US2576277A

US2576277A - Extendable step ladder

Info

Publication number: US2576277A
Application number: US105593A
Authority: US
Inventors: John M Biegen
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-07-19
Filing date: 1949-07-19
Publication date: 1951-11-27
Anticipated expiration: 1968-11-27

Description

Nov. 27,195] J. M. BIEGEN 5 9 EXTENDABLE STEP LADDER I Filed July 19, 1949 2 Sl-lEETS-Sl-IEET 1 Fi qzz v IN V EN TOR.

Jizn J4. Bie e Nov. 27, 1951 J. M. BIEGEN EXTENDABLE STEP LADDER 2 SHEETS-SHEET 2 Filed Jfily 19, 1949 iqzE- view of the upper portion of the auxiliary ladder Patented Nov. 27, 1951 UNITED STATES PATENT OFFICE 'EXTENDABLE STEP LADDER John M. Biegen, Great Neck, N. Y.

. Application July 19, 1949, Serial No. 105,593 40mm. (01. 228-21) This invention relates to step ladders and, more particularly, to extendable step ladders.

An object of the invention is to provide an extendable step ladder having a primary ladder structure and an auxiliary ladder structure, which auxiliary ladder structure can be telescoped into the primary ladder structure.

Another object of the invention is to provide an extendable step ladder, the legs of whichwhen the ladder is extended-are automatically locked against accidental displacement when the ladder is subjected to the weight of the person using the same.

A further object is to provide an extendable ladder which, when not extended, has treads which are broader than the conventional ladder treads.

A still further object of the invention is to provide an extendable step ladder .so constructed that when it is fully extended, a person standing near the top thereof is nearer to the object to be reached, than when standing on the ordinary step ladder.

Still another object of the invention is to provide an extendable step ladder, the auxiliary ladder of which may be raised by a person while standing on the primary ladder.

Another object of the invention is to provide an extendable step ladder having a platform at the top thereof which may be raised or lowered to the proper working height and on which platform there can be placed paint pots, tools, etc.

A still further object of the .invention is to provide an extendable step ladder which has hand rails on each side thereof .for safety in ascending the same being illustrated extended and ready for use;

Fig. 2 is a front view of the step ladder illustrated in Fig. 1;

Fig. 3 is an enlarged fragmentary sectional side structure;

Fig. 4 is an enlarged fragmentary plan view of the upper portion of the auxiliary ladder structure;

Fig. 5 is a detailed sectional view of the upper portion of the primary ladder structure;

Fig. 6 is a fragmentary sectional view taken'on line 6-6 of Fig. 5; and

Fig. '7 is a detailed view looking from the rear of the step ladder, showing the offset latch bar.

Referring to the accompanying drawings by numerals, I0 indicates the primary ladder structure, and II indicates the auxiliary ladder structure which, as will hereinafter be shown, telescopes into the primary ladder structure.

As illustrated, particularly in Fig. 6,-the upper side rails I2 of the auxiliary structure II are slidably mounted within the lower side rails I3 of the primary structure I0. Lower brackets It are afiixed to each of the lower side rails I3 in such manner that each lower bracket aflixed to the right hand lower side rail I3 has its counterpart affixed to the left hand lower side rail I3, on the same horizontal plane.

Secured to these lower brackets I4 are left and right lower hand rails I5. Mounted on each set of lower brackets I4 is a lower tread It.

Upper brackets I! are affixed to each of the upper side rails I2 of the auxiliary ladder structure I I in such manner that each upper bracket I! on the right hand upper side rail I2 has its counterpart on the left hand upper side rail I2, on the same horizontal plane. Mounted on each set of these upper brackets Il is an upper tread I8, having acurved portion I 9. The upper treads I8 are so spaced with relation to the ground level that when the auxiliary ladder structure is not in its fully extended position, the upper tread or treads I8--which are below the top of the primary ladder structure IIl-are on the same horizontal plane as the nearest lower tread It, so that the particular lower tread I6 and the upper I tread I8 form one broad tread.

