US3782691A

US3782691A - Hydraulic lifting device for lifting heavy loads

Info

Publication number: US3782691A
Application number: US00230779A
Authority: US
Inventors: H Lietzke
Original assignee: Schiess AG
Current assignee: Schiess AG
Priority date: 1971-03-09
Filing date: 1972-03-01
Publication date: 1974-01-01
Anticipated expiration: 1991-01-01
Also published as: JPS4881328A; DE2111244A1

Abstract

A hydraulic lifting device for lifting heavy loads, especially by steps, in which two vertically spaced adjusting nuts are arranged on and in meshing engagement with a vertical spindle which is surrounded by an annular cylinder-piston system, the elements of which are relatively movable to each other to perform a major stroke only when at least one of said nuts is being rotated, rotation of either one of the nuts resulting in an axial movement of the spindle.

Description

United States Patent [1 1 Jan. 1, 1974 Lietzke 3,278,158 10/1966 Saldana 254/106 [75] Inventor: Hemz Lietzke Neuss Germ-any Primary Examiner-Othell M. Simpson [73] Assignee: Schiess Aktiengesellschaft, Attorney-Walter Becker DusseIdorf-Oberkassel, Germany [22] Filed: Mar. 1, 1972 [21] Appl. No.2 230,779 57 ABSTRACT [30] Foreign Application Priority Data A hydraulic lifting device for lifting heavy loads, espe- Mar. 9, 1971 Germany P 21 11 244 7 cially by steps, in which two vertically spaced adjusting nuts are arranged on and in meshing engagement [52] US. Cl. 254/106 with a vertical spindle which is surrounded by an an- [51] Im. Cl B66f 1/00, E02d 21/00 l r y n r-p n y m. h m n f which [58] Field ofSearch 254/l05-108, 89 H, 93 R; are relatively movable to each other to perform a 74/1[1; 61/465 major stroke only when at least one of said nuts is being rotated, rotation of either one of the nuts result- [56] References Cit d ing in an axial movement of the spindle.

UNITED STATES PATENTS 3,230,784 H1966 Von Heidenstam et al. 254/105 X 7 Claims, 2 Drawing Figures ii i 15 l3 I4 IlL'I UT I I 1 9 L I I l I l9 --ig 26 I 6 I I9\ H m 10 l a 17 -24 19' l 1 ,5 4 rrn1n1 r l l 3 21 at; 4 228 X X 29 a2 i L l l l l l L l l| 3 .m 2 M uw sma 9 g 7/,

WW Hm l mh In Inn 5 TI 4 v9 {I1 5/4 .10 mm N WIII 2 7 W L 1 M 2 HYDRAULIC LIFTING DEVICE FOR LIFTING HEAVY LOADS The present invention relates to a hydraulic lifting device for lifing heavy loads, especially for step-wise lifting as it occurs, for instance, in the building industry, in order to lower bridges onto their bearings, or in order to lift prefabricated ceilings to the respective height, or for lifting heavy forms for pouring cement, and the like. With operations of this type, lifting devices are required which will be able to lift up to 1,000 tODS.

It is known for lifting or lowering operations to employ assembly winches which, however, become uneconomical when loads are involved that are in excess of 200 tons. Moreover, the employment of such assembly winches are limited by their dimensions. If, for instance, prefabricated ceilings have to be lifted which after being lifted to their required height have to be suspended at a plurality of points on concrete columns or walls, it is necessary in conformity with the number of the intended supporting points to employ a greater number of lifting devices which will assure a lifting operation with equal strokes, since otherwise, a deformation and a breaking of the prefabricated ceiling may be encountered. By means of cable winches, a uniform stroke of a plurality of lifting devices cannot be realized because the cables can stretch differently, for instance, already due to the fact that the cables can wind at different diameter and when resting on cable windings therebelow can slide between said last mentioned windings and thus can yield.

In addition to assembly winches, also devices with lifting cylinders for instance hydraulic lifts for pressing and the like are employed which yield higher lifting forces then cable winches. The heretofore known lifting devices of this type are, however, limited as to their employment because they permit only relatively short lifting strokes. The employment of these last mentioned devices therefore requires a continuous resetting while each resetting operation prior to the lifting operation requires a certain lowering of the load to be lifted, in order from the very start to assure contact with the load to be lifted. Also, with these devices when simultaneously employing a plurality of such devices it cannot be assured that the lifting stroke of all devices will be the same. Disuniformities will occur in particular in connection with the resetting operation when a multiple of that lifting height is required which the device can perform per one stroke.

