Movable And Tiltable Bearing, Especially For Bridges

Abstract

The present movable and tiltable bearing is suitable for supporting heavy loads, such as bridges, by means of an elastically yielding pressure cushion, for example, made of rubber, which is surrounded by retaining ring means. In one embodiment one ring encircles the cushion middle portion to leave gaps above and below the ring. In another embodiment two rings are provided, one inside an annular cushion, the other outside of the annular cushion. Two rings are also used to surround a top and bottom region of a cushion whereby to leave a gap between these rings to permit the tilting movement.

Description

BACKGROUND OF THE INVENTION

The invention relates to a movable and tiltable bearing, especially for heavy loads such as bridges or similar supporting structures, wherein a pressure cushion having rubber-elastic characteristics is arranged between an upper and lower supporting or bearing surface of the supporting structure.

Such bearing means are known as so called rubber bearings or elastomeric bearings. The elastic resiliency of the elastomer permits horizontal movements and tilting movements in all directions to a limited degree. In order to prevent that the elastomer, for example in the form of a plate-shaped pressure cushion, which is mostly polygonal or circular, is squeezed out laterally by the load, prior art constructions have reinforced the pressure cushion by strengthening means such as steel plates or synthetic sheets or layers strengthened by fibers. This construction resulted in an areal bearing which is practically unyieldable in the vertical direction due to the reinforcement for preventing the lateral escaping or yielding of the pressure cushion material. However, tilting movements and horizontal displacements of the upper bearing surface relative to the lower bearing surface of the supporting structure are possible. The sum of the thicknesses of all rubber layers determines the capacity of the bearing for the horizontal displacement and the tilting movement, since the strengthening means are not deformable.

Another prior art tiltable bearing has a pressure cushion surrounded at its circumference by a plurality of rings which are supposed to prevent or substantially limit transverse expansions of the pressure cushion under loads. Such bearing has been disclosed in German published application No. 1,803,312 wherein the reinforcing inserts inside of the pressure cushion have been replaced by rings, thus avoiding non-permissably high tensile forces at said reinforcing insert. The total height of this known pressure cushion is selected in accordance with the desired tiltability and movability. An increase of the tiltability by increasing the height of the pressure cushion, results simultaneously in an increase in the horizontal displaceability.

In many instances, it is desirable that these bearings should be highly tiltable while simultaneously having a small horizontal displaceability.

OBJECTS OF THE INVENTION

The invention aims at achieving the following objects singly or in combination:

To overcome or alleviate the drawbacks of heretofore known movable and tiltable bearings, especially for bridges and similar supporting structures;

To provide a bearing which, although small in height, is characterized by a high tiltability and a comparatively low horizontal displaceability; and

To construct these bearings so that they are rather stiff against horizontal displacement.

SUMMARY OF THE INVENTION

According to the invention, the pressure cushion is circumferentially enclosed by one or two rings such that the total height of the non-enclosed circumferential area of the pressure cushion is large enough to assure the desired tiltability, but simultaneously small enough to limit the horizontal displaceability. As a rough guide for dimensioning the present bearing, the circumferential area of the cushion enclosed by the ring or rings should have a height greater than one half of the height of the pressure cushion. In other words, the ring or rings should have a height corresponding to more than one half of the pressure cushion height.

According to one example embodiment of the invention, the pressure cushion is surrounded by a ring which rests against its circumferential surface and which is freely movable and spaced from the supporting bearing surface whereby the ring is held by the pressure cushion approximately in a middle horizontal plane of the bearing, for example by elastic and form-fitting means such as a tongue and groove.

Another example embodiment comprises an upper ring resting against the upper supporting bearing surface and a lower ring resting against the lower supporting bearing surface whereby a circumferential gap is provided between the two rings which permits sufficient tilting movements of the bearing.

These teachings of the invention have the advantage that the entire height of the pressure cushion is available for the tiltability whereas the horizontal displaceability depends on the height of the pressure cushion which is not enclosed by the ring or rings.

Since the resistance or stiffness of the bearing to tilting movements, as distinguished from its movability due to tilting, is likewise determined by the height of the circumferential area not enclosed by the rings, that is, by the gaps, the invention provides a tiltable bearing having small dimensions and a simple structure and nevertheless good tiltability characteristics while being sufficiently resistant to tilting and to horizontal movement.

