US2776815A

US2776815A - Universal scaffolding machine

Info

Publication number: US2776815A
Application number: US437733A
Authority: US
Inventors: Sheard William Byl
Original assignee: PATENT SCAFFOLDING CO Inc
Current assignee: PATENT SCAFFOLDING CO Inc
Priority date: 1954-06-18
Filing date: 1954-06-18
Publication date: 1957-01-08
Anticipated expiration: 1974-01-08

Description

Jan. 8, 1957 Filed June 18, 1954 w. B. SHEARD 2,776,815

UNIVERSAL SCAFFOLDING MACHINE 9 Sheets-Sheet l /'S ATTORNEY Jan. 8, 1957 w. B. sHEARD 2,776,85

UNIVERSAL SCAFFOLDING MACHINE Filed June 18, 1954 9 Sheets-Sheet 2 74 IVENTOR Jan- 8, 1957 W. B. SHEARD UNVERSAL SCAFFOLDING MACHINE 9 Sheets-Sheet 5 Filed June 18, 1954 INVENTOR /Jfa/zi BY M /7/5 ATTORNEY Jan. 8, 1957 W. B. SHARD 2,776,815

UNIVERSAL SCAFFOLDING MACHINE Filed June 18, 1954 9 Sheets-Sheet 4 INVENTOR hh ATTORNEY Jan. 8,1957 w. B. SHEARD UNIVERSAL SCAFFOLDING MACHINE 9 Sheets-Sheet 5 Filed June 18, 1954 III mum"

BYCQM /w's ATTORNEY Jan. 8, 1957 w. B. SHI-:ARD 2,776,815

v UNIVERSAL SCAFFOLDING MACHINE Filed June 18, 1954 9 Sheets-Sheet 6 I I @i y l INVENTOR /fvl ATTORNEY Jan 8, 1957 w. B. SHEARD 2,776,815

UNIVERSAL SCAFFOLDING MACHINE Filed June 18, 1954 9 Sheets-Sheet 7 l 102 I /f 70521 I INVENTOR M//za//z y/ Jn/M7 EY f.) Wwf /7/'1 ATTORNEY Jan. 8, 1957 w. B. SHEARD 2,776,815

UNIVERSAL SCAFFOLDING MACHINE Filed June 18, 1954 9 SheebS-Sheet 8 INVENTOR BY 69. Qing/u? Jan. 8, 1957 W, B, SHEARD 2,776,815

UNIVERSAL SCAFF'OLDING MACHINE Filed June 18, 1954 9 Sheets-Sheet 9 INVENTOR his ATTORNEY United States Patent O UNIVERSAL SCAFFOLDINGA MACHINE William Byl Shear-d, Pleasantville,N. Y., assignor to The Patent Scaffolding Co., Inc., Long' Island City, N. Y., a corporation of ew Yorkz Application June 18, 1954,.Serial No. 437,733

Claims. (Cl, 2544-168).

This invention relates to safety' scalfolds and more Y particularly to .a scaffold. winch forh handling scaiolds such as used by painters, glaziers, pointers, window washers and maintenancev crews working onthe exterior of the faces of buildings vor `other, elevated structures at some height Aabove the ground;

The universal safety winch. of this invention. may be either power driven or manually operated, depending upon the circumstances and. availabi'lity'of sources of power, such las electriccurrent,compressed yairor coml bustionmotors.

It is often ydesired to` elevate scaffold-5.with aiconsiderable velocity and hand-operated winches havebeen found to be limited in this: respect. However, it is :again desirable to have a machinewhich mayV behand-driven in the event'of: failure of thezpowerr source. My winch, when power-driven, raises lor lowers-tlie'scafold structure attached thereto by rneansof'4 .a cable at considerable speeds and when idle, the braking mechanism therein prevents downward movement of the structure untilthe power unit is `again operated in. either direction. Thus, the winch is particularly adapted for. use by window washers on tally buildings, since onenoperator may con- Itrol the raising Vor loweringgofauthe structure by actuating the power units starter withioneih'and.

My Winch provides :a multiplicityof. safety means to prevent `accidental unreelingV of fthev cable fromfthe drum when such unreeling` is not desi-red or dangerousto the crew :supported by the scaffold structure. Thev winch combines a friction brake system= with a spring clutch/in the same scaffolding machine, the latter being [connected with a ratchet to form acne-Way brake, either brake being adapted to hold the load by itself. Their mode ofi operation and their larrangement in the winch structure are such that one brake Will offset the relatively weaker points of the other.

