NZ546301A - An extension ladder with improved mechanism - Google Patents

Abstract

An extension ladder with improved structure includes a plurality of ladder posts, connection kits, a locking mechanism, and transverse step beams. Each ladder post is a hollow post having a different calibre. The posts can be interconnected by fitting into each other and pulled to extend. The upper end is horizontally provided with a connection kit. Internally, the connection kit is provided with a locking mechanism covered by a transverse step beam. The locking mechanism includes a locking bar which passes through the ladder post.

Description

4 6 3 0 1 *10051099558* COMPLETE SPECIFICATION AN EXTENSION LADDER WITH IMPROVED MECHANISM We Kuo Ching-Yao, of 2F, No. 3, Alley 22, Lane 139, Chiu-chiung Street, Lu-chou City, Taipei, Taiwan, a Taiwanese citizen, and Norman William Liefke, of 800 153255-24 Ave Surrey. B. C. Canada V4A 2H9, a Canadian citizen hereby declare the invention for which we pray that a patent may be 25 granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: 1 (the following page is numbered la) INTELLECTUAL PROPERTY OFFICE OF N.Z. - 3 APR 2Q06 REGitVl0 AN EXTENSION LADDER WITH IMPROVED MECHANISM BACKGROUND OF THE INVENTION Field of the invention The present invention relates to an extension ladder, and more particularly to an extension ladder, which can be assembled easily and firmly for providing superior safety to people.

It is noticed that stepladders have become a requisite tool for casual use. For example, climbing tools such as a ladder or scaffolding enable people to readily process construction or obtain objects at a high place.

A conventional stepladder 800, as shown in FIG. 1, is assembled by 15 two ladder units having a pair of footpads respectively installed at the lower end of the ladder units to prevent slippage, and is provided with parallel spaced step plates therein. The stepladder appears as an A-frame ladder during usage. and inconvenient to carry them. Moreover, the storage of a folded stepladder may occupy a large space, which makes the use of a stepladder inflexible.

Accordingly, the present invention has been invented to solve the above-mentioned problems that occurred in the prior art.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an extension ladder with improved structure, which is composed of multi-segment ladder posts, connection kits, locking mechanisms, and Description of the Prior Art Stepladders are typically large and bulky; therefore, it is uneasy transverse step beams, providing ease and convenience to fold and take along, store, or unfold and use.

According to the extension ladder of the present invention, the locking mechanism has further improvements, such that after the 5 extension ladder is extended for people's uses, the ladder would not become loose and cause danger. So as to confirm user's security, this is the second object of present invention.

In the extension ladder of the present invention, there are a plurality of connection kits, each of the connection kits is locked with a 10 hollow ladder post in place, and then stuck and fastened. This prevents these components from becoming loose and becoming disattached, which serves as another object of the present invention.

According to the extension ladder of the present invention, the locking mechanism provided inside the connection kits are wrapped by 15 transverse step beams, and can avoid the damage of rust, which serves as a further object of the present invention.

The detailed structure, application principle, function, and effects of the present invention will be more apparent from the following descriptions taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a three-dimensional view of a conventional extension ladder; FIG. 2 is a front view showing the present invention before use; 25 FIG. 3 is a front view showing the present invention that has been extended for use; FIG. 3A is a sectional view showing the magnified "A" portion of FIG. 3. INTELLECTUAL PROPERTY OFFICE OFNZ 1 8 JUL 2007 RECEIVED FIG. 4 is a three-dimensional exploded view showing the first ladder post and transverse step beam of the present invention; FIG. 5 is a three-dimensional exploded view showing the ladder post and transverse step beam in the present invention except for the first ladder post; FIG. 6 is a three-dimensional assembly view showing the assembly of the construction of the ladder post and the transverse step beam of the present invention; FIG. 7 is a sectional view showing the assembly of the construction of the ladder post and the transverse step beam of the present invention; and FIG. 8 is a sectional view showing the embodiment of present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 2, the extension ladder 1 with improved structure of the present invention, is foldable and can be pulled to an extension form as shown in FIG. 3. It includes a plurality of ladder posts 2, connection kits 3, and transverse step beams 5. The stepladder appears as a rising ladder when it is extended and used, and can be folded by fitting the ladder posts with different calibers one to another.

