US3910559A

US3910559A - Arrangement for hoisting load

Info

Publication number: US3910559A
Application number: US404912A
Authority: US
Inventors: Zinovy Avramovich Sapozhnikov; Iosif Lvovich Fridman; Moisei Zalmanovich Fridman
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-10-10
Filing date: 1973-10-10
Publication date: 1975-10-07
Anticipated expiration: 1992-10-07

Abstract

In the arrangement, there are two drums disposed in parallel to each other and provided with annular grooves in their cylindrical faces to accommodate a load-carrying rope a length of which passes many times around both drums. In the arrangement, there is also a device for tensioning the length of rope; the device incorporates a roller disposed in a permanent resilient contact and acted upon by a force to hold down the rope to the drum, the force being sufficient to keep the rope from slipping over the drum and to relieve of tensioning the end of that fall of rope which is held down and hangs from a drum.

Description

United States Patent [191 Sapozhnikov et al.

[4 1 Oct. 7, 1975 ARRANGEMENT FOR HOISTING LOAD 22 Filed: Oct. 10,1973

21 Appl. No.: 404,912

[52] US. Cl. 254/184; 242/117; 242/155 BW [51] Int. Cl. B66D, 1/26 [58] Field of Search 254/184, 172, 175.7, 144,

254/186 R, 188; 242/155 BW, 117

' [56] References Cited UNITED STATES PATENTS 1,249,809 12/1917 Noble 254/l75.7 3,063,653 11/1962 Arnold... 242/117 X 3,717,325 2/1973 Peterson 254/175.7

FOREIGN PATENTS OR APPLICATIONS 422,222 1/1935 United Kingdom 254/188 Primary Examiner-M. Henson Wood, Jr. Assistant ExaminerRandolph A. Reese Attorney, Agent, or FirmHolman & Stern [57] ABSTRACT In the arrangement, there are two drums disposed in parallel to each other and provided with annular grooves in their cylindrical faces to accommodate a load-carrying rope a length of which passes many times around both drums. In the arrangement, there is also a device for tensioning the length of rope; the device incorporates a roller disposed in a permanent resilient contact and acted upon by a force to hold down the rope to the drum, the force being sufficient to keep the rope from slipping over the drum and to relieve of tensioning the end of that fall of rope which is held down and hangs from a drum.

9 Claims, 22 Drawing Figures US. Patent Oct. 7,1975 Sheet 1 of 10 3,910,559

HHHHH' IIIIHHW HHIHIHH ll "HIIIIHHH I FILE. 1

US. Patent Oct.7,1975 Sheet2of 10 3,910,559

US. Patent Oct. 7,1975 Sheet 3 of 10 3,910,559

Sheet 4 of 10 3,910,559

U.S. Patent Oct. 7,1975

US. Patent Oct. 7,1975 SheetS of 10 3,910,559

FIE 1U 5; 54 F/Ei Sheet 6 of 10 U8. Patent Oct. 7,1975

FIE IZ FIE I4 FIE I3 Sheet 7 of 10 U8. Patent Oct. 7,1975

Sheet 8 of 10 3,910,559 I US. Patent Oct. 7,197 5 US. Patent Oct. 7,1975 Sheet 9 of 10 3,910,559

US. Patent Oct. 7,1975 Sheet 10 of 10 3,910,559

ARRANGEMENT FOR HOISTING LOAD BACKGROUND OF THE INVENTION The present invention relates to arrangements for hoisting loads and may be used in the most expedient way as a portable winch or hoist intended to handle loads during equipment erection and repair jobs. It may also find application as a crane winch on the bridge crane, for example. i I

There are known rope winches comprising two drums disposed in parallel to each other, operated by a single drive and provided'with annulargrooves in their external cylindrical faces to accomodate a loadcarrying rope a length of which passes many times around both drums, and a device for tensioning the length of rope. Serving as a part of such device in known winches is the weight of the load hoisted by an end of rope with the aid of a load-holding attachment or, in the absence of the load, the weight of the loadholding attachment which may by a cab, cage, etc. Another part of the device for rope tensioning is the weight of the load, that of a load-holding attachment or a counterweight suspended from the other end of rope, or a drum wound on which is this end of rope.