This novel multiple automatic brake construction in my winch immediately stops. any movement of thecable drum when themotor or` handle is not-operated; The operator is not required. to.l control the action Iof the braking system since it will"act"automatically,` when necessary, i. e. `at all times except when thedriving -sh-at of the winch is actually rotated by hand or fromthe power source. The force exerted by the' weight of the load -attached' to the free end of winch cable :automatically oper- .ates the braking system and. Ilocks'v the device until intentional rotational movement` is imparted: to.v the driving shaft of lthe winch; rThe cable drumis also easily disenga-geable from the drivingrmechanism.` in,A a very simple manner to permit unreeling :ofthe cabley independently of the power source.

Since the operation of the friction. brake is affected relatively little by wear, or ati leastless thany that of the springV clutch, it is placed closer to the load; and -is required Ito do most of the braking work; 0n the other hand, the spring clutch .operates independentlyjof the rest' of the system and does not; depend on' the friction in the ydriving mechanism to opera/te automatically, as

ice

2 the friction brake. Therefore, it acts to holdk the driving mechanism stationaryV and forces the rfriction. brake 'to-operate,

-The invention further provides la simple, safe Iand. o'bvious method of disengaging the driving mechanism when not under load, but being very diicufllt to disengage when the winch is under load. y

The disengagingfmechanism also prevents overloading of the winch when the machine is unreeling cable .and prevents the winding or spooling inthe wrong direction which could jeopardize the operation ofthe .automatic load brakes.

Several preferred embodiments. Iof my invention ywi-ll be described yin more det-ail in connection with their illustration in the Iaccompanying drawing, `and .the kinvention will be finally pointed out in theappended claimsln the :accompanying drawing,

Fig. 1 is a perspective ViewA of -theassembled universal scaffolding machine constructed in accordance with. one preferred embodiment ofl my invention;

fFig. 2 is a vertical section taken along line 2-2 in Pig.y l;

Fig. 3 is a section .taken along line 3-3 in Fig. 2;

yFig. 4 is a section Itaken along line 4-4 inFig. 2;

Fig; 5 is a partial-end Vvriewfiof the spring clutch, taken along line 5--5 inFig. 3;

IFig. 6 yshows another embodiment of the inventionk and is ea section along llined-6` in Fig. 7;

Fig. 7.is a view, partly in section, taken yalong lline "7 7 in Fig. 6;

lFig. 8 is ya section. through the spring clutch, taken along line 8-J8`in:Fig. 7; y

Fig. 9 is aview, partly in section, lof Ianother embodiment of my invention, showing. the yfriction'brake. land the spring clutch mounted onthe` same shaft;

AFig. l0. is lan enlarged partly sectional View of the friction brake illustrated inFig. 9;

Fig. l1` is va section through fthe spring clutchtaken along line 11--11 in Fig. 9;

:Fig 12 is a perspective View, partly in section, of two elements within the spring clutch illustrated. in Fig; 9;

lFig. -13 illustrates the spring Iwithin the spring clutch;

Fig. 14 is 'a sectional view .taken along line 14-14`-in Fig. 9 illustrating another cable `drum disengagingy arrangement;

Figs. 15' and 16-are perspectiveviews illustratingelements of the friction brake shown in Figs. 9 and 10;

Fig. 17 is a combinedv plan `and side view of Ia clutch nut mounted onfthe shaft supportingv tthe frictionl brake and .the Ispring clutch; `and Fig. 18 is an illustration of'a Vbrake pinion gear cooperating with the clutch nut shown in Fig. 1.7.

Similar 4characters of reference refer to ident-ical elements throughout the Various views in the drawing.

Referring now in more detail to the illustrated embodiments, and more particularly to Fig. l, there is shown o. support'A, consisting of two suitably shapedl sti-rrups `10 `and 11, Ito whichthe shells 12 land 131of winch casing B1 are secured by lbolts* 14, 14a. Stirrup'lll carries a guard rail lsupport 15;

The winch is driven by an electric motor 17, .operable through switch box 18 by lever 19. However, ka crank ySIS may be yattached. to shaft 38 to adapt the Winch to manu alop eration.

rIlhe Winch mechanism, land more particularly that em- :bodiment thereof wherein the winchy may be either power `driven cr manually operated, is shownin Figs. v2 to4. Referring first to Fig. 3 whichy is a longitudinal section .through shells 12, `13zof lcia-sing` B, there `are shown bracingshafts 20c'z,b, c, connecting

shells

12, 13!-in spaced relationship. A sheavef-WheelfZflf-is mountedy on shaft 20a for free rotational movement between the two `forks or extensions of a member 22 which is mounted on shaft 23. Cable 24 is secured at its outer free end to cornice hooks, Outrigger beams or other Iappropriate anchorage (not shown) in the usual manner. As the cable 24 enters the winch, it passes over -sheave wheel 21 :and down `to cable drum to which its other end is securely attached. When the cable drum 25, on its sha-ft 26, is rotated in clockwise direction, as shown by arrow a in Fig. 2, the cable will spool on the drum barrel 25a, and when rotated in the counterclockwise direction, the cable will unreel from said barrel 25a.