Referring to FIGs. 4, 5, and 6, such a ladder post 2 fits each other by providing a similar-shaped but smaller internal ladder post 2a. Said telescopic-shaped ladder post 2 is provided with a snap-fit hole 21 and an orientation hole 22 on its upper end, and is provided with a through hole 23 on its lower end. Also, an outward extruded blocking ring 25 is provided on the upper end of said through hole 23 at a proper height, 3 and on the surface of said ladder post 2, an inward protruding furrow ring 26 which is extruded inward to the interior of the ladder post 2, is formed at a position properly apart from said outward extruded blocking ring 25. (Please refer to FIG. 3.).

Each connection kit 3 has a ringlike covering part 31, and a pivotal joint 32. Said ringlike covering part 31 is horizontally provided on the upper end of the ladder post 2, and affixed to the ladder post 2 by fastening a screw therein. A plurality of orientation tenons 34 are provided on the inside of said connection kit for engaging with the snap-fit hole 21 of said ladder post 2, so that the connection kit can be assembled with the ladder post 2 quickly. Also, the inside wall of said connection kit is provided with an adhesive channel 35, wherein the adhesive is infused into an adhesive-infusing hole 36 on its one end so that the connection kit can be firmly adhered to the ladder post 2. Moreover, a through hole 30 is provided in the connection kit for interconnection with the internal channel 37 of said pivotal joint 32.

Said pivotal joint 32 is integrally molded with the ringlike covering part 31, and comprises two vertical side plates 321, 322 having a channel 37 between them, so as to hold a locking mechanism 4. On the inner surface of the vertical side plates 321, 322, there are a pair of opposite vertical grooves 38 and two concavities 391, 392, wherein said vertical grooves 38 are formed at the position near the end of the side plates 321, 322; and one of said concavities 391 is formed on each of the upper edge of said side plates 321, 322, while the other concavity 392 is formed on each of the lower edges of said side plates 321, 322. 4 The locking mechanism 4 comprises a base locking construction 4a and a plurality of upper locking constructions 4b. As shown in FIG. 5, each of the upper locking constructions 4b includes a locking gate 41, a locking bar 42, a spring 43, a turning key 44 and a passive key 45; wherein, said locking gate 41 has a fixing plate 410 for inserting into the vertical grooves 38 formed in said plates 321, 322, and at the center of the fixing plate 410, there is a sleeve 413 having an open end facing said through hole 30.

Said locking bar 42 is a cylindric rod, its one end passes through 10 said through hole 30 and said orientation hole 22 formed in said ladder post 2, while the other end can be inserted into said sleeve 413. The spring 43 is installed between said locking bar 42 and said sleeve 413, and said locking bar 42 returns to its original position by the force of spring 43. On the locking bar 42, there are two mounting grooves to 15 form sectional shafts 421, 422 having radii smaller than that of locking bar 42.

Said turning key 44 is formed with a first panel 441 and a second panel 442 being connected in V shape. The upper end of the first panel 441 is formed with a pair of separate arms 443. The space between the 20 separate arms 443 can be used for mounting with the sectional shaft 422 of said locking bar 42. The connection portion of said first panel 441 and second panel 442 is formed with a pair of locking pawls 444 extruded outward from side surfaces. By mounting the locking pawls 444 into said concavity 392 formed in the side plates 321, 322 of said 25 ringlike covering part 31, then when the second panel 442 of said | wl-mualwoperty offic 16 JUL 2007 turning rod 44 is pushed upward from the lower position, the locking bar 42 can be moved to and fro by using the locking pawl 444 as an axis.

Said passive key 45 has a pushing plate 451 having locking pawls 452 extruded outward from its side ends. Similarly, the locking pawls 5 452 can be mounted into said concavities 391, 392 formed in the side plates 321, 322 of said ringlike covering part 31. In addition, the lower end of said pushing plate 451 is formed with a pair of separate feet 453. The space between the separate feet 453 can be used for mounting with the sectional shaft 421 of said locking bar 42. When the locking bar 42 is 10 horizontally removed, the passive key 45 can swing to 90 degrees, such that the pushing plate 451 becomes perpendicular to the side plates 321, 322.

When the upper locking construction 4b is installed in the pivotal joint 32, the transverse step beam 5 is provided on the outside of said 15 pivotal joint 32. On the lower face of said transverse step beam 5, there is a hole 51 formed at a position opposite to the second panel 442 of said turning key 44, while a second hole 52 is formed at a position opposite to the said passive key 45, so as to let said pushing plate 451 protrude upward.

