US1588115A - Hoisting block - Google Patents

Description

Jufie 8,1926; 1,588,115

J. W. KITTREDGE HOISTING BLOCK Filed May'14. 192] 2.Sh eets-Sheet-1 Fig.1.

June" 8 1926.

' Filed May 14, 1921 1,588,115 J. w. KITTREDGE HOISTING BLOCK 2'Sheets-Sheet 2 E Xqdenforrfl atented .lune 8, 1926.

.UNTITEDQSJTVATEJS ATENT oFFicE. j

JOHN w. xrrrnnnen, or AKRON, 01110.

norsrnve BLOCK.

- Application filcd May 14, 1921. Serial No. 469,457.

I My invention relates particularly to an attachment to hand power chain blocks to prevent their being blocks are used for lifting heavy weights and their first and foremost requirement is absolute safety. It is well known, however, that through carelessness and ignorance very many blocksare at some time loaded beyond their proper working strength, thereby breaking them or injuring them so as to make them unsafe thereafter. The objects of my invention are 1st. To provide a block with holding mechanism to hold it against backward movement, and with the parts between the holding mechanism and the 1ifting wheel, of gearing or other positive mechanism, so that there can be no possibility of the load slipping. I c

2nd. To provide a release between-the driving wheel and the holding mechanism which shall automatically release at a certain forward torque on the driving wheel, thereby rendering it impossible to lift a load beyond the working strength of the block.

3rd. To have the release such that while it will not raise an excessive load, it will lower it to the floor, should such excessive load come upon the block through accident or any means other than the blocks own lifting mechanism.

4th. To have the said release such that it will automatically grip and liftits proper load as soon asthe excessive load is re lieved. 1

5th. To have all parts simple and protected from accidental injury. 7

I have shown in the drawings a spur geared block with the brake of my co-pending patent application No. 356,235; but my invention can be applied to worm blocks, to hoists with direct drive, to those with screw and ratchet brakes, to power driven hoists and to a great variety of other types. The holding mechanism may be the lifting .nechanism, as in the case of the worm block, or it may be an independent brake asherewith shown;

I attain theforegoing objects by the mech anism shown in the accompanying drawings, in which ic Fig. 1 is a longitudinal section on line overloaded. Chain EE of F ig. '2; and Fig. 2 is atransverse "section on line -A-B' CDv of Fig. 1, with the plate and the nut 46removed.

Parts fastened rigidly together are crosshatched alike, even though they may be separate pieces of metal. For clearness of description, a given part is designated by a numeral, as 47, and different edges or faces of that part by that numeral with letters, as 47 47 etc. A given piece carries the same number'throughout the several views.

The blocklis hung from an overhead support by the hook 1, which is attached tothe gear case 2 and the brake case 3 by the} swivel bar 4. Bolts 25 and spacers 26 bind the cases firmly together. A lifting sprocket 5. is journaled in hearings in the cases 2 7 and 3, and it carries a liftingjchain 6 and a lifting hook 39. The arrows, in every case, indicate theparts running in the direction to lift .theload. The drive shaft 9'passes centrally through the lifting sprocket 5 and P is journaled in beari'ngs therein. 1 Thewheel 8 with its lug 8 turns freely on the drive shaft 9 through a partial revolution. Lug 8 actuates the lever 31- and lever 31 in turn actuates the drive shaft'9 to which it rigidly keyed. The drive shaft 9 actuates the lifting sprocket 5' and the lifting'chain 6 through the planetary gearing shown. in

Fig.1 and common in chain block construction. v

The leverSl isconnected to theinternal brake band 29 by the lever 34 and the shoes 32 and 33. The wheel 8' and lug 8 col lapse the band and cause it to turn freely; but the load on hook 39, acting through the drive shaft 9, expands the hand against its enclosing walls and causes it to bind and hold the load. i

Integral with the wheel 8 is the threaded portion 83. The wheel 47 has a correspondlng threaded portion 47 engagingB Integral also with the wheel 47 is the lug47 A stud 48 is set in the wheel 8 and extends through a slot inwheel 47. A spring 49 extends from the lug 47 to the stud 48 and tends to screw the wheels 8 and 47 closely together. The sprocket 50 fits against a slip;

50 carries the hand chain 7. The plate 15 issimply a protecting cover.