A disadvanatage of such winches is their bulkiness and high weight which are natural, taking into account the design, and for this reason known winches are commonly not used to cope with equipment erection and repair jobs.

There are also known winches and hoists in which the rope is wound on a traction drum. They, too, are heavy and bulky because, before all, the traction drum is a long oneif the rope is wound in a single layer or a high torque must be applied to the winch drum ifthe rope is wound in a plurality of layers. The point is that the torque increases with each layer of the rope because thediamater of wraps increases too.

A disadvantage of these winches is that the rope may displace along the 'tractiondrum when this is beingrotated'. Consequently, the winch may cockbil in operation-and requires anchoring at more than one point. Taking this into account, such winches are commonly installed during erection jobs in a convenient place away from .the load being hoisted. The rope travels to the place where the load is being hoisted through fleeting sheaves,-embracing the latter. Since the rope displaces along the traction drum when this is being rotated, the winch must be placed at a considerable distance fromrthe nearest fleeting sheave, and this isanother disadvantage of the winch.

Used in equipment erection, and repair jobs are also chain hoists and lever operated hoists. A disadvantage of the former is a rapid increasein their weight with an increase. in the. height to which the load is being hoisted, because of the high weight of the chains used. A disadvantage of lever-operated hoists, which exert a pull of the rope with the aid of twopairs of clamps gripping the rope in succession and .a leverage of the traction mechanism, is the design making them impractical for use as manually-operated units and the need in a wire-core rope lacking adequate flexibility and being In accordance with these and other objects in an arrangement for hoisting loads comprising two drums disposed in parallel to each other, operated by a single drive and provided with annular grooves in their external cylindrical faces to accommodate a load-carrying rope a length of which passes many times around both drums, and a device for tensioning the length of rope, the device for tensioning the length of rope passing many times around both drums incorporates, according to the invention, at least one roller which is disposed in permanent resilient contact with at least one of the falls of the rope and is acted upon by a force to hold down the rope to the drum, the force being sufficient to keep the rope from slipping over the drum and to relieve of having an end of the fall which is being held downhanging untensioned from the drum.

To effect further saving inweight, particularly in those cases when the arrangement serves the purpose of lifting single loads in the course of equipment erection and repair jobs, it is expedient to dispose the rollers of the tensioning device in permanent resilientcontact with two falls of the rope and to apply to the rollers a force to hold down the rope to the drum, the

force being sufficient to keep the rope from slipping over the drum. This allows to dispense with counterweights and the drum for winding the rope or,in the presence of this latter drum, to reduce the pull exerted on the ropewhile this is being wound on the drum.

In a preferable form of the tensioning device conducive to its smaller overall dimensions and. weight, the roller is fitted to a fork-end rod moving inside a housing, the force applied to the roller being the force exerted by a spring provided'on the rod.

To reduce the wear of the rope held down to the drum, it is preferable to replace a single roller by severalr'ollers fitted to an equalizer arm secured to the fork end rod, the force applied to the rollers being the force exerted by a spring provided on the rod. In this case, the force holding down the rope is distributed between several rollers and, consequently, between several lengths of the rope and several, parts of the drum with the result that the. wear of the rope, rollers and drum is reduced.

If two paris of rollers are employed to obtain uniform distribution of the force therebetween, each pair of rollers isfitted at the ends of their equalizer arms and each equalizer arm is fitted to a rocker arm provided at the end of the fork-end rod. Thus, several fork-end rods with their respective springs are replaced by a single fork-end rod withits spring.

To increase the capacity of the load-hoisting arrangement, it is expedient to reeve the untensioned end of the fall of rope being held down into a pulley tackle. The desired effect is obtained without an increase in the size or weight of the drums, drive and tensioning device; an increase in the diameter of rope is also not necessary. i i

To reduce the length of the arrangement when the pulley tackle is in its top-most position and alsoto obtain another reduction in weight, it is expedient to disposed the upper sheaves of pulley, tackle coaxially with one of the drums. For the sake of design simplification, it also preferable to dispose the upper sheaves of pulley tackle on a separate fulcrumpin of their own.

