US1964995A - Scaffold jack - Google Patents

Description

July 3, 1934. MCLAUGHLIN 1,964,995

SCAFFOLD JACK Filed Jan. 2, 1931 Patented July 3, 1934 {UNITED STATES PATENT FFICE SC'AFFOLD JACK Application January 2, 1931, Serial No. 506,199

14 Claims.

The present invention relates generally to scaffold jacks. More particularly the invention relates to that type of jack which is adapted to be used in connection with a dependent cable and several other cable-suspended jacks of like character to support a scaffold alongside of a building in the course of construction, and comprises (1) a stirrup for supporting a cross-beam to which one end of the scafiold is secured; (2) a pair of jaw clutches which are mounted one above the other on a vertically extending rod, operate to support the stirrup and the cross-beam from the cable and are movable vertically one relatively to the other by means of an operating lever is; in order to raise the scaffold with respect to the cable and building; and (8) mechanism whereby the clutches may be alternately released so as to permit the jack and scafiold to be lowered.

One object of the invention is to provide a jack of the aforesaid type in which the stirrup is laterally when the character or shape of the building necessitates such swinging movement.

Another object of the invention is to provide a scafifold jack of the type here under consideration in which the mechanism for releasing the clutches embodies an operating lever and is so formed that when the lever is shifted in one direction one of the clutches is released and the other is held in its closed or operative position, and when the lever is shifted in the opposite direction the action is reversed and the one clutch is released and the other clutch is held in place.

A further object of the invention is to provide a jack of the type to which the invention relates which embodies improved and simple means whereby the clutches are mounted on the rod.

A still further object of the invention is to provide a scafiold jack which consists of but a small number of parts, may be manufactured at a low cost and is generally an improvement upon previously designed jacks of the same general type.

Other objects of the invention and the various advantages and characteristics of the present jack construction will be apparent to those skilled in the art from a consideration of the following detailed description.

In the drawing which accompanies and forms a part of this specification or disclosure and in which like numerals of reference denote corresponding parts throughout the several views;

Figure 1 is a side view of a jack embodying the invention;

Figure 2 is a vertical section;

Figure 3 is a horizontal section, taken on the line 3-3 of Figure 1, and illustrating in detail 69 the specific construction of the upper clutch and the manner in which such clutch is secured to the rod; and

Figure 4 is a perspective of the jaws for the upper clutch.

The jack which forms the subject matter of the invention is adapted to be used with several other jacks of like character to support a scaffold (not shown) alongside of a building. It is associated with a dependent cable 5 and operates as hereinm after described to support the scaffold so that it may be raised or lowered to the desired elevation. The cable 5 is preferably supported from the top of the building by an outrigger or similar instrumentality and is suspended so that it is positioned b in spaced relation with respect to the wall of the building against which the scaffold is placed. The jack comprises an upper clutch 6 and a lower clutch 7. These clutches are associated with a vertically extending rod 8, grip the cable and are movable one relatively to the other in order to raise or lower the scaffold with respect to the cable and the building. In addition to the clutches 6 and 7, the jack comprises a stirrup 9. This stirrup is preferably formed from strap iron and consists of a base 10, a pair of sides 11 and a top 12. The base of the stirrup is substantially fiat and forms a rest or support for one end of a crossbeam 13. The latter is adapted to support one end of the scaffold as well understood in the art and is provided with notches 14 in the sides thereof which receive the sides 11 in order to form an interlocking connection whereby the beam and the stirrup are secured together in rigid relation. The sides 11 extend upwardly from the ends of 95 the base and are joined at the upper ends thereof to the ends of the top 12. The latter is substantially flat and embodies in the central portion thereof a vertically extending opening 15 through which extends the cable 5. The base 10 embodies a central opening 16 through which the cable likewise extends. This opening 16 is aligned with the opening in the top 12 of the stirrup and is formed in the central portion of the base. The stirrup 9 is connected to the lower clutch '7 by means of a clamp 17 and a U-shaped strap 18. The clamp 17 consists of a metallic strip which is bent centrally to form a pair of arms 19 and a connecting portion 20. The latter is mounted slidably on the lower end iing the cable 5.

