US857785A - Extension-ladder. - Google Patents

Description

PATENTED JUNE 25, 1907. F. A. BOBBITT- I 2 sums- 11231 1.

EXTENSION LADDER.

APPLICATION FILED AUG- 30.1906.

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1m 2w n0 3 m w THE NORRIS PETERS CO. WASHINGTON, D. C.

P. A. BOBBITT.

. EXTENSION LADDER.

APPLICATION FILED AUG. 30, 1906.

1n: mmms PETERS co., WASHINGTON, n. c.

PATENTED JUNE 25, 1907.

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FranhJLBobbiii UNITED STATES PATENT orrion.

EXTENSION-LADDER.

Specification of Letters Patent.

Patented June 25, 1907.

Application filed August 30,1906. Serial No. 332,612.

To all whom, it may concern.-

Be it known that I, FRANK A. BOBBITT, a citizen of the United States, residing at Uniontown, in the county of Bourbon and State of Kansas, have invented certain new and useful Improvements in Extension-Lad ders, of which the following is a specification.

My invention relates to improvements in extension ladders and consists in the novel construction, combination. and arrangement of parts hereinafter described, pointed out in the claims and illustrated in the accompanying drawings, in which? Figures 1 and 2 represent front and rear elevations, respectively, of the ladder in a folded condition. Fig. 3 is a transverse section taken on line III III of Fig. 2, with some of the parts removed. Fig. 4, is a broken side elevation of the ladder in an extended condition; Fig. 5 is an irregular section, taken on line V V of Fig. 4. Fig. 6, is a broken section. of the outer and intermediate sections of the ladder, in a folded condition.

While the ladder may consist of any number of sections, I have in the present instance shown but three, comprising an outer section 1, an intermediate section 2, and an inner section 3. The lower ends 4 of the outer section are bent in opposite directions, as shown in Fig. 1, to afford a broad bearing surface for the ladder, so that there will be no danger of the same tipping side-wise when in an' eX- tended condition. Section 1 is provided with a series of rungs 5, and a transverse brace 6, which latter is located at the upper end of the section, and acts as a guide in holding section 2 in alinement with section 1.

7 designates longitudinal grooves arranged in the side pieces 8 of section 1 for the reception of the out turned ends of a plurality of crank-arms 9, carried by the intermediate section.

10 designates a pair of dogs pivotally secured to the inner portions of sides 8 and provided with notches 11, for engaging theout turned ends 12 of crank-arms 9, which latter are arranged in recesses 9 so as not to interfere with side pieces 8.

13 designates a Windlass journaled in the lower portion of section 1. and provided at one end with a ratchet-wl'ieel let, which is normally'engaged by a pawl 15, pivoted to the adjacent side piece 8 and adapted to be held either in or out of engagement with the ratchet-wheel by a retractile' spring 16.

One end of the Windlass shaft is provided with a crank 17 whereby it is rotated.

Intermediate section 2 consists of a pair of longitudinal side pieces 18, a series of rungs 19, and two transverse braces 20 and 21, arranged at the upper and lower portions, respectively, of the side pieces 18. Brace 20 acts as a guide for holding the inner section 3 in longitudinal alinement with section 2, and the ends of brace 21 extend into grooves 7 and act as guides in holding the intermediate section in longitudinal alinement with the outer section 1.. Brace 20 also acts as a stop in limiting the folding movement of section 2, by contacting with brace 6.

Section 2 is normally locked in a folded condition by a latch 22, pivotally secured to one side of section 1, and comprising a foot piece 23, an arm, 24; and a hook 25, which latter normally engages the lower side of an opening 26 in a face plate 27, secured to the lower adjacent side of the intermediate section 2. Hook 25 is normally held in engagement with the faceplate, as shown in Fig. 6, by means of a retractile spring 28.

The inner portions of side pieces 18 are provided with longitudinal grooves 29 which, like grooves'7, flare at their upper ends, as clearly shown in Fig. 6, so as to guide the out turned ends of crank arms 9, and the similar ends of crank-arms 32, into said grooves when the ladder is being folded.

