US2962111A

US2962111A - Combination step-extension ladder

Info

Publication number: US2962111A
Application number: US796935A
Authority: US
Inventors: Roxton C Mckinnie
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-03-03
Filing date: 1959-03-03
Publication date: 1960-11-29
Anticipated expiration: 1977-11-29

Description

Nov. 29, 1960 R. c. MKlNN|E 2,962,111

COMBINATION STEP-EXTENSION LADDER Filed March 3, 1959 2 Sheets-Sheet 1 an if $1 V/////7 H I I;

' /NVE/VT0/?. 2 RoxToN c. McKINNlE A770 EKS Nov. 29, 1960 R. c. MOKINNIE I 2,962,111

COMBINATION STEP-EXTENSION LADDER Filed March 3, 1959 ROXTON C. McKINNlE B) awzzw A77'OR E75 2' Sheets-Sheet 2 United States PatentO COMBINATION STEP-EXTENSION LADDER Roxton C. McKinnie, 2435 Walgrove Ave., Los Angeles, Calif.

Filed Mar. 3, 1959, Ser. No. 796,935

Claims. (Cl. 182-22) This invention relates generally to ladders and more particularly to. an improved combination step and extension ladder.

Combination step and extension. ladders proposed heretofore have included front and rear legs coupled together at their upper ends for swinging movement from the spread apart position providing a step ladder to a second position in which the rear legs are employed in combination with the front legs as an extension ladder. Generally, the front legs are arranged to swing between the rear legs into a nested position, and then telescoped upwardly. Suitable hooks are provided. for interengaging the front and rear legs to retain thelegs in relative overlapping positions in accordance with the desired height of'the extension ladder.

As a result ofthe nesting of the front legs between the rear legs, the front legs must necessarily be closer together than the rear legs. Therefore, when used as a step ladder, the front legs are not as stable laterally as the rear legs. Moreover, to enable proper nesting to take place, the steps between the front legs are made relatively narrow to receive the rear legsand thus do not provide as large a standing area as could otherwise be realized in a conventional step ladder. In manyprior art combination step and extension ladders, there is not room to readily accommodate a pail shelf. As a result, the utility of the structure when in the position of a step ladder is limited.

With the foregoing in mind, it is a primary object of the present invention to provide a greatly improved combination step and extension ladder in which many of the foregoing disadvantages are overcome.

More particularly, it is an object to provide a combination step and extension ladder in which the separation of the rear legs to the end that a more stable ladder is provided when in the step ladder position.

Another important object is to provide a ladder of the foregoing type in which the steps between the front legs may be made relatively wide to provide a relatively stable standing area.

Still another object is to provide a combination step and extension ladder including a pail shelf which, in addition to serving its normal function, also provides a convenient retaining means for holding the rear legs in an extended position when the structure is employed as an extension ladder.

Additional objects of the invention are to provide a combination step and extension ladder which employs a minimum number of movable parts and wherein several of the component parts serve two or more functions simultaneously to the end that a relatively economical and easily operable structure is provided.

Briefly, these and many other objects and advantages of this invention are attained by providing front and rear legs having front and rear steps secured therebetween, respectively. Engaging means are provided for swingably mounting the upper end portions of the rear legs to the upper end portions of the front legs. These engaging means are spaced from the rear; edges of the front legs a distance sufficient to accommodate the width of the rear legs so that the rear legs may be folded against the front legs rather than nested between the front legs as has characterized prior art ladders. With this arrangement, the engaging means also serves as a guide to hold the rear legs in alignment with the front legs when the front and rear legs are employed as an extension ladder. The structure also includes a retaining means in the form of a pail shelf which serves its usual function as; well as a support, for engaging the underside of various ones of the rear steps when the rear legs and steps are folded against the front legs and slid upwardly relative to the front legs to provide an extension ladder.

Suitable biasing springs and improved spreader means are also included in the preferred embodiment of the invention to facilitate ready conversion from a step to an extension ladder and vice versa.

