CA1136177A - Hoist and scaffold bracket - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A plurality of scaffolds stacked one above the other on a support and each scaffold supported on two laterally spaced self-locking scaffold brackets attached to the supports by load-activated locks. A hoisting mechanism is selectively connected to the scaffolds in such a way as to lift each of the scaffolds up sequentially into its final position. Mechanical jacks connected to the load activated locks are used for final small adjustment of the positions of the scaffolds. The jacks are disabled without removing them during the time that the scaffolds are being moved up or down.

Description

113617~7 FIELD OF INVENTrON
The invention relates generally to scaffolds of the type having a platform supPorted on brackets attached to upright posts in a manner permitting the height of the platform to be changed. More particularly, the invention pertains to an improved com~ination of platform supporting brackets employing hoisting mechanisms for raising and lowering them into approximate position in stacked relation to each other~
R~FEREN OE TO PRIOR ART
U~S, Patent 3,970,277 discusses the general practice in the employment of scaffold brackets of the type shown in U.S. Patent No. 2,342,427 to span a pair of spaced uprights with a platform supported upon brackets that are secured to the uprights. U.S. Patent No. 3,970,277 discloses a foot-operated mechanical jack which permits workmen on a bracket-supported scaffold to raise the platform. The foot-operated mechanical jack obtains its lifting force by having the operator exert his weight on a lever by stepping into a stirrup. The foot-operated mechanical jack of the prior art is not intended to be used in conjunction with a platform ~racket using a load-activated lock, but rather is intended for use with locks of the type employing springs to provide the force causing the jaw of the scaffold lock to re-engage the uprights at the end of the lifting stroke. U.S. Patent No.3,970,277 explains the operation of a stop member which so engages with the side plates of the jack lock that when the levers are raised to extreme position as shown in the drawings, the jaws of the jack lock are disengaged from the upright. In . ~, ~

1~3617`7 this condition, the scaffold bracket and mechanical jack can be raised and lowered by means of ~lock and tackle as shown in U.S. Patent No. 3,970,277.

OBJECTS OF T~E INVENTION
It is an object of the invention to provide an improved scaffold-lifting device.
Another object of the invention is to provide an adjustable scaffold device that is simple in construction, economical to manufacture and simple and efficient to use.
Another object of the invention is to provide a foot-operated mechanical jack acting in combination with a scaffold bracket employing a load-activated lock with means whereby the combination may be raised and lowered by a block and tackle.
Another object of the invention is to provide a scaffold device wherein two or more scaffolds can be lifted from the ground upward by means of a hoisting mechanism.
With the above and other objects in view, the present invention consists of the combination and arrangement of parts hereinafter more fully described, illustrated in the accompany-ing drawing and more particularly pointed out in the appended claims, it being understood that changes may be made in the form size, proportions and minor details of construction without departing from the spirit or sacrificing any of the advantages of the invention.
GENERAL DESCRIPTION OF DRAWINGS
Fig. 1 is a side diagrammatic view of a scaffold-supporting device with jack and hoist arrangement according to the invention.

1~3617`7 Fig. 2 is an enlarged v;ew of the hoisting mechanism.
Fig. 3 is an isometric view of the scaffold bracket and lock and mechanical jack s~own in Fig. 1.
Fig. 4 is a cross-sectional view taken on line 4-4 of Fig. 1.
Fig. 5 is a cross-sectional view taken on line 5-5 of Fig. 1.
Fig. 6 is a cross-sectional view taken on line 6-6 of Fig. 1.
Fig. 7 is an enlarged partial view of a part of the ~lock and tackle according to the invention.
Fig. 8 is a side view of the lower block of the block and tackle according to the invention.
Fig. 9 is a side partial view of the lower block in a second-mode according to the invention.
Fig. 10 i9 an enlarged view of another embodiment of the lower block.
Figs. 11-14 are detailed views of the mechanical jack.

