US1569846A - Hoisting machinery - Google Patents

Description

Jan. g

C. W. AVELING HOISTING MACHINERY .Filed Sept. B. 19722l 3 Sheets-Sheet 2 Jan. v19, 1926.

C-. w. AVELING HoIsTIN'G IMHINBRY Filed Sept. a. 1922 3 Sheets-Sheet 5 provide Patented Jan. 19, 1926.

UNITED STATES It l, 1,569,846 PATENT oFF1cE.-

cIIRIs'rIAAN w. AVELING, oF'LocKroRr, ILLINOIS, AssIeNon To JULIA AvnLINe, j

. or Locxron'r, ILLINOIS. j

HOISTING MACHINERY.

Application led September 8, 1922. Serial No. 586,864'.

To all ywhom t Imay concern:

Be it known that I, CHRIs'rIAAN W. ING, a citizen of the United States, residing at Lockport, in the county` of Wlll and State ci? Illinois, have invented new and useful improvements in Hoisting Machinery, of which the following `is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part ot thisv speciiication.

My invention relates to hoisting machinery.

One oi the objects of my invention 1s to provide an improved hoisting'v machine for operating a grab bucket or the like in which a single motor is .used Vtor controlling both the holding drum and lacing drum, and 1n which provision is made whereby when the grab bucket is being closed it will be permitted to dig into the material being handled, to permit the jaws to follow their own inclination in grasping the material.

A Yfurther object of my invention is to pr ovide uny improved hoisting mechanism In which a single motor controls both the holding and lacing drum, in which a yielding tension is exerted on the holding rope durthe grasping movement of the bucket whereby the starting of the holding drum, when the bucket is closed, is facilitated.

A 't fther object of my invention is to an in'iproved hoisting machine in which a single motor controls both the holding and lacing drum, inwhich a delayed actiV i, or lost motion impositive drive is provided between the motor and holding drum, to prevent jerking and jarring and unevenness of operation when the motor takes hold .of 'the holding drum.

si. if'mther object of my invention is to improve the construction of the delayed action transmission mechanism.

Further objects will appear from the de tailed descriptionto follow and from the appended claims.

Rin the drawings in which an embodiment fr? my invention isshown- Figure 1 is a side elevation of a trolley;

ifig. i). is a side elevation of the other side or the trolley; j j

l'fig. 'is a plan viewoi' the trolley vwith part oi the transmission shown insection;

Fig. ll is an end elevation of the trolley;

lig. 5 is an axial sectionalview of the transmission tetweenlthe motor and drums;

Fig. 6 isa section on therline `(ii-6 of lig. 4,

Fig. 7 is a section on the line 7*#7 of Fig. 5; and

Fig. 8 is a section on the line `8-8 of Fig. 5.`

The `construction shown in the drawing comprises a. trolley 10, mounted torun on the track 11, the trolley having the trolley sides 12, mounted onthe trolley wheels `l?) which travel on the track 11. A suitable motor and transmission `(not shown) is provided 'or acting on the trolley wheels 13 to cause the trolley to travel back and forth ,on the rails 11 of the bridge. The trolley shown is provided with a single lacing drum 14, which controls the opening and closing `movement of the bucket 15, and with a divided holding drum having the drum portions 16 and 17 for supporting the bucket 1o during the opening movement of said bucket. A single motor 18 is providedfor controlling both the lacing drum 14 and the holding drum portions 16 and 17, suitable transmission 19 being provided between the motor 18 and the drums to ei'ect the various movements of the holding and lacing drums which are necessary to the operation of the bucket.

The desired operation of the bucket is as iollows-Assuming that the bucket is loaded and that it is desired to elevate the` bucket, transfer the load to a desired point, dump the bucket, bring the bucket back to the supply, and pick up another bucket full of material, with the bucket loaded as aforesaid, the motor is operated to raise thebucket, the motor 18 acting on both the lacing and holding drum to raise the bucket, and the trolley and bridge are moved along their track to bring the bucket to the position desired for dumping. The hoist motor is then reversed to dump the bucket. As soon as thel motor is reversed, a pair of pawls 2O and 21 (Fig. 2) are automatically thrown in which act through a friction holding device to hold the holding drum against movement, the delayed action transmission between the motor and the holding' drum permitting a slackening of the lacing drum to permit the bucket to dump without any 4movement of the holding drum.

