US1388262A - johnston - Google Patents

Description

F. B. JOHNSTON.

HOISTING ATTACHMENT FOR SCAFFOLDS.

\PPucAnoN FILED 0:0. 3; m9.

1,388,262 Patenwd Aug. 23, 1921.

2 SHEETS-SHEET I.

F. B. JOHNSTON.

HOISTING ATTACHMENT ron SCAFFOLDS.

APPLICATION FILED DEC. 3, 199.

1,388,262. Patenflad Aug. 23, 1921.

2 SHEETS-SHEET 2.

4 47 .79 4 ,7 INVENTOR I Q 4% n 1/ By K 1! I I as ATTORNEY UNITED STATES PATENT OFFICE.

rum: 3. :romrsron, or ROSELLE 2m, New JERSEY, ASSIGNOR T0 AMERICAN sAEE'rY DEVICE 00., or NEW YORK, 11. Y.

EOISTING ATTACHMENT FOE SCAFFOLDS.

Specification of Letters Patent.

Patented Aug. 23, 1921.

To all whom it may concern:

Be it known that I, FRANK B. JOHNSTON, a citizen of the United States, and a resident of Roselle Park, county of Union, and State of New Jersey, have invented certain new and useful Improvements in Hoistin Attachments for scaffolds, of which the f0 lowing is a specification. I

The present invention relates to improvements in hoisting attachments for scaffolds, and I particularly propose in the present disclosure to provide a device especially desirable for scaffolds of the swinging ladder type such as are used by painters, stone setters, stucco workers, renovators, etc., althou h it will be understood that it may be use for other types of scaffolds and in other connections where it is desired to raise and lower a latform.

eretofore painters scaffolds have been supported and hoisted for the most part by a block and fall arrangement, which was dangerous, laborious to operate, and was attendant with many disadvantages which made it undesirable. The Manila rope was easily affected by weather conditions and by acids and whitewash which tended to decay and deteriorate it, a great deal of surplus rope had to be carried on the platform, encumbering the workmen, or piled upon the ground forming an obstruction, and its security was never of such a positive nature as to insure against accidents, the support of the scaffold de ending entirely upon the reliability with w iich the workmen fasten the rope.

It is an object of the present invention therefore, to provide a device of relatively light weight, easy to o erate both in raising and lowering the sea old, compact so that the working room of the workmen is not sacrificed or impaired, and having a maximum of safety. A further object residesin providing a device which may be used in substitution of the block and fall, utilizing the usual form of rigging at present employed upon painters scaffolds, and of which a great many are in use, that is, the device may be directly attached to the means provided on the scaffold to which the usual block and fall is attached. I further propose to facilitate the rigging up of the de vice, enabling the suspension cable to be freely spun off the drum, it being proposed to permit disengagement of the winding drum upon which the cable is provided from its holding means, and its free rotation in either direction when desired. A further object is to provide a machine which may be operated from the scaffold when desired.

Other objects are rigidity between the winding drum and the scaffold floor, thereby obtaining a maximum of power, positioning of the device so that the man operating the same may stand properly balanced upon the scaffold permitting him to work the device with the least danger to himself and without loss of power, and facility of attachment to the scaffold, the attachment means carried by the device constituting also tools for carrying out the attachment operation. A further object is to provide a device which may be raised with relative speed and lowered with rapidity and steady control, and with a maximum of safety in either case.

With these and other objects in view, an embodiment of my invention is shown in the accompanying drawings, and this embodiment will be hereinafter more fully described with reference thereto, and the invention will be finally pointed out in the claims.