of the rod 8 so that the stirrup is movable vertically relatively to the rod. The arms 19 are positioned one opposite the other and support therebetween the lower clutch 7. The strap 18 extends between the stirrup and the clamp and consists of a base 21 and a pair of arms 22. The upper ends of the arms 22 are twisted as at 23 and are positioned between the arms 19 of the clamp 17. The strap 18 is connected to the clamp by means of rivets 24 which are carried by the clamp and extend through the upper ends of the arms 22. The base 21 of the strap is substantially fiat. It overlies the top 12 of the stirrup 9 and embodies a vertically extending opening 25 which is aligned with the opening 15 and receives the cable 5. The stirrup 9 is connected pivotally to the strap by means of a hollow bolt 26. This bolt surrounds the cable and is arranged so that the head thereof is supported on the base 21 of the strap 18 and its shank extends through the openings 15 and 25. The lower end of the bolt is provided with a nut 27 and a lock nut 28 which prevent displacement of the stirrup relatively to the strap and are spaced from the head of the nut so that the stirrup is free to pivot or rotate relatively to the clamp 17 and the strap 18. An advantage of connecting the stirrup pivotally to the strap is that the scaffold is supported by the cross-beam 13 so that it may swing laterally. Another advantage is that the clutches 6 and 7 may be swung bodily without displacing the stirrup.

The upper clutch 6 consists of a casing 29 and a pair of jaws 30. The casing is cylindrical in conformation and embodies an open-ended cylindrical socket 31 in the upper end thereof and an open-ended upwardly tapered compartment 32 of circular cross section in its lower end. The socket 31 communicates with the upper end of the chamber 32 and is of greater diameter than the upper end of the chamber so as to form an annular shoulder 33 in the upper end of the casing. The cable 5 extends through the socket and the chamber and is gripped by the jaws 30. The open end of the socket 31 is normally closed by a circular plate 34. This plate is secured to the casing by screws 35 and embodies a hole 36 through which extends the cord 5. The casing is connected fixedly to the upper end of the rod 8 by means of a clamp 37. The latter consists of a metallic strip and is similar in shape and construction to the clamp 17. It consists of a pair of oppositely facing arms 38 and a central connecting portion 39. This connecting portion surrounds the upper end of the rod 8 and is clamped between a pair of nuts 40 on the rod. The arms 38 are secured together by a pair of rivets 41. The casing 29 is disposed between the arms and is provided in the outer periphery thereof with an annular groove 42. The portions of the arms between the rivets 41 are bent outwardly into circular form, as illustrated in Figure 2, and fit in the annular groove in the casing. The jaws 30 are provided in the opposed faces thereof with longitudinally extending grooves 43 for receiv- The upper ends of the jaws are tapered so as to correspond with the tapered compartment 32 and have parts 44 which project into the socket 31. When weight or downward force is applied to the casing, the wall which defines .l the tapered compartment 32 coacts with the tapered upper ends of the jaws to force the jaws toward each other and into clamped relation with the cable. The jaws 30 are urged upwardly into the casing by means of a coil spring 45. This ispring extends around the parts 44 of the jaws and is arranged so that the lower end thereof abuts against the annular shoulder 33 in the casing. The upper end of the spring abuts against a disk-like plate 46 which is secured by screws 47 to the parts 44 of the jaws. By utilizing the spring to urge upwardly the jaws 30, the clutch 6 normally operates to grip the cable.