As soon as the lost motion between the motor and the holding drum has been taken up, the friction holding device which holds the holdin drum against movement is `loosened up, an further action of the motor results in lowering of the bucket under its own weight. The trolley and bridge are caused to travel back to the loading point, and the bucket is lowered in open position down on the material to be handled.

When the bucket has been lowered suiiiciently to be in the right position to grasp ai other load, the motor is again reversed. Immediately upon reversal of the motor the pawls 20 and Q1 are thrown out to permit the holding rope to be paid out, if the action of the bucket in grasping the load demands or requires such action. The motor then causes the lacing drum to act to close tin` bucket to cause it to grasp a load` During this closing movement of the bucket, a yielding force is exerted on the holding rope also, by means of spring-pressed friction devices, this tension on thev holding rope not being suiiicient to raise the bucket against its own weight, and not being suilicient to prevent the jaws from Jfollowing their own'v inclination in digging into and grasping material. but being sufficient to maintain the holding rope taut and to prevent the bucket from Hopping around or tipping over on its side. lhen the grasping movement of the bucket is complete and the brcket has closed on its load, the lost motion transmission to the holding drum has been taken up, and continued action oi the motor raises the bucket in closed position carrying the load. The pawls 20 and 2l which are released immediately upon rotation of the motor in a hoisting direction, and which are automatically7 thrown in upon movement of the hoist motor in a lowering direction, are provided in duplicate for the sake of safety, so that it even one ot them fails to act. the chances are that the other will act. These pawls are controlled in their movement by the transmission to the lacing drum. (as distinguished trom the transmis sionto the holdingr drum) so that they are thrown in or out depending upon the direction which the `lacing drum is rotated. When the lacing drum is rotated in a direction to close the bucket or raise the bucket, the pawls are thrown out, while when the lacing drum is turned in a direction to open the bucket or lower the load the pawls are thrown in. The construction by which this is accomplished will be described more in 'detail hereinafter.

As intimated above, the lacing drum la is al .Travs directly connected with the motor, no lost motion transmission being provided between the motor and this lacing drum. Tte transmission from the motor to the lacing drum comprises the motor pinion 22, the gear 23 meshing with the pinion 22, a hrilt-up sectional tubular housing and transmission casing Q4, on one end of which the gear 23 is mounted, and on the other end of which is formed a inion 25, and a drum gear 26 meshing witi the pinion 25.

VrPhe transmission from the motor to the holding drum is the same as the transmis sion trom the motor to the lacing drum up as ia as the casing and transmission mem ber Q4. From here on the transmission to the holding drum comprises a delayed acticn or lost motion frictional drive or trans mission Q7 housed in the housing member Elfi, a shaft 28 extending through the housing member 24, and driven 'from the lost motion 'friction transmission QT, a unidirectional drive or transmission Q9, driven from the shaft 28, a pinion `30, driven from the trans` mission 29, and the drum gear Si. driven tr-nm the pinion 30.

The unidirectional friction transmission QSI is so constructed that it can drive positively in only one direction so that lowen ing action ot the holding drum can be at coifiplished only under the action ot the weight ol the bucket itseli. Furthermore, 11i-,fans are provided tor holding the holding drum against lowering movement during tut, dumping ot the bucket, (that is to say, during the time that the lost motion transmission is being taken up) these holding means comprising the pawls 20 and 2l pre vtmslv referred to7 which engage ratchet teeth $32, l-ormed on the casing member 323.

This casing member 33 serves as a container 'for the unidirectional rictional drive, and also serves as a positioning means for certain o't the friction discs le of this transmission, these friction discs having peripheral lugs 35, which extend into longitudinal grooves 36 in the casing 33. whereby relative rotation between these 'trirtional discs and the casing is prevented.

The friction discs are controlled by a pair ot` spreader members 3T and 38, having helical engaging surfaces at 39 whereby relative rotation between the spreader members 3T and 3S in one direction will iorce the spreader members apart and relative rotation in the other direction will permit them to approach each other. One of these spreader members 37 is keyed to the drive shaft 28 hereinbefore referred to, while the` other spreader member BS is keyed lo the tubular extension 40 of the holding drum pinion 30. Intermediate 'friction discs 4i. and 42 are provided mounted on the spreader members 37 and 38 respectively. These intermediate friction discs l-l and 4Q are provided with inwardlyv extending lugs el?, (Fig. 7) which extend into longitudinally extending grooves 44: and 45, formed in the spreader members 87 and 38 respectively, so that relative rotation between the discs 4l and Li2 and the spreader members 3T and 3S is prevented.

