US2789791A - Hoist and safety mechanism therefor - Google Patents

Description

April 23, 1957. c. CARROLL HOIST AND SAFETY MECHANISM THEREFOR 3 Sheets-Sheet 1 Filed Dec. 27, 1955 INVENTOR. (we: 5 ('meou.

April 23, 1957 c. CARROLL 2,789,791

HCIST AND SAFETY MECHANISM THEREFOR Filed Dec. 27, 1955- s Shets-Sheet 2 IN V EN TOR.

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April 23, 1957 c. CARROLL 2,789,791 HOIST AND SAFETY MECHANISM THEREFOR 'Filed Dec. 27, 1955 3 Sheets-Sheet 3 United States Pate .HOI ST AN D SAFETY IVECHANISM THEREFOR 'Charles Carroll, Danville, Ill, .assignor to Butt-Norton Company,Pittsburgh, Pa., a corporation Application December 27, 1955,'Serial N o.' 555 349 7 Claims. (Cl. 254-167) .The'present invention relates to improvements in hoist- ,ing'apparatus, .and.rnore specifically to lever-operated chain hoists of the type disclosed inthe'Uriited States Letters Patent 'No. 2,670,176 to Frederick W. (Coiling, granted- February 23, 1954.

The apparatus disclosed in the said patent comprises a *lever-operated chain hoist, wherein the hoisting mechanism :may be readily and easily adjusted to load-raising condition, to load-lowering condition, or to free-running condi- "tion when it is .the desire of the operator toestablish these conditions. It is characteristic of this type of hoisting-mechanism that the operating'lever is pulled downwardly to effect load-raising. To effect load-lowering, the

operating lever is permitted. to move upwardly relatively slowly underthe control'of'the operator. "lhelever mustbe controlled'during its upper movementlbecause the load'tends-to move the lever in that. direction. "lever isdnadvertently released at its lowermostposition, it'vvilltravel through itsoperational are at excessive speed,

If the 'thereby becoming a safety hazard to the operator. "Such excessive speed of movement of the operatinglever may also prevent operation of 4 the ratchet mechanism which normally limits the angular travel of the load chainsheave during'a single upward stroke of the. lever. When the ratchet mechanism fails to operatetheloa'd can"drop, "creating a further hazard to: the operator.

Accordingly; itis" the principal object of thislinvention "to provide-safety mechanism cooperating with'the operating lever and the ratchet mechanism for-locking the ratchet mechanism'when the lever travels at excessive"speedcluring a A lowering cycle of operation of "the". lever.

"In accordance withthis inventionfthere isiprovided a lever-operated chainhoist includingachain'sheave, ratchet "mechanism for controlling the rotation of-- said sheave,

means 'for'controlling said ratchet mechanism vto ,elfect load-lifting, loa'd-loweringor "free-running rotation of said. sheave, an operating lever coupled. to said mechanism for operating it, and means efiective in response to unpcontrolledupward movement of said operating'-lever.- for locking. said ratchet to, preventffree-running rotation.there .of in the. lowering. direction.

Fornthe purpose of disclosing my invention I haveflil lus- .trated an embodiment thereof in the accompanyingdrawingsin which:

.Fig. 1; is a transverse. sectional view of ahoist embodying my invention;

lowering position-with the holding pawl freed;

Fig.6 is-the same as Fig. 5 showing t-heparts' in loadlowering-position withlthe load pawl released;-and

Patented Apr... 23, 1957 Fig. 7 is a partial cross-seetion' taken on line7- 7 of Fig. 2 with partsv omitted.

In the embodiment illustratedl provide a housing. 10 having a front plate closing memberll secured. in place 5 by suitable holding screws 12, shown in. Fig. 2. The

' housing is provided with an ofiset portion'13, whichprovides a housing for the load chain sheave 14, over which is adapted to ride'the link chain 15. This chain'feeds through suitable openings .in the bottom of the oifset13. The chainfsheave .14 is mounted on a shaft 16, one end of which is mounted in' a bearing 17 in the housing lfl. On'the opposite side of theJsheave 14 the shaft 16 is provided with an enlarged portion .18 operating in a bearing "19 supported in a dividing wall of the housing 10. The "shaft' 16 is extendedlin reduceddiameter and the op- "posite end thereof extends into -a bearing 20 in'the cover.

plate 11. Mounted ontheshaft extension is a ratchet Wheel 21 which is keyed 'on thel shaft 16 and,'therefore, is rotatable with the sheave 14.