The lower clutch 7 is similar in construction and general arrangement to the upper clutch 6 and consists of a cylindrical casing 48, a pair of jaws 49 and a coil spring 50 for urging upwardly the jaws 49. The casing 48 is provided at the upper end thereof with an open-ended cylindrical socket 51 and at its lower end with an openended upwardly tapered compartment 52 of circular cross section. The coil spring 50 is disposed in the socket 51 and is confined between an annular shoulder in the casing and a disk-like plate 53 at the upper ends of the jaws 49. The jaws 49, like the jaws 30 of the upper clutch 6, are provided in the opposed faces thereof with longitudinally extending grooves for receiving the cable 5. The central portions of the jaws 49 are tapered and coact with the wall that defines the compartment 52 of the casing 48 to lock the jaws in clamped relation around the cable 5 when weight or downward force or pressure is applied to the casing 48. The casing 48 is disposed between the arms 19 of the clamp 17 and is provided in the outer periphery thereof with an annular groove 54 for receiving the portions of the arms between the rivets 24. By virtue of the fact that the clamp 17 is slidably mounted on the lower end of the rod 8, the lower clutch, as well as the stirrup 9, is movable vertically relatively to the upper clutch. Downward movement of the clamp 17 relatively to the upper clutch is limited by means of a nut 55 which is mounted on the lower end of the rod.

In order to move the lower clutch relatively to the upper clutch and effect raising or lowering of the jack and scaffold with respect to the cable, an operating lever 56 is provided. This lever is associated with a link 57 and is arranged so that one end thereof is positioned between the outer ends of the arms 38 of the clamp 37 and is pivoted on the rivet which secures the outer ends of the arms in clamped relation around the casing 29 of the upper clutch. The other end of the lever is tapered so that it may be connected to an extension bar (not shown) having a socket in one end. The link 57 extends between the upper and lower clutches and is pivotally connected at its lower end to a stud or rivet 58 on the upper end of one of the arms 22 of the strap 18. The upper end of the link is pivotally connected to the central portion of the lever 56 by means of a bolt 59. When it is desired to operate the jack so as to raise the scaffold, the operating lever 56 is swung downwardly. By virtue of the fact that the link 57 is pivoted to the central portion of the lever, this downward movement operates to move the upper clutch 6 and the rod 8 upwardly with respect to the lower clutch 7. During upward movement of the upper clutch the lower clutch is locked to the cable 5 and supports the stirrup 9 and the scaffold. After moving the upper clutch and the rod 8, the operating lever 56 is swung upwardly. This places the load on the upper clutch 6 and at the same time shifts upwardly the lower clutch together with the stirrup and scaffold. When the operating lever reaches the end of its upward stroke, the load reverts to the lower clutch and causes the latter to lock itself to the cable 5 and support the stirrup and scaffold in a raised position. By shifting the operating lever first .down and then up, the jack is operated so as to raise the scafiold step-by-step on the :cable. During upward movement of the clutch 6 or the clutch 7 .on the .cable 5, the jaws are momentarily released from the .action of the tapered compartment in the casing and thus do not impair such upward movement.

In operating the jack so as to lower the scaifold, it is necessary to release alternately the clutches. In order to facilitate release of the clutches, a lever 60 is provided. This lever is associated with a link :61 and is pivotally connected at one end thereof to a pair of lugs 62. The latter embody a pivot pin 63 and project outwardly from the lower part of one of the jaws 49. The link 61 extends vertically and is connected pivotally at its lower end to the central portion of the lever 60. The upper end of the link 61 is connected pivotally to a pair of lugs '64 which project outwardly from the lower part of one of the jaws 30. When the lever 60 is shifted downwardly, the jaws 49 of the lower clutch 7 are urged into their locked position and the link 61 releases the jaws 30 with respect to the casing 29 of the upper clutch. When the lever 60 is raised, the jaws 30 are urged into their locked position and the jaws 49 of the lower clutch are released from the casing 48. In lowering the jack on the cable, the lever 60 is swung downwardly to release the upper clutch 6 and the operating lever 56 at the same time is swung upwardly so as to lower the upper clutch and the rod 8 with respect to the lower clutch. At the conclusion of this operation, the lever 60 is raised so as to release the lower clutch and lock the upper clutch and the operating lever 56 at the same time is swung downwardly so as to lower the lower clutch together with the stirrup 9 and the scaffold. During lowering of the lower clutch and the scaffold, the load is placed on the upper clutch i through the medium of the link 57 and the lever 56. By manipulating or operating the jack in the aforementioned manner, the scaffold may be lowered step by step.

