US2917278A - Hoisting device - Google Patents

Description

Dec. 15, 1959 c. H. ARNOLD HOISTING DEVICE 2 Sheets-Sheet 1 Original Filed June 9, 1955 INVENTOR. CARTER H. ARNOLD BY a WW A 7' TORNE VS Dec. 15, 1959 c. H. ARNOLD 2,917,278

HOISTING DEVICE Original Filed June 9, 1955 2 Sheets-Sheet 2 INVENTOR. CARTER h. ARNOLD A T TORNE VS United States Patent M HOISTING DEVICE h Carter H. Arnold, Redwood City, Calif.

Original application June 9, 1955, Serial No. 514,305,

now Patent No. 2,756,947, dated July 31, 1956. Divided and this application May 28, 1956, Serial No. 587,875

3 Claims. (Cl. 25'4150) This invention relates to hoisting devices of the type generally employed to support. scaffolds and is similar 2,917,278 Patented Dec. 15, 1959 ice Fig. 6 is an enlarged sectional view of the drive mechanism of the device of this invention; and,

Fig. 7 is a sectional view of one form of drum of the device of this invention showing representative dimensions thereof.

In detail, this invention comprises a housing which includes a pair of similar, spaced, opposed, parallel side plates 1, 2 which are secured together adjacent their upper edges by means of studs 3, 4 and adjacent their lower in general operation to that shown in my United States a Patent No. 2,742,261, issued April 17, 1956. This application is a division of application Serial No. 514,305, filed June 9, 1955 now Patent No. 2,756,947.

Heretofore, various hoisting devices have been proposed to avoid the piling up of rope on the drum carried bythe scaffold which is to be raised or lowered. Such devices include one or more drums around which the rope is reeved in such a way that the friction between the rope and the drum is intended to be sufficient to prevent slippage. In this manner, the hoisting device and its associated load in effect travel along the length of rope and no piling up of the latter results at any point.

. Although such prior art devices are theoretically correct, none has been adopted in practice because of various disadvantages such as unnecessary weight, lack of inherent safety in operation, impracticability in'operation, complexity, and costliness. Y

On the other hand, this invention contemplates a hoisting device having many refinements over the prior art devices resulting in a compact, efficient, and inherently safe hoist. r J f It is therefore a main object of the present invention to .provide a hoisting device for scaffolds and the lik e which overcomes the disadvantages of prior art mechanisms of like nature. I I

Another object of this invention is the provision of a hoisting device incorporating novel safety features which render the same'foolproof in operation. I 1

Still another object of this invention is the provision of a hoisting device for scaffolds .which' includes m'eans for preventing the formationrof slack in the'gsuspending I rope at any point along the length of the latter so that the said rope is under control at all times.

Yet another object of this invention is the provision of a hoisting device adapted to be run along the length of a rope and WhlCh'lS more compact than those heretofore available. I

. It is a further object of this invention to provide a hoisting'device including means for automaticallyftightem ing successive ropewindings on a drum to insure adequate frictional engagement therebetween.

; Otherobjects and advantages will becomeiapparent.

from the following description taken in co ection with the accompanying drawings,1in which:

Fig; 1 is a top plan view of the hoistingdevice-of this invention, partly broken away on the drum thereof; 1 1 q Fig. 2 is an elevational view of one side ofthe device of Fig; 1, partly broken away to showinternal structure; ,Fig. 3 is a sectional view taken generally along lines 3 -3-of Fig. 2; l 3 i Fig. 4 is an elevational view ofthe other side of the device of Fig. 1;

Fig. Sis a sectionalview taken to show the rope windings generally along lines -.F s. i

edges by studs 5, 6; Said stubs may be reduced in the diameter at their threadedends or provided with tubular spacers 7 (Figs. 1, 3) so that side plates 1,2 may be positively spaced apart a predetermined distance. Although this invention will be described assuming that side plates 1, 2 are disposed vertically, it will be understood that the invention contemplates various different applications and in many instances the hoist may be used so as to dispose the side plates other than vertically.

