US2348382A - Safety device for hoisting mechanism - Google Patents

Description

E. G. HALBY 2,348,382

' sAFE'TY nnvIcE Fon HoIsTING MEcHANlsM 'Filed sept. 17, 1942 s sheets-,sheet 1 AMM;

May 9 1944- E. G. HALBYl Y "2,348,382

SAFETY DEVICE FOR HOISTING MECHANISM Filed sept. 17, 1942 s sheets-shed 2 May 9, 191141` E. G. HALBY 2,348,382

` `SAFETY DEVICE Fon HoLsT'ING MEQHANISM y Filed sept. 1'?, 1942 s sheets-sheet s Y leased.

Patented May 9, 1944 I SAFETY DEVICE FOR HOISTING MECHANISM Edwin Halby, Marion, Ohio, assigner to The Marion Steam Shovel Company, Marion, Ohio, a

corporation of (ihiov ApplcationSeptember 17, 1942, Serial No. 458,745 s Claims. (C11. 254.487)

This invention relates to a safety device for hoisting mechanism of the drum and cable type and is designed primarily to prevent the falling of the load in the event the hoisting drum is accidently or inadvertently released from its driving mechanism. In hoisting mechanisms of this type the hoisting drum is usually connected with the driving mechanism by a clutch and it is comm-on practice to lower the load by releasing `the clutch and controlling the rotation of the drum in load lowering direction by means of a brake. If the drum is released by the failure of the clutch or the brake, or otherwise, it is free to rotate under the weight of the load on the cable and the load will fall with more or less disastrous results. In hoisting mechanisms of the boom type, such as cranes, excavating machines and the like, in which the boom is supported and movedv to adjusted positions by a hoisting drum and cable the accidental or inadvertent release of the boom hoist drum is particularly serious as the'falling of the boom will usually seriously damage or destroy the same, thus rendering the hoisting mechanism as a Whole useless until the boom has been repaired or replaced.

. One object 'of the invention vis to provide a hoisting mechanism with La simple and efficient' device which will operate automatically to pre-` vent the falling of the load in the event the hoisting drum is accidentally or inadvertently re- A further object of the invention is to provide such a device which will in no way interfere with the normal hoisting and lowering operations of the hoisting'mechanism. I

A further object of the invention is to provide such a device which will prevent any appreciable downward movementof the load when the driving mechanism is not operating and will retard the downward movement of the load to a safe speed when the driving mechanism is operat- A further object of the invention is to provide' such a device which will permit the drum to rotate in load lowering direction at a speed determined by the driving mechanism.

Arfurther object of the invention is to provide such a device which will permit the drum to rotate in load lowering direction while the driving mechanism rotates Vin load lifting direction, and will limit such rotation of theV drum to a speed determined bythe driving mechamsm' i .i

`Other objects of the invention `may appear as the mechanism is described'in detail.

In the accompanying drawings Fig. 1 is a plan view of the platform and hoisting mechanism of a crane equipped with my invention, with the gantry in section; Fig. 2 is a section taken on the line 2-2 of Fig. 1, looking in the direction of the arrows, with the gantry partly broken away; Fig. 3 is a longitudinal sectional view of a clutch mechanism forming a part of the safety device, taken on the line 3-3 of Fig. 1, looking in the direction of the arrows; Fig. 4 is a section taken on the line 4-4 of Fig. 3, showing the clutch mechanism in end elevation and partly broken away; Fig. 5 is a detail view of one of the supporting members of the clutch mechanism; Fig. 6 is a detail of an anchor for the spring for the clutch members; and Fig. 7 is a sectional detail view of a portion of the hoisting drum and the driving clutch and brake mechanism therefor.

VIn these drawings I have illustrated one embodiment of my invention and have shown the same as applied to a crane of a known type but it will be understood that the invention may take various forms and may be used in connection with hoisting mechanisms of various kinds.

