US2774528A

US2774528A - Folding ladder

Info

Publication number: US2774528A
Application number: US416069A
Authority: US
Inventors: Harris W Crouse
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-03-15
Filing date: 1954-03-15
Publication date: 1956-12-18
Anticipated expiration: 1973-12-18

Description

Dec. 18, 1956 H. w. cRousE 2,774,528

v FOLDING LADDER V Filed March 15, A1954 4 Sheets-Sheet l H. W. CROUSE FOLDING LADDER Dec. 18, 1956 4 Sheets-Sheet 2 Filed March l5, 1954 u M. M u .nwdwmdhwww K W/ a, .1.. wr -im .Hoezeys ma. WW ,...m w

www@ am H. W. CROUSE FOLDING LADDER Dec. 1s, 1956 4 Sheets-Sheet 5 Filed March l5, 1954 Handed@ Wqfome, y MQW. uoazqys Dec. 18, 1956 H. w. cRoUsE 2,774,528

FOLDING LADDER Filed March l5, 1954 4 Sheets-Sheet 4 United States Patent O F FOLDING LADDER Harris W. Crouse, Winthrop, Mass.

Application March 15, 1954, Serial No. 416,069

6 Claims. (Cl. 228-37) This invention relates to ladders of the type having pivoted lungs which permit folding so that the upright side bars may be brought close together.

Ladders of this general type which have been previously devised have been found to lack rigidity when erected and are generally unsafe when made in substantial length. The general object of this invention is to provide a ladder which can be quickly and easily folded into compact form for carrying or storing and which, when erected, is as rigid as an ordinary non-foldable ladder and has provision for securely locking the parts in the erected position. Other objects are to produce a ladder of this kind which is simple to manufacture, is readily convertible from a step-ladder to an ordinary ladder, and has means for securing the back braces in the folded position so as to form a unit which is compact and easily carried.

In the drawings illustrating the invention:

Fig. 1 is a side view of a ladder constructed according to the invention, shown in the erected position;

Fig. 2 is a front View of the ladder;

Fig. 3 is a rear view of the ladder;

Fig. 4 is an enlarged detail, partly in cross-section, showing several of the folding rungs in erected position;

Fig. 5 is an enlarged detail, partly in cross-section, showing a rung in partly folded position;

Fig. 6 is an enlarged cross-section of the locking elements at the bottom of the ladder;

Fig. 7 is a cross-section of the right hand lock member of Fig. 6, shown in unlocked position;

Fig. 8 is a cross-section taken along line 8-8 of Fig. 6;

Fig. 9 is a cross-section taken along line 9 9 of Fig. 6;

Fig. 10 is a front view of the ladder as folded;

Fig. 11 is a side view of the ladder folded;

Fig. 12 is a rear view of the ladder folded;

Fig. 13 is an enlarged detail of one of the locks for` the rear legs;

Fig. 14 is an enlarged detail of the lock for the side braces; and

Fig. 15 is a plan view of one of the clips which hold the front and rear uprights of the ladder together in the folded position.

The rungs of the ladder are connected to a pair of

channels

21 and 22, which form the side frames, by means of

pins

23 and 24 respectively. At the top of the channels a pair of

hooks

25 and 26 are mounted and secured by means of nuts. The

legs

27 and 23, which form the rear brace when the ladder is used as a step ladder, are mounted on the hooks. A pair of

crossbraces

29 and 36 are hinged to

collars

31 and 32 on

legs

27 and 28, and a pair of

side braces

33 and 34 are hinged to

collars

35 and 26 on

legs

27 and 23. Another collar 37 is mounted on leg 27 and carries a pin 38. Crossbrace has a notch 39 in its lower end which hooks over pin 38 when the ladder is erected. The cross-brace also carries a swivelled latch arm 4t) which may be jammed against leg 27 to lock the brace in position. Crossbrace 29 has a similar hooked end which engages 2,774,528 Patented Dec. 18, 1956 ICC a pin carried on collar 41 on leg 28, and a latch arm 42 which may be jammed against leg 28.

The mounting of the rungs is exemplified in Figs. 4 and 5. A slide bar 45 is mounted in channel 21 and a similar slide bar 46 is mounted in channel 22. Each rung 2t) has a downwardly curving end projection 47 disposed between pin 23 and the slide bar 45, and an upwardly curving end projection 48 disposed between pin 24 and slide bar 46. A pair of

blocks

49 and 50 are attached to bar 45 and have curved surfaces 51 and 52 which engage the lower and upper edges, respectively, of projection 47. Block 49 forms a stop which prevents the rung from rotating counterclockwise further than the horizontal position. As seen in Fig. 5, however, the curvature of the surfaces of the blocks which engage the edgesof projection 47 is such as to permit free rotation of the rung in the clockwise direction until the ladder is completely folded, with

channels

21 and 22 lying side by side, as in Fig. 10. A similar pair of

blocks

53 and 54 are mounted on slide bar 46. These blocks correspond in shape to blocks 5t) and 49 respectively7 but are mounted in the reverse position so that block 54 limits the upward motion of extension 48 and consequently the counterclockwise rotation of the rung.