Extending between side plates 1, 2, substantially centrally of the latter, is a shaft 8 to which is fixedly secured a drum, generally designated 9. Shaft 8 is rotatably mounted in bearings 10 (Fig. 3) which are preferably press fitted in side plates 1, 2. Said shaft may be held from axial movement by snap rings 11 and prevented from rotating with respect to drum 9 by a key 12,

Drum 9 is preferably provided with four peripherally extending, axially spaced grooves, although a greater or lesser number may be employed. As best seen in Fig. 7 said grooves are numbered 13, 14, 15, 16, respectively, and are preferably U-shaped or semicircular in cross sec tion. Thebottom of said grooves are undercut or recessed at 17 for the purpose of maintaining said grooves in the same shape by promoting even wear.

Grooves 13-16 areadapted to receive therein the windings o'r turns'of a rope, preferablywire rope, with the opposite ends of said rope extending away from the drum in opposite directions. Thus, referring to Fig. 2, run 18 of the rope extends upwardly from drum 9 and run 19 extends downwardly therefrom. Hereinafter, run 18,will becalled the loaded run and run 19, the unloaded run. Between said runs the rope is formed with three turns, that is, one less than the number of grooves, anddesig- Hated-.23, 24, 25, respectively, in the drawings. Spaced upwardly from drum '9, but relatively closely adjacent the periphery thereof are three rollers 26, 27, 28 which extend between side plates 1, 2 and are rotatably mounted at their ends therein by pressed bearings 29 (Figs. 2, 3). The peripheries or rope-engaging surfaces ings is preferably the arc 32 of a circle about center 30.

The effect of' the. above described structure is' that the rope is never subjected to a sharp change in direction and at the same time an extremely compact means is provided" for guiding a portion of the windings in a path spaced from the periphery of drum 9 and for leading the rope from one groove to the adjacent groove.

As best seen in Figs. 1, 3, 5, turn 23 of the rope engages more than 180 degrees of groove 13, then joins with turn 24- in groove 14 and then turn 25 in groove 15.

From groove 15 the rope runs over rollers 26, 27, 28

and enters groove 16 of drum 9-from which said rope extends diagonally over bolt 6 of the housing and down wardly into unloaded run 19. The are of contact between the rope and drum 9 is about 240 degrees in the case of each winding; and, as is apparent, the efliciency of the. device is directly proportional to this are of contact, which in the present. case is much greater than the usual 180 degrees. 7

- Fig. Lshows the rope turns as they appear when drum 9 is being rotated (in a manner to be described) so'that loaded run 18' is. being wound on the drum. In such a case theportions of turns 23, 24', 25 that are on therside of the drums opposite run 13 extend in the plane of the grooves from the. periphery of drum 9 to roller 28. The turns then become slantingly disposed .to enter the adjacent grooves on the other side or" said d'mrn, When the drum: is being turned so as to wind unloaded run. 19

upon. the drum, the slanting portions become planar a pair of spaced radial flanges 31(Figs. '1, 3, 5) at points adjacent the outermost grooves 13, 16. on drum 9,

' Flanges 31, assist in guiding the rope turns from grooves 011 one side-to adjacent grooves on the other side of said drum and to help prevent. fouling of the rope turns. The; natural shifting of the rope turns, as above described, caused. by changes in the tension of the rope, is not impeded in. any way by rollers 26, 27, 28. However, itshould be noted that the use of a grooved drurn' instead of the rollers shown, as has been. attempted in the past, would. result in the wearing and chafing of the rope which is not present in the instant device.

The provision of rollers 26, 27, 28 and their positioning-as, above described is an'extremely important feature of the invention as said rollers provide a compact means for switching the turnsof the rope. The present invention also. contemplates, other means for performing the i functions of. the rollers 26,28. In any case, it is important that the central of the. locus of all'points ofengagement of the rope: should be within. theperiphery of I drum Since; vention; is dependent upon friction between the rope and the grooves in drum 9, it has been found that increa ing the'radiusfrom the drum center of at least one groove the operatiotr of: the hoisting device of this inon the sideadjacent the unloaded run 1? causes auto- 7 matic tightening of the'turns 23, 2d, 25 on said drurn.