DETAILED DESCRIPTION OF DRAWINGS
2Q A diagrammatic side view of the scaffold device according to the invention is shown in Fig. 1. The hoisting mechanism, scaffold bracket and lock and mechanical jack used are shown in more particular detail in Figs. 2 and 3.
The scaffold brackets are supported on upright Ul by the scaffold locks. In the example shown, two scaffold brackets are shown, one above the other, indicated at 10 and 10'. The corresponding parts of the upper and lower scaffolds have similar numbers with a prime added to the upper part numbers.

", i Scaffold bracket 10 employs a pair of rigid, generally triangular members arranged side ~y side to provide rails 12.
To accommodate a wider platform, rails 12 can be lengthened by moving a pivoted member 15 from a position where it is nested with the rails 12 to a position where it forms an extension of rails 12, as shown in Figure 1. Rails 12 are part of a rigid triangular structure having legs 18 and 19 as its other sides. The two rigid, generally triangular structures 10, form the basic platform supporting frame. A rod 22 is disposed at the lower end of the frame to bear upon the face of the upright Ul. A roller may be provided on the rod so that the roller can turn to permit rolling action upon the face of the upright Ul, where it is desired to facilitate raising and lower-ing of the bracket. To hold the lower end of the rigid frame in appropriate relation to the upright, a yoke 22a is mounted on the rod 22.
The scaffold bracket 10 is supported upon the scaffold lo~k 11 in a manner permitting the scaffold lock to pivot relative to the scaffold ~rac~et about a fulcrum "rod" 32 extend-ing between rails 12, as described in my U.S. Patent ~o.2,342,427. The scaffold lock employs a pair of spaced plates 24 havîng an outer ja~ 26 and an inner jaw 27 fixed to the plates in a manner permitting the upright Ul to be received between the jaws with the plates on the opposite sides of the upright. The plates have portions extending beyond the outer jaw 26 which support an interposed bar 28. The pivotal axis formed by fulcrum rod 32 is situated in relation to outer jaw 25 so that when the upright Ul is clamped ~etween the inner and outer jaws, the fulcrum rod 32 is even with or above the horizontal line passing through the line of contact between jaw 26 and the adjacent face of the upright U1.

B

The inner jaw 27 is disposed below the pivotal axis and the downward oblique force exerted by the load on platform 7 upon the fulcrum 32 results in opposing force on the outer jaw 26 to cause the scaffold lock to engage the upright Ul as described in my U.S. Patent No. 2,342,427. Once engaged, the greater the downward oblique force on the pivotal axis, the greater is the clamping force exerted on the upright Ul.
Disposed between the fulcrum rod 32 and the inner jaw 27 is a pivot 23 whose end protrudes through apertures in 10 the plates 24. The pivot is preferably arranged so that it cannot rotate relative to plates 24. The introduction of the pivot 23 between pivotal axis 32 and inner jaw 27 results in an improved locking action when the scaffold bracket is raised by the mechanical jack. The proper location of the pivot can minimize lost motion due to the opening of the scaffold lock on the upright when the platform is raised by the mechanical jack since the scaffold lock immediately reasserts its grip upon the upright when the jacking force is removed. The scaffold bracket, therefore, is held in place on the upright and there is no loss in height due to the opening of the scaffold lock during the jacking operation.
Attached to the cross bar 28 running between the side plates 24 is a light rope 70 reaching to the ground by which the scaffold lock can be disabled when sufficient tension is put on the hoisting mechanism.
A pair of levers 47 and 47a, which are joined at one end by a stirrup 48, are mounted to pivot about an axle 49 extending between plates 41 and 42. Pivotally attached to the other ends of the levers are first ends cf a pair of lifting straps 50 and 51. The other ends of straps 50 and 51 have means for attachment to the pivots 23 on the scaffold lock.

As shown in Fig. 13, disposed about the axle 4^ ia o.