In folding, channel 21 moves upward with respect to channel 22, and slide bar 45 also slides upward with respect to channel 21, while slide bar 46 slides downward with respect to channel 22. It is apparent that, if the slide bars are locked to the channels when the ladder is in the erected position, as illustrated in Fig. 4,

blocks

50 and 53 Will hold

ends

47 and 48, respectively, tightly against

blocks

49 and 54, thus securing the rung 2i) in the horizontal position. As each rung is similarly mounted, the whole structure will thus be rigidly locked in the erected position by locking the slide-bars against vertical motion with respect to the channels. The devices for locking the slide-bars are shown in Figs. 6 and 7.

To lock the left hand slide-bar 45, a U-shape way block 55 is attached to the bar and has a recess 56, which, when the ladder is erected, is engaged by a latch member 57 carried on a latch arm 58 which is swingable on a pin 59 mounted on channel 21. A T-shaped block 60 is slidably mounted in way block 55, and a link 61, mounted on a pin 62 lying across a slot 63 in the T-block, connects the T-block to the lowermost rung Ztl. As the ladder is unfolded, block 6i) is carried upward by the link until, in the erected position, the lower end of the T-block rests on the upper end of latch arrn 58 when the latter is brought up to locking position. The linlfis thus firmly held in the position shown in `Fig. 6 and serves as a diagonal brace for the lowermost rung. To release the left hand lock mechanism when folding the ladder, latch arm 58 is swung out to the position indicated by the dotted line 64. Block 6@ is then free to slide downward and bar 45 to slide upward. A handle 65 is provided for manipulating the latch arm.

The right hand slide bar 46 carries a block 66 near its lower end, having an opening 67. A latch arm 68 is journalled on a pin 68 and carries a latch member 70 which, when the ladder is erected as in Fig. 6, engages under the lower end of block 66 and locks the slide-bar 46 against downward movement. A hook shaped member fits over the upper end of latch arm 68 and is slidably secured thereto by means of a screw 72 running through a slot 73 in member '71. Member 71 has a wedge shaped end 74 which, when inserted between block 66 and latch arm 68 tilts the arrn counterclockwise around pin 69, forcing the latch under the lower end of block 66. A tension spring 75 connected between the upper end of hook member 71 and screw 72 ktends to pull the hook downward so that latch member 70 will engage automatically when the ladder is in the erected position. To further insure positive locking, a lever 76 is journalled on a pin 77 mounted across a slot 78 in arm 68. This lever projects through a slot 79 in member 71, and, when pulled down, engages a pin 80, so as to force member 71 down and jam the wedge end 74 between arm 68 and block 66. Lever 76 also serves as a release for the lock, and for this purpose, has a cam 82. When the lever is pushed upward, it pushes against a cross-piece 81 which is part of member 71 and forces the latter upward against spring 75, carrying wedge end 74 out from between member 68 and block 66. At the same time, the cam 82 presses against bar 46 and rotates member 68 clockwise, as Shown in Fig. 7, carrying latch 70 out of engagement with block 66. When the lever is subsequently released it tends to fall back to a neutral position allowing block 66 to slide past it. it is apparent that the downward travel of bar 46, as well as the upward travel of bar 45, depends on the length of the rung extensions47 and 48, and will vary to some extent as this length is varied. Suitable spacing must be provided between the lock elements and lower rung blocks to avoid interference. As shown in Fig. 14, side brace 33 carries an elongated ring 99 mounted to slide sidewise on a pin 91, on the end 92 of the brace. The ring, when turned at right angles to the brace, locks the brace in channel member 21. The end 92 of the brace is split to receive the ring when the latter is aligned with it and the brace may then be withdrawn through the hole 93 in member 21. Side brace 34 is similarly connected to member 22. To fold the ladder, the side braces are first unlocked and withdrawn from the

channels

21 and 22.