For instance, ifthe diameter of the drum at groove 13 is. 6 and the, diameter at: groove. 14. or 15 is' incfreaicd to 6.010", winding 2,4 or 25 .is forced to 'assumesuch larger diameter and thereby increasefthe overallitension inthewindings- Too great a diflerencein groove diaineters may cause, too muchtension to beapplied to the windings. H l It, has been; found that, inva hoist for use'with aY d ameterrope, a drum of 6"nominal diameter is adeguate. This nominal; dimension isino ted by the letter'A in F g. 7. I Within manufacturing:tolerances it is preferableto' progressively increase the drum diameter by an increment, X, of 0:910". Hence, the diameter at groove 14 1 s shown as A-FX, at groove 15 as A+2X, and at groove 16 as A+3X. Since each groove is of a'semirope asfwould cause the formation of-slack;

rollers .which. simultaneously engage all'of the turns. on

in. Fig. 2. Plates 34 are generally curved with the rollers 36, 37' mounted adjacent the ends thereof and with the center swingably supported by means of a pin'38 to one end of an arm 39 which,.in turn, is swingably, mounted intermediate its ends on stud 5. The end of arm 39 opposite pin 38 is connected to toggle means, generally designatedAO, forurging said arm in a direction to' force rollers; 36, 37 into engagement .with the rope in groove 16 (clockwise in-Eig..2)'. 7 V

Toggle means .40 comprises a. lever 41'. pivoted as by pin 42. to said opposite end' of arrn39; At a point'spaced' from pin 42 a pin 43.pivotally connects lever 41 013. red 44 which; is slidably mounted in an anchor pin 45,

which, in turn, is. rotatably mounted on side plate 2. of

the housing. A compression spring 46, surroundingrod -44, is interposedbetween anchor pin 45 and a shoulder that the. axis of pin 43 is placed slightly'inwardly" from a line between the axis'of pins 42 and 45 so thatspring 46 also retains lever 41 in the locked position within the housing. I. t 1 V "'Tensioning device 35 exerts a radially inwardly. directed pressure along a substantial length of the rope be cause of ,thepresence of the two rollers 36, 37 In addition, because both rollers are: pivoted as a unit about the pin 38, each roller exerts. the same amount of force and there. are noforces exerted along the length of The fact that rollers 36,. 37' engage only thelastturn of the rope adjacent the-unloaded run is extremely'irnportant: in preventing the :formationv of. slack and results in'the; rope. being under some tension at allpoints'along the turns,that engage. the grooves. 13 -16. When the hoist is employed tosupport a scaffold from.

. 1 a vertically extending rope fixed at its upper end to the top; of a biulding, loaded. run 18. supports the load and circular cross section,'. as., previously explained, of substantially the same diameter as the rope,; this increment PPr m t v /30ef the'diameter'ofthe groove cross .sectione C I I It will be noted that thediiferencesiof the'grooves from 1 the axisof drurn 9-may be varied' in differentmanners. To; achieve the results of tightening the. windings,-=-it is necessary only that one of the grooves on the'side of the. loadedrun 18 be. ata lesser-distance from the axis of drum 9 than one of the: grooves on the sideof theun loadedfrun 19..