7 To prevent the low-weight pulley tackle from being either blocked or turned round on the rope in the courseof being lifted or lowered without a load, it is ex pedient that the untensioned end of the fallof rope being held down and reeved into the pulley tackle is passed many times around additional drums made integrally with the primary drums. A symmetrical reeving obtained in this case keeps the pulley tackle from being blocked or turned round on the rope due to the interaction with it, in spite of the fact that the pulley tackle has a low weight.

To reduce the weight of the pulley tackle with multiple reeving, this reduction being obtained by reducing the weight of load-holding attachment and lower sheaves, it is preferable to apply a drive to the upper sheaves of pulley tackle and to gear the sheaves to the drums. An additional urge obtained by the rope reeved into the pulley tackle from an upper sheave enables the load-holding attachment to be lifted and lowered by the pulley tackle in spite of an insignificant weight of the attachment.

Taking into account the possibility of slipping of the rope over sheaves of the pulley tackle while the lowweight load-holding attachment is being either lifted or lowered without load, it is expedient to include an overload coupling into the gear train between the upper sheaves of pulley train and the drums, the coupling providing for the possibility of slipping of the sheaves on their fulcrum pins with respect to the drums. This is conducive to a limitation of an additional torque "imposed by the load and transmitted through the rope and upper sheaves of pulley tackle to the gear train linking the drums to the sheaves. The additional torque comes into play because a possible cocking of lower sheaves of pulley tackle is eliminated, the cocking resulting from the slipping of rope at the instant of loading the arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be best understood from the following description of its preferred embodiment when this description is read in conjunction with the accompanying drawings in which:

FIG. 1 is a longitudinal section view of the arrangement for hoisting load according to the invention;

FIG. 2 is a longitudinal section view of'a drum drive;

FIG. 3 is a front elevation view of the arrangement for hoisting load;

FIG. 4 is a sectional view of a rope tensioning device;

FIG. 5 is a schematic side elevation view of drums with rope tensioning device;

FIG. 6 is a front elevation view of the drums with rope tensioning device as shown in FIG. 5;

FIG. 7 is a longitudinal section view of a rope tensioning device in another embodiment;

FIG. 8 is a side elevation view of the rope tensioning device as shown in FIG. 7 with a portion thereof being illustrated in cross section;

FIG. 9 is a longitudinal section view of a rope tensioning device in still another embodiment;

FIG. 10 is a side elevation view of the rope tensioning device as shown in FIG. 9; I

FIG. 1 1 is a sectional view of a rope tensioning device in a further embodiment;

FIG. 12 is a side elevation view of the rope tensioning device as shown in FIG. 1 1 with a portion thereof being illustrated incross section;

FIG. 13 is a schematic side elevation view of the drums and rope tensioning device according to the embodiment illustrated in FIGS. 11 and 12;

FIG. 14 is a front elevation view of the drums and rope tensioning device illustrated in FIG. 13;

FIG. 15 is a schematic side elevation view of the arrangement disclosed herein with a pulley tackle;

FIG. 16 is a section view taken along the line XVI- XVI of FIG. 15;

FIG. 17 is a section view XVII of FIG. 16;

FIG. 18 is a schematic front elevation view of the ar rangement disclosed herein with a pulley tackle in another embodiment;

FIG. 19 is a side elevation view of the arrangement shown in FIG. 18;

FIG. '20 is a front elevation view of a pulley tackle in still another embodiment;

FIG. 21 is a side elevation view of the arrangement disclosed herein with additional drums; and 7 FIG. 22 is a plan view of the arrangement as shown in FIG. 21.

taken along the line XVII:-

DETAILED DESCRIPTION OFTHE PREFERRED EMBODIMENTS Referring to FIG. 1, the arrangement disclosed herein comprises two drums 1 disposed in parallel by means of bearings 2 on hollow axles 3 which are secured to end plates 4. The external cylindrical faces of the drums l are provided with annular grooves'5 accommodating a load-carrying rope 6. The grooves in one drum are staggered through half-a-pitch with respect to the grooves in the other drum. To keep the rope 6 in the grooves 5 when the arrangement is in operation, there are rollers 7 accommodated by means of bearings 8 on an axle 9 secured to the end plates 4. A length of the rope 6 passes many times around both drums 1 and is held down to one of them with the aid of a device 10 for tensioning the length.

