US3374860A

US3374860A - Self-leveling ladder attachment

Info

Publication number: US3374860A
Application number: US546967A
Authority: US
Inventors: Lyle F Stewart
Original assignee: Lyle F. Stewart
Current assignee: LYLE F STEWART
Priority date: 1966-05-02
Filing date: 1966-05-02
Publication date: 1968-03-26
Anticipated expiration: 1985-03-26

Description

March 26, 1968 l.. F. STEWART 3,374,860

SELF-LEVELING LADDER ATTACHMENT Filed May 2, 1966 r /f/y /l United States Patent C) 3,374,860 SELF-LEVELING LADDER ATTACHMENT Lyle F. Stewart, Tippecanoe, Ohio 44699 Filed May 2, 1966, Ser. No. 546,967 16 Claims. (Cl. 182-204) ABSTRACT F THE DISCLOSURE A leveling attachment for a ladder including yan extension member slidably received in a channel attached to the ladder leg and an eccentric cam pivotally secured to the channel member and adapted to frictionally engage a substantially flat, continuous locking surface on an interior face of the extension member.

This invention relates to a ladder and more particularly to -a leveling attachment for ladders and the like.

It is the primary object of this invention to provide an improved ladder having a leveling attachment secured to at least one side member or leg thereof for supporting the ladder uprightly in a stable and level position on uneven terrain.

It is a further object of this invention to provide an attachment which is inexpensive to manufacture and yet simple and reliable in operation. Moreover, the leveling attachment described herein can be easily adapted to existing ladders and the like.

Another object of this invention is to provide an attachment which could be attached to either leg of the ladder, or preferably to both legs of the ladder. When the leveling attachment is secured to only one leg, this leg is placed on the downhill side of the ladder so that the attachment can be extended to support the ladder in an upright, level position.

It is also an object of this invention to provide an independent attachment for each leg of the ladder. Accordingly, if one attachment should break, the other attachment would still function to level the ladder.

The above objects of the invention are accomplished by providing an attachment for a ladder comprising a channel member adapted to be attached to one leg of the ladder adjacent one end thereof, an extension member slidably received in the channel member, an eccentric cam pivotally secured' to the channel member, and means to rotate the cam to bear against the extension member associated therewith so as to lock the extension member in position.

It is also an object of lthis invention to provide means secured to the ground-engaging end of the extension member for providing an adequate grip on the supporting surface irrespective of the inclination of the ladder with respect to the vertical.

These and other objects of this invention are more clearly depicted in the following detailed description having specific reference to the attached drawings in which the embodiments of the invention are shown, not to limit the scope of the invention in any respect, but so that the principles thereof might be more clearly demonstrated.

In the drawings:

FIGURE l is a front view -of the ladder leveling attachmen-t shown supporting the ladder on uneven terrain;

FIGURE 2 is a side view of the ladder leveling attachment with parts broken away for clarity;

FIGURE 3 is a sectional View taken substantially along the lines 3-3 of FIGURE 2; and

FIGURE 4 is a plan view of the ladder leveling attachment.

Referring to FIGURES l through 4, in which the preferred embodiment of the invention is illustrated, there Patented Mar. 26, 1968 ice is shown a ladder 10 having a pair of disposed legs or side members 12 and a plurality of rungs 14 extending therebetween and being spaced from each other in accordance with the common design of ladders.

The ladder leveling attachment 16 preferably includes two assemblies 18, one adapted to be attached to the lower end 20 of each of the legs of the conventional ladder described above. Both assemblies are substantially alike and are independent of each other in the preferred embodiment of the invention. Each assembly includes a channel member 22 having its flat backing plate 21 bolted or otherwise secured, as at 24, to the outer face 26 of the leg 12 of the ladder. The channel member 22 has an outwardly and laterally turned flange 28 integrally secured on its longitudinal edge thereby forming a groove 30 in which an extension member 32 is received.

The extension member may take a variety of shapes, but as illustrated the extension member 32 is in the form of a channel having outwardly-turned marginal anges 34 secured to its longitudinal edges with the flanges slidably disposed within the grooves 30 formed by the anges 28 of the first channel member 22.