It is, therefore, an object of the present invention to provide a hydraulic lifting device for lifting heavy loads, especially for stepwise lifting, which will have relatively small dimensions and will make it possible to multiply the maximum stroke thereof in steps while means are provided which will safeguard the respective obtained level of the load and when simultaneously employing a plurality of lifting devices will permit a checking and equalization of the lifting stroke of all lifting devices in order in this way to assure an equalization of the lifting stroke of all devices.

These and other objects and advantages of the invention will appear more clearly from the following specification, in connection with the accompanying drawing, in which:

FIG. 1 is a section through a hydraulic lifting device according to the invention, while said device is in use.

FIG. 2 represents a section taken along the line II-II of FIG. I, more clearly showing the drive for the adjusting nut.

The hydraulic lifting device according to the present invention is characterized primarily in that on a vertically arranged threaded spindle on the lower end of which the load may be suspended, or on the upper end of which the load may be rested, there are arranged two adjusting nuts in spaced relationship to each other. The lower one of these two adjusting nuts is adapted to rest on a stationary mounting or bearing and also an annular hydraulic cylinder is adapted to rest on said mounting or counter-bearing, which cylinder, with play, from above extends over the adjusting nut and above the lower adjusting nut extends with play around the spindle. Pressure fluid conveying conduits lead into said annular hydraulic cylinder at the upper and lower end through a reversible valve, said conduits being connected to a source of pressure. An annular piston extends from above into said cylinder while extending below and above the upper adjusting nut with play.

In this way, a hydraulic lifting device for lifting and lowering of heavy loads has been created which permits the following operation: The lifting devices is first, by means of the annular hydraulic cylinder rested on a stationary counterbearing which may be located, for instance, above the lower end of the spindle and to which the load to be lifted is suspended. Subsequently, both adjusting nuts are turned on the threaded spindle so that they are displaced in upward direction. This displacement will be ended when the lower adjusting nut abuts the annular hydraulic cylinder thereabove and the upper adjusting nut abuts the annular cylinder thereabove. Thereupon, the annular piston is moved out of the annular hydraulic cylinder while the annular piston engages the upper adjusting nut from below and through the latter moves the spindle with the load in upward direction. Simultaneously, the lower adjusting nut is so rotated that it, itself, remains at the given height, but at the same time permits the upward displacement of the threaded spindle with the load. The speed of the adjusting nut corresponds to the speed at which the piston carries out its stroke. Thus, the number of the revolutions of the adjusting nut indicates the lifting stroke which may be within the maximum stroke of the piston. When the intended lifting height has been reached, the lower adjusting nut is stopped whereby also a further displacement of the annular piston and thus a further lifting of the spindle with the load is not longer possible. If now the inner chamber of the cylinder is vented, the entire unit will rest on the lower adjusting nut and through the latter on the counterbearing or support. Thereupon, the annular piston is moved into the annular hydraulic cylinder while at the same time the upper adjusting nut is rotated so thatit will again approach the lower adjusting nut until its starting position has been reached. In this connection, the spindle with the load remains at the previously reached level. An upward movement of the spindle with the load is impossible and the operation can be repeated in the same manner in order again to lift the spindle with the load by a predetermined distance.

When simultaneously employing a plurality of lifting devices, a hundred percent synchronism of all lifting devices can be realized by each time temporarily ex eluding that lifing device from the hydraulic circuit in which the lower adjusting nut has carried out a full revolution. The lower nut is again included in the hydraulic circuit as soon as all other lifting devices have completed the same lifting stroke. Inasmuch as the lifting operation of all lifting devices is dependent on that each time after a revolution of the lower adjusting nut a check is effected in such a way that with all lifting devices the corresponding rotation of the adjusting nut was carried out, the danger is eliminated that one of the lifting devices may at a faster rate than the other reach its end value. The above mentioned control may be realized by having the adjusting nut cooperate with limit switches by means of which the flow of the hydraulic fluid into the annular hydraulic cylinder is controlled.