Shaft 23 is provided with suitable helical grooves 23a adapted to receive a guide pin 27 shown in dotted lines in Fig. 2, which is mounted in a recess in member 22 and secured therein by a cotter pin 16 or lthe like. One end of guide pin 27 follows the helical grooves 23a of shaft 23 and since these grooves are continuous and reverse themselves near the ends of shaft 23, member 22 with sheave wheel 21 travels back and forth between

shells

12, 13, thereby evenly distributing the cable convolutions on the drum barrel 25a. A sprocket 28 is keyed to shaft 23 and is driven by a roller chain 29, the chain in turn being driven by sprocket 39 keyed to shaft 26. Sprocket thus always rotates in unison with cable drum 25. The drive from shaft 26 to shaft 23 is so proportioned that the sheave wheel 21 traverses back and forth at a rate required to spool cable 24 evenly across barrel 25a of drum 2S.

Bearings

31, 31a (Figs. 3 and 4) at both ends of shaft 26 reduce the friction of the shaft 26 during the rotation thereof. Barrel 25a is limited at both its ends by

flanges

32, 32a which prevent cable 24 from slipping olf the barrel on either side thereof.

A partition wall 99 encloses with shell 12 the rotation transmitting mechanism and the friction brake.

The winch is driven by an electric or air motor 17 energized by switch 19 or air valves respectively (Fig. 2). Motor 17 drives a sprocket 34 which is rotated clockwise or counterclockwise, depending upon the necessity to cause the scaffold or any other weight attached to cable 24 to ascend or descend. Sprocket 34 is attached to a clutch unit 35 which is driven by the shaft 33 of motor 17. Clutch 35 performs two different functions: (a) it serves as a means to disengage the motor 17 from the other elements of the driving mechanism if the Winch is desired to be operated manually by handle 56; and (b) it is designed in a manner to disengage the motor from the other elements of the driving mechanism in the event that a too heavy load is placed on the scaffold or that the scaffold has been caught by some obstruction on the face of the structure. The rotation of cable drum 25 immediately ceases upon the disengagement of clutch unit 35.

Sprocket 34 drives a roller chain 36 which in turn drives sprocket 37 on shaft 38, sprocket 37 being keyed to the latter. Shaft 38 operates a spring clutch unit 39 which in turn transmits the rotation to gear 41 mounted on shaft 43 by the pinion 40. The manner of operation of this spring clutch unit 39 will be described in more detail hereinafter, in connection with Fig. 8.

As stated, pinion 40 drives gear 41 which is rotatably mounted on the hub extension 44 of a gear 42 mounted on shaft 43 (see Fig. 4). The bore of gear 41 is internally threaded to match the external threads cut on the hub extension 44 of gear 42. Shaft 43 also carries a plain plate ratchet 45 (Figs. 2 and 4) between

gears

41 and 42. The bore of ratchet 45 is larger than the outside diameter of threads on the hub 44 of gear 42 and therefore ratchet 45 rotates freely thereon. Pawl 46, mounted on shaft 38, permits the rotation of ratchet 45 in counterclockwise direction only. When gear 41 is rotated in counterclockwise direction by pinion 40, it rotates upon the threaded hub 44 of gear 42 and is thereby forced to move toward gear 42 until stopped by plain plate ratchet 45. As gear 41 is forced to rotate, it tends to clamp ratchet 45 between itself and gear 42 and therefore gear 41, ratchet 45 `and gear 42 all rotate in unison and pawl 46 merely rides over the teeth of the ratchet 45, when the ratchet 45 rotates. If gear 41 is rotated in the opposite direction, it backs away from plate ratchet 45 until it hits a stop 47 on the hub extension 44 of gear 42 and thus no longer rotates freely on the threads of hub 44; it forces gear 42 to rotate in unison with it on shaft 43.

The backing away of gear 41 from gear 42 automatically unclamps ratchet 45 which is held stationary by pawl 46. When gear 41 hits the stop 47, it rotates in unison with pinion 42 and the cable may unreel from drum 25. lf the rotation of gear 41 is stopped, then the tension in cable 24, working through cable drum 25, shaft 26, ratchet 48,

pawls

49, 49a (see Fig. 2) and

bolts

50, 50a, in that order, causes gear 51 to rotate counterclockwise and thereby causes gear 42 to rotate in clockwise direction. This rotation causes gear 41 to move toward gear 42 and to clamp ratchet 45 between them, as previously described. However, since the direction of the teeth of ratchet 45 is opposed to the pawl 46, a-ll motion of pinion gear 42 stops. This action is automatic and ytherefore the dcscribed arrangement constitutes an automatic braking device to restrain the winch from lowering the scaffold or the like, attached to cable 24, under the force of gravity of said scaffold, except when driven by gear 40.

