EP2497894A1

EP2497894A1 - Leveling device of ladder

Info

Publication number: EP2497894A1
Application number: EP09851119A
Authority: EP
Inventors: Hae-Dong Lee
Original assignee: D&P TECH Inc
Current assignee: D&P TECH Inc
Priority date: 2009-11-03
Filing date: 2009-11-03
Publication date: 2012-09-12
Also published as: EP2497894A4; JP2013510251A; WO2011055863A1

Abstract

The present invention relates to a leveling device of a ladder, which includes: an upper guide plate and a lower guide plate formed with through-holes capable of being inserted by a rod and fixed to a vertical side frame of the ladder in the perpendicular direction thereto; a key provided in a vertical plate which connects the upper guide plate and the lower guide plate to the vertical side frame of the ladder, and protruding in the same direction with the upper guide plate and the lower guide plate protrude; a rod coupled in the through-holes of the upper guide plate and the lower guide plate to be able to slide by the weight thereof, a stopper plate formed in a plate shape with a clearance larger than the diameter of the rod, disposed between the upper guide plate and the lower guide plate and then inserted by the rod through the clearance, and having an edge extended toward the lower portion of the key to be pressed by the bottom surface of the key and inclined with respect to the rod as the key is applied with a downward force together with the ladder; and a spring positioned between the lower guide plate and the stopper plate to elastically bias the stopper plate in the key direction at all times.

Description

[Technical Field]

The present invention relates to a leveling device for a ladder, and more particularly, to a leveling device for a ladder which can maintain a level of a ladder on uneven ground such as sloping land or stairs.

[Background Art]

A ladder consists of a pair of vertical side frames between which are disposed a plurality of horizontal steps. The ladder is used to enable a user to temporarily climb up above the ground on which people normally walk.
In a conventional ladder, since both vertical side frames have the same length, lower ends of the vertical frames are in contact with level ground with uniform height so that there is no problem in using the ladder. However, the above ladder is disadvantageous in that, on sloping land or stairs, it is difficult to balance the ladder.

[Disclosure]

[Technical Problem]

The present invention is conceived to solve the above problem of a conventional ladder, an object of the present invention is to provide a leveling device for a ladder which can always keep the ladder level on sloping land or stairs, to enable the ladder to be utilized.
Another object of the present invention is to provide a leveling device for a ladder which can easily and independently change a length of each of the two vertical side frames of the ladder.

[Technical Solution]

In order to achieve the above objects, a leveling device for a ladder according to the present invention includes an upper guide plate and a lower guide plate formed with through holes into which a rod is inserted, and fixed to vertical frames of the ladder in a direction perpendicular to the vertical frames; a key provided on a vertical plate which connects the upper guide plate and the lower guide plate to the vertical frames of the ladder, the key protruding in the direction in which the upper guide plate and the lower guide plate protrude; the rod coupled in the through-holes of the upper guide plate and the lower guide plate to be able to slide by the weight thereof in the longitudinal direction of the ladder; plate-shaped stopper plates, each of which having a clearance into which the rod is inserted and an edge extended to a lower portion of the key, the stopper plate being disposed between the upper guide plate and the lower guide plate and the clearance being larger than a diameter of the rod, whereby the stopper plate is pressed by a bottom surface of the key and inclined with respect to the rod as a force is applied downward to the key as well as the ladder; and a spring positioned between the lower guide plate and the stopper plate to elastically bias the stopper plate toward the key at all times.
In a case where the leveling device for a ladder having the above structure is assembled to an outer surface, a front surface, or a rear surface of both vertical side frames of a ladder, if the user supports the weight of the ladder so that a load is not applied to the leveling device for the ladder, the rod does not slide, however, if the user draws out the rod by a length which is required for maintaining a level state of the ladder and then places the ladder to apply a load of the ladder to the leveling device for the ladder, the weight of the ladder is applied to the key of the leveling device for the ladder and the key eccentrically presses a portion of the stopper plate corresponding to the ladder to thereby rotate the stopper plate about the rod and incline the stopper plate toward the ladder, and an edge of the lower end of the clearance of the stopper plate applies a force to an outer surface of the rod in the rotational direction of the stopper plate, so that a pressure proportional to the weight of the ladder or the weight of the user climbing up the ladder is applied from the edge of the lower end of the clearance of the stopper plate to the rod in the rotational direction of the stopper plate. As a result, the rod does not slide, but halted.