"The housing isprovided at its' top with a swivel hook 22, the end 23 (see Fig.1) of which extendsthrough 'the' housing to'be'engaged bya holding nut 24 for maintaining the'hook'again'st vertical displacement.

The ratchet wheel 21 is'operated and controlled respec- 25 tively-by load pawl 25 (see Fig. 2) and a holding pawl 26. The-holding pawlis mounted on a stud 26a extend- 'ing between thesidewalls'of'the housing. The end of =thegpawl is adapted to engage the teeth 21a of the ratchet "wheel '21. This'holding'pawl is biased in an engaging directiorr' by coiled spring fi 'attached at oneend to the pin 27 and at" the other end to pin 27a in pawl 26.

"The load-pawl" 25 'is disposed between and carried by a pair'of armsZB swingably mounted upon the shaft 116 *and'disposed on opposite sidesof the'ratchet' wheel'21.

The pawl ispivoted upon astud 30 fixed between'the -arms 28 and has its free'end'biased in a tooth-engaging "direction by' co'iled'springfi. One end of this springis secured to apin 32 on the inner face of one of the arms "28, and its opposite end-is connected to a pin 33'on the inner edge-efthe pawl.

The f-ree ends of the arms 28'are connectedby axlihk 34 'With-an 'oscillating'lever arm 35. "To thisend, one end'o'f-the linked is pivotally'connected by a pin-36 extending between thefree ends of the arms 28, and'the opposite end extends between bifurcated ends "of the -lever--arrn35 and is pivotally connected to the lever arm 35'- by -a pi-n' 37. This'leverarm 35 is a part of an'oscillating shaft"38 (seeFigs. land 2) having one end journaled at 39 in a side wall of the'housing, and the other end enlarged as at 4a and extending through abearing 41-inthe cover-plate lll-(see Fig. l). The outer end er this "enlarged portion at has'a lever arm'receiving 'opening wl't-hrough whichmay'be passed an operating lever -arm="43, and which is adjustably slidable through the opening so that the lever lengthof the same may be adjusted or "the direction or" lever operation may .be changed by sliding the'leverfrom one extremity tothe other. Retainers lFm are to avoidpassing'lever '43 en tirely' outof lever arm receiving opening 42. The lever arm 43 is maintainedi-n its adjusted position through the '-medium of a'set screw- 44.

For preventing free rotation of the'enlarged shaft portion 40, there areprovided friction rings 49a mounted in suitable peripheral grooves as shown in Fig. 1. Rings 40a may be made of rubber orother friction-creating material.

Forcontrollin-g the various positions of the'holding pawl 26 and the load pawl 25,I provide a reversingring 45'(shownin-Figs. 1 and 2), which is rotatahly'm-ounted 'on an extension '46 ofthe bearing forthe'shaft'por'tion 18. This reversing ring is provided with anppera ting cam-47- (see Fig. "2) for openatingaand controlling'ihe position of the holding pawl 26. The holding pawl 26 is provided with a pin 27a which projects into the path of cam 47 to be engaged by said cam when the reversing ring 45 is moved to a predetermined position by spring 51.

A cam 49 oppositely disposed relative to the cam 47 (see Fig. 2) on the reversing ring 45 is adapted to control the position of the load pawl 25. This cam is adapted to engage a pin 50 on the load pawl 25 which extends through a slot 28a in one of the arms 28 and into the path of the cam 49 to be engaged thereby when the reversing ring is moved to predetermined position by spring 51.