A better understanding of the invention and its various features and advantages will be had by now referring to a preferred embodiment thereof as, illustrated in the accompanying drawings in which:

Figure l is an overall perspective view of the improved combination step and extension ladder in a spread apart position for use as a step ladder; Figure 2 is an enlarged fragmentary view partly in cross section of the upper end portions of the front and rear legs taken in the direction of the arrows 22 of F e 1;

Figure, 3 is a view similar to Figure 2 but illustrating a new position assumed in converting the step ladder to an extension ladder; 7

Figure 4 is another viewsimilar to Figure 3 illustrating a subsequent relative positionv of the front and rear legs in providing an extension ladder;

Figure 5 illustrates the relative positions of certain :omponents of the structure in the extension ladder posi- Figure 6- illustrates a first step in reconverting the extension ladder to a step ladder; and, i A I Figure 7' is a rear View of the upper. portion of the ladder taken in the direction of the arrow 7hr Figure 2.

Re fer1iing first to Figure I, there is shown the combination step and extension ladder of the present invent1on as comprising a pair of

front legs

10 and 11 having a plurality of

front steps

12', 13, 14, and I5 secured therebetween. As shown, these frontsteps maybe of the same width as the front legs themselves to provide a relatively wide standing area. Coupled to the'upper end portions of the front legs are rear legs 16' and 17 having a plurality of rear steps in the form of

rungs

18', 19, 20 and 21 secured therebetween. Whilethe rear legs are shown as including rungs, there could be provided steps similar to those on the front legs. Generally, however, when the device is employed as an extension ladder wherein the rear legs and rungs form the upper portion of the ladder, it is infrequent that the rungs are actually employed for standing. Rather they are grasped by the users hands and thus are more convenient with respect to their circular shape as compared to steps such as shown between the front legs.

The coupling of the upper portion of the rear legs to the front. legs. is accomplished by a pair of

brackets

22 and 2 3. rigidly secured to the outer upper" sides of the

front legs

10 and 11, respectively. These brackets extend towards the rear legs and serve to support; an engaging means in the form of; a guide bar 24'. As best; seen in Figures 7 and 3, the guide bar 24 extends herizontal x nd is spaced from the rear edges ofv the; front legs 10 and. 11. by a distance sulficient to accommodate thewidth of the

rear legs

16 and, 17.

Also provided adjacent the upper end portion of the front legs is a retaining means in the form of a pail shelf 25 pivoted between the front legs by a suitable pivot rod 26 for swinging movement from an horizontal position upwardly towards a vertical position. It will be noted by particular reference to Figure 2 that the horizontal guide bar 24 engages underside of the pail shelf 25 in an hori zontal position to hold the pail shelf in this position.

Still referring to Figure 2, the pail shelf structure includes a front spring 27 secured at its lower end to one end of a lever 28 centrally pivoted to the inside of the front leg 11 as at 29. The upper end of the spring 27 connects to the pail shelf at 30 to the left of the pivot rod 26 as viewed in Figure 2. In the position illustrated in Figure 2, the spring 27 has minimum tension applied thereto as a consequence of the position of the lever 28.

A rear spring 31 in turn is secured to the pail shelf at a point 32 to the right of the pivot rod 26 as viewed in Figure 2. The other end of the spring 31 connects to a bracket 33 secured to the inside surface of the front leg 11. The spring 31 is tensioned sufiiciently to overcome any tension in the spring 27 when the lever 28 is in the position illustrated in Figure 2 so that the pail shelf 25 is biased to its horizontal position as shown.

As best seen in Figure 7, the bracket 33 includes an inwardly directed flange 34 which serves as a stop means to limit upward swinging movement of the pail shelf 25 all as will become clearer when the operation of the ladder is described.

As shown in Figures 2 and 7, the upper end portions of the

rear legs

16 and 17 are coupled to the front legs by

hook members

35 and 36 respectively secured to the inside surface of the

rear legs

16 and 17 and positioned with their open book portions facing downwardly to receive the guide bar 2. By this arrangement, the upper end portions of the rear legs are actually swingably mounted to the guide bar 24. By beveling the extreme upper ends of the legs respectively as indicated at 37 in Figures 2 and 3, the flat beveled surfaces may rest in full engagement with the rear edges of the front legs with the cross bar 24 seated within a notch 38 at the point where the

hooks

35 and 36 are secured to the rear legs. In one sense, the angle of the bevel will determine the spread of the rear legs from the front legs and thus is initially cut for a desired spread when the ladder is in step ladder position as illustrated in Figures 1 and 2.