30 designates a pair of dogs pivotally secured to the upper portions of side pieces 18 and intersecting grooves 29, said dogs being provided at their upper terminals with notches 31 for engaging the out-turned ends of the crank-arms 32, which latter are arranged in recesses 33, so as not to interfere with side pieces 18, when the ladder is folded.

34 designates by-passes extending around the front sides of the dogs and communicating with'the grooves 29. As the construction and arrangement of the dogs and the bypasses is identical to the similar parts of section 1, further illustration of the latter is considered unnecessary.

Inner section 3 consists of longitudinal side pieces 34 and rungs 35, the upper ends of the side pieces being provided with rollers 36, adapted to bear against the wall of a building while the ladder is being extended, and thus reduce to a minimum the friction between the upper end of section 3 and said wall. Rollers 36 may also be run upon the ground, when conveying the ladder from place to place, in which instance ends 4 are grasped so that the ladder may be pushed along in the manner of a wheel-barrow. The ends of the lower-most rung 35 are slidably arranged in grooves 29, and thus assist in holding the inner section in longitudinal alinement with the intermediate section.

Crank- arms 9 and 32 have inturned ends 9 and 32 respectively, pivotally secured in the longitudinal side pieces of their respective sections 2 and 3.

37 designates a two-sheave block pivotally secured to a bolt 38 projecting from brace 6.

39 designates a one-sheave block pivotally secured to a staple 4O projecting rearwardly from brace 21. 41 designates another onesheave block pivotally secured to a rod 42, carried by a cross-head 43, red 42 being bent upwardly to prevent block 41 from interfering with block 39 when the ladder is folded, (See Fig. 2).

The ladder is extended by means of windlass 13 and a cable 44, which latter is attached at its ends to said Windlass, and an eye 45 depending from block 37. Said cable extends upwardly from the Windlass, thence through one side of block 37, then downwardly through block 39, up through the opposite side of block 37, thence downwardly through block 41 and upwardly to eye 45.

Cross-head 43 consists of two transverse bars secured together, the ends of the inner one, being slidably arranged in grooves 29, while the ends of the outer one extend around the rear sides of sections 1 and 2,and terminate in forwardly extending members 46, adapted to contact with stop pins 47 projecting from the upper portions of side pieces.

The operation is substantially as follows When it is desired to extend the inner section 3, the Windlass is turned in the direction of arrow at in order to wind the lower portion of the cable thereon. This causes the cable to draw cross-head 43 upwardly, and as the lower end of the inner section rests thereon it will be carried upwardly therewith. As

I section. 3 moves upwardly, the out-turned ends of the crank-arms 32 will pass upwardly behind the dogs 30, as indicated by the arrow 1), and push the same forward, so that they may pass out of the upper ends of grooves 29. Should it be desirable to stop section 3 at any point of its upward movement, it is raised until the crank-arms nearest said point engage notches 31, so that the weight of the section will rest upon dogs 30, and the out-turned ends of the crank-arms engaging the same, thus relieving the cable of all weight. However, should the movement of section 3 be checked at any point between the arms 32, pawl 15, engaging ratchetwheel 14, will lock the Windlass, so that the cable cannot unwind, and allow section 3 to accidentally fall, in case crank 17 is released.

When it is desired to lower section 3, it is raised until the crank-arms engaging notches 31 pass above the upper ends of dogs 30, which ends are immediately drawn into engagement with the rear sides of grooves 29 (see Fig. 6) by springs 43. Then by throwing pawl 15 out of engagement with the ratchet-wheel and turning crank 17 backwardly, section 3 may be lowered as the outturned ends of the crank-arms 32 will contact with the front curved sides of the dogs, and be directed thereby through the bypasses 34, so that section 3 will be free to move downwardly. While section 3 is being raised as above described, section 2 will be prevented from moving upwardly therewith by hook 25 engaging face-plate 27. Should it be desirable to extend sections 2 and 3, section 3 is first raised until its lowermost crank-arms engage notches 31. Then in this position, cross-head 43 rests a short distance below the stop-pins 47, this distance being slightly greater than the distance from the lower ends of the notches 31 to the upper terminals 30 of dogs 30. Latch 25 is now disengaged from the face-plate by pushing backwardly on the foot-piece 23. This movement swings arm 24 upwardly, causing it to raise sections 2 and 3 together, so that the uppermost crankarms will remain in notches 31. As the operator continues to turn the Windlass the cross-head will be brought into contact with stop-pins 47 before it can raise section 3 high enough to disengage crank-arms 32 from the notches 31. The upward movement of the cross-head being checked section 2 will now be drawn upwardly and carry section 3 therewith. When the lower end of section 2 moves above hook 25, the latter will be drawn into contact with a stop 50, which limits its inward movement so that when the section is lowered it will contact with the beveled end 25 of the hook and push the latter out of its path.