The crane as here illustrated comprises a platform I0, which is usually mounted on a truck supported base, not here shown, for rotation about a vertical axis. A boom II is pivotally supported on the front end of the platform for vertical movement and, as here shown, is mounted on a supporting member or bracket I2. This boom is moved to and supported in adjusted positions by a cable I3 secured to the point of the boom, extending rearwardly therefrom about a sheave I4 carried by a gantry I5 and thence downwardly to a hoisting drum I6 to whichlit is secured and about which it is wound. In this particular arrangement a single length of cable is dead-ended on the boom but in many installations the end of the cable is anchored on the gantry and that portion of the cable between the boom and the gantry is passed about sheaves on the boom and gantry. The hoisting drum I6 is mounted on a shaft I 1 for rotation thereon and is connected with and disconnected'from the driving mechanism by means of suitable clutch mechanism. This driving clutch mechanism maybe of any suitable character and, as here shown, it comprises a` circumferential iiange or clutch member I8 rigidly connected with the drum and having inner and outer friction surfaces. An internal friction band I9 is carried, in the present instance, by a gear 20 keyed to the'shaft II and cooperates with' the innerfriction surface of the ber f8 is also operated in a well known manner. A second hoisting drum 2l is also mounted on a shaft El to4 receive andoperate theload elevating cable 22 which extends about a sheave'23 on the point of the boom. In the rear of the drum 2l there is shown at 24 a part of the mechanism for swinging the platform about its vertical axis.

forms any part of the present vinvention but it will be understood that the 'sfafety'device may; if desired, be applied to the hoisting drum 2i 1n the same manner that it is applied to the boom` hoisting drum I6, as hereinafter described.- Thedriving mechanism for the hoisting drums-lr6` may be of any suitable type and, in the illustrated arrangement, itV comprises a driving shaft 25 which is, driven by a motor 28,- tlie driving connection being here shown as rasprocket chain 21 ex-v tending; about sprocket wheels secured respectively to the motor shaft and to the driving shaftA 25. lA pinion 28 rigidly secured to the rijriyirrg shaft 25 meshes with the gear 2n of the clntch mechanism so that the gear rotates in a; direction opposite te the direction ef remmenr of the driving shaft and when the clutch is set the hoisting drum will, ofcourse, rotate in the same direction as the gear. In the hoisting operetre-rr of rire mechanism here illustrated the driving shaft rotatesin the direction of the arr-ow b on"ig. 2 and thev hoisting drum rotates in the direction of the arrow When the boom has teer. adjusted te the desiredp'esiuerr me brake band ita is set to retain the boom in that posie tion. AWhen the boom is to be lowered the brake is released sufficiently to vpermii.theslow 'rotation of the drum in load lowering direction. Should the connection Kbetween the hoisting drum l5 and the 'driving mechanism bev accidently or inadvertently interrptedas by 'the failure of the driving clutch lor brake, the drum I6 Vwould be free @o retate out of control andthe boom would far., ,.1

` 'nt the uncontrolled downward movementof the boom, or other load on' the drum, 'in the event the 'cro'rjn is accidentally er irradvertgently releasedj have `provided ande'vice controlled by the drum for automatically :control-- ling Vits 'rotation so as toyprevent or retard the rotation of lthe drum in'loagd 'lowering direction. Preferably this'd'evice compriseslja'rotatable elenient drivingly` connected with the drum for rotation therewith in either 'direction' in which the drum may rotate and means controlled by theY direction of rotation of Vthat element for positively locking the same Aagainst 'rotation in a load loweringdirecti-on with relation to va' second element. The Vdevice may conveniently be in the formY of a one-wayuclutch, the two members'of which are connected V.respectively Vwith 4the drive ing mechanism and the drum 4for rotation'there-.- by in opposite directions when the drum is rotated in load hoisting directionand for rotation inthe same direction when the drum is rotated in load lowering direction, means being provided for automatically preventing the'drum driven-,member 'from rotating in load lowering direction ata speed greater vthan the speed at which the other member Trotatcs.