. To. provide an; additional restraint for the rope turn and. to keep them at all times in engagement with the drurnwgrooves, it is preferable to provide a tensioning" device generallyzdesignated, 35 (Fig 2) for preventing slack", in-the rope turns. Heretofore analogous devices which have been employed but have" generally comprised length of run unloaded run 19 supports only its own weight. It-will beapparent, therefore, that the tension in the ropewill 7 decrease from .run 18 through turn s 23, 24, 25'and will 'be relatively small at'v the point engaged by tensioning device, 35. The. latter should, of course,- be on the side ofthe'drurnopposite that from which run 18' extends. It is due to the fact: that the tension on the ropeis slight adjacent run. 19' that the tensioning device must exert a radiallyfinwardly' directed: force without drag asabove described. The lower run 19; of course, resists only its own weight an'd'such weight contributes: to the tightness of the ro'pe t'urns on the drum. 7 However, even when the 19 is only a few inches, there is no chance plate 2 of thehousing.v Gear 50 is in mesh with a pinion 51 mounte'don a shaft 52. which is rot'atably supported a in pressed bearing 53 in side plates 1, 2. p

As seen .in' Fig. 3'; pinion 51 is mounted outboard on shaft 52 on the same side of the housing as gear 510. On

the

the other-end of said shaft, adjacent side plate 1, shaft 52 a friction disc 58, and a pressure nut 59. Friction disc,

56, 58 and ratchet wheel 57 are rotatable on shaft 52. The outer end of said shaft is provided with threads 60 for threadedly receiving internally threaded pressure nut 59. It will be seen that rotatingnut 59 with respect to shaft 52 in one direction causes said nut to jam friction disc, 58, ratchet wheel 57 and friction disc 56 together against each other and friction plate 54.

Pressurenut 59 may be providedwith an elongated handle 61 for hand operation of the'hoist or may be gear connected to a motor or the like in the event power operation of the 'hoist is desirable. Rotation of nut 59 in an opposite direction, to cause said nut to back off from side plate 1, allows friction plates 56, 58, ratchet wheel 57 and friction disc 54 to separate and become freely rotat-- able. one with respect to the other. A lug 62 is provided protruding axially from nut 59 into the path of a pin 63 projecting radially from shaft 52 (Fig. 1) for preventing travel of'nut 59 off the end of shaft 2.

In Figs. 1, 2, it will be noted that a ratchet dog 64, rotatably mounted on a shaft 65 extending from the housing, extends into engagement with the teeth in ratchet wheel 57. Dog 64 is yieldably urged into such engaging position by a torsion spring 66 for preventing rotation of said ratchet wheel in the direction indicated by arrow 67 in Fig. 2. The direction of arrow 67 is that taken by shaft 52 upon rotation of drum 9 to unwind loaded run 18 therefrom or in moving the hoist down the rope.

Threads 60 are formed such that, when handle 61 is moved in a clockwise direction in Fig. 2 to wind loaded run 18 onto drum 9, nut 59 travels inwardly to press friction plates 56, 58, ratchet wheel 57 and friction plate 54 into a single revolvable unit. Hence, the rotation of handle 61 will be transmitted to drum 9 through friction plate 54, shaft 52, pinion 51, and spur gear 50. Ratchet wheel 57 will move in a direction opposite arrow 67 merely resting against or clicking by dog 64.

Once the load of the hoist and attached scaffold is placed on run 18, and the clockwise movement of handle 61 is ceased, drum 9 and therefore shaft 52 will be urged in a reverse direction by the tension in run 18. Handle 61 will rest-in a vertical position because of its own weight. This reverse movement of shaft 52 also jams pressure nut 59 into mutual frictional engagement with friction discs 56, 58,"ratchet 57 and friction plate 54. Since ratchet wheel 57 is prevented from moving in this reverse direction;(arrow 6 7) by dog 64, the hoist cannot fall.

Move me nt of-handle 61 in a counter clockwise direction, however, decreases the frictional pressure between the friction discs, the ratchet wheel and friction plate 54 to an extent sufficient to allow shaft 52 to slip with respect to said ratchet wheel. This slippage of shaft 52 is at all times controlled by the movement of pressure nut 59 by handle 61, and therefore the downward movement of the hoist on the rope is adjusted as desired by the operator. If, at any time, counter clockwise movement of handle61 is stopped, shaft 52 immediately catches up thereby jamming friction disc 56 between friction plate.

54 and ratchet wheel 57 to prevent further downward movement of the hoist.

