Rung lock frame for a rung lock assembly for use with an extension ladder

Abstract

A rung lock frame has an upper rung portion, a lower rung portion integrally formed with the upper rung portion, and a bar member formed between the upper rung portion and the lower rung portion. The bar member defines an opening with the lower rung portion for the receipt of a rung of a ladder therein. The upper rung portion, the lower rung portion and the bar member are integrally formed of a glass-reinforced nylon material.

Claims

1. A rung lock frame configured to engage a horizontally-extending rung of a ladder, said rung having a longitudinal axis, said rung lock frame comprising: an upper rung portion; a lower rung portion integrally formed with said upper rung portion; and a bar member formed between said upper rung portion and said lower rung portion, said bar member defining an opening with said lower rung portion for receipt of a rung of a ladder therein, said upper rung portion and said lower rung portion and said bar member being integrally formed of a glass-reinforced nylon material, said upper rung portion having an aperture formed therein, said aperture being of a triangular shape with curved vertices, said upper rung portion having a first side member and a second side member that extend from a juncture in an inverted V-shaped configuration, said second side member having a hook member extending outwardly and downwardly beyond said bar member, said hook member having a thickness extending parallel to said longitudinal axis of said rung, the thickness greater than a thickness of a remainder of said second side member.

2. The rung lock frame of claim 1, said opening being a C-shaped opening or a U-shaped opening.

3. The rung lock frame of claim 1, each of said first side member and said second side member having ribs formed thereon and extending longitudinally therealong.

4. The rung lock frame of claim 1, said lower rung portion extending downwardly from said bar member, said lower rung portion having a transition section extending from said first side member of said upper rung portion, said transition section having a thickness greater than a thickness of said first side member.

5. The rung lock frame of claim 4, said transition section extending above and below said bar member.

6. The rung lock frame of claim 4, said transition section having an outer edge having a thickness greater than a thickness of remainder of said transition section inwardly thereof.

7. The rung lock frame of claim 6, said outer edge defining a generally curved flange.

8. A rung lock frame configured to engage a horizontally-extending rung of a ladder, said rung having a longitudinal axis, said rung lock frame comprising: an upper rung portion; a lower rung portion integrally formed with said upper rung portion; and a bar member formed between said upper rung portion and said lower rung portion, said bar member defining an opening with said lower rung portion for the receipt of a rung of a ladder therein, said upper rung portion having a first side member and a second side member that extend from a juncture in an inverted V-shaped configuration, said second side member having a hook member extending outwardly and downwardly beyond said bar member, said hook member having a thickness extending parallel to said longitudinal axis of said rung, the thickness greater than a remainder of said second side member, said upper rung portion and said lower rung portion and said bar member and said hook member being integrally formed of a glass-reinforced nylon material.

9. The rung lock frame of claim 8, said lower rung portion extending downwardly from said bar member, said lower rung portion having a transition section extending from said first side member of said upper rung portion, said transition section having a thickness greater than a thickness of said first side member.

10. The rung lock frame of claim 9, said transition section extending above and below said bar member.

11. The rung lock frame of claim 9, said transition section having an outer edge having a thickness greater than a thickness of a remainder of said transition section inwardly thereof.

12. The rung lock frame of claim 11, said outer edge defining a generally curved flange.

13. A rung lock frame configured to engage a horizontally-extending rung of a ladder, said rung having a longitudinal axis, said rung lock frame comprising: an upper rung portion; a lower rung portion integrally formed with said upper rung portion; and a bar member formed between said upper rung portion and said lower rung portion, said bar member defining an opening with said lower rung portion for receipt of a rung of a ladder therein, said upper rung portion having a first side member and a second side member that extend from a juncture in an inverted V-shaped configuration, said lower rung portion extending downwardly from said bar member, said lower rung portion having a transition section extending from said first side member of said upper rung portion, said transition section having a thickness extending parallel to said longitudinal axis of said rung, the thickness greater than the a thickness of said first side member, said transition section having an outer edge having a thickness greater than a thickness of a remainder of said transition section inwardly thereof, said outer edge being a generally curved flange, said upper rung portion and said lower rung portion and said bar member being integrally formed of a glass-reinforced nylon material.

14. The rung lock frame claim 13, said second side member having a hook member extending outwardly and downwardly beyond said bar member, said hook member having a thickness greater than a thickness of a remainder of said second side member.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) FIG. 1 is a side elevational view showing a rung lock of the prior art as applied to an extension ladder.

(2) FIG. 2 is an isolated side elevational view of the prior art rung lock as illustrated in FIG. 1.

(3) FIG. 3 is a side elevational view showing the improved rung lock in accordance with the present invention.

(4) FIG. 4 is a perspective end view showing a comparison between the improved rung lock of the present invention and the prior art rung lock of FIG. 2.