The-drums 1 are set into motion from a single drive consistingof electric motors 11 disposed inside the hollow axles 3. Fitted on shafts 12 of the electric motors 11 there are pinions l3 meshing a gear 14 which isa press-fit on the hub of a gear 15. This gear is supported by bearings 16 on a shaft 17 made integrally with a pinion 18 which meshes gear rings 19 of the both drums l. The shaft 17 and, consequently, the pinion 18 are rotated by a gear 20 (FIG. 2) secured to the same shaft and meshing a gear 21 fitted on an intermediate shaft 22. Accommodated on the same shaft is a gear 23 meshing the gear 15. Provided on the shaft 22 is also a load-holding brake 24.

The rope 6 passing, as pointed out earlier, many times around both drums 1' is fastened to a drum 25 with one of its ends whereas the other end serves to accommodate the load being hoisted. The drum 25 is fitted on a hollow shaft 26 which, in its turn, is installed with provision for rotation on an axle 27 secured to the end plates 4. The shaft 26 is rotated through the intermediary of a gear 28 fitted to the shaft 17 and an idler gear 29 meshing a gear 30 which is accommodated on the hollow shaft 26 with provision for rotation. At-

tached to the gear 30 is a pawl 31 engaging a ratchet gear 32 which is made integrally with the hollow shaft 26. Accommodated on the same shaft there is another ratchet gear 33 engaging a pawl 34 which is fitted to an axle 35 secured to the end plates 4. The rotary'movement of the hollow shaft 26 is transmitted to the drum 25 through a friction coupling 36.

The rope 6 (FIG. 3) passes over to the drum 25 through

fleeting sheaves

37 and 38. The sheave 38 is mounted on an axlw 39 with provision for positive axial displacement so as to provide for uniform winding of the rope on the drum 25. Imparting motion to the sheave 38 is a screw 40 threaded from both ends and rotated by a chain 41 which passes over a sprocket 42 (FIG. 2) secured to the drum 25.

The device 10 for tensioning the length of rope passing many times around the both drums comprises a roller 43 (FIG. 4) supported by bearings 44 on a fulcrum pin 45 secured to a fork-end rod 46. This rod is disposed in a housing 47 with provision for axial movement so as to ensure permanent resilient contact of the roller 43 with a fall of the rope 6, as this is illustrated in FIG. 1. The housing 47 is held fast to an end plate 4 with the aid of an adapter plate 48. Fitted on the forkend rod 46 (FIG. 4) there is a spring 49 exerting a force to hold down the rope to the drum by the roller 43, the force being sufficient to keep the rope from slipping over the drum and to relieve of tensioning the hanging end of that fall of rope which is held down.

To reduce the weight and size of the arrangement, there are provided two rollers 43 (FIGS. 5 and 6) each serving a fall of rope as this is indicated in FIG. 5. In this case, the arrangement dispenses with the drum 25 whereas the rope 6 has two untensioned ends hanging from the drum.

To reduce the wear of the rope 6 and drums I, one fall of the rope is held down by a pair of rollers 43 (FIG. 7). In this case, an equalizer arm 51 with fulcrum pins 52 at the ends is fitted to the fork-end rod 46 with the aid of a fulcrum pin (FIG. 8). Supported by bearings 44 on the fulcrum pin 52 are rollers 43. The pins 52 are parallel to the pin 50 and both rollers are disposed in the same plane.

To reduce the weight and size of the tensioning device, the rollers 43 (FIGS. 9 and 10) which hold down both falls of rope are accommodated on one forkend rod 46. In this case, an equalizer arm 54 is attached by means of a fulcrum pin 53 to the end of the fork-end rod and supported by bearings 44 at the ends of the equalizer arm are the rollers 43 disposed in different planes parallel to each other.

To reduce the wear of the drum and rope and make the rope tensioning device a compact one, both pairs of the rollers 43 holding down both falls of rope are accommodated on the same fork-end rod 46 (FIGS. 11 and 12). In this case, a rocker arm 56 is fitted to the fork-end rod by means of a fulcrum pin and secured to the ends of the rocker arm are equalizer arms 57 which carry the rollers 43 supported by bearing 44 at their ends. The rocking action of the rocker arm serves to distribute the force between the rollers in a uniform way. In the rope tensioning device like this, the rollers are all arranged in the same plane and the rope 6 has two untensioned ends hanging from the drum as shown in FIGS. 13 and 14.