The reversing ring 45 is biased in a direction to cause the cam 47 to engage the pin 27a by a coiled spring 51, one end of which is anchored to stud 27 secured in the casing, and the other end of which is connected to a lug 53 on the reversing ring 45. This spring biases the reversing ring 45 in a counterclockwise direction, looking at Fig. 2. The reversing ring 45 is moved in a elockwise direction through the medium of a cam member 54 which is rotatably mounted on a shaft 55 provided with an operating handle 56 which is exterior of the casing. The cam member 54 is adapted when rotated counterclockwise by the handle 56 to engage an arm 57 on the reversing ring and rotate the reversing ring clockwise thereby insuring the disengagement of the cam members 47 and 49 from their respective pawls.

It will be observed that by oscillating the hand lever 43 and shaft 38, the operating lever arm 35 will be oscillated, and in turn will oscillate the load pawl carrying arms 28 through the link 34. Said arms will thereby be caused to oscillate the load pawl about the axis of the sheave 14 relative to the teeth 21a of the ratchet wheel 21.

For raising the load, as shown in Fig. 4, the reversing ring 45 has been rotated clockwise by the engagement of the cam 54 with the arm 57 to move the cam member 47 and the cam member 49 out of position to engage the holding pawl 26 or the load pawl 25. Thereupon, these respective pawls are adapted to ratchet on the teeth 21a of the ratchet wheel 21. Under these circumstances the holding pawl 26 will be in engagement with the teeth of the ratchet wheel thereby holding the same against clockwise rotation under the influence of a load carried by the load end of the chain 15. If now the handle lever 43 be raised or moved clockwise to the hoist, this will rotate the lever 35 in a clockwise direction and through the link 34 the arms 28 will be raised, thus causing the pawl 25 to ride the teeth 21a. As soon, however, as the direction of movement of the hand lever 43 is reversed, the arms 28 will be lowered in a counterclockwise direction with the pawl 25 biting into the teeth 21a of the ratchet 21 thereby rotating the ratchet and with it the chain sheave elevating the load. During this movement the holding pawl will ratchet over the teeth being, however, in a condition to lock into the teeth as soon as the load is released by releasing the downward pressure on the handle 43. By repeated oscillations of the handle 43 the load will be raised.

If, however, it is desired to lower the load, the handle 56 is moved to the position illustrated in Fig. 5, reversing the position of cam 54 relative to the arm 57, and the coiled spring 51 will bias the reversing ring in a counterclockwise direction, or in a direction to cause the cam member 47 to engage the pin 27a freeing pawl 26 of ratchet wheel 21. With the parts positioned as illustrated in Fig. 5, the load pawl 25 has taken the load, being in engagement with one of the teeth 21a of the ratchet wheel 21 and the reversing ring 45 has been biased to the position illustrated in said figures. With the parts in this position, by elevating the handle 43, ratchet 21 rotates clockwise to lower the load. The pawl carrying arms 28 move upwardly, the pawl 26 being free of the ratchet wheel 21. Arms 28 eventually move pin 50 into engagement with the cam member 49, thereby to move reversing ring 45 in a clockwise direction disengaging cam 47 from pin 27a in cam 26 thus permitting spring 29 to cause cam 26 to approach engagement with teeth 21a. Simultaneously, pin rides up the surface of cam 49 lifting pawl 25 away from the ratchet wheel 21. Pawl 26 assumes the load but permits a few degrees of rotation of the ratchet wheel 21 in a clockwise direction. During this few degrees of rotation, pawl 25 is lifted free of the outer edges of the ratchet teeth and one tooth passes under and beyond pawl 25, and the parts are positioned as shown in Fig. 6. At this point lever 34 will have engaged the bumper pin 67 and the movement of lever 43 must be reversed. Slight downward movement of operating lever 43 rotates arms 28 sufficiently for pin 50 to ride downwardly over the surface of cam 49 thereby to cause the pawl 25 to engage the next tooth of ratchet 21. The pin 50 in load pawl 25 continues to ride downwardly on cam 49, and spring 51 moves reversing ring 45 in a counterclockwise direction to cause the cam 47 to lift the pin 27a on holding pawl 26, as shown in Fig. 5. Further downward movement of lever 43 will effect a corresponding downward movement of the arms 28 causing pawl 25 to take the load off the holding pawl 26 by this reverse movement. The holding pawl will be moved out of tooth engagement by the cam member 47 engaging pin 27a. Upon againraising lever 43, the pawl 25 in engagement with the teeth 21a, the load may be lowered thereby, the lowering action being controlled by the lever 43 and pawl 25. Accordingly, by continued operation of the lever 43 in ratchet style, the load may be controlledly lowered step-by-step.