, within the lower hand rails I5. Pivot plates 25 are affixed to the upper portion of the lower side rails I3. Props 26 are pivotally mounted on the ";66..pivot-p1ates 25., A spreader 21 is pivotally mounted on the right lower side rail l3 and the right prop 26, and a spreader 21 is pivotally mounted on the left lower side rail [3 and left prop 26. Rings 28 are secured to the top of each of the spreaders 21. A latch bar 29, having an offset portion 30, is mounted at the top of and between the props 26, above the pivot plate 25.

The ladder is stored in its telescoped or closed position with the spreaders broken so that the props 26 are brought next to the lower side rails In operation, the spreaders 21 are closed by downward pressure so that the props 26 are held rigidly away from the lower side rails l3. If the point of work is not very high, the ladder can then be used as an ordinary step ladder with the advantage that the upper treads I B, being on the same levels as the lower treads 16, a much broader tread is provided and the further advantage that the lower hand rails l5 and the curved upper portion 23 of the upper hand rails 24 provide. safety in ascending and descending the ladder.

Should it be desired to extend the ladder from its telescoped or closed position, the operator need merely grasp the upper hand rails 24 while standing on a lower tread l6 and raise these upper hand rails 24, thus raising the upper side rails [2 to the height desired. In raising these upper side rails I2, the curved portions 19 of the upper treads 18 will cause the offset portion 32 of the latch bar 29 to swing outwardly so that the upward movement of the upper side rails l2 will not be impeded. As each respective curved portion [9 of each upper tread passes above the offset portion 30 of the latch bar 29, said ofiset portionby reason of the pendulum action of the latch bar-- will swing inwardly and immediately under the curved portion I9 of the upper tread it which is then above the latch bar. Thus, the auxiliary ladder structure I I having been raised to the desired position, the downward movement of this auxiliary ladder structure will be arrested when the curved portion IQ of the upper tread I8, which is then immediately above the latch bar 29, hooks onto the offset portion 30 of the latch bar 29.

It is to be noted that when the auxiliary ladder structure I l is raised, not only the upper side rails l2 are raised out of their telescopic engagement with the lower side rails [3, but the upper hand rails 24 are likewise raised out of their telescopic engagement with the lower hand rails l5. However, neither the upper side rails I2 nor the upper hand rails 24 are ever completely raised out of the respective lower side rails l3 or lower hand rails l5 and there is added support given to the ladder at the points where the upper side rails 12 are still telescopically or slidably mounted within the lower side rails l3 and the upper hand rails 24 are still telescopically or slidably mounted within the lower hand rails 15.

When it is desired to lower the auxiliary ladder structure ll so that it will telescope into the primary ladder structure [0, the operator, facing the ladder, merely grasps each ring 28 on the spreaders 2'5 and pulls the rings upwardly. This; breaks the spreaders causing the portion of the props 26 which are below the pivot plates 25 to be brought inwardly towards the rails l3 and at the same time causes that portion of theside props above the pivot plates 25 to swing outwardly.

and upwardly in an arcuate path.' This movement of the upper portion of the props 26. draws the latch bar outwardly in an arcuate path causing the offset portion 30 to become disengaged from the curved portion] Bof the particular uppertread I8, and allows the upper side rails 12 to slide down into the lower side rails l3, and the upper hand rails 24 to slide down into the lower hand rails [5, so that the auxiliary ladder structure l l is telescoped into the primary ladder structure 10 and the ladder is then in its closed position ready for storage.

While the invention has been described in detail with respect to a present preferred form which it may assume, it is not to be limited to such details and form since many changes and modifications may be made in the invention without departing from the spirit and scope of the invention in its broadest aspects. Hence, it is desired to cover any and all forms and modifications of the invention which may come within the language or scope of any one or more of the appended claims.

I claim:

1. An extendable step ladder comprising a primary ladder structure having lower side rails and lower treads, pivot plates mounted on the upper portions of said lower side rails, props pivotally mounted on said pivot plates, spreaders pivotally mounted between said lower side rails and props, an auxiliary ladder structure having upper side rails telescopically mounted within said lower side rails of the primary ladder structure, upper treads with curved portions mounted on said auxiliary ladder structure, a latch bar having an ofiset portion pivotally mounted between said props and above said pivot plates, and so positioned that when the auxiliary ladder structure is raised, the offset portion of said latch bar will normally engage the curved portion of one of said upper treads thus arresting the downward movement of said auxiliary ladder structure, whereby when the spreaders are pulled upwardly, the upward portions of the props above the pivot plates move outwardly and upwardly in an arcu'ate path causing the offset portion of the latch bar to become disengaged from the curved portion of the upper tread and the upper side rails of the auxiliary ladder structure to telescope into the lower side rails of the primary ladder structure.