[Advantageous Effects]

According to the present invention having the above structure and performing the function, there are advantages in that since the leveling device can easily and independently change a length of the vertical side frame of the ladder and fix the ladder in a state where the length is changed, the ladder can stay level on sloping land or stairs at all times, and in a case where lengths of both rods are equally changed to the same length and then fixed, the ladder can be used on level ground in a state where a length of the ladder is increased within a certain range.

[Description of Drawings]

FIG 1 is an exploded perspective view of a leveling device for a ladder according to the present invention;
FIG 2 is an assembled perspective view of the leveling device for a ladder shown in FIG 1;
FIG 3 is an exploded perspective view showing a disassembled state of the leveling device for a ladder shown in FIG 2 and a ladder;
FIG. 4 is a perspective view showing an assembled state of the leveling device for a ladder shown in FIG 2 and a ladder;
FIG. 5 and FIG 6 are views illustrating a method of using a leveling device for a ladder according to the present invention; and
FIG. 7 is a front perspective view of a leveling device for a ladder according to the present invention further including a device for releasing a stopper plate provided thereto.

* Reference numerals indicating major elements in the drawings *

1:: Leveling device for ladder
5:: Jaw
9:: Lower guide plate
13:: Key
21:: Spring
25:: Ball seat
29:: Ball
33:: Cover
37:: Subsidiary plate
45:: Hinge
3:: Rod
7:: Upper guide plate
11:: Vertical plate
19:: Clearance
23:: Foothold
27:: Ball head bolt
31:: Screw
35:: Screw hole
39:: Bolt hole
47:: Handle
49:: Handle supporting hole
101:: Vertical side frame
105:: Bolt hole
100:: Ladder
103:: Step

[Mode for Invention]