The casing 33 serves to back up the friclill lou

l lf) ill'i `tion discs when they are spread apart by the action of the spreader members 37 and 38, the friction discs being then clamped between the ends of the casing 33 and the respective spreader members 37 and 38. The expanding action of the spreader member takes place on the raising movement of the bucket. On the raising movement of the bucket, the spreader members 37 and 38, the friction discs 41 and 42, and the casing member 33 are all clamped together a unitary device, so that the holding drum pinion rotates along with the spreader member 45. i During the dumping of the bucket, the shaft 28 and spreader `member 37 remain idle, because of the lost motion transmission, to be described more in detail hereinafter, and the spreader members, friction discs.l holding pinion 30 and casing 33 are held stationary by the action of the holding pawls `20 and 21 which engage the teeth 32 of the casing 33 as described above.

At the end of the dumping action, the lost motion transmission to the holding drum has been taken up, and the shaft 28 is then Ycaused to rotate in a lowering direction.

The spreader 3T which is keyed to the shaft 28 is thus rotated in a direction to loosen up the spreader members and the friction discs in the casino' 33, and this permits the spreader member 38 to follow along with the spreader member 37, this follow-up action of the friction disc being due to the weight` of the bucket acting on the holding drum, this force being transmitted to the spreader member 38, through the pinion 30, and the `extension sleeve 40 on the pinion 30.

When the open bucket is lowered onto the material to be handled, and the motor is then reversed to cause the bucket to grasp the load, the reversing of the motor will automatically cause the pawls 20 and 21 to be thrown out of engagement with the ratchet' teeth 32 as will be explained more in detail hereinafter.

` Also, as will be explained more in detail hereinafter7 during the closing or grasping movement of the bucket, an impositivo fricn tional force is being exerted on the shaft 28, tending to rotate it in a direction corresponding to the hoisting movement of the holding drum. `This tendency of the shaft 28 to rotate is sufiicient to cause the spreader member 37 to bind the friction discs 35, 41 and 42 and clamp them together to cause a force to be exerted tending to rotate the holding drum pinion 30 in a hoisting direction. There is thus an iinpositive yielding force exerted on the holding drum, and hence on the holding rope, tending to raise the bucket. 'ihis impositive frictional force, however, as will be explained hereinafter, can be adjusted and is so adj usted that it will not be sufficient to raise the bucket, but will simply keep the bucket in proper position for grasp* ing the load, and prevent it. from falling over on its side or rolling down the side of -the pile of material. ,y

The releasing of the pawls 20 and upon the reversal of the motor to cause the bucket; to pick up its load, release the casing or drum 33, so that if a sufficient `force is exerted on the holding rope (due to the action of the bucket in digging into the material) to overcome the impositive frictional force exerted theeron as described above, it will cause the holding rope to be unwound. The advantage of this releasing of the pawle during the loa-ding of the bucket is that it permits the bucket to act naturally in picking up its load, permitting the bucket to dig into the material being handled, and the jaws to follow their own inclination in grasping the material, which would not be the case if the holding rope were lixedly held.

Coming now to a description of the impositive lost motion friction drive 27 .con`

tained in the casing 24, the lost motion or delayed action part of this construction comprises-a pair of sleeves and 47 respectively, the sleeve 48 being smaller in diameter than the sleeve 47 and being threaded inside it. The sleeve 46 has a feathered engagement with the shaft 28, while the `sleeve 47 has a feathered engagement with the casing 24, this feathered engagement permitting longitudinal movement of the sleeves but preventing relative rotation between them and the members on which they are feathered. The two sleeves are thus float ably mounted with respect to the shaft 28 and the casing 24, so that they can move longitudinally with respect to these members but cannot rotate with respect to the member on which theyy are feathered. The two `members together thus constitute an expansible and contractible device which is made use of to bind or release a pair of friction disc sets 48 and 49.` One set of friction discs is located at each end of the sleeve, the sleeves acting equally and in opposite directions on these sets, the floatable mounting of the sleeves permitting thesleeves to adjust themselves, so that they will bear equally on the two sets. Because of the fact that the sleeves are floatably mounted and the discs made in two different sets located at opposite ends of the loatable expansible device, l am enabled to make use of both sets of discs, both on the raising and lowering movement of the hoist as will be explained more in detail hereinafter, which would not be the case if the expansible element were not floatably mounted and did not act between two sets of friction discs.