(5) FIG. 5 is an end view of the improved rung lock the present invention in comparison with the rung lock of the prior art of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

(6) Referring to FIG. 3, there is shown the rung lock 30 in accordance with the preferred embodiment of the present invention. The rung lock 30 is preferably integrally formed of a glass-reinforced nylon material. Because of the use of this glass-reinforced nylon material, the rung lock 30 is substantially stronger than conventional aluminum rung locks or other polymeric rung locks. The glass-reinforced nylon material has a lighter weight than aluminum or metallic rung locks.

(7) The rung lock 30 of the present invention includes an upper rung portion 32, a lower rung portion 34 and a bar member 36. The bar member 36 and the lower rung portion 34 are integrally formed with the upper rung portion 32. It can be seen that there is a C-shaped or U-shaped opening 38 defined by the lower side of the bar member 36 and the lower rung portion 34. The C-shaped or U-shaped opening 38 is configured so as to receive a rung therein.

(8) The upper rung portion 32 has an aperture 40 formed therein. Aperture 40 has a generally triangular shape. The vertices of this triangular shape are curved. The triangular shape of the aperture 40 serves to substantially reduce the amount of material required for the rung lock 30. This triangular-shaped aperture 40 (in combination with the glass-reinforced nylon material) provides substantially greater structural integrity for the rung lock 30. The curved vertices of the aperture 40 further serve to distribute forces in a more even manner.

(9) The upper rung portion 32 includes a first side member 42 and a second side member 44 that extend outwardly in a generally inverted V-shaped configuration from the juncture 46 at the upper end thereof. A pivot hole 48 is formed through the material of the rung lock 32 at the juncture 46. The first side member 42 has a plurality of strengthening ribs formed thereon. The first side member 42 extends downwardly so as to integrally join with the lower rung portion 34. As such, a transition section 44 will extend between the first side member 42 and the lower rung portion 34. The transition section 44 extends from above the bar member 36 to below the bar member 36. The second side member 32 includes a hook member 46. The hook member 46 extends downwardly beyond the lower edge of the bar member 36 and into the mouth of the opening 38. The hook member 46 will serve to engage the rung in a snap-fit relationship.

(10) The lower rung portion 34 extends downwardly from the bar member 36. The lower rung portion 34 includes a finger 48 that curves outwardly from a side 50 of the lower rung portion 34. The upper edge 52 of the lower rung portion 34 defines the opening 38 with the lower side of the bar member 36. The transition section 44 will extend toward the lower rung portion 34.

(11) FIG. 4 illustrates a comparison between the rung lock frame 9 of the prior art and the rung lock 30 of the present invention. In FIG. 4, it can be seen that the hook member 46 of the rung lock 30 of the present invention has a greater thickness than the hook portion 26 of the prior art rung lock frame 9. This wider hook member 46 enhances the structural integrity of the hook member 46 in comparison with the prior art. As such, this establishes a stronger and more rigid connection between the rung lock 30 and the rung that is received within the opening 38. It can be seen in FIG. 4 that this hook member 46 actually has a greater thickness than the first side member 44 of the upper rung portion 32. The thickness of the hook member 46 generally corresponds in thickness to the thickness of the bar member 36. Bar member 36 has a greater thickness than the thickness of the first side member 44 of the upper rung portion 32. Once again, this greater thickness further enhances the structural strength and stability of the rung lock 30 of the present invention.

(12) FIG. 4 further illustrates that the first side member 44 of the present invention has a greater thickness than either the second side member and the first side member 42 of the upper rung portion 32 and greater than the thickness of the downwardly extending lower rung portion 34. Once again, the greater thickness of the transition section 44 enhances the strength and integrity of the rung lock 30 in the area that it is needed most, i.e. in the area of connection between the rung lock 30 and the rung.

(13) FIG. 5 further illustrates the comparison between the improved rung lock 30 of the present invention and the prior art rung lock 9. In FIG. 5, it can be particularly seen that the transition portion 44 has a substantially greater thickness and length than the transition portion 50 of the prior art rung lock 9. This area of greater thickness of the transition section 44 extends above and below the bar member 36. Once again, this area of greater thickness provides strength in the area where it is needed most. It can be seen that the transition section 44 has a greater thickness than the first side member 42 of the upper rung portion 32 and a greater thickness than the lower rung portion 34. The transition section 44 can define a curved flange on the outer surfaces of the transition section 44.

(14) The present invention is lighter and sturdier than prior art rung locks. The rung lock of the present invention is more resistive to abuse or impact than the prior art rung locks. The rung lock the present invention performs is quieter than conventional aluminum rung locks. The glass-reinforced nylon as used in forming the rung lock 30 of the present invention reduces the wear to the rung of the ladder. Ultimately, the cost of the rung lock 30 of the present invention is less or equal to the cost of conventional aluminum rung locks.

(15) The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction can be made within the scope of the present claims without departing from the true spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.