US1542067A - Hoisting machine - Google Patents

Description

June 16, 1925. I 1,542,067-

. I R. M. LOVEJOY HOISTING MACHINE 12. 1922 4 Sheets-Sheet l Filed lnvenior. Ralph M. LDVEJOY K 4 A'rtys June 16, 1925.

R. LOVEJOY uolsnm uacanm Filed July 12. 1922 4 Sheets-Sheet :5

' June 16, 1925. I 7 1,542,067

R. M. LQVEJOY HOISTING MACHINE I Filed July l2, 1922 4 Sheets-Sheet 4 171%. 5. 7 H2 I lnvenrc wr. Ralph M. LOVQJOY Patented June 16, 1925.

UNITED STATES rArsnrore-ice.

RALPH M. LOV JOY. or mamas, NEW HAMRsHinE; assma g no LEWIS-SHEPARD COMPANY, OF scorn BOSTON, MASSACHUSETTS, A CORPORATION or MASSA- cnusn'r'rs.

HOISTING Application filed July 12,

To atl whom it may concern:

1 "Be it known that I, RALPH M. LOVEJOY ZL citizen of the United States, and resident of llfenedith; county of Bel-knap, State of New Hampshire, have invented an Improvement in Hoisting .Machines, of which the following description, in -connectionwith the ac companying drawing, is a specification, like characters on the drawing representing like parts.

This invention relates .to hoisting devices having load supporting means adapted to *be raised and lowered to receive and discharge loads and the principal object of the invention is to provide novel means for controlling the descent of the load supporting means. a i i In hoisting devices of this character means, such as a Windlass having a winding shaft, are employed for raising the *load supponting means and the loadsupporting 'n'leans are permitted to descend by releasing a clutch upon the winding shaft. In such constructions great di'flicu'ltyis found to control the descent of theloadsupporting aneans. T

The Obj-Get of the present invention is to provide a progressively movable controlling means for lowering the load supporting means having means operable to arrest the load supporting means upon the interruption of the progressivemovement'of the controlling means.

More :broadly the invention relates to a n'ieehanical movementcomprising a device imovable in opposite directions having pro gressively movable controlling means for effecting-the :movement of the device in one of said directions and means for arresting the said movement upon interruption of the progressive movement of said controlling means. i a i A. further obiect of the invention is :to provide a hoisting device, such as,a tiering machine, having standards formed in superimposed sections with a plurality of means for locking the sections together when in alinement which cannot be simultaneously or accidentally unlocked so that accidental falling of the standards will be prevented.

. Afurtherobject of the invention is to provide a portable hoisting; lmachine qliaving rear wheels and front legsadapted to rest upon the ground uvith a steering. mecha channel form, a central MAO-nin a 1922. Serial No. 374,517;

'nism "having a vertically swinging tongue and lifting mechanism operable by a vertical movement of said tongue, when in any steering position, to raise the front end of the hoisting device and support the same uponthe steeringmechanism.

A further object of the invention is to provide means for releasably connecting the tongue to'the lifting mechanism so" that when the frame is raised the tongue may be released andifreely moved vertically as well as laterally.

Other objects and features of the invention and the detailed improvements embodying-the same "will be more fully set forth in" the following description and the accom paiiyingdrawings and will-be partioin l-arly pointed out inthe claims.

In the drawings:

Fig. l 'is aside elevation of a hoisting machine of the type-known as a"tiering-ma= chineembodying a preferred form of my invention;

2 is a real-elevation of the same;

' Fig. is a detail view "upon anenlarged scale and centrally broken'away illustrating the difierentially Operable progressively movable -clutch-releasing mechanism;

Fig. 4 is a detail view'of the central portion of the clutch-shifting lever on line 4+4 Fig.3; i it Fig; 5 is a detail side elevatiomon an-enlarged scale, of a portion ofthe frame, the steering-mechanism and the lifting mechanism operable by the tongue showing the same as supporting the frame in elevated position with thetongue connected to the lifting mechanism; and, i

Fig. 6 is a similar view showing the tongue disconnected from the liftingimechanism.