As shown in Fig. each set 48 and 49 of the friction discs comprises an intermediate friction disc 5() feathered on the shaft 28, and engageable by the inner sleeve 46 and izo :i pair of outer Yfriction discs l feathered on the casinav 2d and engageable by the outer threaded sleeve 27.

In order to produce the impositire torce hcreinbe'lore referred to which causes a tendency o'l the holding drinn to rotaie durinfinil the closingij movement ot' the bucket, two sets o` spring 'friction devices are provided 'tor pi Jing; the discs 5l and 50 together. Each of these sets as shown in Figs. 5 and 8 coniprisi'is a number ot spring-pressed cups or plungers 52 engaging the friction discs 51 and pressed thereiigainst by means of the coil igfoininesdon springs 53, the tension of which may be adj usted by means ol the ad- Iinsting1 sci-e' 5i. This yielding pressure ot the spri.nji'presseil cups or plungers 52 presses the friction discs against each other so that an impositivo torce is transmitted through these friction discs Jfrom the drive and ciisine; member 24 to the shaft i8. This iinpositire force causes a tendency ot the holding drinn to be rotated in a direction to tighten the holdingrope duringr the closing inorcmini ci the grab bucket. At the end of the closing` movement oi the grab bucket. the sleeves 46 and el?. due to their threaded engagement with each other, have moved into extended position so that the sleeve 46 will be bearing against the disc 50 of the one set of friction discs, and the outer sleeve Ii7 will be bearing against the disc l ot' the other set ot friction discs. This causes a further increase in the friction between the lriction discs increasing' the hoisting action on the holding' rope and causing the holding rope to assist the lacing rope in raising the bucket.

Due to the tact that during the closing movement ot' the bucket the spring-pressed cups a2 cause a tension in the holding rope, there is no considerable shock or jar when the tens on in the holdingrope is increased by the action of the threaded sleeves t6 and et?. Furthermore7 the additional tension in the holding rope due to the action of the sleeves Lt6 and l? is increased gradually, not abruptly, because oie the cooperation of the spring-pressed plungers 52, which allows the plate 5l to yield under the spreading action of the sleeves etG and 47. The tact that belore the sleeves t6 and 47 get in their action there Ais already a tension in the holdine; rope and the fact that the tension due to Vthe spreading oit the members 46 and 47 increases gradually makes it so that there is no appreciable shock or jar in starting up the holding drum.

It will be noted that the threaded sleeves lli and -l7 are double acting7 in that they act as a lost motion or a delayed action device both during the grasping and during the dumping action of the bucket. This double action is accomplished by making the threaded connection between the `two sleeves such that the inner sleeve can thread its way entirelyv through the outer sleeve so that duringA the grasping action of the bucket the inner threaded sleeve engages the disc 5() ol one set. and during the dumpingr action ot the bucket it engages the disc 5() of the other set ot' friction discs` the enifufrement ol the outer sleeve 4T with rcspctato the discs 51V being also corresiiondingly reversed. i i