2. An extendable step ladder comprising a primary ladder structure having lower side rails, lower treads and lower hand rails, pivot plates mounted on the upper portions of said lower side rails, props pivotally mounted on said pivot plates, spreaders pivotally mounted between said lower side rails and props; an auxiliary ladder structure having upper side rails telescopically mounted within said lower side rails of the primary ladder structure, upper hand rails telescopically mounted within said lower hand rails of the primary ladder structure, upper treads with curved portions mounted on said auxiliary ladder structure, a latch bar having an offset portion pivotally mounted between said props and above said pivot plates and so positioned that when the auxiliary ladder structure is raised, the offset portion of said latch bar will normally engage the curved portion of one of said, upper treads, thus arresting the downward movement of said auxiliary ladder structure, whereby when the spreaders are pulled upwardly, the upward portions of the props above the pivot plates move outwardly and upwardly in an arcuate .path causing the offset portion of the latch bar to become disengaged from the curved portion ofgthe upper tread, and the upper side rails'and' upper hand rails of the auxiliary ladderstruoture, to telescope, respectively, into the lower" side rails and lower handrailsof. the primary ladder structure. .2

3. An extendable step ladder comprising a primary ladder structure having lower side rails, lower treads and lower hand rails, pivot plates mounted on the upper portions of said lower side rails, props pivotally mounted on said pivot plates, spreaders pivotally mounted between said lower side rails and props; an auxiliary ladder structure having upper side rails telescopically mounted within said lower side rails of the primary ladder structure, upper hand rails telescopically mounted within said lower hand rails of the primary ladder structure, upper treads with curved portions mounted on said auxiliary ladder structure, a platform mounted on said auxiliary ladder structure, a latch bar having an offset portion pivotally mounted between said props and above said pivot plates and so positioned that when the auxiliary ladder structure is raised, the offset portion of said latch bar will normally engage the curved portion of one of said upper treads, thus arresting the downward movement of said auxiliary ladder structure, whereby when the spreaders are pulled upwardly, the upward portions of the props above the pivot plates move outwardly and upwardly in an arcuate path causing the offset portion of the latch bar to become disengaged from the curved portion of the upper tread, and the upper side rails and upper hand rails of the auxiliary ladder structure to telescope, respectively, into the lower side rails and lower hand rails of the primary ladder structure.

4. An extendable step ladder comprising a primary ladder structure having lower side rails, lower treads and lower hand rails, pivot plates mounted on the upper portions of said lower side rails, props pivotally mounted on said pivot plates, spreaders pivotally mounted between said lower side rails and props; an auxiliary ladder structure having upper side rails telescopically 6 mounted within said lower side rails of the primary ladder structure, upper hand rails telescopically mounted within said lower hand rails of the primary ladder structure, upper treads with curved portions mounted on said auxiliary ladder structure, a platform mounted on said auxiliary ladder structure, a latch bar having an offset portion pivotally mounted between said props and above said pivot plates and so positioned that when the auxiliary ladder structure is raised, the ofiset portion of said latch bar will normally engage the curved portion of one of said upper treads, thus arresting the downward movement of said auxiliary ladder structure, whereby when the spreaders are pulled upwardly, the upward portions of the props above the pivot plates move outwardly and upwardly in an arcuate path causing the ofiset portion of the latch bar to become disengaged from the curved portion of the upper tread, and the upper side rails and upper hand rails of the auxiliary ladder structure to telescope, respectively, into the lower side rails and lower hand rails of the primary ladder structure and whereby, when the auxiliary ladder structure is telescoped into the primary ladder structure, the upper treads of the auxiliary ladder structure and the lower treads of the primary ladder structure form one common tread.

JOHN M. BIEGEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 74,102 Luzier et al. Feb. 4, 1868 164,683 Hildreth June 22, 1875 548,111 Cardarelli Oct. 11, 1895 886,737 Taylor May 5, 1902