The hoisting device as illustrated in the accompanying drawings comprises a main frame having side bars 1. preferably of transverse girder 2 and a fronttransverse girder 3whichrpreferably is of channel form and rests upon and lie secured to the upper flanges of the side bars .1.

Brackets'i,securedito therear ends of the side bars 1 are provided nals to receive a shaft 5 having wheels '6 which support the rear end ofthe frame. A pair of legs 7, which are secured to the front crossgirder 3,-senve normally to sup- With suitable jourport the front end of the frame, suitable means, which will hereinafter be described, being provided for raising the front end of the frame when the hoisting device is to be transported from place to place.

A pair of vertical guiding standards 8 desirably are supported centrally of the main frame and are secured to the cross girder 2. These standards desirably are made in foldable sections connected by hinges.

As illustrated herein the upper end of the lower section 8 of the standard is provided with a forwardly extending hinge member 9 which is pivotally connected preferably by a transverse shaft 10 to a complementary hinge member 11 which is secured to the lower end of the upper standard section 12.

One of the features of the present invention comprises novel means for locking the standard sections together when superimposed in alinement, such means being particularly designed to enable the upper section to be automatically retained in place when raised to vertical position, the locking means also being so construced that one may be released and moved out of locking position to enable the operator to release the other locking member while standing in position to grasp and lower the upper standard section, the purpose of this novel locking mechanism being to insure the locking of the upper sections when raised to verti cal position and to prevent accidental dropping of the section by the operator when the locking mechanism is released.

The preferred means comprises two similar locking devices reversely arranged upon the upper and lower sections of the respective standards, one being operable by the action of gravity to lock the standard sections together, and the other removable by the action of gravity from locking position.

The particular construction illustrated comprises a U-shaped strap or keeper 13 which is pivotally mounted upon a stud 14c in one of the members 11 and is adapted to engage beneath the under surface of a projection or horn 15 in the complementary member 9. A set screw 16 passes through the curved portion of said strap and engages the under face of the projection 15 and when set up serves to lock the parts firmly in position.

The other locking member comprises a similar U-shaped strap or keeper 17 which is pivotally mounted upon a stud 18 upon the other lower hinge member 9 and is adapted to engage a projection or horn 19 upon the complementary hinge member 11, a set screw 20, which passes through the curved portion of the strap, serving likewise to clamp the locking devices firmly.

The projections or horns 15 and 19 are provided respectively with curved upper and under faces which serve to force the straps or keepers laterally when the frame sections are swung into or out of vertical position.

By reason of this construction the strap 18 will be swung laterally as the upper section 12 is raised into vertical position so that the strap will slip over the projection or horn 15 and prevent accidental dropping of the upper section after it has once been raised. The other strap member 17 may thereafter be raised into locking position and the set screws 16 and 20 set up to insure positive and unyielding engagement of the locking members.

\Vhen it is desired to lower the upper section of the standard the strap 20 is first released and permitted to drop by gravity from engagement with the horn 19. There after the set screw 16 is released and after the operator has secured a firm hold of the upper section the strap member 15 is swung laterally until it disengages the horn 15. The upper section may then be lowered by the operator.

By reason of the fact that these locking members must be released separately there is practically no danger of unexpected or inadvertent dropping of the upper section of the standard.

Load supporting means are arranged to be moved vertically upon and guided by the vertical standards and suitable hoisting mechanism is provided for elevating the load supporting means.

In the preferred construction illustrated herein the load supporting means is in the form of a carriage having a vertically movable frame slidably mounted upon said standards and provided with a horizontal platform. The carriage frame comprises rertical side members 21, preferably channel bars, located upon the outside of the standards 8, and adjacent thereto, connecting cross members 22 and 23 and horizontally extending platform supporting members 24; which are connected to the side members 21. A platform 25, rests upon and is secured to the platform supporting members 24 and preferably a plurality of anti-friction rollers 26 are mounted upon the platform 25 to enable heavy articles placed thereupon to be readily removed.