p 'Vlie niei'hanism Alor i-ontrolliiie' the pawls Lll and, ll will nonv be described.t is stated :ihoi'e` tiro pairls are provided i'or tlicsake ot safety, so that it is noi likely that both ol them u'illl'ail to art at thclsaiiie time. lliiA control tor both pawls is ,.iiiiilar, bolli lining :ontrolled by means ci 'friction rings mounted on the casingi Qll which drives the l i fr drinn. 'llie pawl 2() is, as shown in i2 and inoiintcd on a rock-shaft- 55. :i .segmental pinion :7G heine mounted on the other end o the rock-shaft. which pinion meshes with thi.y se mental near `57 i'ornied :is a part ot the fric-tion rino' 5S. which is ni-rniiitcd in an annular groove hf) in the transnitssion casing 24. ln a similar inaiiner. the paul Ll mounted on a rock-shalt (3d. on the other end ol which is mounted a seg-mental pinion (il, nies-hinar `with a segmental fear o! (Fig. l) loi'ined as a part ot the friction i-ingi' (i which is mounted in the groove tillot' the transmission casing Q4. Suitable adjusting screws are pri'ivided tor scciiriirel the right amount of lfriction between these 'friction rings 58 and G3 and the casing or drinn on which they are mounted. lilith this constructiom when the trans- .inission drinn 2st is turned in a direction to canse hoisting movement oi." the lacing drinn the pairls 2O and 2l are thrown out ot' engagement with the ratchet and `when the transini sion casingl is rotated in a direction to slacken the latini;I rope, the pawls 2() and, 2l are thrown into engagement with the ratchet 32. '.lhiia in dumping, when the lacing rope is slacked (the holding drinn in the meantiinemotlacing' rotated because of the lost motion transmission) the pawls 2O and 2l are. thrown into engagen'ient with the ratchet 2li. and this prevents any lowering motion ot the holding drinn until the delayed action ot the transmission has been taken up. so tl at the holding drinn holds the bucket suspended while the lacingil rope is slackened io permit the bucket to open to dump the load. The paWls 2() and 2l remain in engagement with the ratchet 32 during the lowering' ot the bucket, but as soon as the delayed action transmission has been taken upj the holding' drinn is lowered due to the weight of the bucket, as the. spreader members 38 and 239, as soon as this delayed action transmission is taken up, cease to bind the friction discs, and the spreader 38 follows up the spreader member 39 due to the fil) weight of the bucket. The bucket is thus lowered in open position until it is ready to pick up another load. The motor is then reversed, causing the lacing drinn to be wound up to cause tlieclosing of the bucket, and at the same time causing the pawls 20 and 21 to be thrown out to permit the ratchet wheel 32 to rotate, it necessary, to allow the holding rope to be paid out and permit the bucket to follow its own inclination in digging into the material, the holding drum, however, remaining taut because of the frictional plungers or cups52.

The segmental pinions 56 and 61 remain always in mesh with the segmental gears 57 and 62, respectively, as the movement of the pawls is slight.

In dumping, it is necessary that the friction discs 50 and 51 shall be released prior to the release ot the friction discs 35, 41 and 42, otherwise, it might happen that the bucket would be lowered in closed position and could not be dumped. In order to i n sure that the friction discs 50 and 51 will i be released prior to the release of the ldiscs 35, 41 and 42, I may provide adjustable friction plungeisor cups 66 similar to the cup 52, these cups 66 being sliiring-pressed against the disc 41 by means of a coil compression spring 67, the tension of which may be adjusted by an adjusting `screw 68.

By adjusting the screws 68 any desired pressure maybe exerted on the disc 41 to insure that this set of 'discs willvnot be released before the discs 50 and 51.

The motor 18 is provided with any suit-` able type of magnetic brake 64 which is thrown on automatically when the current is turned off from the motor, in the usual mannerfof magnetic brakes. This, of course, holds the lacing drum 14 against movement when the current is turned olf from the motor and prevents the bucket from dumping before the operator is ready; that is, before lie reverses the motor to unwind the lacing ro e.

IIaving thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is- 1. A hoisting machine comprising a releasable load-grasping device, a holding drum, a lacing drum for controlling the releasing and grasping of said load-grasping device, a single motor for controlling both of said drums, transmission means between said `ing the load an inipositive force is exerted on the holding rope, permitting the holding rope to pay out, to allow the grasping device to dig into the material to be loaded, and exerting a yielding force to facilitate starting the movement of the holding drum, said transmission means including also a positive drive between the motor and the holding drum and means wherebv said impositive drive is effective during the grasping operation of the load grasping device and whereby said positive drive is eiective during the raising movement of the load.

2. A hoisting machine comprising a releasable load-grasping device, 'a holding drum, a lacing drum for controlling the grasping and releasing of the load-grasping device, a single motor for controlling both ot said drums, transmission means between said motor and said drums, including a delayed action transmission between the motor and holding drum, whereby said lacing drum may be given a limited movement without any movement of the holding drum, to

control the grasping and releasing of said i `load-grasping device, an automatically actthe movement oft the holding drum is facilii tated,said transmission means including also a positive drive between the motor and the holding drum and means whereby said impositive drive is eiiective during the grasping operation of the load grasping device and whereby said positive drive is effective during the raising movement of the load.