During use of the hoisting mechanism to lower the load, it can happen that the operator may release the operating lever at the lower extremity at its operational arc. When this happens, lever 43 flies upwardly at relatively high speed because the load tends to rotate ratchet wheel 21 in a clockwise direction. In order to insure that the ratchet will not be free to rotate in a clockwise direction when the operating handle is so released, the cam 54 is provided with a coil spring 54a mounted on shaft 55 between cam 54 and the portion 13a of housing 10. During normal operation, the cam 54 is retained in a depressed position with its upper surface below the arm 57 of reversing ring 45. Thus, the cam 54 may be rotated to its load-raising position, as shown in Fig. 4, or to the load-lowering position, as shown in Fig. 5, as described previously.

In order to provide such normal operation, the front plate closing member 11 has mounted thereon a block bored to receive a relatively heavy coil spring 66 and a bumper pin 67 nested therein. The head 67a of bumper pin 67 engages the free end of spring 66 and is positioned in the way of the upper end of link 34. This normally limits the travel of operating lever 43 to its normal operating are particularly when the operator is grasping the lever 43 and controls the upward movement thereof.

When operating lever 43 is released prematurely during a lowering operation it will fly upwardly at relatively high speed because the load causes ratchet 21 to rotate in a clockwise direction and pawl 25 is in engagement therewith. Lever 34 impacts pin 67 with sutiicient force to depress pin 67 and permit a longer arc of operation of lever 34. In turn, pin 50 engages cam 49 throwing the reversing ring 45 to an extreme clockwise position where the arm 57 swings to its load-raising position beyond the periphery of cam 54. Spring 54a then forces cam 54 outwardly into the plane of arm 57 and prevents its return motion in a counterclockwise direction. As described before, reversing ring 45 permits holding pawl 26 and load-pawl 25 to engage the teeth or ratchet wheel 21. With the pawls in these positions, the ratchet wheel is locked and the load cannot move downwardly.

In order to release the reversing ring 45 from this position, cam 54 is provided with an additional cam surface 54b which slopes upwardly and extends below the plane of the arm 57 on reversing ring 45. By throwing the =lever 56 in a counterclockwise "direction (Fig- 6),

. cam 54 is turnedto bringthe camsurface 54b beneath the lever arm 5 7,-permitting-"it to rotate in a counterclockwise i direction-under the influence of springs 51 and "'58. This returns 'the'mechanism to the' previous loadlowering position. "Spring 58 is' provided with an elongated loop 59 engaging pi1r59a in lever 57,'the opposite e1id'of'spring 58being anchored bygpin 58a secured to casing 10. Spring 58 is tensioned only-when lever 57 engages the periphery of cam 54- and-serves to provide the forceon-lever57which forces-arm- 54 backwardly against "spring'54a. I-t'will be notedthati'the provision of the ,spring' 54a andthe' bumper 'pin'67 'prevents' unintentional ":r'eleaseof" the. load,- -thereby substantially increasing the "safety of operation.

'For permitting the rat'chetwheel' 21 to rotate freely and: thereby 'permitfree chaining'of'the hoist with' no load thereon, I provided atthrow-out means :operable '"from the exterior of the'casing'tothrowout'the load pawl 25, as'shown in Fig.3. This throw-out means commounted in the closing "member "11. Spring 62 biases lever 60 into engagement with'the side of cam 68 rotatably .rnounted in'closing memberll and provided with an external-operatinghandle 69. .Cam 68. includes aflat surface 70, the purpose of which is to permit lever'60 to 30 move under theiinfiuenceof-spring 62 into the way of the pin '50 "which projects upwardly beyond the upper surface of pawlij25. '--With"the operating lever 69in the position shown in Fig. 3, lever-60 will have moved to such a position that its cam surface. 71 will engage pin [StLto holdpawl 25 free of the ratchetlteeth.