The last mentioned possibility presents itself particularly when in conformity with the invention the two threaded nuts are adapted to be motor driven individually, or in common, so that by means of the motors it is possible precisely to adapt the supply and withdrawal of hydraulic fluid to the annular hydraulic cylinder and also to carry out the control by means of limit switches.

According to a further development of the invention, it may be provided that each of the two adjusting nuts is equipped with a gear ring and can be driven by means of a circulating chain.

According to a further feature of the invention, the motor which is associated with the lower adjusting nut may be arranged on the annular hydraulic cylinder while the motor which is associated with the upper adjusting nut may be connected to the annular piston. Both motors may be adapted to be coupled to each other when the annular piston has moved inwardly. A coupling may, for instance, be effected when the spindle while not being under load is to be longitudinally displaced in order to bring the same to their starting position without being under load, for which purpose it is thus necessary to displace the annular piston.

Instead, as described above, to suspend the load on the lower end of the threaded spindle, it is also possible to support the load upon the upper spindle end. In this connection, the working method is the same as described above.

Also, the lowering of a load is possible which was preceded by the outward movement of the annular piston. During the lowering of the load the spindle rests upon the upper adjusting nut, while simultaneously in conformity with the displacement of the annular piston into the annular hydraulic cylinder, the lower adjusting nut is turned without load and thus moves in conformity with the stroke on the spindle onto the upper adjusting nut.

Referring now to the drawing in detail, it will be seen from FIG. I that the illustrated lifting device comprises a threaded spindle 1 on which are arranged in spaced relationship to each other an upper adjusting nut 2 and a lower adjusting nut 3. In the specific position shown in the drawing, the lower surface of the lower adjusting nut 3 rests directly on the support 4 in which instance, for example, a part of a column or wall may be involved during the lifting of a ceiling. With the specific example referred to, it may also be assumed that a prefabricated ceiling is suspended onto the lower end of spindle l. The lifting of said ceiling is'to be effected by means of a plurality of devices which are distributed around the ceiling plate in order thus to assure a uniform lifting. However, it is also possible to rest the load to be lifted on the upper end of the spindle 1.

The annular hydraulic cylinder 5 extends around the lower adjusting nut 3 while said hydraulic cylinder 5 at the same time extends with play over the lower adjusting nut 3 and in addition thereto also extends above the adjusting nut 3 with play around the spindle 1. The cylinder portion which extends around the spindle 1 is designated with the reference numeral 6. Between the cylinder portion 6 and the outer annular cylinder mantle 7 there is located a cylinder chamber 8, into which the annular piston 9 extends from above. Piston 9 sealingly engages by means of its piston ring 10 the outer mantle 7 of the annular hydraulic cylinder 5 and by means of its piston ring 11 sealingly engages the cylinder portion 6. The annular piston 9 extends with play around the spindle 1 below the adjusting nut 2. Furthermore, the annular piston 9 also engages the adjusting nut 2 from below and extends above the adjusting nut 2 near to the spindle 1 while leaving an annular play between spindle 1 and the adjacent portion of piston 9. A driving motor 12 adapted to be hydraulically actuated is fastened to the cantilever 13 of the annular piston 9. A chain sprocket 14 is provided on the driving shaft 19 which extends parallel to the axis of the spindle 1. Chain 15 extends around the sprocket 14 and meshes with the chain gear ring 16 on the adjusting nut 2. Connected to the cantilever 17 of the hydraulic annular cylinder 5 is a hydraulic driving motor 18, the drivng shaft 19' of which, has keyed thereto the chain sprocket 14 around which a chain 21 passes, which chain meshes with the chain gear ring 16 on the lower adjusting nut 3. The other end of the driving shaft 19' which protrudes on the other side of the motor 18 may, by means of the clutch 20, be coupled to shaft 19 of motor 12. Such coupling will be possible when the annular piston 9 has moved into the hydraulic annular cylinder 5, as shown in FIG. 1. Such coupling may be effected when it is desired that the spindle 1 be longitudinally displaced while being under no load. Such longitudinal displacement is brought about by driving the adjusting

nuts

2 and 3 in the same direction of rotation and at the same speed. The drive of the adjusting

nuts

2 and 3 by means of the

chains

15 and 16 is shown in FIG. 1, while FIG. 2 more particularly illustrates the drive of the adjusting nut 2 by the chain 15. FIG. 1 also illustrates in detail the hydraulic control of the lifting device in combination with the hydraulic control of the driving motors l2 and 18 for the adjusting

nuts

2 and 3, respectively. This control will be explained further below in connection with the description of the operation of the device according to the invention.

