US2854293A - Combined scaffold bracket and lock - Google Patents

Description

Sept. 30, 1958- H. J, RlBLET 2,854,293

COMBINED SCAFFOL D BRACKET AND LOCK Filed Oct. 26, 1953 2 Sheets-Sheet 1 INVENTOR HENRY J. RIBLET Sept. 30, 1958 H. J. RIBLET comma SCAFFOLD BRACKET AND LOCK 2 Sheets-Sheet 2 Filed Oct. 26, 1953 FIG. 5

FIG. 5

7 V/VTOR HENRY J. RIBLET Unite tates The present invention relates generally to platform supports of the class which painters and other workmen combine with a suitable upright to form a scaffold readily adjustable in height, and more particularly, it relates to a combined platform support and automatic lock suitable for use on uprights formed of material having a low coelficient of friction, as for example, aluminum, and which may be readily and safely lowered without the use of block and tackle or other cumbersome rigging.

It is an object of my invention to provide a combined platform support and automatic lock which may be lowered by a crank by one or more workmen while on the platform, but which, at the same time, is particularly advantageous by virtue of the high degree of safety inherent in its design whereby the only force required to prevent accidental failure and injury to the workman is provided by his own weight.

It is a further object of my invention to provide a combined platform support and automatic lock which will lock safely at any position on a metal upright, but which is so contrived that the locking mechanism does not in any way wear the upright during its travel up and down the metal upright.

Other and further objects, advantages and features of the invention will become apparent as the description proceeds.

The present application is generally related to and constitutes an improvement and modification of my earlier invention described in U. S. Patent 2,342,427. This patent discloses means whereby the safe operation of a platform support and automatic lock may be made to depend only on the weight of the operator whose safety is involved, and does not require springs or counter weights. The soundness and validity of the concept underlying that invention have been amply demonstrated by the thousands of man hours of satisfactory service which scaffolding employing this invention have given in areas where other adjustable scaffoldings are banned as hazardous.

Briefly, my earlier patent disclosed a platform support which comprised one or more U-shaped metal bands, each embracing an associated rectangular upright, and each freely pivoted about a fulcrum in the support structure. A pair of cylindrical jaws extending through the sidewalls of each band and disposed on opposite sides of the upright provided an automatic lock, operative under the platform load to preclude unintended vertical motion. However, despite the advance achieved by substantially eliminating accidents due to mechanical failure or human error, it was still necessary to use block and tackle to raise and lower the platform held in position by the automatic locking supports.

In the present invention, I replace one of the jaws in the basic automatic lock disclosed in the cited prior patcut, by a serrated bar or serrated roller freely rotatable relative to the U-shaped jaw supporting band. It is clear that such a freely rotating member would ordinarily be a source of danger unless additional provisions were ice made to prevent inadvertent rotation. This is done by mounting it so that the longitudinal axis of the roller jaw is eccentric relative to its bearing holes in the U- shaped supporting band, so that effectively, the spacing between the two jaws in each lock is a function of the angular position of the serrated jaw which is free to rotate. Further, the separation between the jaws is so chosen relative to the size of the upright that when the spacing between the inner and outer jaws is a maximum, the outer jaw is below the horizontal plane containing the fulcrum or in it. Thus, in all other positions possible as the serrated jaw rotates, the outer jaw assumes a lower, unstable position. Thus, these positions are possible only by the deliberate efiort of the operator. He may deliberately lower the outer jaw by depressing the automatic lock, or in one version of my invention, he may rotate the rotatable jaw by means of a crank provided for this purpose, in which case the entire platform support structure lowers in a smooth, completely con trolled manner.

A more comprehensive understanding of this invention will be afforded by the following detailed description considered in conjunction with the accompanying drawings, and those features of the invention which are believed to be novel and patentable will be pointed out in the claims appended hereto.

In the drawings:

Figure 1 is a side view of my invention in which part of the upright is shown, together with the end of the platform. A crank for rotating the eccentric jaw is also shown.

Figure 2 is a perspective view showing the U-shaped member which, together with the fulcrum and two jaws, one rotatable by means of a crank, constitute the central part of my invention.

Figure 3 is a side view of a portion of the platform supporting frame and a portion of the upright together with the automatic lock which is shown with the eccentric rotatable jaw in the position of stable equilibrium where the lock cannot be lowered without the conscious effort of the operator.

Figure 4 is a side view of a similar portion of my invention in which the outer portion of the automatic lock has been lowered, perhaps by a workman turning the crank, to an unstable position which is encountered during the deliberate lowering of the platform supporting bracket.

Figure 5 is a similar view of Figure 3 in which the inner jaw of the automatic lock is eccentrically rotatable.

Figure 6 is a view similar to Figure 4 in which the inner jaw is eccentrically rotatable. This is an unstable position of the automatic lock which will be encountered in raising and lowering the adjustable platform supporting bracket.

Throughout these views, like reference numerals will be used wherever applicable and they will be chosen as far as possible to correspond to those of U. S. Patent 2,342,427 which has been referred to previously.