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spring 52 having its ends anchored upon the plates 41 and 42 and having its center loop 52a engaging the underside of rod 53 extending between levers 47 and 47a. As a matter of convenience in anchoring the ends of spring 52, each of the plates has a tab 41a or 42a bent out from the plate which is engaged by the end of the spring. The spring exerts a force on the tabs, tending to rotate the plates 41 and 42 about axle 49 in the direction which brings the outer jaw 44 upwardly against the face of the uprïght Ul. As viewed in Fig. 3, the spring la force causes the counterclockwise rotation of the plates about axle 49. If the stop member 54 of Fig. 12 is slid along on bar 53 of Fig. 13 until it is in line with the side plate 42 of the jack lock, then, when the levers 47 and 47a are moved into the upright position shown in Fig. 1, they will transmit a force through the stop member 54 to the side plate which will disengage jaws 43 and 44 from the upright. In this condition, the scaffold bracket will be supported by the scaffold lock 11.
Figs. 8 and 9 show a possible arrangement of the lower block 115 of a block and tackle hoisting mechanism. The lower portion of the side members of the lower block 115 support a pivotable cross member 160 which is a gripper and which can be set in a horizontal position as shown in Fig. 9 or a vertical position as shown in Fig. 8. A tie rope 155 is attached to the cross member 160 at one end. Fig. 7 shows how, with the cross member 160 set vertically, the lower block and tie rope will pass freely between two bars 22 and 58 joining the two side members 19 of the scaffold bracket. When the cross member 160 is set horizontally, on the other hand, the lower block is prevented from passing through the scaffold bracket. The same result may be accomplished in a different manner as shown in Fig. 10.

~136177 If the lower portions of t~e lower block is formed into a hook 59 which is provided with an eyelet 71 for a tie rope 55, then, it is easily seen how t~e hook 59 which is a gripper, can be engaged with the cross bar 58 which forms a trap for hook 59 by proper management of the tie rope in one mode of operation and arranged to pass freely through the space formed by cross rods 58, 22, and the side plates 19 in another. It is also clear from Figs. 4-6 how the lower block with its tie rope, when set in the proper position, can pass freely through one bracket to another.

OPERATING THE HOISTING MEC~ANISM SHOWN
Assuming that all of the scaffolds are at the bottom of the supports Ul, they may be hauled up into their final position, as shown in Fig. 1, by the hoisting mechanism shown in Fig. 2. The mechanical jacks on each bracket are then used for final small adjustment of the scaffold in position. ~n order for the brackets and mechanical jacks to be moved up and down by the hoisting mechanism, the jacks must be disabled by moving the levers 47a of the lower mechanical jack and 47a of the upper mechanical jack to the position shown in Fig. 1 with the stop member 54 in position to engage the side plate 42.
The operator can then operate the hoisting mechanism so that the hook 59 engages the bar 58' of the upper scaffold bracket. The upper scaffold ~racket 10' may then be hoisted into position up along the upright Ul, when it is held in place by its scaffold lock. The operator then lowers the lower ~lock by its tie rope, engages the next lower scaffold ~racket and repeats the procedure until all the scaffold brackets are in place.

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.A( , 1~3617!7 To lower the scaffold brackets, the procedure is reversed. The operator w~ile on the ground first engages the hoo~s 59 under the rod 58 of the lower scaffold bracket.
Then, with the mechanîcal jack dîsabled by swinging lever 47a to the position shown ;n Fig. 1, with stop member 54 engaged, t~e operator exerts an upward lifting force on the hoisting mechanism to take the load off the jaws 26 and 27.
A downward orce is then exerted on the tie rope 70 to hold the jaws 26, 27 out of engagement with the upright so that the scaffold bracket can slide down upright Ul. The operator can then lower the scaffold brackets by means of the hoisting mechanism, meanwhile holding the jaws 26, 27 out of engagement with the upright by means of tie rope 70. ~hen the lower scaffold bracket has been lowered to the desired position, pull down rope 70 is released, allowing jaws 27 and 28 to support the lower scaffold brackets. The lower block 115 is passed up through this scaffold bracket in a manner already explained, and the procedure is repeated on the next lower scaffold bracket ~hich is still above ground level. It is clear that this procedure can be repeated until all the scaffold brackets are at ground level.
It is clear that the operation of my invention depends on an arrangement where~y the lower block of the hoisting mechanism can be passed up through the scaffold brackets in one mode of operation, while in another mode of operation, can be used to hoist them one at a time. Figs. 7-10 show two alternate arrangements for doin~J this. It will be clear to those familiar with the art how this might be accomplished by a suitable dog or pawl attached to the scaffold bracket itself.