3. A hoisting machine comprising a releasable load-grasping device, a holding-` drinn` a lacing drum for controlling the grasping and releasing of the load-grasping device, a single motor for controlling both of said drums, and transmission means between said motor and said drum including a delayed action transmission between the motor and holding drum, whereby said lacing drum may be given a limited movement without any movement ofthe holding drum, to control the grasping and releasing of said loadgrasping device, said transmission means comprising a rotatable drivin'g element for the lacing drum. a rotatable driving element for the holding drum, a sleeve slidably keyed to said lacing drum driving element, a sleeve slidably keyed to saidholding drum driving element, said sleeves having screw-threaded lil engagement with each other, and being` floatably mounted with respect to said driving elements and triction elements engaged by said sleeves.

4;. A hoisting machine comprising a re leasable load-grasping device, a holding1 drinn, a lacing drinn for controlling the grasping and releasing of the load-grasping device, afsiiigle motor tor controlling both ot' said driims, and transn'iission means between said motor and said drinn including a delayed action transmission between the motor and holding drinn. wherebyT said lacing drum may be given a limited movement without any movement of the holding drum, to control the grasping and releasing oli said loadgrasping device, said t `ansn'iission means comprising a rotatable driving element for the lacing drinn, a rotatable driving element tor the holding drum, a sleeve slidablv keyed to said lacing drinn driving element, a sleeve slidably lieyed to said holding drinn driving element, said sleeves having screw-threaded engagement with each other. and being floatably mounted with respect to said driving elements, friction elements engaged by said sleeves, there being two sets ot t'riction elements, and said sleeve being located intermediate said sets of friction elements.

5. A hoistingl machine comprising' a releasable load-grasping device, a holding drum, a lacing drinn tor controlling the grasping and releasing ot' the load-grasping device, a single motor tor controlling both ot said drums, and transmission means between said motor and said driini including a delayed action transmission between the niotor and holding drinn` whereby said lacing drinn max v be given a limited movement without anyv movement ot the holding drum. to control the grasping and releasing of said loadgrasiiiing device, said transmission means iomprising a rotatable driving element 'tor the lacing drum, a rotatable driving element l'oi' the holding driim, a sleeve slidablv keyed to said lacing driinji driving clement, a sleeve slidablv keyed to said holding drinn driving element, said sleeves having screw-threailed engagement with each other, and being tloatably mounted with respect to said driving` elements, and friction elements engaged b v said sleeves, there being two setsot friction elements, saidsleeve beingl located intermeiliate said sets ot 'trio i tion elements, said inner sleeve being capable otbeing threaded completely through said outer sleeve, whereby in hoisting the outer sleeve will engage one set of friction elements, and-the inner sleeve the other set of 'friction elements, and in loweringthe relation will `be reversed.

6. A hoisting mechanism comprising a releasable load-grasping device, a holding drinn, a lacing drum for controlling the grasping and releasing ot the load-grasping device, a single motor tor controlling both of said drums, transmission means hetwcen said motor and said drains, including a delayed action transmission between the motor and holdingl drinn, whereby said lao ing drinn may be given a limited movement without anyv movement olf the holdingl drinn to control the grasping and releasing of said load-grasping device. said traiisniission means including also ii positive drive between thc motor and the holding drinn and means wherebyv said impositivo drive eil'eiu tive during the grasping operation of the load grasping device and ivlierebv said positive drive is ell'ective during the raising movement ot' the load, means for holding said holding` drinn against iniivenient when the lacing drinn is releasing the load-grasp ing device, comprising a rotatable member, means 'tor preventing rotation ol said rotatable member during the releasing ot said load-grasping derive, anil means operated aiitomatieallxi upon the reversal ol the motor for rendering said rotation preventing means ineffective during the load-grasping movement oit the lacing drinn. whereby said holding drum is released 'trom the control ot' said rotation preventing means to permit the holding rope to pay out, to allow the loadgrasping device to dig into the material heing handled.