With reference now to the drawings, and more particularly to Figures 1 and 2 thereof, the character 1 denotes an upright which is embraced by the U-shaped band 2, and the automatic lock 3. The automatic lock comprises the U-shaped portion 4, an inner jaw 6 and an outer jaw 5. The lock is free to rotate about a fulcrum 7, provided simply by a bolt and nut. The open portion of a U-shaped member 2 is held apart by a separator 8 upon which there freely rolls a sleeve 10. The bolt 11 which secures the open end of U-shaped member 2 also carries an oblique diagonal support 12 and a substantially vertical support 13. Both supports 12 and 13 carry a horizontal member 14, to which they are respectively fastened by bolts 15 and 7. Platform 16 is carried by horizontal'member 14, and prevented from slipping by the extension on the upper end of diagonal bar 12.

In Figures l-4, the outer jaw is free to rotate in bearing holes provided in the U-shaped member 4. Fig- 'ure 2 shows how'the outer jaw 5 is provided with serrations or irregularities for gripping upright 1. If this upright is metallic, these serrations may be hardened for longer life. In Figures 5-6, it is the inner jaw 6' which is free to rotate while the outer jaw 5' is fixed.

serrations are cut and which contacts the vertical upright does not coincide with the line joining the centers of the bearing holes provided in the U-shaped member 4 in which the reduced diameter eccentric ends of the rotating jaw 5 or 6' rotate. This displacement of the two lines may vary from .010" to .125 in practical embodiments and is not particularly critical, and is clearly shown in all of the figures.

In Figures 1-4, the rotating jaw 5 is provided with an integral crank extension '18 by which the jaw 5 can be caused to rotate and which can be used as will be explained to lower the platform supporting bracket. In

Figures 5 and 6, no crank is shown. This latter arrangement appears to be preferable when the vertical upright is metallic, and the position of the platform supporting bracket is controlled by a rope and pulley system as shown in the patent already referred to.

U. S. Patent 2,342,427 has taught the principle that an automatic lock, consisting of a band supported on a fulcrum and having inner and outer jaws, has as its only stable position its locked position wherein the outer jaw lies substantially in the same horizontal plane or lower than the fulcrum, while the inner jaw is substantially lower; and is unstable in any unlocked position, provided that some load is available on the platform supporting bracket.

The present invention teaches that one or both of these jaws may be freely rotatable so long as the rotation is eccentric and for no position of the rotatable jaw does the outer jaw rise above the horizontal plane containing the fulcrum. This point will be demonstrated when it is shown that once the outer jaw has obtained its position of maximum height relative to the fulcrum, that the rotating jaw is no longer free to rotate and may be considered fixed.

Consider Figure 3 in which the outer jaw 5 is free to rotate eccentrically with respect to the axis of its supporting holes. The eccentric rotating jaw 5 is illustrated in the position where the longitudinal axis of the serrated cylindrical surface is in the same horizontal plane as the center of the supporting holes 19, but is displaced farther from the vertical upright 1. Also, the distance between the inner jaw 6 and outerjaw 5 has been chosen so that the fulcrum 7 and inner jaw 5 lie substantially in the same horizontal plane. It is now clear that any rotation of the outer jaw 5 must result in a tipping of the automatic lock 3 as shown in Figure 4. This position, however, as'we have seen, is unstable when the platform is loaded. Thus, the automatic lock 3 will return to the position of Figure 3 as soon as the platform supporting bracket attempts to move downward.

In the locked position of Figure 3, the outer jaw 5 will not rotate merely under the influence of a load, and thus, the inner jaw 6 land the eccentric rotatable jaw 5 will cooperate to support the platform supporting bracket if they are properly spaced relatively to each other, and sufficient friction exists between them and the vertical upright. In the event that the vertical upright 1 is metallic, sufiicient friction to prevent slipping may be insured by providing the rotating jaw 5 or 6 with serrations 5a, as shown in Figure 2.

To-insure that the slideable bracket may be freely lowered, when the rotating eccentric jaw 5 has rotated to the position where its axis is in the, same horizontal plane as the centers of the supporting holes 19, but is displaced nearer the vertical upright as in Figure 4, the rotating eccentric jaw 5 must be above the horizontal plane containing the inner jaw 6. This insures that further lowering of the automatic lock 3 will release the inner jaw 6 from the vertical upright regardless of the position of rotation of the eccentric rotating jaw 5.-

It will be clear to one familiar with the art that similar remarks can be made concerning Figures 5 and 6, where the inner jaw.6' is free to rotate eccentrically in bearing holes 19 provided in the U-shaped strap 4. Figure 5 shows the position of the automatic lock 3 in the stable locked position and Figure 6 shows how the automatic lock 3 may be depressed, as-for example, by placing the heel on the upper end of the outer edge thereof, so that the inner jaw 6 will not grip the vertical upright 1.-