l. n1 rhefparueuiarembourmenthere 'illustrare-r1 'z5' the one-way clutch comprises a member 29 rigidly secured t0 the shaft il and a second member 3o rotatably mounted on that shaft and having secured thereto a sprocket wheel 5i winch is connected by a sprocket chain 32 with a sprocket wheel 33 rigidly secured to the drum. The member 3&3 is provided with a circumferential friction surface extending about the member 29 and here shown as the inner surface 34 of a flange 35 carried by and forming a part of the member the flange being provided on its outer surface with heat radiating fins 3G. The

Neither the drum 2| nor the swinging mechanism .member 29 being rigid with the shaft Il will of course rotate in a direction opposite to the direction of londhoisting' rotation of the drum while Athenreinber' 36,'through the sprocket chain drive, will rotate in the same direction as the drum. Clutehin-gdevices, such as friction shoes 3l, are arranged to engage the friction surface of the member 3o and are so connected with the member 29 that they will rotate with that member but may have a limited movement with relation thereto to enable them to be moved into and out of clutching engagement with the friction surface 34. The clutching devices 3l may be connected wither rsupported by the clutch member 29 in any suitable manner but preferably they are carried by supporting members mounted on the member 2S for rotation therewith and for movement with relation thereto about axes arranged on opposite sides Vof and spaced from the of rotation of the member 29. In the pres. ent construction the member 29 is provided with plates d3 rigidly connected with the clutch mem-V ber 29. The two supporting members `are provided respectively, on opposite sides of the clutch member 29, with arms44 to which the friction shoes 31 are pivotally connected by pins`45. Each supporting member'has in that side thereof opposite the pin .45 .a slot 46 to receive the head of the shoe supporting :pin '45 of the other supporting member.. The pin and'slot connections betweenv the two members limit their relative movement ontheir respective eccentric :bearing surfaces and maintain the same in .proper relative positions, but the slots 46 are 'of a Width su'iciently greater than the diameter of the pin heads to permit of a slight movement of each `menfrber with relation to the other member.. The arrangement of the supporting members and friction devices is 'such that the latter are so supported with relation to the friction surface l34 that when the two clutch members, 29 and '30, rotate in opposite directions the movement of the supporting members Kon their eccentric bearing surfaces will .permit the friction devices to be Vmoved by the drum 'driven clutch member Sllfto non-'clutching positions, and when the clutch'membe'r 30 rotates'in the same direction as the "clutch member 29 and tends to rotate 'at a'greater speedthan the methber 29 the shoes will be move'dinto clutching en'- gagement with the friction surface 3'4 to connect the two members one with the other and the speed of rotation of the member 30 will be limited t'o that of the member 29. If the clutch member- 39 `tends to rotate in thel'ast mentioned-direction while the clutchl member T29 islheld against rota..

tion the clutchingshoes will engage the friction surface 34 land positively lock the member 3D against such rotation.

1, In order g that the clutching operation of the clutch shoes` may be quickly effected when rotative force exerted on the clutch member 39 tends to rotate,A that member in the same direction as and `with relation to the clutch member 29, they shoes are maintained at all times in light contact with the friction surface 34 but this contact is not sufncient to interfere with the relative rotation of the clutch members, or to produce objectionable heat, when those members rotate in opposite directions. As here shown, each supporting member is acted upon by a spring 41 to move the same in a direction to maintain contact between the clutch device and the friction surface. Each spring is connected at one end with a projection 48 on the corresponding supporting member 4| and at its other end with a pin 49 mounted in the adjacent plate 43 and the circumferential projection 5i) and extending across a narrow portion of said supporting member.