Hereinafter, a preferred embodiment of a leveling device for a ladder according to the present invention is described in detail with reference to the accompanying drawings.
FIG. 1 is an exploded perspective view of a leveling device 1 for a ladder according to the present invention, FIG 2 is an assembled perspective view of a leveling device 1 for a ladder shown in FIG. 1, FIG. 3 is an exploded perspective view showing a disassembled state of the leveling device for a ladder shown in FIG 2 and a ladder, and FIG. 4 is a perspective view showing an assembled state of the leveling device for a ladder shown in FIG. 2 and a ladder.
The leveling device 1 for a ladder according to the present invention is formed of metal such as cast iron, steel, brass, and aluminum, or high-strength engineered plastic.
Referring to FIG. 1 and FIG. 3, the present invention is characterized in that a rod 3 which can slide in the direction of a vertical side frame 101 is employed as a means for changing a length of both vertical side frames 101 of a ladder 100, and a stopper plate 17 inserted into the rod 3 with a clearance with respect to the rod to allow the stopper plate to be inclined toward the ladder by the weight of the ladder 100 or a user is employed as a means for halting the rod 3 in a state where a sufficient length of the rod 3 is drawn out. The stopper plate 17 has a clearance 19 formed thereon, and if the clearance 19 has a larger diameter than the rod 3, when the weight of the ladder 100 or the user is eccentrically applied to a side (corresponding to the ladder) of the stopper plate 17 to which the rod 3 is inserted, the stopper plate 17 is rotated with respect to the rod 3, and as a result, an edge (corresponding to the ladder) of a lower end of the clearance 19 of the stopper plate 17 presses an outer surface of the rod 3 in the rotational direction of the stopper plate 17 to prevent the rod 3 from sliding. Since an edge (corresponding to the ladder) of a lower end of the clearance 19 presses the rod 3 in the rotational direction with a pressure which is proportional to a load applied by the ladder 100 or the user, if an extremely large load is applied to the ladder, a state in which the rod 3 is halted without sliding is maintained.
For achieving the above, as shown in FIG. 1 and FIG. 2, the leveling device 1 for the ladder according to the present invention is provided with an upper guide plate 7 and a lower guide plate 9 formed with through holes 15a, 15b into which the rod 3 can be inserted and fixed to vertical frames 101 of the ladder 100 in a direction perpendicular to the vertical frames. The through holes 15a, 15b formed on the upper guide plate 7 and the lower guide plate 9 are in line with each other to enable the rod to be continuously inserted thereinto, and are sized such that the rod can slide. The upper guide plate 7 and the lower guide plate 9 can be manufactured individually and attached to the vertical frames 10 of the ladder. However, as shown in FIG. 1 and FIG. 2, it is preferable that the side ends corresponding to the ladder are connected to each other through a vertical plate 11 to form the upper guide plate 7, the lower guide plate 9 and the vertical plate 11 integrally with each other. The vertical plate 11 is provided with a key 13 protruding slightly in the direction in which the upper guide plate 7 and the lower guide plate 9 are advanced. Since the upper guide plate 7, the lower guide plate 9 and the key 13 are fixed to the vertical plate 11, these members are moved together in response to movement of the vertical plate.
The rod 3 is coupled to the through holes 15a, 15b of the upper guide plate 7 and the lower guide plate 9 in a state where the rod can slide in the longitudinal direction of the ladder 100 by the weight of the ladder. At an upper end, a jaw 5 is provided for preventing the rod 3 from sliding down from the through hole 15a of the upper guide plate 7.
The stopper plate 17 has a plate shape and has a clearance 19 formed thereon and having a diameter larger than that of the rod 3, and the stopper plate is disposed between the lower guide plate 9 and the key 13 and then assembled with the rod 3 by inserting the rod 3 into the clearance 19. An edge of the stopper plate 17, which corresponds to the ladder, is extended under the key 13 so that the above edge is pressed by a lower surface of the key 13 and inclined with respect to the rod 3 when a force is applied downward to the key 13 and the ladder 100.
Although, the drawings illustrate the structure consisting of three (3) stopper plates 17, only one stopper plate can be utilized, and two (2) stopper plates or four (4) or more stopper plates can be stacked, if necessary. However, it is desirable to stack two (2) to six (6) stopper plates.
A spring 21 is assembled to a lower side of the stopper plates 17 to press the stopper plates 17 toward the key 13. The spring 21 is disposed between the lower guide plate 9 and the stopper plate 17 to elastically bias the stopper plates 17 toward the key 13 at all times. Due to the spring 21, the stopper plates 17 are always in contact with the key 13.
A foothold 23 is assembled to a lower end of the rod 3 to allow the foothold to be inclined in the inclination direction. In order to enable the foothold 23 to be inclined in the inclination direction, as shown in FIG. 1 and FIG. 5, a sunken ball seat is provided on an upper end of the foothold 23, a cover 33 having a screw hole 35 is joined to an upper part of the ball seat 25, and a ball 29 of a ball head bolt 27 is inserted between the ball seat 25 and the cover 33. A thread of the ball head bolt 27 is exposed to the outside through the screw hole 35 of the cover 33 and coupled to a lower end of the rod 3. For achieving the above, a tap (not shown in the drawings) is formed at a lower end of the rod 3.
In the leveling device 1 for the ladder according to the present invention, a bolt hole is formed on the vertical plate 11 to enable the vertical plate to be coupled to the vertical frames 101 of the ladder 100 by a bolt 41 and a nut 43. As shown in FIG. 3 and FIG. 4, however, it is preferable to attach a subsidiary plate 37 to a rear surface of the vertical frame 11, to form a bolt hole 39 on the subsidiary plate 37, and then assemble the subsidiary plate to the vertical frames 101 of the ladder 100 by the bolt 41 and the nut 43.
Once the leveling device 1 for the ladder according to the present invention is assembled to the ladder, the subsidiary plate 37, the vertical plate 11, the upper guide plate 7, the lower guide plate 9 and the key 13 are secured integrally so that the above members are moved together by the same distance, and the weight of the ladder or a user climbing the ladder is directly transmitted to the key 13.
FIG. 5 and FIG. 6 are views illustrating a method of using the leveling device for the ladder according to the present invention on stairs 107a and 107b.
FIG. 5 illustrates a state in which the user lifts the ladder to allow the rod 3 to slide to the lowest position and no load is applied to the stopper plate 17. In this state, while the user continuously supports the ladder, the foothold 23 of the left side rod 3 reaches the higher stair 107a first and the right side rod 3 then reaches the stair 107b which is lower than the stair 107a so that once the user releases the ladder, the weight of the ladder is applied to the stopper plate 17 through the key 13 as shown in FIG. 6, the stopper plate 17 is rotated about the rod 3 and inclined by a load leaning toward the ladder, and a corner M (corresponding to the ladder) of a lower end of the clearance 19 of the stopper plate 17 strongly presses the surface of the rod in the direction in which the stopper plate is rotated. In practice, a corner (corresponding the ladder) of a lower end of the clearance 19 minutely penetrates a surface of the rod. In this state, accordingly, the rod does not slide but is halted, and if the user climbs up the ladder, the corner (corresponding to the ladder) of a lower end of the clearance 19 more strongly penetrates a surface of the rod so that the rod 3 is firmly halted.
FIG. 7 is a front perspective view of the leveling device 1 for a ladder according to the present invention further including a device for releasing the stopper plate 17 provided thereto.
As shown in FIG. 7, if a hinge 45 is formed on an outer side of the clearance of the uppermost one of the stopper plates 17 and a handle 47 capable of pressing downward on the stopper plate 17 is provided on the hinge 45, in a case where weight is mistakenly applied and the stopper plate 17 presses the rod in a process of adjusting a length of the rod, it is possible to easily release the stopper plate. At this time, it is preferable that the uppermost stopper plate 17 is furthermore extended outward. It is preferable that the upper guide plate 7 is also slightly further extended outward, a handle-supporting hole 49 into which the handle 47 is inserted is formed on the upper guide plate, and the handle is passed through and installed in the handle-supporting hole.
Although the construction in which the leveling device for the ladder according to the present invention is provided on a lower portion of the vertical frames of the ladder is described and shown in the drawings as an example, if a supporting surface of the upper end portion of the vertical side frame of the ladder has a stair-shape or is inclined, the leveling device for the ladder according to the present invention can be installed at an upper portion of the vertical side frame to allow the foothold 23 to be directed upward. In addition, although the drawing illustrates that the leveling device for the ladder according to the present invention is provided on a straight ladder, the leveling device for the ladder according to the present invention can be applied to "^"-shaped ladders without modification.