The eccentric rotating outer jaw 5 .of Figures 1-4 has been provided with a crank 18. With this, a workman sitting or standing on platform 16 can gradually lower the platform supporting bracket without any danger of a sudden or accidental fall. All he has to do is to rotate the crank 18 in a clockwise direction; If sufficient friction exists between the eccentric rotating jaw Sand the vertical upright 1, as can always be provided by suitably serrating this jaw, this will force the outer jaw downward to a point where the friction between the inner jaw 6 and the vertical upright 1 is exceeded by the load and the force applied by the crank, and the platform supporting bracket begins to descend. It is clear that the rate of descent cannot exceed that permitted by the crank, since for all fixed positions of the crank, a stable locked position results. Moreover, if the crank were accidentally released by the workman, the platform supporting bracket could at most fall to the stable locked position of Figure 3. In the event thatthe platform supporting bracket is controlled by rope and pulleys as shown in my earlier invention, and the vertical upright is metallic, perhaps aluminum, the arrangement shownin Figures 5 and 6 is preferred. Although the same general etfectfor this application could be achieved by serrating a fixed nonrotating jaw, such as "arrangement would tend to wear the vertical upright, whereas when the serrations are placed on an eccentric rotating jaw as in the present invention, these serrations never tend to wear the upright, because they are always in rolling contact, on the vertical upright whenever they are moving relative to it.

It will be evident from the foregoing description that I have provided a combined platform, supporting member and automatic lock which realizes the objectives given earlier in the specification.

Various changes may be made in the specific embodiment' of the present invention without departing from the spirit thereof, or from the scope of the appended claims. i

What isclaimed is: l. A scaffold locking device in combination witha platform supporting frame and an upright, means connecting the lower portion of said frame to said upright in slidable non-gripping relationship, a lock, lock pivoting means for pivotally fastening said lock to the upper portion of said frame, said lock being formed with vertically oflset outer and inner jaws, one of said jaws lying inner jaw lower than said lock pivoting means, and so that in the unlocked position said outer jaw bears against said upright and said. inner jaw is spaced inwardlytaway from said upright and is farther below said lock pivoting means than when said lock was insaid locking position, onev of said jaws comprising a cam freely and continuously rotatable with its surface in continuous contact with said upright.

2. A scaffold locking device in combination with a platform supporting frame and an upright, said frame em bodying an upwardly extending member adjacent to said upright, a laterally extending member and a diagonally extending member connected to and extending between said other two members, a pin member at the junction of the lower portions of said upwardly and diagonally extending frame m mbers, means securing said pin member to said upright in non-gripping relationship, a lock, loci; pivoting means for pivotally fastening said lock at one end thereof to the end of said laterally extending member adjacent said upright and connected to said upwardly extending member, said lock being formed with outer and inner jaws so positioned relative to each other and to said lock pivoting means that in the locking position, said outer jaw and lock pivoting means are substantially in horizontal alignment with said outer and inner jaws bearing against said upright and with said inner jaw lower than said lock pivoting means, and so that in the unlocked position, said outer jaw bears against said upright and said inner jaw is spaced inwardly away from said upright and is farther below said lock pivoting means than when said lock was in said locking position, said outer jaw comprising a cam formed with a serrated substantially cylindrical outer surface, and a hand crank for rotating said outer jaw about an axis displaced from and parallel to the axis of its serrated cylindrical surface with the latter surface in continuous contact with said upright for raising and lowering said platform support ing frame.

3. In combination with a scaffold having an upright of generally rectangular cross-section, a platform supporting frame, and means for attaching the lower end port on of said supporting frame to said upright in a slideable non-gripping relationship; an automatic lock, said antomatic lock comprising a pair of rigidly spaced sidewall members embracing said upright, a pivot for pivotally joining said members to said frame, first and second parallel jaws formed with cylindrical outer surfaces extending between said members on opposite sides of said upright, said second jaw being disposed on the side of said upright most removed from said pivot, said first jaw being disposed to bear against the side of said upright adjacent said pivot below both said pivot and second jaw, said second jaw comprising a cam continuously rotatable about an axis displaced from and parallel to the axis of its cylindrical outer surface and arranged whereby during each complete revolution of said cam with the surface thereof in continuous contact with said upright, the spacing between said jaws cyclically varies between a predetermined minimum under which condition said pivot is raised above said second jaw, and a predetermined maximum under which condition said pivot and second jaw are disposed substantially in the same horizontal plane.

References fitted in the file of this patent UNITED STATES PATENTS 138,385 Elliott Apr. 29, 1873 166,758 Fellows Aug. 17, 1875 431,745 Haven July 8,1890 446,472 Roberts Feb. 17, 1891 618,510 Kail Jan. 31, 1899 878,455 Carter Feb. 4, 1908 1,366,487 Pitou -2 Jan. 25, 1921 1,441,806 Hoitsma Jan. 9, 1923 2,038,899 Hoitsma Apr. 28, 1936 2,164,519 Hayner July 4, 1939 2,342,427 Riblet Feb. 22, 1944 2,605,074 Bucsko et a1. July 29, 1952

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