In normal operation, pinion 42 meshes with a gear 51 mounted on shaft 26. Pinion 42 rotates said gear 51 in clockwise direction when the cable 24 is spooled onto cable drum 25, and in counterclockwise direction when cable 24 is being unreeled from the drum. Gear 51 rotates freely on shaft 26. As this gear 51 rotates, it forces

pawls

49, 49a against the teeth of ratchet 48 which is keyed onto shaft 26 (see Fig. 2).

Pawls

49, 49a are fastened to gear 51 by means of shouldered cap screws 50, 50a and are free to rotate upon the shoulders of the screws. Leaf springs 53, 53a are attacehd to

pawls

49, 49a and bear against the projecting rim of gear 51, thereby keeping

pawls

49, 49a normally in engagement with the teeth of ratchet 48. Ratchet 48 is keyed nonrotatably to shaft 26 and thus in turn rotates cable drum 25 to reel or unreel cable 24.

The tension in the cable 24 tends to rotate ratchet 48 through cable drum 25 and shaft 26 in counterclockwisc direction and thereby keeps the teeth of ratchet 48 in contact with

pawls

49, 49a.

If the motor 17 drives gears 40, 41, 42, 51 in the lowering direction, pawls 49, 49a tend to disengage from the teeth of ratchet 48. However, the tension in cable 24 resulting from the weight of the scaffold attached thereto tends to rotate the ratchet 48 in the same direction and keeps

pawls

49, 49a in engagement with the teeth of ratchet 4S.

The main reason for driving shaft 26 from gear 51 through ratchet 48 and

pawls

49, 49a is that this manner of driving provides a simple and reliable means of dis engaging cable drum 25 from the rest of the driving mechanism by merely prying

pawls

49, 49a out of engagement and clear of the teeth of ratchet 4S and inserting a pair of pins into holes 54, 54a and letting part of these pins to project into similar aligned holes in gear 51. The pins hold

pawls

49, 49a clear of the teeth of ratchet 48 and thus ratchet 48, shaft 26 and cable drum 25 are free to rotate independently of the driving mechanism. The cable 24 can be readily unreeled from drum 25 when, for example, rigging the winch for operation. Other advantage of this ratchet and pawl combination is in that it prevents cable 24 from being wound on the drum 25 in the wrong direction, and should cable 24 jam while it is being unreeled, the drive will merely ratchet. This combination also permits the use of a locking or safety pawl 55, as shown in Fig. 6, without any danger of overloading the driving mechanism. This pawl 55 ratchets on ratchet of disc 32a shown in Fig. 3.

The main feature of my novel winch is the use of the friction brake in combination with a one-way brake, consisting of a spring clutch and a ratchet, in the same scaffolding machine, eitherof which can hold' the load by'itself. However, by the novel' wayof combining both brakes in a single winch, each `brake is` capable of" off# setting the weak points of the other brake by its own strong points.

The spring clutch 39, shown in more detail in-Fig. 8, is mounted on shaft 38. This clutch, which works inde'- p'endently of lthe rest ofy the system, doesv not depend on the friction of the driving mechanism as the Iabovedescribed friction brake. It is housed? in anelongated cylindrical shell `66V andy a cylindrical sleeve 61 abutting said shell 69 and having a reinforcing ring 62"which partly fits over shell 60 to prevent entryiof foreign materialinto the spring clutch. Shell V60 carries a ratchet wheell 63 cooperating with pawl 64 mounted" on bolty 65, as seen in Fig. 1 and in more detail in Fig. 5. Bearings 84 and-84a reduce the friction of shaft 38within shells 12; 1-3.

Sleeve 61 is either integral or firmly connected to pinion 40, the pinion having a vbore 38a for the passage of shaft 38. Sleeve 61 has a segmental cutout66limitedby walls 67 and 68. Within sleevei61 andshell60tis-a cylindrical member 69 which is keyed to shaftl 38, the vslot to receive key 74 being `shown at 7i?. Onetend' of the cylindrical member `69 which is adjacent the-closingwall`71 of shell 60* has a collar 72 which is interruptedat 73 toform a slot therein into which Ioneend ofspring-76 its-7 as will be explained in more detail hereinafter. The other end of cylindrical member 69' which is withinl sleeve 61 is provided-With a projection 75Lto looselyftinto the `segmental cutout 66. This segmental cutout 66 prevents independent lrotation of member 69 with respect ytosleeve 61 rin case that the spring 76 should break or become displaced, or excessively worn.