A pair of anti-friction rollers 240. mounted upon a suitable shaft journalled in the platform supporting members 2 1. engages the rear walls of the vertical standards 8 and a similar pair of anti-friction rollers fill carried by a shaft which is mounted in suitable brackets 242 extending forwardly from the upper end portion of the side members 21 of the platform carrier engage the front faces of the vertical standards 8. By reason of this construction the weight of the platform and the load supported upon it forces the rollers 240 and 241 into engagement respectively with the front and rear faces of the vertical guiding standards 8 and enable the load supporting means to be raised easily by the hoisting. mechanism while the side members 21 of the platform carrier, which lie outside of and embrace the vertical guiding standards 8, prevent any lateral movement of the load supporting means which might otherwise occur by reason of uneven loading of one end of the platform. f

The transverse members22 and 23 of the carriage, also desirably are connected by braces 27 which converge from the upper transverse member 22 and overlap and are secured to the member 23 by a bolt or pin 28 to which the hoisting mechanism disclosed in the present embodiment of the invention is connected. i

. The preferred form of hoisting mechanism illustrated herein is in the form of a rope and Windlass r winch. The rope 29, which is connected by. the pin or bolt 28 tothe frame, passes over a suitable sheave 30 which is carried by a bracket or frame construction 31 mountedbetween a transverse girder 32 and a top girder 33 of the upper section of the standard. The rope, passing over the sheave 30, is connected to a winding drum 34 carried by a shaft 35 which, together with the Windlass-actuating mechanism, is mounted upon vertical standards or ;a frame mechanism located in front of the vertical standards 8. i

This frame mechanism, as illustrated herein, comprises a vertical member, pref-- erably a channel bar 36, which is secured at its bottom to the crossgirder 2 of themain frame, extends upwardly intermediate of the standards 8 and is secured at its upper end to a cross girder 37.

The rear ends of the shafts of thewind lass and certain of the hoisting mechanism are mounted in this channel bar or in brackets carried thereby. The other endsof such shafts are mounted in a suitable vertical frame member or standard 38, preferably in the form of a channel bar, whichis carried by the forward transverse girder 3 of the main frame. The vertical standard 38 is connected to the channel bar construction 36 by one or more horizontal girders 39.

Any suitable means may be provided for actuating the indlass 34 to elevate the load supporting means. As illustrated herein a gear 40, which is fixedly secured to the Windlass drum and shaft 35, engages a pin. ion 41 upon a countershaft 42 which is provided with a gear 43 which meshes with a pinion or gear 44 rotatably mounted upon a winding shaft 45.

Suitable means are provided for releasalbly connecting the gear 44 to the winding shaft 45 as will be hereinafter more fully described. H a

The winding shaft 45 may be driven in any suitable manner. Two means are illustrated herein for actuating this winding shaft, one being a crank 46 which preferably is detachably secured to the end of the shaft 45 which extends forwardly beyond the frame. The other driving means comprises an electric motor 47 the base of which is mounted upon the transverse girders 39 of the forwardly extending frame. The shaft of the electric motor has a gear 48 which meshes with a reducing gear 49 upon a stud shaft 50 from which rotation is transmitted to the winding shaft 45.

, In the particular construction illustrated herein a sprocket wheel 51 on the shaft 50 drives a sprocket chain 52 which passes over a sprocket wheel 53 which is fixedly secured upon the winding shaft 45, but obviously other usual power transmitting mechanism may be substituted for this chain drive.

7 A ratchet 54, fixedly secured to the shaft 45 and a co-operating pawln55 pivotally mounted upon the vertical central channel member or standard 36, serves normally to prevent retrograde movement, of the winding shaft 45. The pawl 55, however, may be so mounted as to be swung out of engagement with the ratchet to permit lowering of the platform by retrograde rotation of the winding shaft.

One of the principal objects of the present invention consists in providing progres. sively movable controlling means for lowering the load supporting means and means for arresting the descent of the load supporting means upon interruption of the progressive movement of the controlling means, the purpose being to provide means which will compel progressive movement of the controlling means to enable the load supporting means to be lowered so that any interruption of said progressive movement will cause the arrest of the descent of the load supporting means. By this invention the operator is required to maintain control of the descent of the load supporting means throughout its entire descent and the acci dental dropping of the load supporting means is, therefore, avoided. v

The controlling mechanism preferably comprises co-operating clutch members fixedly secured respectively upon the winding shaft 45 and the gear 44 which is rotatably mounted thereon and differentially operable lever mechanism for controlling the clutch members, the winding shaft 45 being held from retrograde movement by the pawl and ratchet mechanism above described, or in any other suitable manner.