113617~

The foregoing specification sets forth the invention in its preferred, practical forms ~ut th.e structure shown is capa~.le of modification within a range of equivalents without departing fram t~e invention which is to he understood is ~roadly novel as ;s commensurate with th.e appended claims.

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Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In combination, an upright member;
a scaffold, comprising a scaffold bracket and a scaffold lock means, the scaffold bracket being attached to the scaffold lock means by connecting means, the scaffold lock means supporting the scaffold bracket on the upright member;
an extended hoisting mechanism means for raising or lowering the scaffold on the upright member, the extended hoisting mechanism means being attached to the scaffold by connecting means that may be either fixed or releasable;
elongated scaffold lock disabling means attached to the scaffold lock means;
the elongated scaffold lock disabling means being accessible to a person below the scaffold whereby a tensile force applied to said elongaged scaffold lock disabling means will release the scaffold lock means from the upright member allowing the scaffold to be lowered by the hoisting mechanism means.

2. The combination recited in claim 1, and also comprising mechanical jack means, including, jack lock means connected to the scaffold for raising the scaffold, and jack lock disabling means, the scaffold being adapted to be lowered when the jack lock means is disabled.

3. The combination recited in claim 1 wherein the said scaffold lock means comprises, an inner jaw and an outer jaw spaced from each other and adapted to slidably receive said upright therebetween, said inner jaw being disposed between said connecting means and said outer jaw, said outer jaw being disposed between said inner jaw and said elongated scaffold lock disabling means.

4. The combination recited in claim 1, wherein said extended hoisting mechanism means comprises, a rope hoist having a pulley at the top and a pulley at the bottom and a gripper on said lower puller, said gripper has a pull-down rope connected thereto and extending downwardly therefrom, whereby said gripper can be pulled down from said scaffold bracket to a scaffold bracket supported below it on said upright member and can be brought into engagement with said scaffold bracket below said first-mentioned scaffold bracket.

5. The combination recited in claim 1, wherein the extended hoisting mechanism means includes on its lower portion a gripper means adapted to grip a trap on the scaffold to raise the scaffold when the extended hoisting mechanism means is raised, the gripper means also being adapted to disengage the trap on the scaffold after the scaffold has been raised, that gripper means further being adapted to freely pass below the scaffold when it is lowered below the scaffold.

6. The scaffold recited in claim 5, wherein a gripper means on the lower end of said hoisting mechanism means is adapted to move between an inner jaw of said scaffold lock means and said connecting means, and means on said gripper means to engage a trap means on said scaffold when said hoisting mechanism means is raised and to slide down between said inner jaw and said connecting means when said hoisting mechanism means is lowered.

7. The scaffold recited in claim 5, wherein said gripper means comprises, a bar having its intermediate part connected to a lower portion of said hoisting mechanism means and extending outwardly from each side thereof and adapted to underlie said scaffold bracket when extending perpendicular to said hoisting mechanism means and to slide between an inner jaw of said scaffold lock means and said connecting means when said bar is disposed generally parallel to the direction of movement of said hoisting mechanism means,

8. The scaffold recited in claim 7 wherein an elongated member is attached to said bar at one end thereof, whereby said bar can be moved from a horizontal position to a vertical position.

9. The scaffold recited in claim 5, wherein said gripper means comprises a hook, whereby said hook can be moved upwardly to engage a trap means or be moved downwardly away from said trap means, and said hoisting mechanism means can be pulled downward away from said scaffold.