What I claim as my invention, and desire to secure by Letters Patent, is

'1. In an extension ladder, a plurality of sections slidably arranged upon each other, a Windlass mounted upon the outermost section, a cross-head for extending the innermost section, stops for limiting the upward movement of said cross-head, and a cable attached at its ends to the Windlass and the outermost section, and suitably connected to the intermediate section and the crosshead.

2. In an extension ladder, a plurality of sections slidably arranged upon each other, a Windlass mounted upon the outermost section, a cross-head for extending the inner most section, a latch for holding the intermediate section while the innermost section is being extended, and a cable attached at its ends to the Windlass and the outermost section, and suitably connected to the intermediate section and the cross-head.

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upwardly and be guided by said dogs into the by-passes when the sections move downwardly.

4. An extension ladder consisting of a plurality of sections slidably arranged upon each other, the outermost and intermediate sections having longitudinal grooves, dogs which normally close the upper portions of said grooves, said dogs having notches and extensions, by-passes extending around one side of the dogs and communicating with the grooves, arms pivoted to the intermediateand innermost sections and having out-turned ends which traverse the grooves and the bypasses, said ends being arranged to successivel-y engage the dogs as they move upwardly and be guided by said dogs into the by-passes when the sections move downwardly, a cross-head for moving the innermost section upwardly, stops for limiting the upward movement of the cross-head, said stops being located at a point slightly higher than the dogs, and means for initially raising the intermediate section so that the crosshead will contact with the stops while the lower arms on the innermost section are in engagement with the dogs on the intermediate section.

5. In an extension ladder, a section having longitudinal grooves and by-passes which latter communicate with the former, dogs pivoted to said section between the grooves and the by-passes and provided with notches near their upper terminals which latter are normally held in engagement with one side of the grooves, a second section slidably mounted upon the first-mentioned one, and pivoted members carried by said second section arranged to traverse the grooves and the bypasses and successively engage the notches, substantially as described.

6. In an extension ladder, a section having longitudinal grooves and by-passes which latter communicate with the former, dogs pivoted to said section between the grooves and the by-passes and provided with notches near their upper terminals which latter are nor mally held in engagement with one side of the grooves, a second section slidably mounted upon the first-mentioned one, pivoted members carried bysaid second section arranged to traverse the grooves and the bypasses and successively engagethe notches, and means forraising and lowering said sec ond section.

7. An extension ladder consisting of a plurality of sections slidably arranged upon each other, the outermost and intermediate sections having longitudinal grooves, dogs which normally close the upper portions of said grooves, said dogs having notches and extensions, by-passes extending around one side of the dogs and communicating with the grooves, pivoted members carried by the intermediate and innermost sections arranged to traverse the grooves and the by-passes and engage the dogs as the sections move u wardly and be guided by said dogs into t e by-passes when the sections move downwardly, a device for moving the innermost section upwardly, stops for limiting the upward movement of the device, said stops being at a point slightly higher than the dogs, and a latch for holding the intermediate section while the innermost one is being extended, said latch being provided with a member for initially raising the intermediate section so that the device will contact with the stops while the lower pivoted members on the innermost section are in engagement with the dogs on the intermediate section.

In testimony whereof I affix my signature, in'the presence of two witnesses.

FRANK A. BOBBITT.

Witnesses:

A. L. SHERMAN, F. G. FrsoHER.

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