMES OF INVENTORS:
Harold Anthony Ernest Beck
Jason Todd Anthony Beck
FIELD OF THE INVENTION
The present invention relates to a ladder levelling device
BACKGROUND OF THE INVENTION
There is extensive patent literature relating to ladder
levelling devices. The ladder levelling devices generally
consist of a housing which is attachable to a ladder, a member
that is telescopically received in the housing and a locking
mechanism that locks the telescopic member in a selected
position in relation to the housing. The unique aspect of each
ladder levelling device generally centers upon their mode of
adjustment.
United States Patent 1,251,192 which issued to Drummond
in 1917, United States Patent 3,484,814 which issued to Meehan
in 1969, United States Patent 4,085,820 which issued to Cerny
in 1978 all use housings having a plurality of apertures spaced
at regular intervals. The corresponding locking mechanism
consists of locking members biased by springs into engagement
with the apertures. When the spring is compressed the members
retract permitting the telescopic member to move relative to
the housing.
United States Patent 1,329,740 which issued to Barron in
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1920, United States Patent 1,887,495 which issued to Carter in
1932, United States Patent 3,179,206 which issued to Studer in
1965, and United States Patent 3, 882, 866 which issued to Fasano
all use housings having a plurality stops. The corresponding
locking mechanism is a pivotally mounted lever biased by
springs into engagement with a selected one of the stops.
United States Patent 3,527,321 which issued to Brown in 1970
discloses a variation on the housing with stops. The
corresponding locking mechanism is a cantilever lever secured
at one end of a flat spring which biases the lever into
engagement with a selected one of the stops.
United States Patent 2,147,052 which issued to Noone in
1939 uses jaws that are clamped in interlocking engagement and
held in position by fasteners.
United States Patent 4,014,406 which issued to Easton in
1977 uses a rack within the housing that is engaged by a pair
of opposed inclined plane wedges forced locked in a selected
position by a compound lever.
United States Patent 4,423,797 which issued to Batten in
1984 extends locking pins through aligned apertures in the
housing and telescopic member.
United States Patent 4, 807, 720 which issued to Kim in 1989
uses a travel slot in the housing with a plurality of notches
designating locking positions. A latching pin travels along
the slot and is biased by a spring into engagement with a
selected one of the notches.
SUN~IARY OF THE INVENTION
What is required is ladder levelling device that has a
mode of adjustment that is fast and easy to use.
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According to the present invention there is provided a
ladder levelling device which includes a housing, a telescopic
member and a lever. The housing has an interior cavity, a
first end, a second end, a ladder attachment side, an opposed
side, an bearing edge and an opposed edge. A plurality of
bearing profiles are positioned at spaced at intervals in the
bearing edge. Means is provided for securing the ladder
attachment side of the housing to a ladder. The telescopic
member is telescopically received in the interior cavity of the
housing. The telescopic member has an interior cavity, a
handgrip end, a ground engaging end, a ladder facing side, an
opposed side, an aperture bearing edge and an opposed edge.
The telescopic member is longer than the housing. The handgrip
end extends past the first end of the housing. The ground
engaging end extends past the second end of the housing. An
aperture is provided in the aperture bearing edge of the
telescopic member at an intermediate position between the
handgrip end and the ground engaging end. A lever access
opening extends through the opposed side of the telescopic
member at the handgrip end. The lever is positioned within the
interior cavity of the telescopic member. The lever has a
mounting end and a gripping end. The mounting end of the lever
is pivotally mounted at the ground engaging end of the
telescopic member. The gripping end of the lever is accessible
through the lever access opening at the handgrip end of the
telescopic member. A contact member is carried by the lever
at an intermediate position between the mounting end and the
gripping end. The lever is pivotable between a locking
position and a release position. In the locking position the
contact member carried by the lever extends through the
aperture in the telescopic member and engages one of the
plurality of bearing profiles in the housing. In the release
position, the contact member is retracted from the bearing
profiles in the housing. Means is provided for biasing the
lever into the locking position.
The ladder levelling device, as described above, can be
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rapidly adjusted by merely pulling on the gripping end of the
lever. The lever provides a mechanical advantage reducing the
force required a to make the adjustment . When ladder levelling
device is lifted off the ground, telescopic member falls by
force of gravity when lever is in the release position.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more
apparent from the following description in which reference is
made to the appended drawings, wherein:
FIGURE 1 is an exploded perspective view of a ladder
levelling device constructed in accordance with the teachings
of the present invention secured to a ladder.
FIGURE 2 is a partially cut away front elevation view of
the ladder levelling device illustrated in FIGURE 1.
FIGURE 3 is side elevation view, in section, of the ladder
levelling device illustrated in FIGURE 1 in a locking position.
FIGURE 4 is side elevation view, in section, of the ladder
levelling device illustrated in FIGURE 1 in a release position.
FIGURE 5 is side elevation view of the ladder levelling
device illustrated in FIGURE 1 with an ice pick in a stored
position.
FIGURE 6 is side elevation view of the ladder levelling
device illustrated in FIGURE 1 with the ice pick in a ground
engaging position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment, a ladder levelling device
generally identified by reference numeral 10, will now be
described with reference to FIGURES 1 through 6.
Referring to FIGURES 3 and 4, ladder levelling device 10
includes a housing 12, a telescopic member 14 and a lever 16.