Referring to FIG. 4, the base locking construction 4a has a spring 43, a turning key 44 and a passive key 45 which are identical in structure of the same elements of said upper locking construction 4b. The statements regarding structures of the spring 43, the turning key 44 and the passive key 45 are not repeated herewith. The structural differences between the base locking construction 4a and the upper locking construction 4b INTELLECTUAL PROPERTY QH-Hit OF NX 1 6 JUL 2007 RECEIVED are stated as follows.

As shown in FIG. 4 and FIG. 5, the locking bar 42 of the base locking construction 4a not only has a pair of sectional shafts 421, 422 for mounting the corresponding elements of said turning key 44 and passive 5 key 45, but also has a narrow sleeve 423 formed at the section for the mounting spring 43 such that a C-shaped clamp 424 can be fixed inside the sleeve 423, and there is a clamping part 425 formed at one end of the locking bar 42. At the position of the upper locking construction 4b for locating the locking gate 41, there is a vertical fixing plate 46 having a 10 through hole 461 at its center part, to be inserted into the vertical grooves 38 formed in said plates 321, 322 of said pivotal joint 32.

In addition, there is installed a manual control button 47 and a connection rod 48. At the upper end of said manual control button 47, there is a guiding plate 471 having a horizontal groove 472 formed at its 15 lower end, such that the guiding plate 471 can be pushed into a shifting hole 53 formed in the lower side of the transverse step beam 5, and the manual control button 47 can be mounted into the shifting hole 53 to move to and fro in the shifting hole 53.

Furthermore, the central part of manual control button 47 has a 20 furrow 473, so as to connect the manual control button 47 with one end of said connection rod 48 by a pin 474. Said connection rod 48 has the front end penetrated through the through hole 461 of said fixing plate 46, and then connected to the clamping part 425 of the locking bar 42 by a pin 426. The other end of said connection rod 48 is bent downward, so 25 as to penetrate the shifting hole 53 of said transverse step beam 5 and 7 INTELLECTUAL PROPERTY OFFICE OF N.Z. 1 6 JUL 2007 oerceivcrn extend into the furrow 473 of said manual control button 47 to connect together with it.

In addition, the lower end of the ladder post 2a is provided with a conical sleeve-shaped buffering device 6. The upper end of said buffering device 6, by means of a hooked tip 61 provided thereon, is affixed to the opening 24 of said ladder post 2a. The outside of the lower-end of said buffering device 6 is provided with an elastic seal ring 62 to increase friction when it contacts with the inside of said ladder post 2a and reduce noise. When the ladder post 2a is pulled upward, the ladder can be pulled extensively without resistant force, and when the ladder post 2a is pushed downward, the elastic seal ring 62 then shall generate a force against the lower and external ladder post 2 to slow down the downward movement of the ladder post 2a. Also, the internal part of said buffering device 6 can be provided with a mylar with its surface having a hole, which allows airs to enter the cavity of said mylar when the buffering device 6 moves upward and downward, and thus enhances the cushion effect.

When the assembling has been completed, as shown in the figures, the bottom of the ladder post 2a is provided with the buffering device 6 and the elastic seal ring 62 to increase the friction between the external ladder post 2 and the inside wall of the internal ladder post 2a, so that the purpose of slowing down the descending can be achieved. Also, the connection kit 3 fixed onto the upper end of said ladder post 2 are provided with the adhesive channel 35 to infuse the adhesive therein, so that the connection kit and the ladder post 2 can be adhered to each 8 other. Accordingly, the present extension ladder is assembled integrally and securely. Moreover, the provided locking mechanism 4 is fully covered by the connection kit 3 and the transverse step beam 5, which not only makes it easy and convenient to control the locking mechanism, 5 but also prevents damage caused by any foreign object.

When the internal ladder post 2a and the external ladder post 2 are relatively extended, the blocking ring 25 having a larger caliber on the outside of said internal ladder post 2a is firmly against the inwardly protruding furrow ring 26 so as to be fixed at its position (as shown in 10 FIG. 3A) in the external ladder post 2. Meanwhile, the through hole on the lower end of said internal ladder post 2a is directly located in a route having the orientation hole 22 of said external ladder post 2, the through hole 30 of said connection kit, and the locking bar 42, which enables the locking bar 42 to be inserted in the fixed position smoothly 15 when it is moved forward.