The first channel member 22 has a hollow boss 36 projecting inwardly into a bore 38 in the leg 12 of the ladder. A shaft 40, having a handle 42 on its inner end 44, extends through the boss 36 and carries a locking cam 46 fast on its outer end portion beyond the first channel member 22. The cam may be eccentrically formed and .axially mounted on the shaft or it may be round and eccentrically mounted on the shaft. The locking cam preferably has a plurality of teeth or ridges 48 on its rim which enables it to bear against one side 50 of the extension member when it is rotated into engagement therewith thereby locking the extension member in a set position. When not locked in position, the extension member can be moved parallel to the ladder leg so as to provide a ground-engaging extension thereof. It will be seen that the cam engages the side 50 of the extension below a horizontal line passing through its axial center. When weight is applied to the ladder, the cam 46 tends to rotate counter-clockwise as seen in FIGURE 2 because of the grip of the teeth 48, thus insuring an even tighter grip between the teeth 48 and the side 50.

Inasmuch as both legs are movable independently of each other, it will be appreciated that the primary object of the invention would be accomplished if only one leg had a leveling assembly. This sole attachment would provide an extension for the leg on the downhill side of the ladder. If two attachments are used on the ladder, it is only necessary to adjust one of the attachments to move the ladder into a level position. However, it will be appreciated that both attachments could be utilized to accomplish this leveling purpose and to add a limited amount of height to the ladder.

It is also an object of this invention to provide a pivoted, ground-engaging foot 52 at the lower end of the extension member so as to accommodate various inclinations of the ladder while maintaining the base 54 of the foot in full engagement with the ground. The limited pivotal movement of the foot is shown in dotted lines at 56 in FIG- URE 2.

As best shown in FIGURE 3, the foot 52 is pivotally connected to the lower end of the extension member by `means of a pin 60 secured within the base wall 62 of the channel-shaped extension member and a plate 64' con'- necting the ilanges at the lower end of the extension member. The abutment of the plate 64 against the securing means 24 and the foot against the lower end of the ladder leg limits the upward movement of the extension member.

The base 54 of the foot is preferably corrugated, as at 58, and made out of material such as rubber to provide a non-slip surface. The base could also be made with spikes for use on ice and the like.

The advantages of the pivoted ground-engaging foot would not be fully utilized if only one extension member were used. Thus, in the preferred embodiment of the invention a separate leveling assembly is attached to each leg.

At its upper end the extension member carries an inwardly projecting pin 64 which receives the upper end of a tension spring 66. The lower end of the tension spring is connected to the outer end of the shaft 40 at a position beyond the cam 46. When the cam is disengaged from the extension member so as to unlock the same, the tension spring 66 causes the extension member to extend to its lowermost position. Thus, with the cams released, the ladder can be lowered until the feet of both extension members engage the ground. The cams are then locked to maintain the ladder -in an upright, level position.

It will be appreciated that within the scope of the invention, the channel member 22 and the extension member could take other configurations so that they could slidably cooperate with each other. Furthermore, the channel member could be mounted on any face of the ladder leg. Moreover, while the attachments are shown having individual operating handles, it be appreciated that the shaft 40 could extend across the base of the ladder so as to cooperate with both attachments, thereby enabling a single handle to operate the same.

While the preferred form of the invention has been illustrated in the drawings and discussed above, it should be adequately clear that considerable modification may be made thereto without departing from the principles of the invention. Therefore, the foregoing should be considered in an illustrative sense rather than a limiting sense and accordingly the extent of this invention should be limited only by the spirit and scope of the claims appended hereto.

I claim: 1. A ladder leveling attachment comprising: a channel member adapted to be attached to one leg of a ladder adjacent one end of the leg;

an extension member slidably received in the channel member and having a fiat locking surface on an interior face of the extension member adapted to be frictionally engaged by a cam;

an eccentric cam pivotally secured to the channel member and having a roughened arcuate surface adapted to frictionally engage only the fiat locking surface of the extension member; and

means for moving the roughened arcuate surface of the cam into frictional engagement with the fiat surface of the extension member so as to lock the member in position whereby when the roughened surface of the cam frictionally engages the fiat locking surface of the extension member the distance between the fiat surface of the extension member and the pivotal center of the cam is less than the radial distance from the pivotal center of the cam to a point on the cam arcuate surface disposed clockwise from the point on the cam in contact with the fiat surface and greater than the radial distance from the pivotal center of the cam to a point on the cam arcuate surface disposed counterclockwise from the point on the cam in contact with the flat surface.

2. The leveling attachment defined in claim 1 wherein the channel member has groove means and wherein the extension member has tongue means, the tongue and groove means cooperating for slidably securing the channel member and extension member together.

