US3241632A - Combination step, stair, and extension ladder - Google Patents

Description

March 22, 1966 R. c. M KlNNlE 3,241,632

COMBINATION STEP, STAIR, AND EXTENSION LADDER Filed Dec. 50, 1965 INVENTOR. ROXTON C. McKlNNIE United States Patent 3,241,632 COMBINATION STEP, STAIR, AND EXTENSION LADDER Roxton C. McKinnie, 2435 Walgrove Ave., Los Angeles, Calif. Filed Dec. 30, 1963, Ser. No. 334,326 3 Claims. (Cl. 182-26) This invention relates generally to ladders and more particularly to ladders which may be converted from step to stair or extension ladders.

Combination step and extension ladders have been provided heretofore. Generally, these structures include front and rear pairs of legs pivoted together at their upper ends so that their lower ends may be spread apart to provide a step ladder. To convert the ladder to an extension type ladder necessitates swinging the front and rear legs together into parallel relationship and then removing the pivoted type connection or alternatively, providing a complicated pivoting arrangement which will permit relative sliding movement of the rear legs with respect to the front legs.

In many instances, a painter or other worker may wish to paint a wall area adjacent stairs or uneven floor structures. In such cases it would be desirable to provide a step ladder in which the rear legs were effectively shorter than the front legs so that the rear legs could be positioned on one of the steps with the front legs on a lower step or on the floor. The problem can be solved by simply stacking boxes or other types of spacer members beneath the front legs so that the front legs are effectively longer than the rear legs. However, the resulting structure is not always stable. Further, the spacing elements may not be available.

Oftentimes a worker will be on a roof or other elevated structure. If he should wish to move along the edge of the roof or along a scaffolding, it would be convenient if he, could move the ladder along with him so that he could descend at his finishing position. With such extension ladders as are available, if the worker pulls on the extended legs, he will often disengage the rung supported by rung members secured on the lower legs so that the ladder will tend to come apart. In other words, many extension ladders are locked in their extended position only against telescoping movement in a downward direction. If an upward pull is exerted on the extended legs, it will simply serve to extend the ladder further or possibly cause separation of the extended legs. With all of the foregoing in mind, it is a primary object of the present invention to provide a novel combination step, stair, and extension ladder in which the foregoing problems are overcome.

More particularly, it is an object to provide a combination ladder which may serve as a conventional step ladder, or alternatively, may be adjusted to function on stairs or different levels so that the rear legs can be effectively shortened with respect to the front legs and the top of the ladder will still remain level, or which may be readily converted to an extension ladder to provide access to elevated positions. I

Another object is to provide a combination ladder meeting the foregoing objects which is extremely rugged in construction, employs a minimum number of parts, and which is extremely safeto use, all to the end that the ladder may be produced economically and provide great versatility.

i A particular object of this invention is to provide novel locking means for securing the rear legs of the ladder in a stationary position with respect to the front legs when both in a step ladder position or in an extension ladder position.

Patented Mar. 22, I966 Another particular object is to provide a combination ladder incorporating a pail shelf usable when the ladder is positioned either as a step ladder or stair ladder.

Briefly, these and many other objects and advantages of this invention are attained by providing pairs of front and rear legs arranged to be pivoted for swinging movement relative to each other. Towards this end, there is provided a guide means slidably supporting the rear legs and pivoted to the front legs.

Cooperating with the guide means is a holding means for securing the rear legs in selected stationary positions relative to the guide means.

In addition, the invention contemplates the provision of a pail shelf secured to the guide means so that it will always remain at a given level relative to the front legs. Moreover, by securing the pail shelf to the guide means there will be no interference with the movement of the rear legs relative to the front legs when converting from a step to a stair or extension ladder.

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

FIGURE 1 is a perspective view of the combination step, stair and extension ladder of this invention in position for use as a step ladder;

FIGURE 2 is a greatly enlarged side elevational fragmentary view of the upper portion of the ladder of FIG- URE 1 with the front and rear legs in an intermediate position when converting the same from a step to a stair or extension ladder;

FIGURE 3 is a fragmentary cross-section taken in the direction of the arrows 3-3 of FIGURE 2.;

FIGURE 4 is a perspective view similar to FIGURE 1 but illustrating the ladder used as a stair ladder; and,

FIGURE 5 is a side elevational view of the ladder used as an extension ladder.