The jack disclosed herein consists of a comparatively small number of parts and may be manufactured at a low and reasonable cost. It is safe and exceedingly eflicient in operation for the reason that the lever 60 and the link 61 operate during lowering of the scaffold to insure positively the locking of one of the clutches to the cable. By virtue of the fact that the stirrup 9 is connected pivotally to the strap 18 so that it is free to swing laterally, the scaffold may be swung or shifted laterally into different angular positions without effecting displacement of the clutches and the clutches, if desired, may be swung bodily relatively to the stirrup and the scaifold.

The invention is not to be understood as restricted to the details set forth since these may be modified within the scope of the appended claims, without departing from the spirit and scope of the invention.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a scaffold jack, means for raising and lowering the jack upon a cable, and a supportingstirrup for the scaffold swivelled to said raising means so as to swing in either direction laterally.

2. In a scaffold jack, means for raising and lowering the jack upon a cable, and a supporting-stirrup for the scaffold swivelled to said raising means so as to swing in either direction laterally, the swivel means consisting of a tubular bolt through which the cable passes.

3. In :a scaffold jack, means for raising and lowering the jack upon a cable, and a supporting-stirrup for the scaffold swivelled to said raising means so as to swing in either direction laterally, the swivel means consisting of a tubular bolt through which the cable passes, said stirrup being provided with a hole for the passage of said cable so that the stirrup will swivel laterally on an axis coincident with the cable.

4. In a scaffold jack adapted to be used with 'a cable, a pair of clutches working independently on said cable, the lower clutch having suspended to it means for supporting the scaffold, a lever arrangement for connecting the clutches for giving them an alternate step-by-step elevation on the cable, and a single lever-actuated means for alternately releasing the clutches.

5. In a scaffold jack adapted to be used with a cable, a pair of clutches working independently on said cable, the lower clutch having suspended to it means for supporting the scaffold, a lever arrangement for connecting the clutches for giving them an alternate step-bystep elevation on the cable, and a single leveractuated means for alternately releasing the clutches, means being provided for guiding the two clutches with respect to each other and for limiting the distance apart the clutches shall be separated.

6. In a scaffold jack, the combination of a pair of automatic clutches arranged one above the other and adapted to grip a dependent cable, one of said clutches comprising a casing having an upwardly tapered compartment of circular cross section extending therethrough, a plurality of elongated vertically positioned jaws extending through and shaped correspondingly to the compartment and arranged to grip the cable therebetween, and a spring associated with the casing and applied to urge the jaws into gripping relation with the cable, and means for relatively moving the clutches to raise or lower the jack on the cable.

.In a scaffold jack, the combination of a pair of automatic clutches arranged one above the other and adapted to grip a dependent cale, one of said clutches comprising a casing having an upwardly tapered compartment extending therethrough, a plurality of elongated vertically positioned jaws extending through and shaped correspondingly to the compartment and arranged to grip the cable therebetween, and a spring housed in the casing and 130 applied to the upper ends of the jaws so as to urge the jaws into gripping relation with the cable, and means for relatively moving the clutches to raise or lower the jack on the cable.

8. In a scaffold jack, the combination of a 135 pair of automatic clutches arranged one above the other and adapted to grip a dependent cable, one of said clutches comprising a casing having an upwardly tapered compartment extending therethrough, a plurality of elongated vertically 14g positionedjaws extending through and shaped correspondingly to the compartment and arranged to grip the cable therebetween, and a coil spring extending around the upper parts of the jaws and applied to urge the jaws into gripping rela- 1 5 tion with the cable, and means for relatively moving the clutches to raise or lower the jack on the cable.