To increase the capacity of the load-hoisting arrangement, one of the hanging untensioned ends of the rope 6 is reeved into a pulley tackle 58 (FIG. 15). The pulley tackle has an upper sheave 59 mounted on a fulcrum pin 60 secured to an end plate 4. This sheave is rotated through the intermediaryof a

gear train

61, 62 and 63. Disposed on both sidesof the sheave 59 there are rollers 64'lholding the rope against the sheave. The pulley tacklealso incorporates lower sheaves 65 mounted in a yoke 66 to which a hook 67 for lifting a load is attached.

The gear 61 (FIG. 16) is made integrally with the shaft 17 as is the gear 18 meshing the gear rings of drums.

To ensure the possibility of slipping of the sheave 59 on its fulcrum pin 60 with respect to the drums 1, there is a safety coupling with one of its coupling members 68 made integrally with the gear 63 and fitted onto the sheave 59 with provision for rotation about this sheave. The coupling member has grooves 69 fitted into which are flat springs 70 (FIG. 17). The other coupling member 71 is made integrally with the sheave 59 and is provided with flats 72 coming abutting against which are the springs 70.

To reduce the length of the arrangement when the pulley tackle is in its top-most position and also to obtain another reduction in weight, the upper sheave 59 (FIGS. 18 and 19) of the pulley tackle is accomodated on the axle 3 of one of the drums 1. In this case, the rope 6 is reeved in four parts and the hook 67 is attached to a cross piece 73 which also serves as a fulcrum pin for the lower sheaves 65 of the pulley tackle. The drive of the drums 1 consists of the electric motor 11 disposed in parallel with the drums and secured to the end plates 4.

For heavy-duty applications, i.e., when the load hoisted is over 5 tons, the pulley tackle incorporates several upper sheaves 59 (FIG. 20) disposed on the axle 3 of one of the drums 1. In this case, a hook 74 for suspending the arrangement in operation is also attached to the axle 3 with the result that a further reduction of the length of the arrangement with the pulley tackle in its top-most position is obtained.

To reduce the possibility of blocking or turning around of the low-weight pulley tackle on the rope while being lifted or lowered withhout a load, that end of the rope 6 which is reeved into the pulley tackle also passes many times around additional drums 75 (FIGS. 21 and 22) made integrally with the drums 1. In this case, the drum 25 for winding the rope 6 is disposed under the drums 1 and the rope is wound on the drum 25 from a drum 1 directly, i.e., without fleeting sheaves.

PRINCIPLE OF OPERATION For operation, the arrangement is suspended from the hook 74. The load is attached to the free end of the rope 6 whereas the other end passes many times around the both drums 1, passes over the

fleeting sheaves

37 and 38 and is anchored to the drum 25. When the elec tric motors .11 issetinto operation, the drums are rotated by means of

gears

13, 14, 15, 23, 24, 21, 20, 18, 19 so that the free end of the rope 6 shortens and the load attached thereto is lifted. The gear 20 rotates the shaft l7and this-causes the drum 25 to rotate too through the intermediary of

gears

28, 29, 30, 31, 32

and 36 so that the other end of rope anchored to the drum is wound thereon.

The length of the rope 6 betweena drum. 1 and the drum 25 obtains the requisite tensioning because the .hollow shaft 26 tends, through the intermediary of the friction coupling 36, to rotate the drum 25 at a circumferential velocity exceeding the velocity at which the rope is being wound off the drums 1. In tendingto limit the velocity at which the drum 25 rotates, the rope becomes taut, causing the friction coupling 36 to slip. When the drums 1 rotate so as to lift the load, the pawl 34 slips over the ratchet gear 33 whereas the pawl 31 causes the ratchet gear 33 to rotate. When the drum 25 is rotating, the sheave 38 is moved axially due to the action of the screw 40 actuated by the chain 41 from the sprocket 42 rigidly fitted to the drum 25. The sheave 38 moves with each revolution of the drum 25 by an amount equal to the diameter of the rope, assuring its uniform winding on the drum. The roller 43 of the rope tensioning device is disposed in permanent resilient contact with the rope 6, assuring the requisite tensioning of the length of rope passing many times around both drums when there is no load at the hook.