Referring first to FIGURE 1, the ladder includes a pair of front legs 10 and 11 and a pair of rear legs 12 and 13. As shown, there are provided a plurality of steps 14 extending between the front legs 10 and 11 and a plurality of rungs 15 extending between the rear legs 12 and 13.

Guide means 16 in the form of a channel member partially encircles the rear leg 12 so that the rear leg may slide longitudinally relative to the guide means. The

' guide means itself is pivoted to the front leg 10 as at 17.

While only one guide means 16 is visible in FIGURE 1, there is provided a second guide means indentical to the first guide means for the far rear leg 13 pivoted to the upper end of the far front leg 11. The arrangement is such that the guide means may pivot about the pivot point 17 and since these guide means encircle the rear legs, the rear legs will be constrained to swinging or pivoting movement along with the guide means.

In accordance with an important feature of this invention, there is provided rear leg holding means in the form of a swingable arm 18 pivoted to the guide means 16 and arranged to engage the rear legs to lock the rear legs against longitudinal movement along the guide means 16 at predetermined positions. Also included is another holding means which effectively locks the rear legs against longitudinal movement relative to the guide means 16 in the form of a rung engagement member 19 secured to the upper portion of the front legs. This latter holding means is only used when the ladder is asssembled as a step or stair ladder and is not used when the ladder is employed as an extension ladder as will become clear as the description proceeds.

As shown in FIGURE 1, there is provided a conventional type spreader means 20 connected between the front legs and the guide means 16. By connecting the spreader means from the front legs to the guide means rather than directly to the rear legs, the rear legs may be shifted longitudinally relative to the guide means without interference with the spreader structure. Further, there is provided a pail shelf 21 coupled to the guide means 16 so that the pail shelf 21 will remain at substan tially the same level above the ground since the guide means 16 is limited in movement through the pivot 17 to the front legs.

In the enlarged view of FIGURE 2 the arrangement of the various elements will become clearer. In addition to the structure described, there is included rung supporting means 22 secured to the front legs and used to engage one of the rungs of the rear legs when the structure is employed as an extension ladder, as will also hecome clear as the description proceeds.

On the outside upper portions of each of the rear legs there is provided a laterally projecting bracket 23 functioning as a stop. As shown in the position of FIGURE 2, when the rear legs are slid longitudinally downwardly all the way through the guide means 16 to a position to function as a step ladder, the stop projection 23 will engage the upper portion of the guide and thus prevent the rear legs from passing completely through the guide.

The upper edges of the rear legs such as at 12 may also include small rubber cushions such as indicated at 24 for engaging a wall or other area when the structure is used as an extension ladder.

As will also be clear from FIGURE 2, the rear leg locking means in the form of the pivoted arm 18 terminates at its lower end in a projecting pin 25 arranged to be received within any one of a plurality of holes 26 distributed along the rear edges of the rear legs. It will be clear that the rear legs may be locked against longitudinal movement relative to the guide means 16 by urging the pin 25 in one of the openings 26 of the rear legs when the legs are adjusted so that an opening is juxtaposed to the pin.

FIGURE 3 illustrates the foregoing in cross-section wherein it will be noted that the guide means is channel shaped and terminates in opposed edges 16a and 16b to cradle the leg. The slot defined between the opposed edges will accommodate the rung 15 when longitudinal movement of the leg takes place with respect to the guide. Also, it will be noted that the pin 25 on the arm 18 is received through an opening in the edge of the guide registering with one of the openings 26 When locking the leg relative to the guide.