7. A hoisting mechanism con'iprising a releasablc load-grasping device. a holding drinn. a lacing drinn jt'or` controlling the grasping and releasing ol the load-grasping device. a single motor for controlling both ot' said driims. transmission means between said motor and said drums, including a den layed action transmission between the motor and holding driim, wl'iereby said lacing drinn may be given a limited movement ivithoiit any movement ot the holding driin'i 1o eontrol the grasping :ind releasing oi said loadgrasping device, said transmission means incltiding` also a positive drive between the motor and the holding drinn and moans whereby said inipositive drive is ellectivc during the grasping operation ot the loadgrasping device and whereby said positive drive is effective during the raising movement ot the load` means 'tor holding said holding drinn against movement when the lacing drinn is releasing the load-grasping device, comprising a rotatable member, means including a ratchet and pawl for prc venting' rotation ot` said rotatable member during the releasing of said load-grasping device, and means, including means operated automaticallyY iipon the reversal of the motor for moving the pawl out of enfragement with the ratchet, for rendering said rotation preventing means ineffective during the loadgrasping movement of the lacing drum,

lit)

whereby said holding drum is releasedfroin the control of said rotation preventing means to permit the holding rope to pay out, to allow the load-grasping device to vdig into the material being handled.

8. A hoisting mechanism comprising a. rcleasable load-grasping device, a holding drum, a lacing drinn for controlling `the grasping and releasing ot the load-grasping device, :i singl(` -motor lor controlling both of said drums, transmission n'lcans between said motor and said drums, including a do layed action transmission between the motor and holding drum, whereby said lacing drum may be given a limited movement, without any movement of the holding drnm to control the grasping and releasing of saidloadgrasping device, said transmission means including also a positive drive between `the motor and the holding` drum and means whereby said impositive drive is effective during the grasping operation oif the load grasping device and whereby said positive drive is etiiective during the raisingmovement of the load, means, including an automatic brake, for holding said holding drum against movement when the lacing drum is releasing the load-grasping device, compris ing a rotatable member, means for preventing rotation ot' said rotatable member during the releasing of said load-grasping device, and means operated automatically upon the reversal of the motor for rendering said rotation preventing means ineffective during the load-grasping movement of the lacing drum, whereby said holding drum is released Yfrom the control of said rotation preventing means to permit the holding rope to pay out, to allow the load-grasping device to dig into the material being handled.

9. A delayed action friction drive comprising a driving member, a driven member, a sleeve lioatably keyed on said driving member, a sleeve loatably keyed on said driven member and having a screw-threaded engagement with said other sleeve, and friclion members engaged by said sleeves and acting as transmission between said driving member and said driven member.

l0. A delayed action friction drive comprising a driving member, a driven member,

a sleeve loatably keyed on said driving memi ber, a sleeve flotably keyed on said driven member and having a screw-threaded4 engagement with said other sleeve, and friction members engaged by said sleeves and acting as transmission between said driving member and said driven member, said friction members comprising two sets of friction discs, said sleeves being mounted inter mediate said discs.

ll. A hoisting mechanism comprising a releasable load-grasping device, a. holding drum, a facing drum for controlling the grasping and releasing of the load-grasping device, a single motor flor controlling both ot' said drums, transmission means between said motor and said drums, including a delayed action transmission between the motor and holding drum, whereby said lacing drum may be given a limited movement without any movement of theholding drum to control the grasping and releasing of said load-grasping device, means for holding said holding ldrum against movement when the lacing drum is releasing the loadgrasping device, comprising a rotatable member, means including a ratchet and pawl for preventing rotation of said rotatable member during the releasing of said loadgrasping device, and means, including means for moving the `pawl out of engagement with the ratchet, for rendering said rotation preventing means ineffective during the loadgrasping movement of the lacing drum, whereby said holding drum is released from the control of said rotation preventing means to permit the holding rope to'pay out, to allow the load-grasping device to dig into the' `to control the grasping and releasing o the load-grasping device, a unidirectional fric tional transmission between the said lost motion friction transmission and said holding drum, means for operating on the unidirectional transmission to hold said holding drum against lowering movement during` the dumping ot the load, and `means whereby on releasing the load-grasping device the lost motion t'rictional transmission will be released in advance of the unidirectional frictional transmission.

In witness whereof, I have hereunto subscribed my name.

C. W. AVELING.

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