US2800371A - Ratchet ladder - Google Patents

Description

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July 23, 1957 c. QUERCETTI RATCHET LADDER s Shee ts-Sheet s Filed June 22, 1954 INVENTOR. Z001] C. QUL /QCETT/ BY ATTOlP/VEX V United States Patent flice 2,806,371 Patented July 23, 1957 2,800,371 RATCHET LADDER Louis C. Quercetti, Philadelphia, Pa.

Application June 22, 1954, Serial No. 438,525

7 Claims. (Cl. 304-) My invention relates to a new and useful ratchet ladder and has for one of its objects to provide a structure including a supporting frame, a pair of relatively small platforms or movable steps slidably mounted on the supporting frame, and cooperating mechanisms on said supporting frame and the movable steps whereby the latter may be alternately elevated by the lifting of the users feet to produce a climbing effect.

Another object of the invention is to provide companion units joined together in a unitary structure and each unit including duplicate elements of a supporting frame, which units comprise side rails with the sliding shoes of movable steps mounted thereon, said steps having ratchet pawls or detents cooperating with ratchet toothed racks on the frame units whereby the movable steps may be alternately and intermittently advanced in small rectilinear move ments, said supporting frame having an adjustable base at the lower end thereof and provided with a platform or shelf at the upper end of the same, said shelf preferably being on an extensible member. The steps being movable short distances provides for adjusting them to the best position relative to work to be done or the height of a workingman or both.

Another object of the invention is to provide a ratchet mechanism to reduce to a minimum the likelihood of the parts becoming disengaged and to retain said steps in any adjusted position.

Another object of the invention is to provide means for tethering the companion movable step to each other which constitutes an additional safety factor by limiting the descent of one step relative to the other in case either step is accidentally freed and the companion step is held fast.

A further object of this invention is to provide a novel construction of movable step having shoes slidable on the side rails of a frame unit, each shoe partially surrounding its respective side rail and extending about the same for more than one hundred eighty degrees, and said step structure embodying means to adjust the step itself to a substantially horizontal position regardless of the angular position of the frame.

A still further object of the invention is to provide safety props for the base of the ratchet ladder frame having choke members to hold said props in various adjusted positions whereby the ladder is prevented from tilting outwardly away from a wall against which it is resting even though the center of gravity of the steps and their load is outwardly beyond the base of the ladder.

With the above and other objects in view, as will become apparent from the description below, this invention consists of the details of construction of elements hereinafter set forth and then designated by the claims.

In order that those skilled in the art to which this invention appertains may understand how to make and use the same I will describe its construction in detail referring by numerals to the accompanying drawing forming a part hereof, in which:

Fig. 1 is a side elevation of the ratchet ladder constructed according to my invention and illustrating its general appearance when set up against a wall surface, a portion being broken away to indicate that such a ladder may be of any appropriate length.

Fig. 2 is a front viewof Fig. 1.

Fig. 3 is an enlarged fragmentary detail sectional view on the line 33 of Fig. 2 illustrating the construction and operation of a movable step structure.

Fig. 4 is a top plan view of Fig. 3 at the line 44 of Fig. 3.

Fig. 5 is a sectional view on the line 5-5 of Fig. 3 to illustrate certain details of construction.

Fig. 6 is an underneath view of the step structure on the line 6-6 of Fig. 5 with the tread plate removed.

Fig. 7 is an elevational view of one shoe of a movable step and its relation to a frame unit side rail on which it is slidably mounted.

Fig. 8 is a section on the line 8-8 of Fig. 7.

Fig. 9 is an enlarged fragmentary view, in perspective, of the ratchet mechanism.

Fig. 10 is a sectional view on the line Ill-10 of Fig. 9.

Fig. 11 is an enlarged sectional view on the line 1111 of Fig. 2 to show the arrangement of the cross braces in each frame unit.

Fig. 12 is an enlarged fragmentary elevational View in the region of the flexible tether of the two movable steps.

'Fig. 13 is an enlarged fragmentary View partly in elevation and partly in section, of the upper end of the ladder to show the extensible head-piece and shelf with relation to the frame.

Fig. 14 is a side or edge view thereof looking at the left hand side of Fig. 13.

Fig. 15 is an enlarged fragmentary front elevation of the base end of the ladder to show the foot-piece and props.

Fig. 16 is a side or edge view, partly in section, looking at the left hand side of Fig. 15

In carrying out my invention as herein embodied 20 represents the supporting frame of the ladder comprising, generally, two identical frame units 21 and 22, Figs. 2, 13 and 15, the parts of which consist, preferably, of light weight but strong metal such as, for example, a hard or tough aluminum alloy.