'EThus, for free chaining operation with no load-on the hoist and with lever 43 in any position, but with handle 56 in load-lowering position, the handle 69 may be swung in counterclockwise direction. This rotates cam 68 into position to engage surface 759 with lever 61 whereby spring 62 moves lever 60 in a counterclockwise direction. This action will lift pawl 25 free of engagement with ratchet teeth 21a. Thus, with the holding pawl maintained in disengaged position by the cam 47 and the load pawl 25 maintained in disengaged position by the cam surface 71 of lever 60, the load chain is free to move in either direction.

I claim:

1. A chain hoist comprising a casing, a shaft mounted in said casing, a chain sheave and ratchet wheel fixed to said shaft, an operating lever and cooperating lever system mounted on said casing and shaft in operative relation thereto, a load pawl coupling said system to said ratchet wheel during movement of said lever in one direction, said load pawl including a control pin, a holding pawl pivoted to said casing to engage said ratchet wheel during movement of said lever in the opposite direction and including a control pin, a reversing ring mounted on said shaft and including a first cam operatively associated with the load pawl control pin and a second cam operatively associated with said holding pawl control pin, spring means biasing said reversing ring and said cams in a direction normally to disengage said pawls from said ratchet wheel, a rotatable and reciprocable control cam operatively associated with said reversing ring and manually rotatable into a first position for rotating said reversing ring and said cams out of engagement with the control pins of said pawls, whereby said lever is operative to lift a load, said cam also being'rotatable into a position for permitting said spring means to move said reversing ring into a position where its cams may alternately engage the control pins of said pawls to permit lowering action of said lever, compressible stop means operativelyassociated-with said lever system for normally --=preveh"ting said load pawl pin from rotating 1 said reversing ring 'int'o load-lifting position, and spring means operativ'ely associated with said control cam 'for reciprocat- 5 sing it into thewayof saidreversing ring, when saidstep meansis compresse'd; tohold said reversing ring in the "load liftingposition.

2. "A chain "hOlSlll comprising a casing, a shaft mounted dmsaidcasing; a:chain sheave'and ratchet wheel fixed to saidshaft,an'operating-lever and:cooperating lever systemtrnounted on said casing and shaft in operative rela- "tion thereto, a loadpawl'coupling said system tosaid ratchet" wheel "during movement of said lever in one.direc'tion,;a' holding pawl, pivoted to .said casing to engage said'ratchetwheeltduring. movement of said lever in .the .oppositedirectioma reversing'ring mounted on said shaft and including a first cam operatively associated with the load pawl anda second cam operatively-associated with said holding pawl, means'for moving said reversing ring and. said cams in a directionmorm'a'lly to disengage said pawls from said ratchet wheel, a rotatable and reciprocable control cam operatively associated with said reversing. ring. andmanually. rotatable into at first position .for; rotating said. reversing ringandtsaid cams out ofen- .gagement withtsaidi pawls whereby said .lever is operative ,.to,lift, a load,..said. cam, also being rotatable .into 'arposi- ,tion. for tpermittingsaid reversing ring. to move into .a position vwhere ,itsr-cams may alternately. engage said pawls to permit lowering action of said lever, stop means 1operativelynassociated withsaid lever system for norimally-preventingsaid.loadpawl from rotating said re- Versing: ringainto..loadzlifting.position, and means opera- .tivelyassociated with. said control-cam for reciprocating :it into theway of said reversing ring whensaidstop means ,isocompresse'd ato holdasaid reversing 'ring in theload lifting position.