The spring 76 consists of a cylindricallywound band 77 with both ends 78 and 78a bentin a direction parallel to the axis of the spring. Endl 73 lits into the slot 73 of collar '72 in cylindrical member-'691, andV end-78a-iits into a hole 73h bored into the wall 61a'of sleeve-6L When inserted into the spring clutch 39, the'spri'ng 76 surrounds with its convolutions 77 the cylindrical member 69-within shell '60 and sleeve 61. The diameter of spring 76 is slightly larger than the diameter of the bores of shell 60 and sleeve 61; therefore, its convolutions must be slightly compressed when inserted into shell 60Y and sleeve 61 of the spring clutch.

The operation of the clutch 39 is as. follows:

When shaft 33 is rotated inclockwise direction, either by chain 36 from clutch 35,' or by'fhandle 56, it' rotates the cylindrical member 69 which isy keyed t-o shaft 38 by key 74l`insert-able into slot 70-of member 69 andslot 73a of shaft 38. The wall of the slot 731in'collar 72 'of member `69 bears against end 78 of' spring 76. This causes the convolutions 77 to expand radially` and to press more tightly against the inner surfaces of shell 60 and sleeve 6l, thus rotating both shell 60 and sleeve 61 in clockwise direction, pawl 64 riding loosely over the teeth of ratchet 63. The end 76a of spring 76l is forced against the wall of bore 73b and `thus additionally causes sleeve 61 with pinion di) to rotate in the clockwise direction; The rotation of pinion 40 causes gear 41 and pinion 42 on shaft 43l to rotate counterclockwise and the gear 51 on shaft 26 to rotate clockwise and to reel the cable. 24" ont-o cable drum 25.

When motor 17 is stopped, or the rotation of shaft 38`by crank 56 is ceased, the tension in cable 24 'tends to rotate gearSl in Icounterclockwise direction, this in turn tending to rotate pinion 42 and gear 41 in clockwise and pinion 4t) with sleeve 61 in counterclockwise direction. The wall of the hole 73h is then forced against the end`78`a` of spring 76 and tends t-o expand the spring 76 which in turncauses the spring to more firmly adhere to the inner surfaces of shell 6@ and sleeve 61 and tendsy to rotatel the same in counterclockwise direction. However, ratchet 63 which is secured to or integral withA Shel-l 60, is, prevented from rotation in the counterclockwise ydirection by pawl 64 andthus any rotation in counterclockwise directionfof shaft 38 is prevented.

If it is'desired to unreel cable 24 from drum 25, shaft 38 is v rotated in counterclockwise direction. Then, cylindrical member 6'9 which is keyed to shaft 33, also rotates in counterclockwise direction and causes wall of slot 73fin cylindrical member 69fto-press against end 'I8 of spring 76 in count-erclockwisefdirectionthus ten-ding -to radially compress its convolutions anddisengaging spring 76- from the inside surface ofi shell 601 and allowing the outer surface `of Spring 76-to slide within the bore of shell 60 which is heldstationary by pawl 641 in engagement with ratchet 63. As the spring 76I-sli-des, the'tension of cable 24 then causes the pinion 40and sleeve 61 to follow the rotation in counterclockwise direction through gear '51, pinion 42 `and gear 41.

itV may be seen from the above that the cableZ/t-'can be unreeled from drum-25 only-when theshaft'SSiis` actually rotated in countercl'ockwise direction. When the handle is simply releasedor the motor stopped, the spring "/'6 will expand radially against the innersurface of' shell 60sand enough friction willdevelop between these two members to cause rotation 'of spring 76 withrespect to shell 60 to cease. Shell 60 is prevented from rotation in the lowering direction by ratchet 63 and pawl 64. Thel spring clutch will prevent any unreeling of the cable untilthe shaft- 38 is actually rotated anticl'ockwise by the motor 17 or crank 56. Projection 75^of cylindrical member 69 has freedom of movement in the segrnental'cutouty 66 within sleeve 61 and does not touch the walls of sleeve 611 at any `time unless the spring 76 should break or wear out. In other' words, the angle of the segmental cutout issoproportionedthat the springy 76, when inoperative condition, bears the load through ends 78 and 78a, and does not let projection 75 touch thewalls'of cutout 66 insleeve 61 at any point.

Should the spring 76 break or become displaced, then y this projection 75 comes in-to Icontact with either wall. 67

or Wall 68 of cutout 66 and transmits theload directly from pinion 40' to cylindrical 'member '69 andl thus to shaft 38, instead through spring 76 which has been displaced or had broken down. This is anadditional safety measure in the spring clutch arrangement.