It may be assumed that the spindle l, the annular piston 9 and the annular hydraulic cylinder 5 occupy their respective position relative to the support 4 as shown and it may furthermore be assumed that the load to be lifted is suspended at the lower end of the spindle 1. In this starting position, the adjusting nut 3 has its lower surface resting on the support 4 and a similar situation prevails with the lower surface of the annular hydraulic cylinder 5. If now, fluid under pressure is pressed through the conduit 23 and inlet opening 22 into the cylinder chamber 8' below the annular piston 9, the pressure medium will move the annular piston 9 out of the hydraulic cylinder 5. This outward movement is first possible only to the extent of the play 24 between the upper surface of the adjusting nut 3 and the associated surface of the annular hydraulic cylinder 5. Inasmuch as during the outward movement of the annular piston 9, the adjusting nut 2 and thus also the spindle 1 are moved along with the piston 9, a further outward movement requires that the adjusting nut 3 is displaced along the spindle 1 relative to the outward movement of the spindle. This displacement is effected in view of the fact that by means of the motor 18 through the intervention of the chain 21 the adjusting nut 3 is rotated in the sense of a downward movement. In conformity with the distance or stroke of the displacement of the adjusting nut 3, it is thus possible that the annular piston 9 moves upwardly and can take along the spindle 1 and thereby the load to be lifted. If it is assumed that the load is lifted by a plurality of devices according to FIG. 1, it is possible by means of limit switches on motor 18 to bring about that the motor 18 respectively is stopped and will standstill each time after a revolution of the lower adjusting nut 3 and will start moving again only when the motors 18 of all lifting devices have rotated the lower adjusting nut 3 once. In this way, it will be assured that the individual lifting strokes of all lifting devices will be equal and the maximum lifting stroke of a lifting operation can correspond to the total stroke of the annular piston 9.

For purposes of carrying out a lifting action by a stroke which exceeds the maximum outward stroke of the annular piston 9, a following up of the device is effected in the following manner. After the annular piston 9 has moved out of the annular hydraulic cylinder 5 by its maximum stroke while the lower adjusting nut 3 was correspondingly turned for displacement on spindle 1, a slight further displacement of the lower adjusting nut 3 is effected in such a way that the last mentioned nut will have its lower surface in engagement with the support or counterbearing 4. Thus, the spindle 1 and the load are no longer supported by or rested on the annular piston 9, but instead through adjusting nut 3 rests directly on the support 4. Thereupon, the annular piston 9 is moved into the annular hydraulic cylinder 5 while the pressure medium escaps from the annular hydraulic cylinder 5 through the opening 22 and the conduit 23. This escape can be aided by introducing pressure fluid through inlet 26 in the hydraulic cylinder 5 through conduit 25. The displacement of the annular piston 9 into the annular hydraulic cylinder 5 requires that simultaneously the upper adjusting nut 2 is turned in such a way that it is correspondingly displaced downwardly on spindle 1. To this end the sprocket wheel 14 is driven by motor 12 so that the adjusting nut 2 will, by means of chain 15, be turned correspondingly. When the annular piston 9 has moved completely inwardly, a new outward movement of the annular hydraulic cylinder is possible while the spindle l is again taken along and thus also the load. To this end the above mentioned steps for lifting are initiated.

The operation is effected in a corresponding manner when the load rests from above on the spindle.

The starting position of spindle 1 can be set while the annular piston 9 is in its inward position, by turning the adjusting

nuts

2 and 3 in synchronism by means of

motors

12 and 18 so that exclusively the spindle 1 will be longitudinally displaced in one or the other direction. In order to assure the said synchronism, the two shafts l9 and 19' of the

motors

12 and 18 can be coupled by means of the coupling 20.

FIG. 1 also diagrammatically shows the hydraulic control of the annular piston 9 and the hydraulic control of the driving motors 12 and I8.