In the preferred construction illustrated herein the differentially operable clutch mechanism comprises a manually operable clutch-releasing lever and a compensating lever upon whichthe clutch-releasing lever is fulcrumed, the compensating lever being moved in the opposite direction from that of the clutch-releasing lever by means actuated by the descent of the load supporting means so that upon interruption of the progressive releasing movement of the clutchreleasing lever the compensating lever will cause reengagement of the clutch members and, since the winding shaft is held against retrograde rotation, will arrest the descent of the load supporting means.

The clutch-releasing means which is illustrated in Fig. 1, and in the enlarged detail view Fig. 3, comprises a pair of frictional disks 56 and 57 which are secured to the winding shaft 45 and are rotatable. therc with, and a pair of con'ipleinentary frictional disks 58 and 59 which are secured to the rotatable gear 44 by suitable bolts passing through the disks and said gear. The frictional disks 56 and 57 desirably are provided with facings 60 of fibrous material of any usual character,

The frictional disk 56 desirably is formed integral with the ratchet 44. and is seemed to the winding shaft 45 by a pin 61. The frictional disk 57 is slidably secured upon the shaft, but prevented from rotation thereupon by a feather 62. The hub of the disk 57 has a flange (53 which is engaged by a suitable clutch-actuating mechanism preferably in the form of a clutch-shifting lever 64 which is pivotally mounted upon a bracket 65 carried by the transverse girder 39, or some other member of the supporting frame. The lever 64, which is shown in elevation in Fig. 4, is provided with a central aperture 66 the walls of which are provided with diametrically oppositely positioned recesses or grooves 67 to receive trunnions 68 of a yoke-shaped member 69 which embraces the flange 63 upon thehub of the clutch member 57. A helical spring 7 0,'surrounding the winding shaft 45 and abutting at one end against the bearing 71 of the winding shaft and at its opposite end abutting against the flange 63 of the clutch member 57 normally tends to force the clutch member 57' longitudinally of the winding shaft 45 and to cause positive and effective engagement between the clutch disks 57 and 56 of the winding shaft and the clutch members 59 and 58 of the gear 44. v

The clutch-shifting lever is actuated through a slotted link 7 2 which is connected to said lever by a pin 7 3 extending through the bifurcated end of the clutch-shifting lever. The slotted link section 72 is connected by a screw connection to a section 74 which in turn is pivotally connected to a stud 75 upon a clutch-releasing lever 76.

By reason of th screw threaded connec tion between the sections 74 and 72 of the link the length of the link may be adjusted Meade? and a suitable nut may be provided for retaining these sections in properly adjusted positions.

The clutch-releasing lever 76 is fulcrumed upon a stud 77 upon a compensating lever 7 S which is fulcrumed upon a stud or bolt 79 upon the vertical member 38 of the front portion of the frame. The lower or free end of the compensating lever 7 8 is pivoiaily connected to a link 80 which is' moved in a direction opposite to the direction of movement of the clutch-releasing lever by mechanism operated by the descent of the load supporting means,

As illustrated herein the link 80 is slidably mounted in a-journal in a bracket 81 which is mounted upon the transverse girder 3 and extends well through said 1ournal. The end of the link 80 is screw threaded and is engaged by coi'nplementary internal screw threads in a nut 82 of a rotatable member 83 which is suitably supported in the lower portion of the frame.

The rotatable member 83, which is illustrated herein, is substantially cylindrical in form and provided with an enlarged hollow cylindrical portion 84, in which the nut member 82 is in the form of a web extending across a chamber in said rotatable member. At one end the rotatable member is provided with a journal and stuffing box which is rotatably mounted upon the link 80. A gear 86 is securedupon this end of the rotatable member and meshes with the gear 40 of the winding drum. The opposite end of the rotatable member is provided with a cylindrical axial aperture 87 which receives the end of a stud shaft 88 which is mounted upon a bracket 89 carried by the vertical channel,member 3G. The end of the rotatable member 83 abuts against the bracket 89 so that longitudinal movenient of the nut member is prevented.