In the normal operation of the hoisting mechanism the motor drives the shaft 25 in a direction to rotate the hoisting drum I6 in load hoisting direction, that is, a direction which will cause the cable to elevate the point of the boom and which is opposite to the direction of rotation of the shaft 25 and the clutch member 29. The hoisting drum when thus rotated by the driving mechanism rotates the clutch member 30 in the direction of rotation of the drum which, as above stated, is opposite the direction of rotation of the member 29. This opposite rotation of the two clutch members causes the clutching devices or friction shoes to be moved to non-clutching positions so that the two clutch members can rotate freely so long as the hoisting drum rotates in load hoisting direction. When the hoisting drum is disconnected from its driving mechanism, either intentionally or accidentally, and is not restrained by the brake, the weight of the load on the drum tends to rotate the same in a reverse or load lowering direction and the force thus exerted on the drum tends to cause the clutch member 30 to rotate in the same direction as the clutch member 29 rotates. The friction surface 34 being at all times in light contact with the clutching shoes any tendency of the clutch member 38 to rotate at a speed greater than the speed of the clutch member 29 will cause the shoes to tightly grip the clutch member 39, thereby locking the member 39 against rotation with relation to the member 29 in the direction in which the latter is rotating and preventing the rotation of the drum in load lowering direction at a speed greater than that permitted by the rotation of the shaft I1 and the clutch member 29. The continued operation of the driving mechanism, in the initial direction, thus causes the load to be lowered at a safe speed. Due to the fact that both clutch members are rotating in the same direction at the time the locking action takes place locking is effected and the lowering of the load is checked without subjecting any part of the mechanism to severe shock or strain. If the drum and clutch member 39 tend to rotate in load lowering direction while the driving mechanism is inoperative the clutching shoes will instantly grip the clutch member 3i! and lock the same against such rotation before any appreciable rotation has been imparted thereto, thus positively locking the hoisting drum against rotation inf-load lowering direction and preventing the downward movement `of the boom or other load.;,,.'V

While I have shown and describedv one embodiment of my invention I wish it to be `understood thatl do not desire tobe limited to the details thereof asvarious modifications may occur to a person` skilled inthe art. i.

Having now fully described my invention, what I claimas new anddesire 4to secure by Letters Patent, is:

1. In a hoisting mechanism comprising a hoisting drum, a load supporting cable wound on said drum, a shaft, means for rotating said shaft, and a driving connection between said shaft and said drum to impart load hoisting rotation to the latter in a direction opposite the direction of rotation of said shaft, Ia clutch including a member rigidly connected with said shaft, a second member rotatably supported on said shaft and having a friction surface extending about said rigidly connected member, supporting members mounted on said rigidly connected member for rotation therewith and for movement with relation thereto about axes spaced laterally from the axis of said shaft, and friction elements carried by said supporting members and movable to non-clutching positions by the rotation of said second member in a direction opposite the direction of rotation of said rigidly connected member and movable into clutching engagement with said friction surface of said second member by said second member when the latter tends to rotate with relation to said rigidly connected member in the direction of rotation of the latter, and a driving connection between said drum and said second clutch member to rotate the latter in the same direction that said drum rotates. 2. In a hoisting mechanism comprising a hoisting drum, a load supporting cable wound on said drum, a shaft, means for rotating said shaft, and a driving connection between said shaft and said drum to impart load hoisting rotation to the latter in a direction opposite the direction of rotation of said shaft, a clutch including a member rigidly connected with said shaft, a second member rotatably supported on said shaft and having a friction surface extending about said rigidly connected member, supporting members mounted on said rigidly connected member for rotation therewith and for movement with relation thereto about axes spaced laterally from the axis of said shaft, and friction elements carried by said supporting members and movable to non-clutching positions by the rotation of said second member in a direction opposite the direction of rotation of said rigidly connected member and movable into clutching engagement with said friction surface of said second member by said second member when the latter tends to rotate with relation to said rigidly connected member in the direction of rotation of the latter, a driving connection between said drum and said second clutch member to rotate the latter in the same direction that said drum rotates, and yieldable means to hold said friction elements in light contact with said friction surface when said clutch members rotate in opposite directions.

3. In a hoisting mechanism comprising a holsting drum, a load supporting cable wound on said drum, a shaft, means for rotating said shaft, and a driving connection between said shaft and said drum to impart load .hoisting rotation to the latter in a direction opposite the direction of rotation of the shaft, a clutch including a member non-clutching relation to said friction surface fby 10 the rotation of said clutch members in opposite directions and into clutching engagement with said friction surface by said second clutch member when rotative force is exerted on said second member in the direction of rotation of the rst mentioned clutch member, and fa driving connection between said drum and said second clutch member to rotate the latter in the same direction that said drum rotates.

EDWIN G. HALBY.

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