In the accompanying drawings,

Figure 1 is a side elevation showin a painters scaffold of the swinging la der type provided with an embodiment of my hoisting device;

Fig. 2 is a plan view thereof;

Fig. 3 is a perspective view looking from one end of the scaffold;

Fig. 4 is a front elevation of the hoisting device according to the present embodiment of my invention;

Fig. 5 is a side view thereof;

Fig. 6 is a fragmentary view showing the worm gear employed therein shifted during raising of the scaflold;

Fig. 7 is a similar view showing the worm gear retained in shifted position to free the drum therefrom;

Fig. 8 is a front view of the ratchet engaging dog provided on the hand lever for raising the scaffold;

Fig. 9 is a top view thereof;

Fig. 10 is a detail sectional view taken along the line 1010 of Fig. 4; Fig. 11 is a similar view taken along the line 1111 of Fig. 6; and

Fig. 12 is a side view of a machine showing means for operating it from the ground.

Similar reference characters indicate corresponding parts throughout the several figures of the drawings. L

Referring to the drawings, and particularly to Figs. 4 to 11 thereof, the machine according to the present embodiment of my in-- a rod 14 having mounted thereon a rotatable shift pulley wheel 15, loosely slidable sleeves 16 and 17 being disposed at each side thereof. The periphery of the groove of the pulley wheel is in a vertical line with the axis, of the shaft of the drum so that the cable 18extending from the drum is in a direct vertical line with the axis of the drum, the shifting of the pulley permitting the cable to be wound evenly upon the drum.

The lower end 19 of the frame is formed of a separate piece from the uprights, its upwardly bent end portions being secured to the lower ends, of the uprights by bolts and nuts 20. To the portion 19 there is secured by a bolt 21, an inverted U-shaped clamping strap 22 having its side portions.

disposed at an angle and connected by spaced bolts 23 and 24 also angularly disposed, the bolts 23being secured by a nut 25, while the bolt 24 is secured by engagement with the threaded hole 26 provided at one end of a wrench 27, the other end thereof being provided with a squared aperture 28 adapted to engage the nut 25 to remove or secure it.

The drum 10 comprises a hub upon which the cable 18 is wound, and side flanges or cheeks 29 and 30, the hub being loosely mounted to turn on. the shaft 11, theche'ek 29 being substantially of greater thickness than the check 30 and provided at itsperiph-- ery with ratchet teeth 3l engaged by a pawl 32 pivotally supported by a pin 32 upon the upright of the frame. During lowering of the machine, as will hereinafter be more fully pointed out, the pawl 32 is disengaged from the ratchet 31 by throwing the same over so that its upper surface rests without effect upon the surface of the teeth'as indicated indottedlines in Fig. 5.

A hand lever 33 is pivotally mounted on the shaft 11 between the cheek 29 and the adjacent upright portion of the frame and has mounted thereon a sliding dog comprising a face plate 34 extending over the inner side of the ratchet, and a toothed block 35 secured thereto and adapted to engage the teeth of the ratchet. A strap member 36 is secured at its endsto the face plate and extends about the lever, and to this strap member vthere is secured a block 37 adapted to weight "the dog to cause it to slide readily into and out of engagement with the teeth by gravity as the hand lever is raised and lowered. When the hand lever is not being operated it is normally in its lowered position, the dog falling vout of engagement with the ratchet by gravity.

The shaft 11 is provided at the side of the cheek 30 with an enlarged portion 38 upon which there is slidably and rotatably mount ed a worm gear 39 having radialratchet teeth 40 provided at its inner side adapted .to engage the radial ratchet teeth 41 provided upon the outer side of the cheek 30 of the drum, a spring 42 disposed on the shaft 11 between the worm gear 39 and the side frame constantly forcing the ratchet teeth 40in yielding engagement with the teeth 41.

The'worm' gear is engaged by a worm 43 having its shaft 44 journaled in the ends of a bracket 45, one end of the shaft being. extended and provided with a squared portion 46 adapted to be engaged by a handle 47 to turn the worm. Shoulders 43 and 43* are provided upon the worm, spaced from the ends of the bracket 45 so that the worm may shift longitudinally, a coil spring 43 forcing the worm when it is unresisted rear wardly so that the shoulder 43 is abutted by the rear end of the bracket as shown in Figs;

6 and 11. The dimensions of the worm and worm gear are suchlthat the gear may be shifted upon its shaft to disengage the ratchet teeth 40 from the teeth 41, without the teeth of the worm gear becoming disengaged from the worm, the worm constantly acting as apositive lock to the worm gear.