For lowering the load, the electric motors 11 are started in reverse, causing the drums l to rotate in the opposite direction through the

gears

13, 14, 15, 23, 24, 2

l

2O, 18 and 19. The free end of rope becomes longer and the other end winds off the drum 25. The pawl 31 slips over the ratchet wheel 32 whereas the pawl 34 engages the ratchet wheel 33 which is secured to the hollow shaft 26, causing this shaft to stop. The drum 25 is rotated due to the action of the rope 6, overcoming the resistance of the friction coupling 36, and that length of the rope 6 which is between the drums l and 25 is thus tensioned. The sheave 38 moves in the same way as described above.

When use is made of the rope tensioning device shown in FIGS. and 6, the arrangement operates on the same lines save that it dispenses with the rope winding drum 25. Both ends of the rope hang untensioned from the drums 1 and the rollers 43 of the rope tensioning device are disposed, due to the action of the springs 49, in permanent resilient contact with both falls of rope, assuring the requisite tensioning of that length of rope which passes many times around both drums 1. The springs 49 exert a force holding down the rope to the drums which is sufficient to keep the rope from slipping over the drums when the arrangement is in operation.

When use is made of the rope tensioning device shown in FIGS. 13 and 14, the arrangement operates on the same lines as described above with the only exception that both falls of the rope 6 are held down to one of the drums with the aid of the rollers 43.

When the arrangement incorporates the pulley tackle (FIG. the load is suspended from the hook 67. When the drums are set into rotation, the end of rope reeved into the pulley tackle 58 becomes either longer or shorter depending on the direction of rotation, so that the hook 67 is either lowered or lifted.

The upper sheave 59 of the pulley tackle is rotated from the shaft 17 through the intermediary of the

train

61, 62, 63, 68, 70 and 71. When thecoupling member 68 rotates, the coupling member 71 is rotated too integrally with the sheave 59, being caused to do so by the springs 70. The circumferential velocity at which the sheave rotates depends on the diameter of winding and is half the velocity at which the rope is being wound by the drums 1. The rope 6 moves with the sheave 59 because of the force of friction between the rope and sheave coming into play due to the weight of the rope, yoke 66 with the sheaves 65 and hook 67 and also due to the fact that the rope 6 is held down to the sheave 59 by the rollers 64. Thus, if operating without a load, the drive sheave 59 urges the yoke 66 to move without being blocked because the rope reeved through the pulley tackle is being moved forcibly. If, while operating with a load, there is a disagreement between the velocity of the drums 1 and that of the sheave 59, the sheave slips with respect to the gear 63, preventing thus the

gears

63, 62 and 61 from damaging their teeth. At this moment, the coupling member 68 with the springs 70 rotates relatively to the coupling member 71.

When use is made of the additional drums and the pulley tackle 58 (FIG. 22), both ends of the rope 6 are wound simultaneously by the drums l, a length of rope.

passing many times around both main drums l and another length of rope passing many times around both additional drums 75. In other respects, the arrangement operates on the same lines as described hereinabove.

What is claimed is:

1. An arrangement for hoisting a load comprising: two axles disposed parallel one to the other; end plates with said axles immovably secured thereto; two main drums mounted on said axles by means of bearings, said two drums being adapted for rotation and provided with annular grooves in their external cylindrical faces to accommodate a load-carrying rope; means for imparting rotation to said two drums; a length of said rope passing many times around both said drums; and at least one roller disposed in permanent resilient contact with at least one of the falls of said length of rope and acted upon by a force to hold down said length of rope to one of said two drums, said force being sufficient to keep the rope from slipping over the drums when these hoist a load in rotation and to relieve of tensioning that end of the fall which is held down and hangs from a drum, a housing; a fork-end rod disposed in said housing with provision for movement therein; a roller secured to the end of said fork-end rod; a spring fitted on said fork-end rod and exerting a force on said roller so as to hold down the rope to one of the drums; and an equalizer arm secured to said fork-end rod and carrying rollers acted upon by a force exerted by a spring fitted on said fork-end rod.