The hydraulic medium is selectively, by means of the pressure pump 27 via control valve 28 pressed through conduits 23 and into the cylinder chamber 8 depending on whether the annular piston 9 is to be moved outwardly or inwardly. The pressure relief valve 29 will see to it that the supply of the pressure medium into the cylinder chamber 8 will be stopped when the annular piston 9 is, due to its abutment against one or the other adjusting

nut

2, 3 prevented from being further displaced so that the stroke is determined by the respective speed of the adjusting

nut

2 or 3 in conformity with the direction of the stroke. The control of the

drive motors

12 and 18 is effected hydraulically through the intervention of the pressure pump 31 with following relief valve 32. An electrohydraulic control valve determines the direction of rotation of the hydromotors l2 and 18. Additionally there may be provided limit switches, the pulses of which actuate the control valve 30. By means of this control it is made possible that when employing a plurality of lifting devices, individual strokes can be effected which, for instance, correspond to one revolution of a

spindle nut

2 or 3 so that a total number of lifting steps can be carried out in one working operation which total number corresponds to the total stroke or any desired partial stroke of the annular piston 9.

It is, of course, to be understood that the present invention is, by no means, limited to the particular showing in the drawing, but also comprises any modifications within the scope of the appended claims.

What I claim is:

1. A hydraulic lifting device for lifting heavy loads, especially for lifting such loads in steps, which includes: a vertically movable threaded spindle, two adjusting nuts respectively arranged on said spindle in spaced relationship to each other and in meshing engagement with said spindle, stationary supporting means, the lower one of said two adjusting nuts being adapted to engage and rest on said supporting means, an annular hydraulic cylinder surrounding said spindle with play and also with play extending around said lower nut and adapted to rest on and be supported by said supporting means, an annular reciprocable double acting piston having a first section reciprocably mounted in said annular cylinder and also having a second section surrounding said spindle with play and extending with play above and below said upper nut, said annular cylinder within the range of its longitudinal extension being provided with fluid inlet and outlet means for selective communication with a fluid pressure source and with a fluid reservoir, and actuating means respectively drivingly connectable to said first and second nut for engaging the same in either direction to thereby selctively move said spindle uwardly and downwardly.

2. A device according to claim 1, which includes motor means for driving each of said nuts independently of the other.

3. A device according to claim 1, which includes driving means common to said nuts for driving the same.

4. A device according to claim 1, in which each of said adjusting nuts is provided with circumferential teeth adapted to mesh with and to be driven by means .of a chain.

5. A device according to claim 4, which includes a first motor associated with said cylinder and equipped with a first sprocket wheel, and also includes a second that one of said two motors is connected to said cylinder.

7. A device according to claim 6, which includes clutch means respectively associated with said first and second motors for drivingly interconnecting said motors when said piston occupies its substantially innermost position in said cylinder.

Claims

1. A hydraulic lifting device for lifting heavy loads, especially for lifting such loads in steps, which includes: a vertically movable threaded spindle, two adjusting nuts respectively arranged on said spindle in spaced relationship to each other and in meshing engagement with said spindle, stationary supporting means, the lower one of said two adjusting nuts being adapted to engage and rest on said supporting means, an annular hydraulic cylinder surrounding said spindle with play and also with play extending around said lower nut and adapted to rest on and be supported by said supporting means, an annular reciprocable double acting piston having a first section reciprocably mounted in said annular cylinder and also having a second section surrounding said spindle with play and extending with play above and below said upper nut, said annular cylinder within the range of its longitudinal extension being provided with fluid inlet and outlet means for selective communication with a fluid pressure source and with a fluid reservoir, and actuating means respectively drivingly connectable to said first and second nut for engaging the same in either direction to thereby selctively move said spindle upwardly and downwardly.

4. A device according to claim 1, in which each of said adjusting nuts is provided with circumferential teeth adapted to mesh with and to be driven by means of a chain.

5. A device according to claim 4, which includes a first motor associated with said cylinder and equipped with a first sprocket wheel, and also includes a second motor associated with said piston and equipped with a second sprocket wheel, and first and second chain means respectively drivingly connecting said first and second sprocket wheels with the respective circumferential teeth of their respective adjacent adjusting nuts for driving same.

6. A device according to claim 5, in which each of said first and second motors is a hydraulic motor, and that one of said two motors is connected to said cylinder.