Referring now to FIGURES 4 and 5, the manner in which the ladder may be converted to a stair or extension ladder will become clear. Assuming first that the ladder is in the step ladder position illustrated in FIG- URE 1, should a worker wish to effectively shorten the rear legs so that the ladder will remain level when placed on steps, such as the step 27 indicated in FIGURE 4, the spreader will be first collapsed so that the legs may be pivoted towards each other to an intermediate position such as illustrated in the enlarged view of FIGURE 2. The worker will then lift upon one of the lower rungs to slide the rear legs through the channel shaped guide means 16 to a position in which the lower ends of the rear legs are above the lower ends of the front legs by the depth of the step shown in FIGURE 4. This step depth may correspond approximately to the distance between rungs. The worker need then only pivot the legs apart about the pivot point 17 so that one of the intermediate rungs 15 is received within the rung engaging members 19 at the top ends of the front legs. Locking of the spreader means 20 will then secure the ladder in the position illustrated in FIGURE 4. Preferably, the holes 26 in the rear legs are positioned to receive the pin from the arm 18 when a rung is received in the engaging rung member 19. Thus the arm 18 may be swung downwardly to insert the pin 25 in a corresponding hole 26 when the ladder is in the position illustrated in FIGURE 4 to provide a double lock for the rear legs.

In the event that the depth of the step is less than the distance between rungs, the worker may employ one of the various holes 26 which are distributed between the rungs as well as juxtaposed the rungs and then insert the pin 25 at the end of the arm 18 in such hole so that the rear legs will again be locked relative to the guide means 16 notwithstanding that there is no rung position to be received within the rung engaging member 19.

If now the worker desires to convert the ladder to an extension ladder, he will again crook the spreaders 20 and collapse the legs completely together so that the front edges of the rear legs will engage the rear edges of the front legs in generally parallel relationship. The worker may then slide the front legs up through the guide means 16 and hook one of the rungs over the rung supporting member 22. The ladder will then assume the position illustrated in FIGURE 5. In this respect, the worker may also employ the locking arm 18 and pin 25 to provide a further lock of the rear legs relative to the guide means 16. This latter locking feature is important when the ladder is used as an extension ladder since the worker may move the entire ladder while on a roof by simply pulling on the upper portions of the rear legs 12 without resulting in further extension movement of the rear legs relative to the front legs. In other words, by locking the rear legs relative to the guide by means of the pivoted arm 18, the rear legs are locked against extending movement in an upward as well as a downward direction. Without the locking arm 18, the rear legs would only be blocked against downward telescoping movement by the rung supporting members 22.

To reconvert the ladder back to a simple step ladder, the worker need simply let the rear legs slide through the guide means after removing .the locking pin 25 and disengaging the rungs from the rung supports 22, until the stop 23 engages the upper portion of the guide. The legs may then be spread apart and the top rung 15 will then be received within the rung engaging member 19. With the spreader means 20 properly spread, a stable step ladder will result all as illustrated in FIGURE 1.

It is important to note that by attaching the spreader to the guide means rather than the rear legs, it is effective when the ladder is used both as a step ladder and as a stair ladder. Further, by coupling the pail shelf to the guide means 16 it may also be used when the ladder is used either as a step ladder or a stair ladder. When the ladder is used as an extension ladder, the pail shelf may be readily folded flat against the rear edges of the guide 16 as depicted in FIGURE 5.

From the foregoing description, it will be evident that the present invention has provided a greatly improved combination step, stair, and extension ladder. The provision of two independent locking means in the form of the swingable arm 18 and pin 25 and in the form of the rung engaging member 19 cooperating with the rungs 15 when the ladder is used as a step or stair ladder, results in a far safer ladder of the type under considera- .tion than has been available heretofore. While it is not necessary to use both locks at the same time, so using both locks when the rungs are in proper position to be engaged by the engaging member 19 will provide a safety factor.

While only one particular embodiment of the inven- .tion has been shown and described, various modifications that fall clearly within the scope and spirit of the invention will occur to those skilled in the art. The combination step, stair, and extension ladder is therefore not to be thought of as limited to the one embodiment set forth merely for illustrative purposes.