The operation of the block is as follows The, operator pulls the chain in the direction of the arrow, and thereby actuates the sprocket 50. Sprocket 5O binds with wheel 47 through heavy,friction andtturns it arrow-wise. WVheel 47 through lug 47 spring 49 and stud 48 turns wheel 8;;arrowwise and, within the strength of the spring 49, these parts all move together as-asingle rigid piece; And wheel 8, through its lug 8t; lever "31, drive shaft 9, sprocket 5 andthe connecting gears, actuates the=chain Gand the hook 39- andliftstheload. When, however, the load is excessive, the wheel'S-jand the studSremain stationary. As the operator theni pulls the chain 7* arrow-wise, the sprocket 50 turns on the ball bearing 51 and turns wheel 4E7 "with it through friction the spring; 49 yields; and the" wheel 17' screws away from the wheel 8- until thefriction between wheel Hand sp rocket- 5O issufficien-tly relieved to, allow sprocket 50 to By, making thespring, 49' of proper strength, it .will transmit torque suiiicientto lift' a' proper load, but" willyield' within the'working strength of the blockand preventoverloading. When. the. excessive load is relieved,,the;s1'iing a9 at once expands, screwing the. wheeltti tightly down onthe wheel 8,. causing heavy friction between Wheel iffandsprocket .50, and, again trans: mittingsuificienttorquegto lifta proper load:

Suppose now that an excessive load should be put upon the block through independent means; as that, it should/be hooked to the block andlthen the supports taken from beneathit: It would act upon the sprocket 5, the gearing, the drive shaft and the brake, and these would hold it positively to the limit of their strength. The slip member, being beyondthe brake, wouldnot affectihe holding in any way whatsoever. It would,

however, prevent lifting the load higher as justdescribed. Suppose now, the operator, finding the load excessive, wishes to lower it to the floor. He pulls the chain 7 counterarrow-wisc. The chain pull, as well,as'the force of the spring, tends to screw the wheels 47 and 8. together, firmly, gripping the sprocket 50, and he thus lowers the load to;;th e floor.

The maximum forward torque on the driving wheel 50iscontrolledby the spring 49-," the-strength of which is approximately constant, and not by the coefficient offriction'which is widely variable. Suppose-two blocks-withisprin-gs 49 equal 'to each other; thejfirst with oil '-on thefriction' surfaces of wheel 47, and" sprocket! 50'; the second with said' surfaces dry andrusted: Qn-the. first, slipping Wlll occur when the pressure beto physical position. driving member 50 actuatcs the clutch-meme coefficient of friction, the smaller will be the pressure, and their product, which controls theslip, willbeapproximately constant.

Similar construction can be applied to hoistsand blocks of other types as hereinbefore described.

In the following claims, the word between is intended to have reference to the sequence; of j'the driving operations, and not F or instance, if'the bers47' andS, and the member Sthen moves the friction'meniber 29, the members i? and 8 are said to be between the; driving; member' 50' and the friction member 29, even though they should not-be'b'etween them in physical position.

Having thus described my invent-ion, 1 claim as new and desire to secure by Let ters Patent 1. Incombination, a hoistingblock comprising a driving member, a driven member, said driven membenadapted t'ocarry a-pload, avdrive connection from said driving member to said driven member, friction membersbe tween said driving and driven members adapted to hold the load through friction against baclnvard' movement, andfriction clutch members between the drivingmember and the saidfriction members, the an rangement being such that backward torque drive conuecticn from the; cont-milled].eic

ment' to the driven wheel including positive driving);elements,the arrangement being such baclw .sd tcrque upon the driving clutch member: causes the clutchmembers to grip, that a given forward torque upon the driving clutch member causes the clutch members to release, ant that the clutch members grip automatically whenever the torque on the driving-clutch member-is less than the-given torque aforesaid.

3. In combination, a heisting block com prising a driving member, a driven memher, a drive connection therebetween, a brake adapted to retard an element of, the said drive connection against backward rotationfsaid drive Connection from the retarded element to the driven member being positive drivingmembers, and a slip clutch in the said drive connection.