Normally when the machine is suspended by thev cablev and at rest, or during lowering. when the pull of the cable forces the drum in a direction to turn the worm gear with it, the worm is forced. forwardly aga nst the force of the spring 43 with the shoulder 43 abutting against the forward end. of the bracket 45, as indicatedv in Figs. 4, 5 and 10. During raising of the machine, the ratchet a force exerted against the face of the ratchet teeth 40. Should for any reason the pawl 32, preventing backward movement of the drum during raising, fail, the ratchet teeth Fig. 4.

40 of the worm gear will be engaged by the ratchet teeth 41 of the drum, and will be allowed to be fully engaged by expansion of the spring 42 before the actual resistance afforded by the worm gear; and worm becomesefi'ective incident to the yielding of the spring 43. Thus any danger of stripping the teeth is prevented as would be the case if the worm gear were held rigidly and the ends of its ratchet teeth 40 suddenly and forcibly engaged by the ratchet teeth 41.

Upon the side of the frame there is pivotally mounted a dog 48 which may be swung downwardly to enga the inner face of the worm gear to hold t e ratchet teeth 40 outof engagement with the ratchet teeth 41. If, at the same time, the pawl 32 is disengaged from the ratchet teeth 31 of the check 29, the drum will be free to rotate in either direction, so that the cable may be rapidly run off the drum, thereby facilitating the ri ging up of the scaffolds upon the ground. The dog 48 may if desired, be mounted below the worm gear to beswung up into holding position.

he frame 13 has a thumbscrew 13, which is screw-threaded throughout its length, and engages screw-threads 13 in the member 13. The gear 39 has a recess 39, which is provided with screw-threads. When the recess 39 is in registration with the screw 13, the gear 39 is moved to the position indicated in Fig. 7, with the teeth 40 and 41 disengaged, and the thumbscrew 13 is turned so as to have its threads engage the threaded recess 39* of the gear 39, and when such engagement takes place, the gear 39 is held toward the frame 13, and when so held in position, there is no possible chance of the ratchets 40 and 41 engaging with each other. On the other hand, the thumbscrew may be again disengaged from its threaded recess, and moved out to a position sufficiently far to allow for the play of the movable gear 39 with its ratchet 40, as shown in Fi 4 and 6. The object of this is to limit t e movement of the gear 39, and prevent its movement beyond a desired position, that is, a position be 0nd that necessary to permit its play to an fro.

When the ratchets 40 and 41 mesh, the thumbscrew is moved so that its end is inward, close to the gear 39, with simply a slight clearance between the end of the screw and the ear 39, as shown in dotted lines, hen on the rotation of the gear, there will be no engagement between the recess of the gear and the thumbscrew, and the thumbscrew will act as an abutment limiting the movement of the gear. By the positioning of the screw into this position, the ratchet 40 will be held against disengagement from the ratchet 41, and the desired engagement will be maintained. The thumbscrew thus serves three objects; first, to hold positively the ratchet 40 out of mesh with the ratchet 41; secondly, to limit the movement of the gear 39 in one direction, and thirdly, to hold the gear in a definite position, so that the ratchets continually intermesh. In its function of holding the ratchet 41 out of engagement with the ratchet 40, the thumbscrew 13 may act either in cooperation with or independently of the dog 48.

The scaffold illustrated is of the usual ladder type employed by painters, consisting of the platform 49 provided at its ends with scaffold irons 50 and 51 of inverted V- shape, and looped as at 52 at their apices. The machines are secured to these irons by engaging the strap 22 about the loops 52, the bolt 23 being first secured through the loop, its nut 25 being tightened by means of the wrench 27. The bolt 24 is placed beneath the loop, and is secured in place by engaging the threaded end of the wrench therewith. This method of securing makes the machine substantially rigid with the scaffold irons. The frame being at an angle to the irons, the angular disposition of the strap 22 causing the frame to assume this position, results in the hand levers extending at the sides of the scaffold so that a free space is provided in front of the machine substantially the full width of the scaffold, and the workman may therefore stand in the center of the scaffold and properly balance himself during raising and lowering of the scaffold.