A chamber 90 in the enlarged portion of the rotatable member 83 provides a lubricant reservoir and apertures 91 in the web or nut portion 83 establish communication between the portions of the chamber "90 which lie upon the opposite sides of the web.

A plugged oil hole 92 provides means for introducing lubricant into the aperture 87 and the chamber 90.

The chamber 90 has a furthe r function of providing an expansion chamber to prevent anaccumulation of hydraulic pressure in the chamber 90 when the link St) is forced end-wise into the chamber by the rotation of the rotatable member 83.

In the operation of the machine, with the parts positioned as illustrated in. Fig. 1, the clutch members 56 and57 upon the driving shaft engage positively the coi'nplementary clutcl'rmembers 58 and 59 of the nut 44 so that rotation of the winding shaft 45, acting through the train of gears 43, 41 and 40,

elevation.

rotates the Windlass 34 in a direction to Wind the cable 29 upon the Windlass, thereby raising the load supporting means. The pawl 55, which engages the ratchet 54 upon the winding shaft, prevents retrograde movement of the 'windingshaft so that the load supporting means may be sustained at any desired elevation to permit the discharge of'a load from, or the placing of a load upon, the platform of the load sup porting means when in such position. Consequently, the platform nay be loaded and unloaded either when in the loweredposition illustrated in Fig. l,or

Consequently, boxes, barrels, etcqmaybe piled up or tiered Conveniently by this machineg a When it is desired to low'erthe platform,

either when loaded or unloaded,from any elevated position, the operator grasps the clutch-releasing lever 76 and movesthe same progressively, toward the left as illustrated in the drawing. This movement of" the lever draws the sectional links 74 and 72 to the left and thereby swings the clutch shifting lever 64 about its pivot and releases 1 the clutch members 57 and 56 from effective or positive engagement with the complementary clutch members 59 and 58 respectively so that the gear 44 is permitted to rotate upon the winding shaft 45.

The leverage of the clutch-releasing lever is such that a considerable movement of its handle is required to actuate the clutchshifting lever; consequently, the clutch members will be gradually removed from engagement and a braking action upon the clutch members 58 and asthe Weight oftheload acting through the Windlass and train of gears rotatesthe gear 44 ina retrograde direction. During this retrograde movement the Windlass gear 40 drives the gear 86, thus rotating the rotatable member 83 and causes its nut'82 to force the link which it engages inwardly, to the right.

clutch-releasing lever 76 so that upon any interruption of the progresslve 'movement by the operator of the clutch-releasing lever the i compensating lever will permit the thereby breakfand quickly arrest the descent of the loadsupporting means. 1

Any excess of longitudinalmovement of the link80 to the right afterthe clutch members 57 and 56 havepositively engaged the complementary clutch: members 59 and 58 of the nut 44 will be relieved. by a the movement :of the slotted move the handle supporting means.

at any desired 59 will be effected,

This moves the lower end of the compensatinglever to the rightinthe' opposite direction to the movement of the tongue in a position in which it can otation of the rotatable nut-carryingmember 83-, and consequent end of th'elink 72"upon tliestud 73 of the lever 64. A a

By reason of this construction, therefore, the operator is required to progressively of the clutch-releasing lever, to the left, in

remains continuously under the control of the operator during its entire lowering movement and any inadvertent arrest ofthe progressive movement'of the lever will almost immediately stop the descent of the load supporting means.

Another feature of theinvention consists in providing a novel hoisting mechanism for raising the front end of the frame so that it will be supported upon suitable steering mechanism with the legs 7 of the frame removed from the floor a sufiicient distance to permit thehoisting device to be trans order to lower the load Consequently, the load ported from place to place as a truck, either i when loaded or unloaded.