In using the present invention, as shown in FIG. 7 and FIG. 8, the manual control button 47 of said base locking construction 4a is moved to the central part of said transverse step beam 5. Then the connection rod 48 pulls the locking bar 42 out of the orientation hole 22 of said 20 ladder post 2. When the locking bar 42 is moving, said turning key 44 is pushed to rotate in the clockwise direction and said passive key 45 is pushed to rotate in the counter-clockwise direction. Finally, the pushing plate 451 of said passive key 45 extends outward from the second through hole 52 of said transverse step beam 5.

Then, the pushing plate 451 of said passive key 45 passes through I INTELLECTUAL property office of N.z. 1 6 JUL 2007 the through hole 51a of the second transverse step beam 5a, and pushes the second panel 442a of the turning key 44a inside the second transverse step beam 5a. Then the turning key 44a rotates clockwisely. At the same time, the turning key 44a pushes the locking bar 42a inside 5 the second transverse step beam 5a and moves it out of the orientation hole 22a of said second ladder post 2a. The ladder becomes unlocked and the second ladder 2a then can be pulled upward until the passing hole 23a of said second ladder post 2a is opposite to the through hole 30 of said base ladder post 2a. Then the locking bar 42a will be inserted 10 into said passing hole 23a by the action of the spring 43a, and the second ladder post 2a therefore obtains an extended condition. In addition, when the locking bar 42a moves out of the orientation hole 22a of said second ladder post 2a, the passive key 45a installed on the second transverse step beam 5a then rotates counter-clockwisely, so that its 15 pushing plate 451a then extends outward and continuously pushes the turning key inside the third transverse step beam, such that the locking constructions of other levels are unlocked.

When the locking bar 42 returns to the locking position, and the pushing plate 451 of the passive key 45 does not completely return to 20 the horizontal locking position, if the transverse step beam 5 is mistakenly stepped or pressed downward, the locking bar 42 will be pushed into the ladder post and rigidly lock the construction. Therefore, the present invention has very good functions of security.

Accordingly, the extension ladder with improved structure in the 25 present invention are integrally assembled securely by providing a INTELLECTUAL PROPERTY OFFICE OF N.Z. 1 6 JUL RECEIVED snap-fit hole 21, orientation tenon 34, and blocking ring 25 between the connection kit 3 and ladder post 2 for quick and correct orientation. Also, the ladder assembly can be secured by providing the adhesive channel 35. Furthermore, the locking mechanism 4 is provided on the 5 connection kit 3 for making the assembling more convenient, the control of the ladder easier, and prolonging ladder life.

As described above, the extension ladder apparatus in the present invention certainly enhances appliance safety, and makes folding and using quick and convenient, which can improve the deficiencies of 10 conventional ladders. Also, since the present invention has not yet been opened to the public, it complies with the conditions of allowable patents.

Although the above-mentioned embodiments of the present invention have been described for illustrative purposes, those skilled in 15 the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 11 INTELLECTUAL PROPERTY OFFICE OF NX 1 6 JUL 2007 RECEIVED

Claims (14)

What we claim is:

1. An extension ladder with improved mechanism comprising: a plurality of ladder posts, connection kits, a locking mechanism, and 5 transverse step beams, wherein each ladder post is a hollow post having different caliber, which can be interconnected by fitting into each other and pulled to extend; its upper end is horizontally provided with a connection kit, while inside the connection kit is provided with a locking mechanism covered by said transverse step 10 beam; wherein said locking mechanism includes a locking bar which passes through said ladder post, on the locking bar, there are a pair of mounting grooves forming sectional shafts; one of said mounting grooves is mounted with a pair of separate arms of a turning key, the 15 other one is mounted with a pair of separate feet of a passive key, while one end of said turning key and passive key has respectively a pair of locking pawls extruded outward on the side surfaces of said turning key and passive key, such that when said locking bar moves to and fro, said turning key and passive key rotate by using said 20 locking pawl as an axial center, the one end of said passive key is installed with a pushing plate, and when said locking bar moves out of said ladder post, said pushing plate then extends outward to push a turning key inside the connection kit of a transverse step beam thereabove, and then the locking mechanism becomes unlocked. 25 2. The extension ladder with improved mechanism as claimed in claim 1, wherein said locking mechanism installed inside the connection kit 12

INTELLECTUAL PROPERTY OFFICE OF N2. 1 6 JUL 2007 nr/%piiicn of a base locking construction has one end of the locking bar connected to a transversely movable manual control button.