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The housing 12 has an interior cavity 18, a first end 20, a
second end 22, an aperture bearing edge 24 and an opposed edge
26. A plurality of apertures 28 are spaced at intervals along
aperture bearing edge 24. Referring to FIGURE 2, housing 12
5 has a ladder attachment side 30 and an opposed side 32. Bolts
34 extend from ladder attachment side 30 of housing 12 whereby
housing 12 is attached to a ladder 36 and secured in position
by nuts 38. Referring to FIGURES 3 and 4, the telescopic
member 14 is telescopically received in interior cavity 18 of
housing 12. Telescopic member 14 has an interior cavity 40,
a handgrip end 42, a ground engaging end 44, an aperture
bearing edge 46 and an opposed edge 48. Telescopic member 14
is longer than housing 12. Handgrip end 42 extends past first
end 20 of housing 12. Ground engaging end 44 extends past
second end 22 of housing 12. A single aperture 50 is
positioned in aperture bearing edge 46 of telescopic member 14
at an intermediate position between handgrip end 42 and ground
engaging end 44. Referring to FIGURE 2, telescopic member 14
has a ladder facing side 52 and an opposed side 54. Referring
to FIGURE 3 and 4, a lever access opening 56 extends through
opposed side 54 of telescopic member 14 at handgrip end 42.
Telescopic member 14 has shoulders 58 and 60 located at
handgrip end 42 and ground engaging end 44, respectively.
Shoulders 58 and 60 serve as stops to limit the travel of
telescopic member 14 relative to housing 12. Lever 16 has a
slight dogleg bend. Lever 16 is positioned within interior
cavity 40 of telescopic member 14. Lever 16 has a mounting end
62 and a gripping end 64. Mounting end 62 of lever 16 is
pivotally mounted by pivot pin 66 at ground engaging end 44 of
telescopic member 14. Gripping end 64 of lever 16 is
accessible through lever access opening 56 at handgrip end 42
of telescopic member 14. A locking pin 68 is carried by lever
16 at an intermediate position between mounting end 62 and
gripping end 64. Lever 16 is pivotable between a locking
position illustrated in FIGURE 3 and a release position
illustrated in FIGURE 4. Referring to FIGURE 3, in the locking
position locking pin 68 carried by lever 16 extends through
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single aperture 50 in telescopic member 14 and engages one of
plurality of apertures 28 in housing 12. Referring to FIGURE
4, in the release position locking pin 68 is retracted from
apertures 28 of housing 12. A spring 70 is disposed in
interior cavity 40 of telescopic member 14, biasing lever 16
into the locking position. Referring to FIGURES 5 and 6, an
optional additional features is the provision of ice pick plate
72. Ice pick plate 72 is pivotally mounted to ground engaging
end 44 of telescopic member 14 for movement between a ground
engaging position illustrated in FIGURE 6 and a stored position
illustrated in FIGURE 5.
The use and operation of ladder levelling device 10 will
now be described with reference to FIGURES 1 through 6.
Referring to FIGURES 1 and 2, ladder levelling device 10 is
secured to ladder 36 by drilling holes 74 through ladder 36 and
inserting bolts 34 which extend from ladder attachment side 30
of housing 12 through holes 74. Bolts 34 are then secured in
position by nuts 38. Referring to FIGURE 3, spring 70 biases
lever 16 into the locking position. In the locking position,
locking pin 68 carried by lever 16 extends through single
aperture 50 in telescopic member 14 and engages one of
plurality of apertures 28 in housing 12. Referring to FIGURE
4, in order to move lever to the release position a person must
reach through lever access opening 56, grip gripping end 64 of
lever 16 and move lever 16 to overcome the biasing force of
spring 70. In the release position, locking pin 68 is
retracted from apertures 28 of housing 12. It should be noted
the ease of adjustment with lever 16, as compared to the means
3 0 of adj ustment taught in the prior art . Lever 16 provides a
mechanical advantage making it easier to overcome the biasing
force of spring 70. This also enables a more powerful spring
to be used for spring 70 without adversely effecting a persons
ability to make adjustments. Referring to FIGURE 2, there is
illustrated an uneven surface provided by a set of stairs 76,
where ladder levelling device 10 is required to stabilize
ladder 36. There are two environments, in particular, where
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ladder levelling devices sometimes have problems. One
environment is on narrow stairs. Each of ground engaging ends
44 of telescopic member 14 have inwardly extending base plates
78. Base plates 78 provide for greater stability on narrow
stairs, where one of ground engaging ends 44 would otherwise
be teetering on an edge of the stair. Another environment is
on ice, where ground engaging ends 44 of ladder 36 are in
danger of sliding. Ice pick plate 72 is pivotally mounted to
ground engaging end 44 of telescopic member 14 for movement
between a ground engaging position illustrated in FIGURE 6 and
a stored position illustrated in FIGURE 5. In most situations
in will remain in a stored position. When ice is encountered,
ice pick plate 72 is pivoted to the ground engaging position
illustrated in FIGURE 6 to prevent ladder levelling device 10
from slipping on ice.
It will be apparent to one skilled in that art that other
types of contact member can be substituted for locking pin 68.
It will also be apparent to one skilled in the art that blind
bores, slots, grooves, and other types of bearing profiles can
be substituted for apertures 28 in housing 12. It will further
be apparent to one skilled in that art that it may be desirable
to configure lever access opening 56 along one edge so as to
preclude the entry of dirt into telescopic member 14. It will
finally be apparent to one skilled in the art that
modifications may be made to the illustrated embodiment without
departing from the spirit and scope of the invention as
hereinafter defined in the Claims.