As illustrated herein the steering mecha nism comprises a front steering wheel 93* having a'steering and slidably journalled in a bracket 95 which'is secured to the-front end of the post 94 which is rotatably frame,preferably to the standard '38. A

collar 96 is fixedly secured to the upper end of the steering post 94 and is provided with apair of upwardly extending ears 'or lugs 97 carrying a 'transverse shaft, 98 upon whichthe steering tongue and a member of thelifting mechanism for the frame is pivotally mounted.

The steering tongue desirably is made in telescopically movable sections, one of which comprises a tubular member 99 having arms 100 which are pivotally mounted on the shaft 98 outside of theears 97011 the collar 96. The "arms 100 desirably are provided with extensions presenting shoulder-s 101"" so formed as toengage stop shoulders 102 t upon the collar when the tongue 1s ralsed nearly to vertical position. The engagement of the shoulders 101 and stops 102' serves to prevent the steering tongue from swinging upwardly beyond a predetermined distance and alsoprovides means for arresting the upward movement of the to push the truck rearwardly.

The other section 103 of the tongue, which desirably is of tubular form and is provided with theusual transverse handle 104, is slidably mounted at its lower end in the tubular be used member 99. The tongue member 103 is pro 1 vided with a pin 105which extends into oppositely disposed slots 106' in the tubular member 99 so that the tongue .section 103 may have a short longitudinal movement urelatively to the tubular member 99 ofthe tongue .mechanism, the purpose of thisf longitudinal movement being to i provide :means for releasably locking the vertical of the frame comprises a toggle construe-a tion consisting of a bell crank lever 107, the upper arm of which is pivotally connected by a stud 108 to the lower end of a link 109 which is pivotally connected at its upper 'end to a stud 110 in a swivel 111 the shaft 112 of which is rotatably journalled in a bracket 113 secured to the standard 38. The bell crank lever 107 has a downwardly eX- tending arm 11.4: which is so constructed and positioned as to engage a shoulder 115 upon the inner end of the tubular member 99 of the steering tongue, and the member 103 of the steering tongue when forced inwardly or toward the truck in the tubular member 99 engages beneath the cndof the arm 114 of the bell crank lever thereby effectively locking the bell crank lever to the telescoping tongue members.

In the normal position of the hoisting machine, when the legs 7 are resting upon the'floor, the pivotal connection 108 of the toggle mechanism is swung to the left of the line connecting the pivots 98 and 110 of the togglemechanism as illustrated in Fig. 1. Inthis position the shoulder 115 of'the tubular section of the steering tongue is in engagement with the end of the arm 114 of the bell crank lever and the end of the telescoping section 103 of the tongue extends beneath the end of the bell crank leverso that said end of 'the bell crank lever is clamped between them.

hen it is desired to raise the front end of the frame upon the steering mechanism' and to lift the legs 7 fromthe floor so that the-hoisting machine may be transported from place to place the operator swings the tongue 103 downwardly thereby rocking the bell crank lever 117 about its pivot 98 until the pivot 108 connecting the upper end of the bell crank lever with the link 109 swings across the line connecting the pivots 98 and 100 and until the arm 11 1 of the bell crank lever rests'upon the shoulder 116 upon' the upper end ofthe' collar 96. During this movement the steering post 94 is forced downwardly and consequently raises the front end of the frame from the floorand when the arm 114 of the bell crank lever has been swung downwardly to engagement with the shoulder 116 the pivot 108, connecting the bell crank lever with the link 109,Wlll have swung across the line connecting the axes 98 and 110 and consequently will lock the platform in elevated position.

hen the elevating mechanism is thus locked the member 108 of the tongue may be pulled end-wise so that its end will pass from beneath the end of the bell crank arm 114 so that the tongue may be raised to steering position.

The shaft 112 of the swivel is in vertical alinement with the axis of the steering post 1M so that the tongue may be moved to any guiding position for pulling, pushing or steering the truck without disturbing the position of the lifting mechanism.