3. The leveling attachment defined in claim 1 wherein the channel member has a substantially flat plate having outwardly and laterally turned flanges integrally secured to its longitudinal edges, the flanges forming grooves in which the extension member is received and the fiat plate being secured to the ladder leg.

4. The leveling attachment defined in claim 3 wherein the extension member comprises a channel having outwardly turned marginal flanges integrally secured to its longitudinal edges, the flanges being slidably disposed within'the grooves formed by the flanges of the channel members.

5. The leveling attachment defined in claim 1 wherein the channel member has an inwardly projecting hollow boss adapted to be received within a hole in the ladder leg and wherein the means for moving the cam comprises a shaft extending through the boss and having a handle on vits inner end and the eccentric locking cam mounted fast on the other end beyond the channel member.

6. The leveling attachment defined in claim 1 wherein the locking cam is round and is eccentrically mounted on the other end of the shaft.

7. The leveling attachment defined in claim 6 wherein the locking cam has a plurality of teeth.

8. The leveling attachment defined in claim 1 additionally comprising a tension spring secured at one end to the upper portion of the extension member and operatively secured at the other end to the fixed channel member so as to extend the movable extension member to its lowermost position when unlocked.

9. The leveling attachment defined in claim 1 additionally comprising a ground-engaging foot pivotally connected to the lower end of the extension member.

)10. The leveling attachment defined in claim 9 wherein the ground-engaging foot has a corrugated base.

11. The leveling attachment defined in claim 1 wherein the channel member comprises a flat plate having integral outwardly and inwardly extending flanges and having a hollow boss adapted to be received within a hole in the ladder leg; wherein the extension member comprises a second channel member having integral outwardly extending fianges slidably received between the flat plate and fianges of the first channel member; wherein the means to move the cam comprises a shaft extending through the hollow boss with a handle secured to its inner end and the cam secured adjacent its outer end beyond the first channel member; and additionally including a tension spring secured at one end to the upper portion of the extension member and at the other end to the outer end of the shaft.

12. The leveling attachment defined in claim 11 comprising a ground-engaging foot pivotally secured to the lower end of the extension member.

13. A ladder comprising:

a pair of disposed legs;

a plurality of rungs extending between the legs and being spaced from each other;

a channel member adapted to be attached to one leg of the ladder adjacent one end of the leg;

an extension member slidably received in the channel member and having a fiat locking surface on an interor face of the extension member adapted to be frictionally engaged by a cam;

means for moving the roughened arcuate surface of the cam into frictional engagement with the fiat surface of the extension member so as to lock the member in position whereby when the roughened surface of the cam frictionally engage the fiat locking surface of the extension member the distance between the fiat surface of the extension member and the pivotal center of the cam is less than the radial distance from the pivotal center of the cam to a point on the cam arcuate surface disposed clockwise from the point on the cam in contact with the flat surface and greater than the radial distance from the pivotal center of the cam to a point on the cam arcuate surface disposed counterclockwise from the point on the cam in contact with the ilat surface.

14. The ladder dened in claim 13 additionally comprising a second channel member adapted to be attached to the other leg/of the ladder adjacent the end of the other leg corresponding to the end of the rst leg on which the rst channel member was placed, a second extension member slidably received in the second channel member, a second eccentric cam movably secured to the second channel member, and means to move the second cam to bear against the second extension member associated therewith so as to lock the extension member in position.

15. The ladder dened in claim 14 wherein each channel member comprises a lat plate having integral outwardly and inwardly extending flanges and having a hollow boss adapted to be received within a hole in the associated ladder leg; wherein each extension member comprises a second channel member having integral outwardly extending flanges slidably received between the at plate and anges of the rst channel member; wherein each means to move the cam comprises a shaft extending through the hollow boss with a handle secured to its inner end and the cam secured adjacent its outer end beyond the rst channel member; and additionally including a tension spring secured at one end to the upper portion of each extension member and at the other end to the outer end of each shaft.

16. The ladder 'dened in claim 15 additionally comprising a ground-engaging foot pivotally secured to the lower end of each extension member.

References Cited UNITED STATES PATENTS 1,718,891 6/1929 Bratt 182--201 2,911,134 11/1959 Derby et al. 182-201 2,914,135 11/1959 Crouch 182-201 2,205,869 6/ 1940 Wakeman 182-201 3,165,288 1/1965 Jackson 182-87 3,179,206 4/ 1965 Studer 182-205 FOREIGN PATENTS 563,847 9/ 1958 Canada.

REINALDO P. MACHADO, Primary Examiner.