It is obvious that other means could be used to urge nut 59 and the associated parts of the clutch 55 into mutual frictional engagement such a face cam secured on shaft 52 and engageable with a mating cam on nut 59. The clutch device shown in Fig. 6, however, has been founded to be more practical.

Rigidly mounted on stud 3 adjacent side plate 2 is a grooved guide or fairlead 69 (Figs. 1, 2, 4) having its grooved edge in line with loaded run 18 extending from drum 9. In effect, groove 70 completesthe projected half. circle of groove 13 on said drum. Fairlead 69 therefore acts to guide run 18 into groove 13.

As a valuable safety feature the present invention includes an elongated clamping arm generally designated 71 (Figs. 1, 2, 4), which cooperates with guide 69 in a manner now to be described. Arm 71 may be formed from a heavy plate and is swingably supported intermediate its ends on a stud 72 extending between and secured to side plates 1, 2. Arm 71 is coplanar with fairlead 69 and is formed with an arcuate, grooved end 73 to receive the side of loaded run 18 that is opposite the side engaged by fairlead 69. i

End 73 of arm 71 is formed to the arc of a circle having a center opposite stud 72 from end 73 so that clockwise swinging of arm 71 (Fig. 2) urges the grooved end 73 to clamping relation with fairlead 69 so as to clamp the rope run 18 therebetween(Figs. l, 4). The end 74' of arm 71 that is opposite the clamping end is relatively long and of sufiicient mass to urge the arm into clamping engagement of upper run 18 of the rope at all times due to gravity.

rotate drum 9.clockwise (Fig. 2) the housing will tend to move downwardly relative to run 18 and securely clamp the rope against fairlead 69, thereby positively preventing such downward movement. However, if it is assumed that drum 9 is positively rotated so as to wind the run 18 therein, the housing moves up relative to stationary run 18 and swings arm 70 counterclockwise away from clamping position (Fig. 2). It will be understood that arm 71 is always in engagement with run 18 but has no effect thereon except when the housing tends to fall relative thereto. When it is desired to move the housing downward relative to run 18, it is merely necessary for the operator to lift the end 74 of arm 71 outof clamping engagement with run 13. This may be facilitated by running the device upwardly slightly. 9

With respect to Fig. 2, it is obvious that a spring may be employed to urge arm.71 in a clockwise direction into clamping engagement with loaded rope run 18. The arm illustrated has sufiicient unbalanced weight in the portion 74 to effect a proper automatic working of the safety device when used with a vertically extending rope. However, additional yieldable urging on the arm may be desirable in many instances, especially when the device is employed with a rope inclined to the vertical or the horizontal. As previously mentioned, the novel combination of clamping arm 71 and fairlead 69 also functions to guide run 18 into the groove 13 on drum 9 at all times, and there is no chance of the rope separating from fairlead .69.

merely necessary to prevent the accidental rotation of drum 9, if an additional safety device is desired. To this end a pawl 75 (Fig. 4) may be swingably mounted on the end of shaft 65 opposite dog 64 and outboard of side plate 2 (Fig. 5). Said pawl is unbalanced so as to be urged into engagement with the teeth of gear 50 (Fig. 4) by gravity. It is obvious that a spring could be used to yieldably urge pawl 75 into engagement with gear 5'!) if required. Pawl 75 is shaped so as to prevent counterclockwise rotation of gear 50 (Fig. 4) which is equivalent to downward movement of the housing with respect to the rope.