Figs. 6 and 7 show that embodiment of the-novel winch wherein the device is operated only manually by crank 56. This structure is essentially the same as the previously described power-driven winch, except that the arrangement of the brakes has been changed and the sheave wheel 21 within member 22 slides along the outer surface lof bracing bolt 20a without guide pin 27' and grooves 23a; thus, the tension of -cable 24 causes its lconvolutions Vto arrange themselves around the barrel ofv cable rdrum 25 on shaft 26. These two figures also show ay ratchet St? formed on the ange 32a of cable drum barrel 25a, which cooperates with pawl 55 held againstA the teeth of ratchet 8) by spring '81. This is an additional safety measure and any unwinding of cable 24V from drum 25 lis impossible unless pawl 55 is disengaged froml the teeth of ratchet 8G; when the cable 24 is reeled onto drum 25, the pawl 55 merely rides over the teeth of ratchet 86.

it is evident from the abovey description. of the friction brake and ythe spring clutch that either of these alone can prevent theV unreeling of cable 24 when such um'eeling is not desired or is dangerous. As mentiond above, it is preferable to place the friction brake 4closer to the load and the spring clutch: closer to the driving mechanism. However, their relative arrangement is such that the load is directly transmitted from: the one to. t-he other, which considerably increases 'the safetyof the winch structure since, should the friction brake break or otherwise fail to operate, the spring clutch with ratchet-63 will immediately take up the load and prevent any undesired unreeling of lthe cable or vice versa. This relative interconnection is shown in the figures vof 'the drawing bythe arrangement of pinion 40 and gear 4l. Gear 411cm Y shaft 43, which together with pinion 42^andl its integral hub extension 44, ratchet 45, pawl 46 and stop 47 forms the friction brake, directly transmits the load from gear 5l and 'thus from cable 24 to pinion 40 and therethrough to thc spring clutch. On the other hand, this pinion 40 of spring clutch 39 directly transmits the rotational movement of shaft 30 from either crank 56 or from motor 17 to gear 41 and thus to the friction brake, and through gear 51 to cable drum 25.

Fig. 9 shows another preferred relative arrangement of the friction brake and the `spring clutch. This embodiment shows both devices mounted on the same shaft 38, which is partly done for space considerations.

The spring clutch pinion 40 shown in Fig. 8 has been extended into a hollow connecting shaft 100 screwed into a clutch nut 101; brake pinion 102 is rotatably mounted on this shaft 100. This new brake pinion 102 combines the functions of

pinions

40 and 42. -One end of shaft 100 is threaded into sleeve 61 of the spring clutch 39, as shown at 100:1, with a left-hand thread, which tends to tighten under the action of the load on the scaffold winch. The other end 100b of shaft 100 is also provided with a left-hand thread to take the clutch nut 101. This thread also tightens under load. Hollow shaft 100 is free to rotate on shaft 38.

The description of the embodiment of friction brake shown in Fig. 9 will be made partly in connection with the explanation of its operation and partly in connection with Fig. l which is an enlarged illustration of the friction brake. Some elements of the friction brake are also shown in Figs. l to 18.

T he load on the winch tends to rotate pinion 102 in counterclockwise direction. As pinion 102 rotates, its jaws forming the spiral clutch 103 work against the jaws 101:1 of the clutch nut 101. Pinion 102 rotates and slides freely on shaft 100, together with its integral hub 104. The pressure of clutch jaws 101:1' against jaws 103 causes pinion 102 to move toward the spring clutch 39 and to thereby exert pressure against shoulder 105:1 of collar 105; this shoulder 1050 in turn transmits the pressure to the friction brake ratchet 106. The wall 106e of ratchet 106 further transmits the pressure to

discs

91 and 92. However, since

discs

91 and 92 are restrained from axial movement by pressure cup 107 which bears against shoulder 108 of hollow shaft 100, the axial movement of pinion 102 forces outer discs 91 into tight frictional contact with inner discs 92. The resulting frictional force tends to lock

discs

91 and 92 together and causes their rotation in the same direction. Discs 92 are keyed non-rotatably to the hub 104 of pinion 102 by means of projections 92a which fit into slots 92b in hub 104, as may be seen in Figs. l0 and 15.

The outer discs 91 are keyed in a similar manner to the ring-shaped driving cup 109 which is secured to ratchet 106 by means of cap screws 110. This is illustrated in Figs. 10 and 16.

Ratchet 106 rotates freely on sleeve 105 having a shoulder 105e, but pawl 111 permits it to rotate in the clockwise direction only. Thus, when the load creates axial pressure by the action of clutch jaws 103 and 101:1 against each other and

locks discs

91 and 92 together, the whole assembly of

parts

102, 100, 106, 109, 107, 91 and 92 will tend to rotate together in the counterclockwise direction because of the action of the load on pinion 102. However, pawl 111 prevents this assembly from rotating counterclockwise and therefore prevents he friction brake from rotating in this direction. Clutch nut 101 is prevented from rotation by Shaft 100 to which it is attached, and the shaft 100 in turn is prevented from rotation by the normal action of the spring clutch 39, as described in connection with Fig. 8.