What is claimed is:

1. A combination step and extension ladder comprising first and second pairs of legs, said second legs including a plurality of rungs extending therebetween; guide means along which said second pair of legs can slide pivoted to the upper portions of said first legs; a plurality of lock means distributed along at least one of said second legs; an arm member connected to said guide means and having a portion cooperating with at least one of said lock means, said lock means being spaced at distances less than the spacing between said rungs to prevent sliding movement of said second legs in either direction relative to said guide means and thereby lock said second legs to said guide means in predetermined positions intermediate said rungs; a rung engaging member rigidly secured to said first legs and facing in a direction to engage one of said rungs of said second legs; and a pail shelf connected to and supported solely by said guide means so that said pail shelf will remain at a fixed level relative to said first pair of legs.

2. A combination step, stair, and extension ladder comprising: front and rear legs having steps and rungs respectively; guide means along which said rear legs are slidable, said guide means being pivoted to said front legs; spreader means connected between said front legs and guide means for limiting pivoting movement of said guide means from said front legs; a plurality of lock means distributed along at least one of said rear legs; rear leg holding means connected to said guide means and cooperating with at least one of said lock means, said lock means being spaced at distances less than the spacing between said rungs for locking said rear legs in given longitudinal positions relative to said guide means against movement along said guide means in either direction; and a pail shelf connected to and supported solely by said guide means whereby said rear legs may be spread apart from said front legs to provide a step ladder and whereby said rear legs may be slid partially along said guide means and locked in a given position intermediate said rungs with said spreader spread to provide a stair ladder with said pail shelf at a fixed level relative to said front legs, and whereby said spreader may be collapsed and said guide means and rear legs swung against said front legs in parallel relationship and said rear legs moved along said guide means and locked in a given position to provide an extension ladder.

3. A ladder according to claim 2 including at least one member secured to the upper end portions of said legs and having an arouate cut out opening in a general horizontal direction to receive one of said rungs when said ladder is assembled as a step and stair ladder.

References Cited by the Examiner UNITED STATES PATENTS 359,186 3/1887 Staring 182-l26 601,714 4/1898 Napier l82-22 851,696 4/ 1907 Schaefer 18226 2,593,122 4/1952 Droeger 18218O 2,873,903 2/ 1959 Ososvski 182-26 2,881,028 4/1959 Baird l8'2--l 16 3,068,957 12/1962 Best 18226 REINALDO P. MACHADO, Primary Examiner.

HARRISON R. MOSELEY, Examiner.

Claims (1)

1. A COMBINATION STEP AND EXTENSION LADDER COMPRISING FIRST AND SECOND PAIRS OF LEGS, SAID SECOND LEGS INCLUDING A PLURALITY OF RUNGS EXTENDING THEREBETWEEN; GUIDE MEANS ALONG WHICH SAID SECOND PAIR OF LEGS CAN SLIDE PIVOTED TO THE UPPER PORTIONS OF SAID FIRST LEGS; A PLURALITY OF LOCK MEANS DISTRIBUTED ALONG AT LEAST ONE OF SAID SECOND LEGS; AN ARM MEMBER CONNECTED TO SAID GUIDE MEANS AND HAVING A PORTION COOPERATING WITH AT LEAST ONE OF SAID LOCK MEANS, SAID LOCK MEANS BEING SPACED AT DISTANCES LESS THAN THE SPACING BETWEEN SAID RUNGS TO PREVENT SLIDING MOVEMENT OF SAID SECOND LEGS IN EITHER DIRECTION RELATIVE TO SAID GUIDE MEANS AND THEREBY LOCK SAID SECOND LEGS TO SAID GUIDE MEANS IN PREDETERMINED POSITIONS INTERMEDIATE SAID RUNGS; A RUNG ENGAGING MEMBER RIGIDLY SECURED TO SAID FIRST LEGS AND FACING IN A DIRECTION TO ENGAGE ONE OF SAID RUNGS OF SAID SECOND LEGS; AND A PAIL SHELF CONNECTED TO AND SUPPORTED SOLELY BY SAID GUIDE MEANS SO THAT SAID PAIL SHELF WILL REMAIN AT A FIXED LEVEL RELATIVE TO SAID FIRST PAIR OF LEGS.

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