10. The combination recited in claim 5, wherein said scaffold lock means is a load-activated lock.

11. In combination, a scaffold bracket, a scaffold lock, a mechanical jack for use with an upright post, said scaffold bracket being of the type employ-ing a rigid frame for supporting a platform and said scaffold lock having side members, said rigid frame being supported by said side members in a manner permitting relative rotation only between said scaffold lock and said frame about a pivotal axis, said side members carrying an inner jaw and an outer jaw in a manner permitting said upright to be received between said jaws and said side members and causing said jaws to clamp said upright when a downward, oblique force is exerted upon the pivotal axis, said inner jaw being located between and below said Pivotal axis and said outer jaw when in locked position, the improvement comprising attachment means on said scaffold, said attachment means being adapted to be engaged by said mechanical jack, said mechanical jack comprising, a jack lock comprising, an inner jaw and an outer jaw spaced from each other and connected to spaced plates defining a space receiving said upright post, a lifting mechanism, spaced levers connected to said spaced plates and having a foot engaging stirrup fixed to one end of spaced levers and spaced straps connected to the end of said levers, said spaced straps being connected to said scaffold bracket, an extended hoisting mechanism means connecting the scaffold to the upper portion of the upright member for raising said scaffold, and jack lock disabling means attached to said jack lock whereby said jack lock can be held from locking to said upright and said jack lock with a scaffold can be lowered by means of the extended hoisting mechanism means.

12. A scaffold adapted to be supported on an upright comprising, a scaffold bracket, scaffold lock means, to slidably receive said upright, to grip said upright for supporting said scaffold bracket at a predetermined height, and to slidably receive said upright for up and down movement of said scaffold, connecting means supporting said scaffold bracket on said scaffold lock means, mechanical jack means, connecting means attaching said mechanical jack means to said scaffold bracket for selectively raising said scaffold bracket causing said scaffold bracket to slide up said upright, a jack lock means for supporting said mechanical jack means on said upright, jack lock disabling means on said mechanical jack means for disabling said jack lock means from gripping said upright, and scaffold lock disabling means connected to said scaffold lock means, including a member attached to said scaffold lock means and extending downwardly therefrom, whereby said scaffold lock means can be held out of gripping engagement with said upright by a person at a substantial distance from said scaffold lock means, and an extended hoisting mechanism means connected to the upper portion of the upright member and having gripper means thereon connected to said scaffold bracket and adapted to raise and lower said scaffold bracket when said jack lock means and said scaffold lock means are disabled and held out of gripping engagement with said upright.

13. In combination, a scaffold bracket, an upright member, and scaffold lock means, comprising side plates and an inner and outer jaw, supporting said scaffold bracket on said upright member by connecting means, extended hoisting mechanism means connecting the scaffold bracket to the upper portion of the upright member for raising and lowering said scaffold bracket, and elongaged scaffold lock disabling means connected to said scaffold lock means for disabling said scaffold lock means when lowering said scaffold bracket by said hoisting mechanism means, said extended hoisting mechanism means having a gripper, for engaging a trap on the scaffold bracket to hoist said scaffold bracket when the gripper is raised by the hoisting mechanism means but freeing itself from the trap when the gripper is lowered.

14. The combination recited in claim 13 in combination with a mechanical jack comprising:
a lock, levers and straps, connected together, said mechanical jack further including means for restraining said levers of said lock so that the lock jaws do not bear against opposed faces of said interposed upright.

15. The combination recited in claim 13 in which the hoisting mechanism means is a block and tackle and the gripper is attached to its lower pulley.

16. The combination recited in claim 13 in which the scaffold lock means is a load-activated lock.

17. The combination recited in claim 14 in which the scaffold lock means is a load-activated lock, and a mechanical jack is attached to it at a point between the inner jaw and the point where it supports the scaffold bracket.

18. The combination recited in claim 14 wherein the mechanical jack comprises, a jack lock, a jack lever, strap means, said jack lock having an inner jaw and an outer jaw spaced from each other and adapted to slidably receive said upright therebetween when said jack lever is moved in a first direction, and to grip said upright when said jack lever is moved in the other direction, said jack lever being pivotally connected to said jack lock, said jack lock inner jaw being disposed between said jack lock outer jaw and said pivot means, said strap means connected to said jack lever and to said scaffold lock means between said scaffold lock inner jaw and said connecting means.

19. The combination recited in claim 13 wherein a mechanical jack is connected to said scaffold bracket, said mechanical jack comprising a spring-activated lock adapted to be supported on said upright member, levers pivoted to said spring-activated lock, link means on said levers extending downward therefrom and attached to said restraining means, said levers having jam means thereon adapted to engage said spring-activated lock deactivating said spring-activated lock when said jam means are put in a predetermined position, thereby permitting said spring-activated lock to move freely up or down on said upright member.