Each frame unit 21, 22 includes two opposed side rails 23 and 24 preferably of tubular formation and joined together in spaced relation by the tubular cross rounds 25 which may project into the side rails, Fig. 11, and be exteriorally welded or otherwise secured in place. The two frame units 21, 22 are assembled in side by side spaced relation by the upper fixed tubular tie member 26, Fig. 13, and the lower detachable tie member 27, Fig. 15, which may be either a tube or rod. The tie member 26 projects through the adjacent side rails 24, 23 of the assembled frame units and the ends of said tie member 26 are fixed to the exteriors of the far or outside side rails of said frame units. This leaves the bores of said outside side rails clear at their upper ends for a purpose to be presently described. The lower tie member 27 is projected through both side rails of both frame units with the ends of said tie member 27 protruding beyond the outside side rails of the assembled frame units for the reception of nuts 28 to detachably hold the parts together. A tubular spacer 29 may be mounted on the lower tie member 27 between the two frame units or between the inside side rails of the respective units.

A base 30, adapted to set substantially flat on a ground surface, has upstanding lugs 31 adjacent the ends journalled on the protruding ends of the lower tie member 27 whereby said base is swingingly automatically adjustable relative to the ladder frame structure.

A frame extension or ladder head 32 of substantially inverted U-shape includes a reach element 33, Fig. 13, of suflicient length to reach from the outside rail of one frame element, as the side rail 23 of frame unit 21, to the outside side rail of the other frame unit, as the side rail 24 of the frame unit 22, and from the ends of said reach member extend the legs 34 slidably mounted in the bores of the upper ends of said outside side rails of the assembled companion frame units. The extension or head 32 is held in any selected adjusted position by thumb screws 35 threaded through walls of the outside side rails of the assembled frame units and engaging the respective legs of said extension. A shelf 36 is secured to the reach element of the extension as by welding indicated at 37 in said Fig. 13 or some equivalent means. By reference to Fig. 1 it will be apparent that what I term the back edge of the shelf, preferably, is substantially in line with the back of the ladder frame while the front portion of said shelf eX- tends forwardly a considerable distance.

A ratchet rack 38 is mounted on the rounds 25 of each frame unit midway between and parallel to the side rails of the respective frame units and, preferably, is in the form of a cross, see Figs. 5, 9 and 11, including vertical and horizontal webs 39, 40, respectively. In assembling the ratchet rack the rounds 25 are projected through the vertical web 39 contiguous and below the horizontal web so that the latter rests on the rounds and said rack is then welded to said rounds as at 41, Fig. 11. The portion of the vertical web 39 above the horizontal web 40 has the upwardly facing ratchet teeth 42 formed thereon.

To the lower end of each ratchet bar is pivoted the upper end of a prop 43 of sufficient length to extend over the base 30 and engage the ground surface while the ladder is in various usual inclined positions against a supporting or wall surface such as indicated by the vertical dot and dash line in Fig. 1. After the ladder is positioned as desired the lower or outer end of one or each prop is caused to engage the ground surface in front of the base of the ladder and then fastened by the choke member 44, Fig. 16, comprised of a flexible element, such as a chain temporarily detachably connected to an anchoring member 45, such as a hook, on the base 30. The props will hold the ladder against accidental outward tilting should the center of gravity of the load on the ladder be located or shifted to a position forward of the lower end of said ladder where it rests on the ground surface or the axial center of the lower tie member 27.

The movable steps 46 and 47, one for each frame unit 21, 22, respectively, each consists of a rectangular border framework 48 having a set-in portion or bay 49, Fig. 6, all of angle sections with a longitudinal T shaped center rib 50 extending from the inner side of the outer end of arm 57 and an angle inner arm 58 welded to the body of i the shoe at "substantially opposite locations with straight parallel forwardly projecting portions secured together as by welding.

The movable step 47 is pivoted at its inner end to the upper brackets 53 of a pair of companion shoes 54 by means of a pintle rod 59 projecting through the step framework including the side angles of the set-in or bay portion 49, Figs. 3-6 and 9. The outer end of the movable step is held in various angular adjustments by braces 60, Fig. 3, pivoted at their lower ends to the lower brackets 55 on the companion shoes and the upper ends of said braces are selectively held in difierent positions on the sides of the step framework by removable fastening means 61, Fig. 6, such as bolts and nuts, projected through the upper ends of said braces and individual holes of rows of holes 62, Fig. l, in said sides of the step framework.