In order to raise the scaffold, the hand lever 33 is raised to its upper position so that its sliding dog engages the teeth of the ratchet, and by moving the same downwardly, the drum is turned and the cable wound thereon, the raising of the scaffold being relatively ra id. Durin this action, the pawl 32 engaging the rate et, prevents back movement while the drum is additionally locked against back movement by the worm gear and worm, the large bearing surface provided by the teeth of the ratchets 40 and 41 and the positive locking action of the worm affording a positive, powerful, efficient and evenly distributed control. As the drum is turned in the direction to wind the cable thereon, the ratchet teeth 41 exert a cam action on the worm gear shifting it outwardly, the spring 42 immediately returning it as the teeth of the ratchet 40 pass over the points of the teeth of the ratchet 41 so that during hoisting the worm is constantly yieldable to permit of the hoisting movement, and at the same time is constantly in position to prevent backward movement.

In lowering the scaffold, the pawl 32 is disengaged from the ratchet 31, and by turning the worm by means of the handle 47, the ca le islet off from the drum and the scaffold descends, the constant and positive lock afforded by the worm permitting the descent with a maximum of safety, and with the least expenditure of time and exertion on prevent or produce'backward motion, said 65 means of said worm gear being yieldable the part of the workmen. The uncertainty and danger of the block and fall and the necessity for untying and'tying hitches in the rope whenever it is desired to raise or vlower the scaffold are entirely eliminated.

The machines are compact, light in weight, powerful and positive in their action, and entirely safe, the safety clutch provided by the worm being at all times in automatic engagement. The cable need only be of a length corresponding to the drop of the scaffold, the surplus cable being wound upon the drum and therefore entirely out "of the way of the workmen.

In Fig. 12, I have shown the manner in which the machine may be operated from the ground to raise the scaffold without any one on it. Upon the end of the hand lever '33 there are provided a pair of rings 55 and 56 to which are secured ropes or cables 57 and 58 extending to the ground, the rope 58 being first carried in a loop over one of the sleeves provided on the rod 15. By pulling upon the rope 58, the hand lever is moved to its raised position, the ratchet dog automatically falling into engagement with the teeth. of the ratchet, and by pulling on the rope 57 the lever is lowered turning the drum and winding the cable thereon, and by continuing this operation alternately, first pulling on one rope and then on the other, the scaffold is raised. The scaffold irons are held against slippage on the platform by means of staples and pins and 61 embracing the sides of the irons.

I have illustrated and described a preferred and satisfactory embodiment of my invention, but it is obvious that changes may be made therein within the spirit and scope thereof as defined in I claim:

1. In a hoisting and lowering means for scaffolds, a frame, a drum in the frame adapted to receive a cable thereon, operating means for turning the drum whereby to hoist the frame on the cable, and a holding pawl adapted to maintain the drum from turning in a reverse direction, in combination with a yieldable normally inactive rethe appended claims.

verse preventing means for the drum a'dapted to normally permit free operation of the latter and adapted to hold the drum from reverse movement and absorb shock imposed on the drum when said pawl fails to operate.

2. A hoisting and lowering machine for scaffolds, comprising a drum, a frame supporting said drum, releasable means adapted to operate the drum in hoisting direction, a ratchet rotatable with said drum, a worm gear having means engaging/the teeth of sald ratchet, a .worm engaglng sald worm gear,'sa1d worm and wormgear adapted to axially away from said ratchet of said drum to permit rotation of said drum in a hoisting direction.