In addition to the foregoing structure, the ladder may be further stabilized in step ladder position by means of a spreader 39 secured to the outside of the front leg 10. In the particular embodiment illustrated, this spreader constitutes a novel feature in that it is formed from spring steel biased into a slight bow shape. With this arrange ment, the free end portion of the spreader will be urged against the outer side of the rear leg 16. By providing a suitable peg 40 and receiving hole in the rear leg, the free end of the spreader will be biased into secured position.

Spaced above the point of securement of the spreader 39 to the front leg is a second receiving hole 41 where by the spreader 39 may be pulled outwardly from the rear leg 16 and swung upwardly, the peg 40 then being inserted in the hole 41 when it is desired to convert the step ladder to an extension ladder. A similar spreader may be provided between the front and

rear legs

11 and 17, if desired.

From the foregoing description, the operation of the combination step and extension ladder of this invention will be evident. To convert the step ladder to an etxension ladder, the spreader means 39 is secured adjacent to the front leg 10 as described and the

rear legs

16 and 17 folded against the rear edges of the front legs to the position illustrated in Figure 3. Since the horizontal guide bar 24 is spaced sufficiently from the rear edges of the front legs to accommodate the width of the rear legs, it will serve as a guiding and holding means for the rear legs when folded against the front legs.

After the foregoing folding operation is completed, the rear legs may be urged upwardly as indicated by the solid arrow in Figure 3. As a consequence of this upward movement, the first rung 18 between the rear legs will engage the bottom of the pail shelf 25 swinging the pail shelf about the pivot rod 26 from its horizontal position upwardlly towards a vertical position. The rear spring 31 will normally hold the bottom surface of the pail shelf 25 againt the rung 18 but this tension is readily overcome by upward movement of the rear legs.

Referring to Figure 4, it will be noted that continued upward movement of the rear legs will swing the pail shelf 25 almost to a vertical position until the rung 18 passes the tip of the pail shelf. At this time the pail shelf will then fall back between the

rungs

18 and 19 towards an horizontal position, the spring 31 aiding in this movement. However, the shelf will immediately be raised again by the next rung 19. This ratcheting action continues until the rear legs are extended upwardly a desired distance to meet the contemplated use of the extension ladder. The flange 34 on the bracket 33 serves as a stop to limit the upward swinging of the pail shelf and thus prevents the shelf from inadvertently swinging entirely about the pivot rod 26.

When the desired height of the rear legs is reached, they may be lowered slightly until the pail shelf 25 moves to one of its horizontal positions between adjacent rungs. The upper of the adjacent rungs will then be engaged my the pail shelf. Preferably, a notch 42 may be provided in the pail shelf for this purpose as illustrated in Figure 5. It will be evident from Figure 5 that the rear legs are securely locked to the front legs against possible further downward sliding movement, the horizontal guide bar 24 serving the dual function of supporting the bottom of the pail shelf as well as holding the rear legs against the rear edges of the front legs. In the position illustrated in Figure 5, it will be evident that the ladder may be readily transported about an an extension ladder and used accordingly.

When it is desired to reconvert the extension ladder back into a step ladder the lever 28 may be swung in a clockwise direction about the pivot 29 as indicated by the arrow in Figure 5 until the free end of the lever engages the front edge of the front leg 11 as shown in Figure 6. As a consequence of this aaction, the tension in the front spring 27 is increased sufficiently to overcome the tension provided by the spring 31 and weight of the shelf and will thus cause the pail shelf 25 to swing in a counterwise direction about pivot rod 26 to the position illustrated in Figure 6.

In the above described position, it will be evident that the pail shelf 25 is free from interference with the various rungs between the rear legs so that the rear legs may readily be moved downwardly as indicated by the solid arrow. This downward movement will continue until the

books

35 and 36 as shown in Figure 7 engage the horizontal guide bar 24 after which the legs may then be spread apart to the original position illustrated in Figure l. The free end of the spreader means 39 may then be removed from the retaining hole 41 and moved to the horizontal position with the peg 40 inserted in the receiving hole of the rear leg 16. Finally, the lever 28 is rotated in a counter clockwise direction to relieve tension on the spring 27 and thus permit the pail shelf 25 to assume its normal horizontal position.