9. In a scaifold jack, the combination of a pair of automatic clutches arranged one above the 150 llll U for relativei j pendent cable, each of said clutc the clutches,

other and adapted to grip a dependent cable, one of said clutches comprising a casing having an upwardly tapered compartment extending therethrough, a plurality of elongated vertically positioned jaws extending through and shaped correspondingly to the compartment and arranged to grip the cable therebetween, a plate secured to the upper parts of the jaws and projecting laterally therefrom, and a spring applied to the plate to urge the jaws into gripping relation with the cable, and means for relatively moving the clutches to raise or lower th jack on the cable.

10. In scaitold jack, the combination or" a pair of automatic clutches arranged one above the other and adapted to grip a dependent cable, one of said clutches comprising a casing having an upwardly tapered compartment in the lower part thereof and a socket in its upper part of greater width than and communicating with the compartment, a plurality of elongated vertically positioned jaws extending through and shaped correspondingly to the compartment arranged to grip the cable thcrebetween and so that the upper ends thereof project into the socket, a plate secured to said upper ends of the jaws projecting laterally therefrom, and a spring disposed in the socket and around the said upper parts of the jaws and applied to the plate to urge the jaws into gripping relation with the cable, and means moving the clutches to raise or lower the jack on the cable.

11. In a scaffold jack, the combination of a pair of relatively movable automatic clutches arranged one above the other and adapted to grip a dees comprising a casing having a vertical compar nent extending therethrough and a plurality of springpressed jaws located in the comp. rtment and arranged to grip the cable therebetween, a guide rod for means for attaching one of the clutches to the rod corn ising a clamp mounted on the rod provided with a pair or" arms for engaging the sides of the casing of said one clutch, and means for relatively moving the clutch s to raise or lower the jack on the cable.

12. In a scaffold jack, the combination of a pair or" relatively movable automatic clutches arranged one above the other and adapted to grip a dependent cable, each of said clutches comprising a casing having a vertical compartment extending therethrough and a plurality of spring-pressed jaws located in the compartment and arranged to grip the cable therebetween, a vertically extending guide rod for the clutches, a clamp secured fixedly to the upper end of the rod and provided with a pair of arms embracing the sides of the casing of the upper clutch, a similar clamp slidably mounted on the lower end of the rod and secured to the casing of the lower clutch, and means for relatively moving the clutches to raise or lower the jack on the cable.

13. In a scaiicld jack, the combination of a pair of relatively movable automatic clutches arranged one above the other and adapted to grip a dependent cable, each of said clutches comprising a casing having a vertical compartment extending therethrough and a plurality of spring-pressed jaws located in the compartment and arranged to grip the cable therebetween, a vertically extending guide rod for the clutches, a clamp secured fixedly to the upper end of the rod and provided with pair of arms embracing the sides of the casing of the upper clutch, a similar clamp slidably mounted on the lower end of the rod and secured to the casing of the lower clutch, and means for relatively moving the clutches to raise or lower the jack on the cable embodying a lever pivotally connected to the clamp for the upper clutch and a link I etween the central portion of the lever and the casing of the lower clutch.

i i. In a scaffold jack, the combination of a pair of relatively movable automatic clutches arranged one above the other and adapted to grip a dependent cable, each of said clutches comprising a casing hav ng a vertical compartment ex ending therethrcugh and a plurality of spring-pressed jaws located the compartment and arranged t to grip the cable therebetween, a vertically extending guide rod for th clutches, a clamp secured fixedly to the upper end of the rod and provided with a pair of arms embracing the sides of the casing of the upper clutch, a similar clamp slidably mounted on the lower end of the rod and e ured to the casing of the lower clutch, means for relatively moving th clutches to raise or lower tie jack on the cable, and mechanism for alternately releasing the clutches comprising a lever connected pivotally to one of the jaws of one of the clutches and a link having one end thereof pivotally connected to the central portion of the lever and its other end pivotally connected to one or" the jaws of the other clutch.

MONTAGUE MCLAUGHLIN.

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