It will be understood that the embodiment of the invention herein is of an illustrative character and is not restrictive and that the mechanisms herein claimed may be adapted for other purposes than in a hoisting machine within the spirit and scope of the following claims.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is:

1. A hoisting device comprising load supporting means, means for raising said load supporting means including cooperating rotatable clutch members, means for preventing retrograde rotation of one of said clutch members, progressively movable controlling means operable to release said clutch members from effective engagement and means for restoring said clutch members into effective engagement upon interruption of the progressive movement of said controlling means.

2. A hoisting device comprising load supporting means, means for raising said load supporting means including co-operating rotatable frictional clutch members, resilof one of. said clutch members, progres-,

sively movable controlling means operable to release said clutch members from effective engagement and thereby to permit descent of the load supporting means and means automatically operable upon the descent of said load supporting means for restoring said clutch membersinto effective engagement upon interruption of the progressive movement of said controlling means.

A hoisting device comprising load supporting means, means for raising said load supporting means including cooperating rotatable frictional clutch members, resilient means normally acting to force said clutch members into effective engagement, means for preventing retrograde rotation of one of said clutch members, a progressively movable clutch-releasing lever connected to one of said clutch members operable to release said clutch members from effective engagement and'therelo'y to permit descent of said load supporting means and a compensating device connected to said clutch-releasing lever and means operable by the descent of said lead supporting means to cause said compensating device to tend to neutralize the movementof said clutch-releasing lever and upon interruption of the progressive movement thereof to restore said clutch members into effective engagement.

4. A hoisting device comprising load supporting means, a Winding shaft, means for holding said shaft against retrograde rotation, a gear rotatably mounted on said winding shaft, co-operating clutch members fixedly secured respectively to said gear and Winding shaft, operable by the rotation of said Winding shaft to elevafe said load sup-- porting means, progressively movable controlling means operable gradually to release said clutch members from effective engagement and compensating means operable by the descent of said load supporting means to restore said clutch members to effective engagement upon interruption of the progressive movement of said controlling means and thereby to arrest the descent of said load supporting means.

5. A hoisting device comprising load supporting means, a winding shaft, means for holding said shaft against retrograde rotation, a gear rotatably mounted on said winding shaft, co-operating clutch members fixedly secured respectively to said gear and winding shaft, operable by the rotation of said Winding shaft to elevate said load sup porting means, differential clutch-controb ling mechanism comprlsing a clutch-releas ing lever progressively movable to release said clutch members and permit the descent of said load supporting means and a compensating member operable by the descent of said load supporting means tending to neutralize the effective movement of said clutch-releasing lever and operable to restore said clutch members to efiective engagement upon interruption of the progressive movement of said clutch-releasing lever.

6. A hoisting device comprising load supporting means, means for elevating said load supporting means including a windlass having a gear, a winding shaft, means for holding said shaft against retrogradeiroize the effective movement of said clutchreleasing means and acting to restore said clutch members to positiveengage-ment upon interruption of the progressive movement of said controlling means.

7. A hoisting device comprising load supporting means, means including a Windlass, having a gear, for elevating said load supporting means, a winding shaft, means for rotating the same in one direction and means for holding said shaft against retrograde rotation, a gear rotatably mounted on said ,winding shaft operable to rotate said windsaid clutch-releasing lever to arrest the descent of the load supporting means.

8. A hoisting device comprising load supporting means, means including a Windlass, having a gear, for elevating said load supporting means, a winding shaft, means for rotating the same in one direction and means for holding said shaft against retrograde rotation, a gear rotatably mounted on said winding shaft operable to rotate said windlass gear, co-operating clutch members rigid respectively With said Winding shaft and said winding shaft gear, differentially operable clutch-controlling means including a' manually operable clutch-releasing lever and a compensating lever upon which said' clutch-releasing lever is fulc-rumed, a screw connected to said compensating lever, a nut on said screw having a gear engaging said Windlass gear and operable by the reverse rotation of said Windlass, when said clutch members are released from effective engagement, to move said clutch-releasing lever in a direction tending to restore said clutch members to effective engagement and acting upon interruption of the progressive movement of said clutch-releasing lever to arrest the descent of the load supporting means. 7

In testimony Whereof, I have signed my name to this specification.

RALPH M. LOVEJOY,

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