Braces

33 and 34 can then be folded down against

legs

27 and 23 respectively and are received in

U-shaped clips

94 and 95 mounted on the respective legs. The cross-braces 29 and 39 are unlocked at the bottom by throwing back the latch arms 4t) and 42 and disengaging the hooked lower ends of the braces from the pins carried by

collars

37 and 41. The cross-braces can then be folded flat against the rear legs, and are secured in

U-shaped clips

96 and 97. l

Next, the rear legs are folded at against the

channels

21 and 22. Each rear leg carries a clip of the type shown in detail in Fig. 15. The clip 99 encircles leg 28 and has two spaced arms, 190 and 101 which engage between them the channel 22, shown in dotted line. Leg '27 has a similar clip 98 which engages channel 21. The folding of the ladder is completed by releasing the lock members for the slide bars 4S and 46, as previously described, and rotating the rungs until the channels lie side by side. The ladder, when folded, is extremely compact and all the parts are secured together for convenient carrying.

To use the ladder with the rear leg and brace assembly, the

hooks

25 and 25 are unscrewed, and the whole rear assembly detached from the

channels

21 and 22. This may be done in either the folded or the erected position. In the latter case, the side braces 33 and 34 would have to be detached from

channels

21 and 22 in the manner previously described.

What is claimed is:

l. A folding ladder comprising: a pair of side uprights; a bar mounted on each of said uprights and slidably in the longitudinal direction thereof; a plurality of rungs connecting said uprights and journalled thereon for rotation from a position perpendicular thereto to a position nearly parallel thereto; and means on said bars for locking said rungs in said perpendicular position, said locking means comprising a series of pairs of blocks, mounted on said bars, each pair engaging an end of a ring and limiting the rotation `of the rung with respect to the bar, and lock members adapted to X said bars to their respective uprights when said rungs are in sai perpendicular position.

2. A folding ladder comprising.' a pair of spaced parallel channels serving as upright members of the ladder; a plurality of rungs connecting said channels and journalled thereon for rotation from a position perpendicular thereto to a position nearly parallel thereto; a rst bar mounted in one of said channels and slidable up and down therein, said bar having means engaging each of said rungs and preventing rotation of the same when the bar is restrained from sliding, said engaging means being adapted to prevent further upward motion of the bar when the rungs are in said perpendicular position; and a second bar mounted in the other of said channels and slidable up and down therein, said second bar having means engaging each of said rungs and preventing rotation of the same when the second bar is prevented from sliding; said last named engaging means being adapted to prevent further downward motion of the second bar when the rungs are in said perpendicular position.

3. A folding ladder as described in claim 2, having means for locking said first bar against downward motion when said rungs are in said perpendicular position, said locking means comprising: a first block attached to said first bar and having a recess; a second block slidably mounted on said irst block and keyed thereto, said second block having a lower edge aligned with the upper edge of the recess when said rungs are in said perpendicular position; a link connecting said second block with one of said rungs; and an arm hinged on the channel within which said first bar is mounted, said arm carrying a latch adapted to engage said recess and the lower edge of said second block when said rungs are in said perpendicular position.

4. A folding ladder as described in claim 2, having means for locking said second bar against upward motion when said rungs are in said perpendicular position, said locking means comprising: a block attached to said second bar, having a recess; a latch arm rotatably mounted on the channel within which said second bar is mounted, carrying a latch member adapted to engage under the low edge of said block when said rungs are in said perpendicular position; a lever connected to said latch arm and having a fulcrum point thereon below the axis of rotation of said arm on said channel, said lever having a cam surface adapted to project through said recess and bear against said second bar, so as to rotate said arm and disengage said latch member from said block; a hook shaped member, mounted to slide up and down on said arm, having a downwardly directed wedge portion adapted to enter between said block and the upper end of said arm; and a member on said hook shaped member adapted to be engaged by said lever, to draw the hook shaped member downward, thereby driving said wedge portion between the block and the arm and rotating the latter to cause engagement of the latch member with the block.

5. A folding ladder as described in claim 2, the ends of the rungs adjacent said first bar overhanging their pocket of attachment to the channel and terminating in a downwardly curved portion, and the engaging means for each of said ends comprising a first block mounted on the bar above the said end and slidably engaging the upper surface of the curved portion, and a second block mounted on the bar below the said end and engaging the lower surface of the curved portion, the second block constituting a stop for the said end and preventing rotation of the rung beyond said perpendicular position.

6. A folding ladder as described in claim 2, the ends of the rungs adjacent said second bar overhanging their point of attachment to the channel and terminating in an upwardly curved portion, and the engaging means for each said ends comprising a first block mounted on the bar above the said end and slidably engaging the lower surface of said curved portion, and a second block mounted on the bar above the said end and engaging the upper surface of the curved portion, the second block constituting a stop for the said end and preventing ro- 785,810 tation of the ring beyond said perpendicular position. 1,500,891

References Cited in the le of this patent UNITED STATES PATENTS 5 536,094

299,833 Mott June 3, 1884 6 Koopman Mar. 28, 1905 Quehi July 8, 1924 FOREIGN PATENTS Great Britain May 2, 1941