4. In combination, a hoisting block comprising a driving member, a driven HIGH}? her, a drive connection from the driving member to the driven member, a brake,fsaid brake retarding an elementof'the said drive connection against backward rotation, the said drive connection from the said retarded element to the driven member being positive driving members, a friction clutch in the said drive connection between the driving member and the said retarded element, a spring in the said friction clutch, and connectingmeans whereby it exerts pressure between the friction surfaces'of the clutch and whereby the forward torque of the driving member tends to relieve the said pressure. 1 v

5. In combination, a hoisting block comprising a driving wheel, a drive shaft, a driven wheel, a positive drive connection from the drive shaft to the driven wheel,-a friction brake, a connection from the brake to the drive shaft, a drive connection from the driving wheel to the drive shaft through the said brake connection, a friction clutch in the said last mentioned drive connect-ion, and a spring in the said friction clutch adapted to exert pressure between the friction surfaces thereof.

6. In "combination, a hoisting block comprising a driving member, a driven memher, a clutch member, the clutch member be ing in frictional engagement with the driving member, a positive drive connection from the clutch member to the driven memher, a screw on the clutch member whereby said clutch member tightens or loosens its frictional engagement with the said driving member, a spring'acting on the said-clutch member, the direction of the screw being such that the spring tends to tighten the vsaid frictional engagement and the forward torque} of the driving {member ,tends' to loosen it. V

7. In a hoisting block, the combination of a screwthreaded clutch member, a second clutch .member, said clutch members havlng cone surfaces in engagement, a' spring adapted to turn'the'screw member and there- 8..In con'ibination, a hoisting block comprising adrivingwheel,a driven wheel, a gear drive adapted to drivethe said driven wheel, driving means fromthe driving wheel to an element of the said gear drive, a'fric tion clutch 'in thesaid driving means, a spring in thesaid friction clutch adapted'to exert pressure between the friction surfaces thereof and to yield at a given-forward torque ofthe driving Wheel and. thereby relieve the said'pressure, a brake, connect-' ingfmeans from the brake to an element of thesaid gear drive wherebybackward torque of the said element tends to set the brake and forward torque-of the said element tends to release the brake, and means where; by backward torque of the driving wheel tends to release the said brake.

9. In combination, a hoisting block comprising a drive shaft, a driven member,a

driven member, a friction brake, a positive connection from the brake tothe drive shaft, friction clutch elements, spring means adapted to press the said clutchelements into driving frictional'engagement and to yield at a given forward torque of the driving clutch element and thereby release the clutch elements, and a driveconnection from the driven clutch element to .the drive shaft through the brake connection. 10. In combination, a hoistingblock comprising a friction clutclrniechanisin, spring means in the said clutch-mechanism adapted to press the friction; surfacesthereof into driving frictional engagement, "a lifting mechanism, said lifting mechanism comprising a lifting wheel, a planetary gear train, a drive shaft thereto,"and abrake, and a drive connection from the driven, clutch element through said brake to the shaft.

gear c'onn'ectioirfrom the drive shaft to the lill) 1].. In combination, a hoisting block comdrive shaft, a friction clutch in the said driving means, a spring connected to the driven clutch member, means whereby it ex erts pressure between the members of said clutch and whereby the forward torque of'the driving wheel reduces thesaid pressure, a brake, and a direct connection from the brake to the drive shaft.

. 12. In a hoisting block, the combination of a driving sprocket, a driven sprocket, a lifting chain fitted to the driven sprocket, a clutch wheel bearing on one side of the driving sprocket through a friction cont-act, a second wheel bearing on the opposite side of the driving sprocket with less friction therebetween than in the friction contact of the clutch'wheel, ascrew connection between the two said wheels, a spring'connection bcward rotation of the clutch releases the said brake.

21. In a hoisting block, the combination ing sprocket through a friction contact, a

second wheel bearing on the opposite side of the driving sprocket with less friction therebetween than in the, friction contact of the clutchwheel, a screw connection between the two said wheels, a spring connection between the said wheels tending to screw them together, the direction of the screw such'that the forward torque of the driving sprocket tends to screw the two said wheels ed to control an element of the said drive connection in its backward rotation, and the element to the driven sprocket being positive driving element.

I 22. In a hoisting block, the combinatio of a friction clutch mechanism, screw elements therein, a spring connection between the said screw elements whereby the said elements press the clutch surfaces into driving frictional engagement, a. driven wheel, a drive connection from the-driven clutch element'to the drivenwheel, a brake adapted to control an element of said drive connection in its backward rotation, and the said drive connection from the retarded ele ment to the driven wheel comprising posi- May, 1921. v p

- p JOHN W. KITTREDGE.

said drive connection from the controlled

Images