3. The extension ladder with improved mechanism as claimed in claim 2, wherein an upper end of said manual control button has a guiding plate having horizontal grooves formed at its lower end, such that said guiding plate can be pushed into a shifting hole formed on a lower side of said transverse step beam, and the manual control button can move at the lower side of said transverse step beam.

4. The extension ladder with improved mechanism as claimed in claim 2, wherein the locking bar has a narrow sleeve formed at an end where said locking bar and connecting rod is connected, such that a C-shaped clamp can be mounted inside said narrow sleeve, and there is also a spring mounted onto an end portion of said locking bar, and an another end of said spring then pushes against a vertical fixing plate inserted into a connection kit, thereby the locking bar can return to its locking position by the force of the spring after it is moved to unlock the mechanism.

5. The extension ladder with improved mechanism as claimed in claim 1, wherein said locking mechanism installed inside the connection kit of an upper locking construction has a locking gate to be inserted inside said connection kit, and said locking gate has a fixing plate having a sleeve installed at its central part, and an open end of said sleeve is installed with a spring and said locking bar.

6. The extension ladder with improved mechanism as claimed in claim 1, wherein a joint part of said ladder post and connection kit is 1C. INTELLECTUAL PROPERTY OFFICE 1,3 OF N.Z. 1 6 JUL 2007 Rprpi\/rn provided with an orientation hole to interconnect with a through hole formed in said connection kit, so that the locking bar of the locking mechanism in an internal part of said connection kit can be moved forward and backward to a predetermined position through 5 the joint part.

7. The extension ladder with improved mechanism as claimed in claim 6, wherein said ladder section and connection kit are adhered to each other by engaging the orientation hole on the ladder post with an orientation tenon of said connection kit, and then infusing an 10 adhesive into an adhesive channel on the inside of said connection kit.

8. The extension ladder with improved mechanism as claimed in claim 3, wherein said connection kit is connected with the ladder post by means of a ringlike covering part, and a pivotal joint on the 15 connection kit is provided with a locking mechanism.

9. The extension ladder with improved mechanism as claimed in claim 8, wherein said pivotal joint of the connection kit is integrated with said ringlike covering part, and comprises two vertical side plates.

10. The extension ladder with improved mechanism as claimed in 20 claim 9, wherein said vertical side plates have a channel between them, and on the inner surface of said vertical side plates, there are a pair of opposite vertical grooves and two concavities, wherein said vertical grooves are formed at a position near the end of said vertical side plates, and one of said concavities is formed in each of the upper 25 edges of said vertical side plates, while the other concavity is formed 14 1 6 JUL 2007 in each of the lower edges of said vertical side plates.

11. The extension ladder with improved mechanism as claimed in claim I, wherein the lower end of said ladder post is provided with a sleeve-shaped buffering device, and an elastic seal ring is provided on the bottom outer rim of said buffering device to maintain friction when it contacts with the inside of said ladder post, and to reduce noise and slow down the folding.

12. The extension ladder with improved mechanism as claimed in claim II, wherein the inside of said buffering device is provided with a mylar, in which a hole is formed to enhance the cushion effect by allowing air to enter into the cavity of said mylar via the hole when the buffering device moves upward and downward.

13. The extension ladder with improved mechanism as claimed in claim 1, wherein a lower section of said internal ladder post is provided with an outward extruded blocking ring, and an inward protruding furrow ring extruded inward to the interior of the ladder post is provided at an upper section of said ladder post, such that when the internal ladder post and the external ladder post are pulled in opposite directions, said outward extruded blocking ring of said internal ladder post shall move to a position against said inward protruding furrow ring to define the length of the extended ladder.

14. An extension ladder substantially as described herein with reference to figures 2 through 8 of the drawings. Kuo Ching-Yao and Norman William Liefke By their Attorneys: M. J. Service & Associates INTELLECTUAL PROPERTY OFFICE 0FN2. 15 \ 6 JUL2M7 opr.FiVED