2. The arrangement as claimed in claim 1, in which there is a rocker arm fitted with provision for rocking to said fork-end rod and carrying said equalizer arm.

3. An arrangement for hoisting a load comprising; two axles disposed parallel one to the other; end plates with said axles'immovably secured thereto; two main drums mounted on said axles by means of bearings, said two drums being adapted for rotation and provided with annular grooves in their external cylindrical faces to accommodate a load-carrying rope; means for imparting rotation to said two drums; a length of said rope passing many times around both said drums; at least one roller disposed in permanent resilient contact with at least one of the falls of said length of rope and acted upon by a force to hold down said length of rope to one of said two drums, said force being sufficient to keep the rope from slipping over the drums when these hoist a load in rotation and to relieve of tensioning that end of the fall which is held down and hangs from a drum, a pulley tackle reeved into which is that untensioned end of the fall which is held down and hangs from a drum, and at least one of the upper sheaves of said pulley tackle being disposed coaxially with one of said drums.

4. An arrangement for hoisting a load comprising: two axles disposed parallel one to the other; end plates with said axles'immovable secured thereto; two main drums mounted on said axles by means of bearings, said two drums being adapted for rotation and provided with annular grooves in their external cylindrical faces to accommodate a load-carrying rope; means for imparting rotation to said two drums; a length of said rope passing many times around both said drums; at least one roller disposed in permanent resilient contact with at least one of the falls of said length of rope and acted upon by a force to hold down said length of rope to one of said two drums, said force being sufficient to keep the rope from slipping over the drums when these hoist a load in rotation and to relieve of tensioning that end of the fall which is held down and hangs from a drum, a pulley tackle reeved into which is that untensioned end of the fall which is held down and hangs from a drum, and at least one of the upper sheaves of said pulley tackle being mounted on a separate fulcrum pin of its own.

5. An arrangement for hoisting a load comprising: two axles disposed parallel one to the other; end plates with said axles immovably secured thereto; two main drums mounted on said axles by means of bearings, said two drums being adapted for rotation and provided with annular grooves in their external cylindrical faces to accommodate a load-carrying rope; means for imparting rotation to said two drums; a length of said rope passing many times around both said drums; at least one roller disposed in permanent resilient contact with at least one of the falls of said length of rope and acted upon by a force to hold down said length of rope to one of said two drums, said force being sufficient to keep the rope from slipping over the drums when these hoist a load in rotation and to relieve of tensioning that end of the fall which is held down and hangs from a drum, a pulley tackle reeved into which is that untensioned end of the fall which is held down and hangs from a drum, and additional drums made integrally with said main drums and passing many times around said additional drums is the end of that fall of rope which is reeved into said pulley tackle and is held down.

6. An arrangement for hoisting a load comprising: two hollow axles disposed parallel one to the other; end

plates with said axles immovably secured thereto; two main drums mounted on said hollow axles by means of bearings, said two drums being adapted for rotation and provided with annular grooves in their external cylindrical faces to accommodate a load-carrying rope; means for imparting rotation to said two drums; a length of said rope passing many times around both said drums; and at least one roller disposed in permanent resilient contact with at least one of the falls of said length of rope and acted upon by a force to hold down said length of rope to one of said two drums, said force being sufficient to keep the rope from slipping over the drums when these hoist a load in rotation and to relieve of tensioning that end of the fall which is held down and hangs from a drum, a pulley tackle reeved into which is that untensioned end of the fall which is held down and hangs from a drum, and at least one of that upper sheave of said pulley tackle which is mounted on said separate fulcrum pin is a drive sheave linked up movably with said means for imparting rotation to said main drums.

7. The arrangement as claimed in claim 6, in which said drive sheave linked up movably with said means for imparting rotation to said main drums comprises an overload coupling providing for the possibility of slipping of said sheaves on their fulcrum pin with respect to the drums.