It will be evident from the foregoing description that the present invention presents many advantages. First and as described briefly heretofore, the folding operation wherein the rear legs are merely folded against the rear edges of the front legs, enables the spread between the rear legs to be the same as between the upper portion of the front legs so that stability is insured when the ladder is in the step ladder position. In addition, this feature also provides the same distance or length of steps between the rear and upper front legs so that with respect to this lateral distance, substantially the same standing room is provided when the ladder is used as an extension ladder between the rear legs as between the upper portions of the front legs.

Further, it will be evident that the guide bar 24 serves many functions simultaneously. First, it serves as a swingable pivot for the rear legs; second, it serves as a horizontal support for the pail shelf to retain the pail shelf in a horizontal position; and, third, it serves as a guide when the rear legs are being slid upwardly with respect to the front legs thereby maintaining the rear legs in substantial alignment with the front legs. The bracket 33 for the rear spring 31 also serves a dual function in that it retains one end of the spring 31 and serves as a stop with respect to counter clockwise movement of the pail shelf so that the pail shelf cannot be swung completely over in a counter clockwise direction.

Finally, the pail shelf itself serves the desirable dual function of providing a large area for placing paint cans and the like and also as the retaining means for holding the rungs of the rear legs in a desired raised position when the device is used as an extension ladder.

While a preferred embodiment of the invention has been described, various modifications that fall within the scope and spirit thereof will occur to those skilled in the art. The combination step and extension ladder is, therefore, not to be thought of as limited to the particular embodiment chosen merely for illustrative purposes.

What is claimed is:

1. A combination step and extension ladder comprising: a pair of front legs having a plurality of front steps disposed therebetween; a pair of rear legs having a plurality of rear steps disposed therebetween; guide bar means secured to said front legs adjacent the upper rear edges thereof, said bar means being spaced from said edges a distance sufficient to accommodate the width of said rear legs; engaging means on the upper portions of said rear legs swingably mounting said rear legs to said bar means for movement from a spread apart position to provide a step ladder to a folded position; a pail shelf pivoted between said front legs for arcuate swinging movement from a horizontal position upwardly to provide room for said rear legs when in said folded position to move upwardly past said pail shelf between the rear edges of said front legs and said bar means, said pail shelf moving back to its horizontal position between adjacent rear steps to engage the underside of the upper of said adjacent rear steps to retain said rear legs and steps in position to provide an extension ladder; a front spring having one end connected to said pail shelf; and tensioning means secured to the other end of said spring for increasing the tension thereof whereby said pail shelf when moved from its horizontal position to its uppermost position, may be retained in said uppermost position to enable free up and down movement of said rear legs and rear steps relative to said front legs.

2. The subject matter of claim 1, in which said guide bar means comprises a horizontal bar upon which the underside of the free end portion of said pail shelf rests when in said horizontal position to hold said pail shelf in said horizontal position.

3. The subject matter of claim 1, including a rear spring secured at one end to said pail shelf biasing said pail shelf to said horizontal position, the biasing force of said rear spring being less than the maximum tension to which said front spring can be increased by said tensioning means and greater than the minimum tension to which said front spring is subject.

4. The subject matter of claim 3, including bracket means secured to said front legs for holding the other end of said rear spring, said bracket means including an inwardly directed flange positioned to check upward swinging movement of said pail shelf after it has swung through a sufiicient arc to enable said rear steps to pass upwardly.

5. The subject matter of claim 4, including spreader means of spring steel having one end secured to one of said front legs, said spreader means being biased inwardly against a side of a corresponding rear leg; and a peg projecting from the free end of said spreader means receivable in a hole in said side of said rear leg, said one of said front legs being provided with a hole in a position above the point of securement of said spreader means to receive and retain said peg when said rear legs are employed as an extension ladder.

References Cited in the file of this patent UNITED STATES PATENTS 218,742 Hill Aug. 19, 1879 349,189 Vanderslice Sept. 14, 1886 531,534 Howard Dec. 25, 1894 1,207,552 Hill Dec. 5, 1916 1,283,212 Kloepfer Oct. 29, 1918 1,635,705 Cardarelli July 12, 1927