On the pintle rod 59 of each movable step underneath of the latter is pivoted the upper end of a ratchet or detent 63, Figs. 3 and 9, the same being retained in a central position by tubular spacers 64 mounted on said pintle rod between said ratchet pawl and appropriate parts of the step framework, such as the sides of the setin or bay 49 of said framework. The lower end of the ratchet pawl 63 has a plurality of ratchet teeth 65, Fig. 9, for coaction with the ratchet teeth 42 of the ratchet 1 bar 38 towards which the lower toothed end of said the framework to the set-in portion 49 and being cut out at the ends whereby the head of the T-shaped center rib is flush with the top inturned legs of the framework angles and the upright web of said rib underlies said inturned legs of said step framework. A tread plate 51, preferably foraminous, is mounted on the step framework and welded or otherwise appropriately fastened thereon and said tread plate has a recess 52, Fig. .4, coinciding with the set-in portion of said step framework.

Each movable step 47 is pivotally connected to brackets 53 at the upper ends of the shoes 54 slidably mounted on opposed side rails of a ladder frame unit which shoes 9 also have brackets 55 at their lower ends. Each shoe 54,

Figs. 7 and 8, comprises a body 56 of considerable length and curved in cross section to embrace more than one hundred eighty degrees of the outer circumference of its respective side rail on the outer side wall of the latter thereby providing an open inner side wall to the shoe whereby said shoe may pass the rounds 25 and tie members 26 and 27 during the sliding movements. The brackets 53 and 55 project from the outer side of their respective shoe and may consist of a curvilinear outer ratchet pawl 63, is urged by a suitable spring pressure means 66 Fig. 3.

For purposes of illustration, the spring pressure means is shown as comprised of a shackle 67 pivoted to the back of the pawl 63 and provided with a shoulder 68 and a tubular arm 69, and a second shackle 70 pivoted to the T-shaped center rib 50 of the step framework and provided with a shoulder 71 and an arm 72 telescoped into the tubular .arm 69 with a coil spring 73 mounted on said arms and the opposite ends of said spring in engagement with the opposed shoulders 68 and 71. To keep the toothed lower end of the ratchet pawl 63 in line with the ratchet bar 38, side flanges 74, Fig. 9, are provided on said toothed lower end of said ratchet pawl which overlap the toothed portion of said ratchet bar 38 and said side flanges may be in the form of plates secured to opposite sides of the ratchet pawl.

To disengage the toothed lower end of the ratchet pawl from the ratchet bar there is provided an operating trigger 75, Figs. 3 and 9, consisting of two spaced parallel members 76 of identical formation positioned on opposite sides of the pawl 63 and joined at their forward ends by an outwardly projecting bridge or connector 77. The members 76 each include a limb 78 and a branch 79 at an acute angle to one another extending from a juncture where the trigger is connected by a pivot 80 to the pawl 63 intermediate the ends of the latter so that each branch underlies its respective limb. The branches 79 are the fulcrums or lifting elements of the trigger and engage the horizontal web 40 on opposite sides of the toothed portion of the vertical web 39 of the ratchet bar 38. The limbs 78 have open end slots 81 in the backs thereof for registration with the pintle bar 59 or, more particularly, the spacers 64 on said pintle bar to allow for certain movements of the trigger while preventing accidental displacement thereof. At the forward end of each limb 78 is an inwardly projecting stop finger 82 normally spaced from the horizontal web 40 of the ratchet bar 38 but adapted to contact said horizontal web to limit the outward throw of the toothed lower end of the pawl.

Outwardly of each stop finger 82 and forward of the side walls of the bridge 77 is a stop shoulder 83 for c0- action, under certain conditions, with the inverted U- shaped stirrup 84 having its ends pivoted to the movable step in the region of the set-in portion or bay of said step and the forward edges of said side walls of the bridge are slightly beveled in the arc of the swing of said stirrup as plainly shown in Fig. 3. When the stirrup is in engagement with the bridge 77 of the operating trigger 75 the pawl 63 is locked in holding condition with relation to the ratchet bar 38 and the movable step cannot be accidentally released for descent. On the other hand, when the stirrup is raised as shown herein the toe of a persons shoe may be inserted therein or projected thereunder so that the lifting of the foot will elevate the movable step a distance commensurate with the distance the foot is lifted.

As there are two movable steps side by side on the appliance a person stands on both of said steps and by lifting one foot and then the other these steps are alternately elevated until the desired height is attained and since the ratchet pawls are spring pressed they automatically hold the steps in the intermittently elevated position and since the ratchet structures permit short movements of the steps they can be adjusted to the work in a manner which will be most suitable for and agreeable to the workingman. The steps are designed to accommodate the full length of the feet of a person thus making it comfortable during the work operations.