8. An arrangement for hoisting a load comprising: two rotatable drums mounted in parallel with each other and having annular grooves on their outer cylindrical surfaces for accommodation of a load-carrying rope; means for imparting rotation to said drums; a length of said rope passing many times around said drums; rollers in permanent resilient contact with at least one of the falls of said length of rope, said rollers being loaded with a force for urging said rope against one of said drums sufficient to prevent said rope from slipping relative to said drums during the lifting of a load during the rotation of said drums and to relieve of tensioning the end of the fall of said rope which is urged against the drum and hangs from the drum; said rollers being mounted on an equalizer arm supported on a rod movably mounted in a housing under the action of a spring mounted on said rod for applying said force to said roller for urging said rope against one of said drums.

9. The arrangement as claimed in claim 8 including a rocker arm mounted for rocking on said rod and supporting said equalizer arm.

Claims

1. An arrangement for hoisting a load comprising: two axles disposed parallel one to the other; end plates with said axles immovably secured thereto; two main drums mounted on said axles by means of bearings, said two drums being adapted for rotation and provided with annular grooves in their external cylindrical faces to accommodate a load-carrying rope; means for imparting rotation to said two drums; a length of said rope passing many times around both said drums; and at least one roller disposed in permanent resilient contact with at least one of the falls of said length of rope and acted upon by a force to hold down said length of rope to one of said two drums, said force being sufficient to keep the rope from slipping over the drums when these hoist a load in rotation and to relieve of tensioning that end of the fall which is held down and hangs from a drum, a housing; a fork-end rod disposed in said housing with provision for movement therein; a roller secured to the end of said forkend rod; a spring fitted on said fork-end rod and exerting a force on said roller so as to hold down the rope to one of the drums; and an equalizer arm secured to said fork-end rod and carrying rollers acted upon by a force exerted by a spring fitted on said fork-end rod.

3. An arrangement for hoisting a load comprising; two axles disposed parallel one to the other; end plates with said axles immovably secured thereto; two main drums mounted on said axles by means of bearings, said two drums being adapted for rotation and provided with annular grooves in their external cylindrical faces to accommodate a load-carrying rope; means for imparting rotation to said two drums; a length of said rope passing many times around both said drums; at least one roller disposed in permanent resilient contact with at least one of the falls of said length of rope and acted upon by a force to hold down said length of rope to one of said two drums, said force being sufficient to keep the rope from slipping over the drums when these hoist a load in rotation and to relieve of tensioning that end of the fall which is held down and hangs from a drum, a pulley tackle reeved into which is that untensioned end of the fall which is held down and hangs from a drum, and at least one of the upper sheaves of said pulley tackle being disposed coaxially with one of said drums.

4. An arrangement for hoisting a load comprising: two axles disposed parallel one to the other; end plates with said axles immovable secured thereto; two main drums mounted on said axles by means of bearings, said two drums being adapted for rotation and provided with annular grooves in their external cylindrical faces to accommodate a load-carrying rope; means for imparting rotation to said two drums; a length of said rope passing many times around both said drums; at least one roller disposed in permanent resilient contact with at least one of the falls of said length of rope and acted upon by a force to hold down said length of rope to one of said two drums, said force being sufficient to keep the rope from slipping over the drums when these hoist a load in rotation and to relieve of tensioning that end of the fall which is held down and hangs from a drum, a pulley tackle reeved into which is that untensioned end of the fall which is held down and hangs from a drum, and at least one of the upper sheaves of said pulley tackle being mounted on a separate fulcrum pin of its own.

6. An arrangement for hoisting a load comprising: two hollow axles disposed parallel one to the other; end plates with said axles immovably secured thereto; two main drums mounted on said hollow axles by means of bearings, said two drums being adapted for rotation and provided with annular grooves in their external cylindrical faces to accommodate a load-carrying rope; means for imparting rotation to said two drums; a length of said rope passing many times around both said drums; and at least one roller disposed in permanent resilient contact with at least one of the falls of said length of rope and acted upon by a force to hold down said length of rope to one of said two drums, said force being sufficient to keep the rope from slipping over the drums when these hoist a load in rotation and to relieve of tensioning that end of the fall which is held down and hangs from a drum, a pulley tackle reeved into which is that untensioned end of the fall which is held down and hangs from a drum, and at least one of that upper sheave of said pulley tackle which is mounted on said separate fulcrum pin is a drive sheave linked up movably with said means for imparting rotation to said main drums.