To lower the load, it is necessary to bypass both ratchets, i. e. ratchet 106 of the friction brake and ratchet 63 associated with the spring clutch. This is accomplished in the following manner:

When shaft 38 is rotated in the counterclockwise direction, either by handle S6 or by sprocket 37, it rotates the cylindrical member 69 within the spring clutch 39 in the same direction. Member 69 acts on the end 78 of spring 76 received in slot or notch 73 thereof. Since the spring has its convolutions wound left-hand, the action tends to coil up the spring and to thereby decrease the diameter thereof. As its diameter decreases, the friction between the wall of bore in shell 60 and the spring 76 also decreases until the spring 76 slides freely in said bore, and thus bypasses the restraining influence of ratchet 63 and pawl 64. When the spring 76 is released from its frictional engagement with shell 60, then the sleeve 61 rotates counterclockwise and in turn rotates shaft and clutch nut 101 in the same counterclockwise direction. As the clutch nut 101 rotates, it permits brake pinion 102 to move in the direction away from the spring clutch 39 because of the action of clutch jaws 101:1 on jaws 103. As soon as the pressure is released,

discs

91 and 92 move apart and no longer are locked by their mutual friction. Therefore, discs 92 rotate independently of discs 91 and are consequently free of ratchet 106 and pawl 11.1. The pinion 102 is now free to rotate in counterclockwise direction and to lower the load through gear 51.

However, when the rotation of shaft 38 ceases, spring 76 within spring clutch 39 automatically expands and i again frictionally engages with its circumference the wall of bore in shell 60. Shell 60 is prevented from rotation in counterclockwise direction by ratchet 63 and pawl 64. The rotation of

parts

61, 100, and 101 also ceases and causes the action of spiral clutch jaws 103 against 101:1. This induces brake pinion 102 to move toward the spring clutch and to again frictionally lock

discs

91 and 92, as previously described. The pinion 102 is then locked against rotation through

parts

92, 91 and 109. Since ratchet 106 is prevented from counterclockwise rotation by pawl 111, a double braking action is obtained.

In raising the load, handle 56 or sprocket 37 is rotated in clockwise direction. The locked assemblies of both brakes rotate in unison, since

pawls

64 and 111 merely ride over their

corresponding ratchets

63 and 106. When the motion of handle 56 or of sprocket 37 ceases, the pawls again engage the teeth of their respective ratchets and prevent counterclockwise rotation and unreeling of the cable 24 from 4drum 25.

Figs. 9 and 14 show a different arrangement for releasing the brake drum 25 from the driving mechanism. As illustrated, ratchet 48 is moved to the opposite side of drum 25 and the shape of

pawls

49 and 49a has been changed permitting leaf springs 112, 112:1 to act on those portions thereof which engage the teeth of ratchet 4S and to permit leaf springs 113, 113:1 to retain these pawls away and clear of the ratchets teeth when engaging portions 49', 49 of the pawls. Ratchet 48 is keyed to shaft 26 at 48a and the

pawls

49, 49a are rotatably supported on flange 32a of cable drum 25 by means of

bolts

50, 50a.

Members

114, 114a and 115, 115:1

support leaf springs

112, 112a and 113, 113:1 on the flange 32:1. Gear 51 is also keyed to shaft 26 on the opposite side of drum 2S. Drum 25 is free to rotate on shaft 26 and has welded or otherwise secured thereto sprocket 30 through sleeve 30a and therefore always rotates in unison with the sprocket.

When gear 51 rotates in either direction, together with shaft 26, ratchet 48 follows their rotation at all times unless disengaged by leaf springs 113, 113:1. In that case, the cable drum rotates independently together with sprocket 30. In Fig. 14, one pawl 49 is shown in engagement with ratchet 48 due to the action of leaf spring 112, whereas the other pawl 49a is disengaged and held clear of the teeth of ratchet 48 by leaf spring 113g.