In order that pawl 75 will be disengaged from gear 50 only upon unclamping of the brake arm 71, pawl 75 is provided with a pin 76 eccentric with respect to shaft 65 and extending axially thereof through an open ing 77 in side plate 2 into the path of end 73 of clamping arm 71. Hence, upon rotation of arm 71 in a clockwise. direction (Fig. 4) to unclamp run 18 of the rope, end 73 strikes pin 76- to rotate pawl 75. outot engagement with gear 50; This allows downward movement ofithe hoist with trespect to run 18 ofthe' rope in the manner'previo'uslydescribed. f V p 7 Although the present invention has many applications;

its greatest use, lies in supporting scaffold or the like from a pair of stirrups or hangers 78' (Fig; 4') at op posite ends thereof, in which case a hoisting device is" employed with each such stirrup. ,Ordinaril'y, such stir-' rups are formed from steel rod or strap and are provided with an eye portion 79 from which the scaiiold is suspended. In such a case side plates 1, 2 are preferably. provided with an offset portion so that stud 5 is in vertical alignment with loaded run 18i of. the rope. I

v In order'to position the eye portion 79 in vertical alignment with the run 18, the former may be directly carried by stud 51in Fig; 4. A positioning collar on" stud '5 may serveto 1101a the vertical alignment between run 18 and the eye 79 of the stirrup. 1 By the above described structure the line of action is'always vertical and the housing is therefore held vertical at all times;

When used with a 650 pound working load, it'has-been found that side plates 1, 2 need not be longer than 12",

thus making an extremely compact, lightweight unit which when the rope is wound unevently on' a drum as in conventional hoists.

extremely importa ntlfeature of the invention is that. the load bearing stirrup and the loaded runiof the wire rope are in perfect vertical alignment as seen in Fig. 4. This constitutes-an extremely beneficial safety' feature inasmuch as there is no tendency for the hoisting device to tilt from an upright position when the load is applied or removed. 7 7

Although the invention has been described and illustrated in detail, such is' not to be taken as restrictive thereof, since it is obvious that modifications could be made therein without departing from the spirit and scope of the invention; 1

I'claim: r l.- In' combination with a hoisting device, a housing, arope drum rotatably supported in said housing and provided with a plurality of circumferentially extending parallel peripheral grooves, a hoisting rope, said rope being formed intermediate its ends with a'plurality of axially spaced loops surrounding said drum with the major portions ofsaid loops received in said grooves, guide slat-7,278

means, carried by said housing engaging thev'junctures connecting adjacentportions of said; loops for leading said rope from one groove to the adjacent groove, said rope having opposite loaded and unloaded ends extends: ing; outwardly from said, drum whereby said loops are" the only. connecting means between said rope and sai'clj drum, one of said grooves' being formed to a smallet" circumferential extent than. the adjacent groove nearerv said loaded end whereby said rope tightens on sair.lf dru m toward said loaded end assaid" drum rotates. t t

2. In combination with a hoisting device, ahousin'g;

a rope drum-rotatably'supported in said housing 'andprovided' with apluralityof circumferentially extending para allel peripheral grooves, a hoisting rope,, said rope being Wardly'fromsaid drum whereby said loops are the only connectingmeans between said rope and said drum; said grooves. being formed 'to progressively smaller diameters from said unloaded end toward said loaded end whereby ,said rope progressively tightens on said drum toward said loaded end as said drum rotates.

3. In combination with a hoisting, device, a housing; a ropedrum rotatably supported in said housing and pro- I vided with a-plurality o f circumferentially extendingparallel peripheral grooves, .a' hoisting rope, saidvrope being formed intermediate itsends' with a pluralityofaxially spaced loops surrounding said drum with themajor per tions of said loops received-in said' grooves, guide means carried by said housing engaging, the junctures' connectin'g'adjacent portions or said loops for leading sai d rope fromone groove to the adjacent groove, said rope an ing opposite loaded and 'unloaded ends extending outwardly from said drumwhereby said loops are the:

only connecting means between said rope and said drum,

said grooves being formed to progressively smaller diameters from said unloaded end toward said loaded end whereby said rope progressively tightens on'saidf drum toward said loaded end as said drum rotates, the change in diameter between adjacent grooves being of the order of'a fraction of onepercent of the diameterof said drum.

References Cited intthe file of this patent v ,7 UNITED STATES PATENTS Miles Mar. '7, 1922 1,682,083 Johnston "Aug; 28, I928: 2,495,392 Smith Jan. 24,1950

2,662,734 Allenbau'gh Dec. 15, 1953

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