[Industrial Applicability]

According to the present invention, since the leveling device can easily and independently change a length of the vertical side frame of the ladder and fix the ladder in a state where the length is changed, the ladder can stay level on sloping land or stairs at all times. And when lengths of both rods are equally changed to the same length and then fixed, the ladder can be used on level ground in a state where a length of the ladder is increased within a certain range.

Claims

A device for maintaining a level of a ladder and changing a length of the ladder, comprising:
an upper guide plate 7 and a lower guide plate 9 formed with through holes into which a rod is inserted, and fixed to vertical frames 101 of the ladder 100 in a direction perpendicular to the vertical frames;

a key 13 provided on a vertical plate 11 which connects the upper guide plate 7 and the lower guide plate 9 to the vertical frames 101 of the ladder 100, the key protruding in the direction in which the upper guide plate 7 and the lower guide plate 9 protrude;

the rod 3 coupled in the through-holes 15a, 15b of the upper guide plate 7 and the lower guide plate 9 to be able to slide by the weight thereof in the longitudinal direction of the ladder 100;

plate-shaped stopper plates 17, each of which having a clearance 19 into which the rod 3 is inserted and an edge extended to a lower portion of the key 13, the stopper plate being disposed between the upper guide plate 7 and the lower guide plate 9 and the clearance being larger than a diameter of the rod 3, whereby the stopper plate is pressed by a bottom surface of the 13 and inclined with respect to the rod 3 as a force is applied downward to the key as well as the ladder; and

a spring 21 positioned between the lower guide plate 9 and the stopper plate 17 to elastically bias the stopper plate 17 toward the key 13 at all times.
The device for maintaining a level of a ladder of claim 1, wherein the rod 3 has a jaw 5 formed at an upper end thereof for preventing the rod 3 from sliding down from the through hole 15a of the upper guide plate 7, and has a foothold 23 assembled to an upper end thereof to allow the foothold to be inclined in the inclination direction.
The device for maintaining a level of a ladder of claim 1, wherein the vertical plate 11 has a subsidiary plate 37 attached to a rear surface thereof and assembled to the vertical frames 101 of the ladder 100.
The device for maintaining a level of a ladder of claim 1, wherein the uppermost stopper plate 17 has a hinge 45 formed on an outside of the clearance 19 thereof, and the hinge 45 is provided with a handle 17 that is capable of pressing downward the stopper plate 17.