An additional safety factor is provided by using a flexible leash 85, such as a chain, Figs. 1 and 12, between the two movable steps of the apparatus. Actually the opposite ends of the leash are fastened to the adjacent or inside shoes of companion movable steps and is of sufiicient length to allow a considerable but limited movement of one step relative to the other. Should one step become unlatched for some unknown reason and the other remain latched in place the unlatched one will descend below the latched one only a distance equal to the length of the leash and probably prevent a serious accident.

To descend, the person using the apparatus depresses the forward end of the operatng trigger 75 by pressing inwardly on the bridge 77. This will swing said trigger inwardly about its pivot 80 and since the branches 79 are resting on the ratchet bar 38 said pivot 80 will be moved away from the ratchet bar a suflicient distance to lift the toothed lower or rear end of the pawl out of engagement with the teeth of the ratchet bar and when the pressure is removed from the bridge the pawl will be returned to its holding position by the spring pressure means 66.

Of course I do not wish to be limited to the exact details of construction herein shown and described as these may be varied within the scope of the appended claims without departing from the spirit of my invention.

Having described my invention what I claim as new and useful is:

1. In a ladder including a pair of generally parallel spaced frame units and a step mounted on each frame unit for movement therealong: the improvement comprising a toothed ratchet rack extending longitudinally along and fixed to each frame unit, a pawl pivoted to each step for swinging movement into and out of interengagement with the adjacent rack, resilient means biasing said pawls into engagement with said racks to limit said steps to movement in one direction along said frame units, and a pair of selectively actuable triggers each pivoted to one of said pawls and engageable with the adjacent frame unit upon pivotal movement relative to the associated pawl to swing the latter out of engagement with its adjacent rack against the force of said resilient means, whereby said steps are movable in the other direction along said frame units.

2. The improvement according to claim 1, in combination with locking means pivoted to each of said steps for swinging movement into and out of engagement with the adjacent trigger to prevent pivotal movement of the latter, to thereby lock said pawls in interengagement with said racks.

3. The improvement according to claim 1, in combination with locking means comprising a stirrup pivoted to each of said steps and adapted in one position of their pivotal movement to receive the foot of an operator for actuating said steps in said one direction of movement along said frame units, each of said stirrups being shaped to engage in another position of its pivotal movement with the adjacent one of said triggers to prevent pivotal movement of the latter, and hence lock the respective pawl in interengagement with the adjacent rack.

4. A device for adjustably positioning a step movable along a ladder frame, said device comprising a toothed ratchet rack extending longitudinally along and fixed to said ladder frame, a pawl pivoted to said step for swinging movement into and out of interengagement with said rack, resilient means biasing said pawl into engagement with said rack to limit said stepped movement in one direction along said frame, and selectively actuable trigger means pivoted to said pawl and engageable with said frame upon pivotal movement relative to said pawl to swing the latter out of engagement with said rack against the force of said resilient means, whereby said step is movable in the other direction along said frame.

5. A device according to claim 4, in combination with a stirrup pivoted to said step and adapted in one position of its pivotal movement to receive the foot of an operator for moving said step in said one direction, said stirrup being engageable in another position of its pivotal movement with said trigger means to prevent rotation of the latter, and hence lock said pawl in interengagement with said rack.

6. In a ladder construction, an elongate frame unit adapted to be arranged in upstanding relation, a toothed ratchet rack extending longitudinally along and fixed to said frame unit with its teeth facing upwards, a step mounted on said frame unit for sliding movement therealong, a stirrup pivoted to said step and adapted in one position of its pivotal movement to receive a persons foot, a pawl pivoted at its upper end to said step and provided at its lower end with ratchet teeth for interengagement with said rack to prevent downward step movement, said pawl being swingable about its pivotal axis into and out of interengagement with said rack, spring means carried by said step and resiliently urging said pawl into interengagement with said rack to limit said step to upward movement, and a selectively actuable trigger pivoted to said pawl and engageable with said frame unit upon pivotal trigger movement relative to said pawl to swing the latter out of interengagement with said rack against the force of said spring means, whereby upward step movement may be effected by a persons foot engaged in said stirrup and downward step movement may be efiected by actuation of said trigger.

7. A ladder construction according to claim 6, in combination with an upward trigger extension shaped to be engaged by said stirrup upon pivotal movement of the latter to prevent pivotal movement of said trigger, to thereby lock said pawl in interengagement with said rack and prevent both upward and downward movement of said step.

References Cited in the file of this patent UNITED STATES PATENTS 565,539 Hartzell Aug. 11, 1896 621,856 Schwarz Mar. 28, 1899 788,992 Bauer May 2, 1905 852,141 Sebree Apr. 30, 1907 1,182,706 Priest May 9, 1916 1,918,293 Seiler July 18, 1933

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