Figs. 17 and 18 illustrate on an enlarged scale the clutch nut 101 and the brake pinion gear 102 with its hub 104. As an additional safety measure in case of a breakdown of spring clutch 39, a pin 116 is screwed into shaft 38 Within cutout 117. The purpose of this pin 116 arrears is identical with that of projection 75 within segmental cutout 66 with its walls 67 and 68 in the spring clutch,

described in more detail in connection with Fig. 8. InY

case vof a breakdown, pin 116 acts against the Walls 117a, b of segmental cutout 117 and thus directly transmits the load from shaft 38 to the pinion 102 and the frictionV brake without requiring operation of the spring clutch. Gears 118 and 119 on shaft`43 transmit the rotational movement to gear 51 andthe cable drum 25, l

and a winding drum on said first shaft for reception of a` length fof cable, one end of said cable being anchored in said drum, the combination of driving means for imparting rotational movement to said drum in clockwise and counterclockwise direction, means rotatablewith said drum for distributing said cable on the periphery of said drum when said drum is rotated in a direction to `wind said cable thereon, means for disengagingsaid drum from said driving means, a friction brake between said driving means and said drum for preventing rotation of said drum while said driving means is not actuated, a 'second brake including a spring clutch, a ratchet and a pawl, operatively connected between said friction brake and'said driving means for preventing rotation of said drum while said driving means is not actuated, and a clutch member between said second brake and said driving means for disengaging said driving means at a predetermined tension in said cable.

2. The structure of claim l, wherein said drum is rotatable o-n said first shaft and said means for disengagng said drum from saidV driving means consists of a ratchet non-rotatably attached to said first shaft, a plurality of pawls rockably supported by said drum, resilient members for urging said pawls into engagement with the teeth of said ratchet, and means for retaining said pawls disengaged from the teeth of said ratchet on a predetermined rocking of said pawls away from the teeth of said ratchet.

3. The structure of claim l, wherein said winding drum consists` of a substantially cylindrical barrel and a flange at each extremity of said barrel, said barrel with said fianges Vbeing rotatably attached to said first shaft, said driving means including a gear rotatable with said first shaft, said means for disengaging said drum from said first shaft consisting of a plurality of pawls rockably supported on one of said flanges of said drum, resilient members for urging said pawls into engagement with said ratchet, and means for retaining said pawls away from said ratchet while said pawls are disengaged therefrom, and a second shaft is provided in said casing for said second brake and said friction brake, said second shaft being operatively connected with said driving means, and an operative connection between said friction brake and said gear on said first shaft.

4. In a scaffolding machine having a casing, a support connected with said casing, a first shaft in said casing, a winding drum on said first shaft, and a length of cable having one end thereof anchored in said drum, the combination of means for releasably connecting said drum with said first shaft for rotation therewith, means for distributing said length of cable on the periphery of said drum when said first shaft with said drum is rotated in a direction to wind said length of cable thereon, a second shaft in said casing, a spring clutch mounted on said second shaft, said spring clutch having a cylindrical housing consisting of two cupped portions having an open and a closed end and abutting each other with said open ends thereof, the first of said portions having a ratchet 1 secured thereto at its closed end and having an interior recess iny said closed end, a pawl for engaging said ratchet to permit rotation thereof with the first of said portions in a direction to wind said cable onto said drum only, an

elongated sleevesurrounding said second shaft and connected at one extremity thereof to said closed end of said second portion, a nut having annularly disposed jaws with the other extremity of said sleeve secured to said nut, a cylindrical member fixedly connected tosaid second shaft in said spring clutch housing, said cylindrical member having a slot in ,one extremity thereof within said first portion of said housing, a coilspring surrounding with a plurality of its convolutions said cylindrical member in said housing, one end of said spring being held in said slot in said cylindrical member and the other end offsaid spring being insertable into said interior recess in said closed end of said first cupped portion, the rotation v of said sleeve in one direction expanding the convlutions of said spring to engage said first portion for rotational pinion, said pinion having a hub slidably surroundingk said sleeve, and annularly disposedjaws for engaging said nut, a hollow ratchet slidably mounted on said hub, a plurality of first discs axially movably and non-rotatably inserted into said hollow ratchet, a plurality of second discs axially movablyv and non-rotatably surrounding said hub, said first and said second discs alternately contacting each other, a shoulder on said sleeve for limiting axial movement of `said hollow ratchet and a pawl for engaging said hollow ratchet to limit its rotational movement to one direction only, the rotation or" said sleeve and of said nut in one direction urging said pinion with said hub away from said nut by the action of said jaws whereby said pinion moves said hollow ratchet toward said shoulder to frictionally engage said first discs by said second discs and -to actuate said friction brake, and rotation of said sleeve in theopposite direction releasing said frictionally engaged first discs from said second discs to release said hollow ratchet, said nut at the other end of said sleeve` embodying a safety device, power driven means operatively connected with said second shaft, and a clutch Vmember between said power driven means and said second i shaft for disengaging said power driven means on a pre-v second shaft, said nut having a segmental cutout with v radial walls for engaging said pin to rotate said nut with said axle when said friction brake is inoperative.

References Cited in the file of this patent UNITED STATES PATENTS 1,555,094 Adams Sept. 29, 1925 2,582,987 Hagenbrook Ian. 22, 1952 2,662,732

Allenbaugh Dec. 15, 1953