3. A hoisting and lowering machine for scaffolds, comprising a drum, a frame, a

shaft carried by said frame supporting said drum, releasable means adapted to operate the drum in hoisting direction, and steady control and operating means comprising a worm gear on-said shaft, a ratchet fixed to said drum, a ratchet rotatable with said Worm gear, a worm engaging said worm 'gear, and spring means retaining said ratchet of said worm gear in axially yielding engagement with said ratchet of said drum.

4. A hoisting and lowering machine for scaffolds, comprising a drum, a frame, a

shaft carried by said frame supporting said drum, releasable means adapted to operate the drum in hoisting direction, a worm gear' on said shaft, a ratchet fixedto said drum,

a ratchet fixed to said worm gear, a worm ngaging said worm gear, and spring means retalnlng sald ratchet of sad worm gear in axially yielding engagement with said ratchet'of said drum, said worm gear adapted to shift upon said shaft against the force of said sprlng means as said drum is op-' erated in hoisting direction, and adapted during sald shlftlng to malntain constant engagement with said worm.

5. A hoisting and loweringmachineforrotatable with-said worm gear, and spring means retaining said ratchet of said worm gear in' axially yielding engagement with said ratchet of said drum.

6. A hoisting and lowering machine for scaffolds, comprising a drum, a framesupporting said drum, means, adapted to operate said drum in hoisting directiommeans carried by said frame adapted to cooperate with the drum to prevent or produce backward, motion, while automatically permitting the forward hoisting motion, and I means rendering said last named means yieldable to a limited degree against the force of the backward motion of said drum.

7. A hoisting and lowering machine for scaffolds, comprising a drum, a frame supporting said drum, means adapted to opcrate said drum in hoisting direction, a.

worm gear, and a worm adapted to cooperatelwith the drum to prevent or produce backward motion, while automatically permitting the forward hoisting motion, said worm gear and worm being yieldable to a limited degree against the force of the backward motion of said drum.

8. A hoisting and lowering machine for scaffolds, comprising a drum, a frame, a shaft carried by said frame supporting said drum, flanges at each end of said drum, ratchet teeth upon one of said flanges, a hand lever pivoted at the axis of said drum, a sliding dog on said hand lever adapted to drop by gravity into and out of engagement with said ratchet as said hand lever is raised and lowered, a pawl engaging said ratchet to prevent backward movement of said drum, operation of said hand lever adapted to operate said drum in hoisting direction, and means for operating said drum in lowering direction when said hand lever and said pawl are released.

9. A hoisting and lowering machine for scaffolds, comprising a drum, a frame, a shaft carried by said frame and supporting said drum, a cable wound on said drum and extending upwardly therefrom, a shaft at the upper end of said frame, a pulley slidable on said shaft and adapted to guide said cable upwardly in vertical line with the axis of said drum, sleeves on said shaft at the sides of said pulley adapted to limit the sliding movement thereof, releasable means for operating the drum in hoisting direction, and means for operating the drum in lowering direction when said first named means is released.

10. A hoisting and lo'wering machine for scafi'olds, comprising a drum, a frame supporting said drum, releasable means adapted to operate the drum in hoisting direction, a ratchet rotatable with said drum, a worm gear having means engaging the teeth of said ratchet, a Worm engaging said worm gear, said worm and worm gear adapted to prevent or produce backward motion, and means carried by said frame adapted to maintain said means of said worm gear in engagement with said ratchet.

11. A hoisting and lowering machine for scaffolds, comprising a drum, a frame supporting said drum, releasable means adapted to operate the drum in hoisting direction, a ratchet rotatable with said rum, a worm gear having means engaging the teeth of said ratchet, a Worm engaging said worm gear, said Worm and worm gear adapted to prevent or produce backward motion, said means of said worm gear being yieldable axially away from said ratchet of said drum to permit rotation of said drum in a hoisting direction, and means carried by said frame adapted to limit the axial movement of said means of said worm gear.

In testimony that I claim the foregoing as my invention, I have signed my name hereunder.

FRANK B. JOHNSTON.

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