3.. A chainnhoist:cornprising a:casing a shaft mounted vin.'saidcasirigs-a .chainssheave and ratchet-wheelxfixed to said shaft, an operating lever and cooperating lever systern mounted on said casing and shaft in operative relation thereto, a load pawl coupling said system to said ratchet wheel during movement of said lever in one direction, a holding pawl pivoted to said casing to engage said ratchet wheel during movement of said lever in the opposite direction, a reversing ring mounted on said shaft and operatively associated with the load pawl and said holding pawl, means for moving said reversing ring in a direction normally to disengage said pawls from said ratchet wheel, a rotatable and reciprocable control cam operatively associated with'said reversing ring and manually movable into a first position for moving said reversing ring and freeing said pawls, whereby said lever is operative to lift a load, said cam also being movable into a position for permitting said reversing ring to move into a position where it controls said pawls to permit lowering action of said lever, and means operatively associated with said control cam for reciprocating it into the way of said reversing ring to hold said reversing ring in the load lifting position. 4. A chain hoist comprising a casing, a shaft mounted in said casing, a chain sheave and ratchet wheel fixed to said shaft, an operating lever and cooperating lever system mounted on said casing and shaft in operative relation thereto, a load pawl coupling said system to said ratchet wheel during movement of said lever in one direction, a 65 holding pawl pivoted to said casing to engage said ratchet wheel during movement of said lever in the opposite direction, cam means operatively associated with the load pawl and said holding pawl, spring means biasing said cam means in a direction normally to disengage said pawls from said ratchet wheel, a rotatable and reciprocable control cam operatively associated with said cam means and manually movable into a first position for releasing said pawls, whereby said lever is operative to lift a load, said control cam also being movable into a position for T permitting said spring means to move said cam means into a position where it may alternately control said pawls to permit lowering action of said lever, compressible stop means operatively associated with said lever system for normally preventing movement of said cam means into load lifting position, and means operatively associated with said control cam for reciprocating it into the way of said cam means when said stop means is compressed to hold said cam means in the load lifting position.

5. A chain hoist comprising a casing, a shaft mounted in said casing, a chain sheave and ratchet wheel fixed to said shaft, an operating lever and cooperating lever system mounted on said casing and shaft in operative relation thereto, a load pawl coupling said system to said ratchet wheel during movement of said lever in one direction, a

holding pawl pivoted to said casing to engage said ratchet wheel during movement of said lever in the opposite direction, cam means operatively associated with the load pawl and said holding pawl, a control cam operatively associated with said cam means and manually movable into a first position for releasing said pawls, whereby said lever is operative to lift a load, said control cam also being movable into a position for controlling said pawls to permit lowering action of said lever, stop means operatively associated with said lever system for normally preventing said cam means from moving into load lifting position during lowering action of said lever system, and means operatively associated with said control cam for moving it to control of said cam means when said stop means is operated to hold said cam means in the load lifting position.

6. A chain hoist comprising a casing, a shaft mounted in said casing, a chain sheave and ratchet wheel fixed to said shaft, an operating lever and cooperating lever system mounted on said casing and shaft in operative relation thereto, a load pawl coupling said system to saidwith the load pawl and said holding pawl and manually movable into a first position for releasing said pawls, whereby said lever is operative to lift a load and movable into a second position for controlling said pawls to permit lowering action of said lever, and means operatively associated with said cam means and said lever system to hold said cam means in the load lifting position in response to abnormal movement of said operating lever during lowering action of said operating lever.

7. A chain hoist comprising a casing, a shaft mounted in said casing, a chain sheave and ratchet wheel fixed to said shaft, an operating lever and cooperating lever systern mounted on said casing and shaft in operative relation thereto, a load pawl coupling said system to said ratchet wheel during movement of said lever in one direction, a holding pawl pivoted to said casing to engage 'said ratchet wheel during movement of said lever in the opposite direction, cam means operatively associated with the load pawl and said holding pawl and manually movable into a first position for releasing said pawls, whereby said lever is operative to lift a load, said cam means also being movable into a position for controlling said pawls to permit lowering action of said lever, stop means operatively associated with said lever system for normally preventing said cam means from moving into load jlifting position during lowering action of said lever system and means operatively associated with said cam means for moving it into the load lifting position when said stop means is operated by abnormal movement of 30' lever system during load lowering action.

References Cited in the file of this patent .UNITED STATES PATENTS 2,417,492 Hinchclitfe Mar. 18, 1947 2,480,303 Pennell Aug. 30, 1949 2,670,176 Cofling Feb. 23, 1954 2,738,954 Du Bois Mar. 20, 1956

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