BRIEF FIGURE DESCRIPTION

In order that the invention may be clearly understood, it will now be described, by way of example, with reference to the accompanying drawings, wherein:

FIG. 1 is a cross section through a tiltable bearing according to the invention wherein the pressure cushion is surrounded by one ring;

FIGS. 2 to 6 are partial cross sectional views through modifications of the tiltable bearing according to FIG. 1;

FIG. 7 is a cross section through a sliding or gliding bearing according to the present invention;

FIG. 8 shows a preferred embodiment of a fixed bearing with an annular cushion;

FIG. 9 is a cross section through a sliding bearing with an annular cushion and arranged permitting sliding in one direction only;

FIG. 10 is a cross section through a tiltable bearing with two circumferential rings rather than one;

FIGS. 11 and 12 illustrate modifications of the tiltable bearing of FIG. 10, in cross section, whereby the embodiment of FIG. 12 includes reinforcing inserts;

FIG. 13 is a cross section through a bearing that is slidable and tiltable and which has two circumferential rings;

FIG. 14 illustrates a cross section through a movable sliding bearing with two circumferential rings whereby the bearing is movable in a predetermined direction; and

FIG. 15 is a fixed bearing with two inner and outer circumferential rings each.

DESCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS OF THE INVENTION

In the drawings the same reference numerals have been used for designating the same or corresponding parts.

The tiltable bearing shown in FIG. 1 comprises a pressure cushion 1, for example made of rubber or plastic material, and a ring 2, for example made of steel, surrounding the cushion. Upper and lower supporting bearing surfaces 3 and 4 respectively are formed by the supporting structure, for example a bridge member 5 and a foundation member 6 bearing or resting against the pressure cushion. The ring 2 is provided with a circumferential groove 7 approximately in a plane extending horizontally through the middle of the ring. A circumferential rib 8 around the pressure cushion 1 forms a tongue which engages the groove 7 in a form-fitting manner. Thus the ring 2 is rigidly secured to the pressure cushion 1.

However, outside the tongue and groove engagement, the pressure cushion 1 rests elastically and slidingly against the inner circumferential surface 11 of ring 2. Surface 11 is substantially cylindrical. Since the ring 2 is secured to the pressure cushion 1 merely by the groove 7 and tongue or rib 8 and since a gap 9 is provided between the ring and the members 5 and 6 of the supporting structure, ring 2 may move freely with respect to the supporting structure when the bearing is under load by the supporting structure.

When the pressure cushion is deformed sliding movements occur at the inner circumferential surface 11 of the floatingly supported ring 2. These sliding movements merely slightly impede the free shear deformation of the pressure cushion 1 in the area of its circumference. The inner edges of the ring 2 are rounded in order to prevent damage to the pressure cushion in the vicinity of said inner edges. Preferably, the pressure cushion 1 is a circular disk, however, it may have any desired and suitable shape, for instance a polygonal shape. The inner circumferential surface 11 of ring 2 is fitted to the outer circumferential surface of the pressure cushion 1. The outer circumferential surface of ring 2 may be geometrically similar to the inner circumferential surface 11, but this is optional and the outer circumferential surface of the ring 2 may have any desired shape, that is it may be, for instance, rectangular or polygonal.

The form-fit between the pressure cushion 1 and the ring 2 which operates as a self centering of the ring relative to the pressure cushion, may be accomplished by curved circumferential surfaces on the ring as well as on the pressure cushion, for instance by making these surfaces concave or convex as viewed relative to a vertical plane, whereby a relative movement between the marginal or circumferential areas of the pressure cushion with respect to the inner circumferential area of the ring is made possible along the entire width of the ring.

The pressure cushion 1 shown in FIG. 2 has a cross sectional, convex circumferential surface whereas the ring 2 has a correspondingly curved concave inner circumferential surface 11a. Due to these curved surfaces, the ring is attached to the pressure cushion in a form fitting manner. In addition, a further form-fit may be provided in the central plane of the ring. More specifically, in FIG. 2 this is realized by a circumferential groove 7a in the ring 2 and a circumferential rib 8a on the pressure cushion 1 fitting into the groove. The curvature of the surfaces may be selected in accordance with the tilting movement of the supporting structure that is to be expected in practice. The ring 2 of FIG. 2 has a greater vertical height then the pressure cushion 1. The upper and lower bearing surfaces 3a and 4a respectively of the structures 5a and 6a of the load and foundation rest on the pressure cushion 1. Therefore, these supporting surfaces 3aand 4a extend into the ring 2 sufficiently to form a gap 9a so that the free movement of the ring 2 is assured. The embodiment of FIG. 2 permits a rather small horizontal movement of the bearing since the circumference of the pressure cushion 1 is almost completely supported by ring 2. On the other hand, the entire height of the pressure cushion is available for its tiltability due to the the gaps 9a above and below the ring 2. The width of the gaps 9a determines the extent of the tilting movement.

FIG. 3 shows the slidable bearing according to the invention. A sliding layer 12 is embedded preferably in the upper, outer surface of the pressure cushion 1. The sliding layer 12 is slidably movable on a sliding plate 13 of the adjacent structure 5. The ring 2 has a convex cross sectional surface, where it faces the pressure cushion 1 whereas the latter is provided with a respective concave circumferential surface.

It is to be understood that the circumferential surface of the pressure cushion in the embodiment of FIG. 2 as well as of FIG. 3 may be straight or cylindrical in cross section whereby a corresponding curvature or indentation of the circumferential surface will result when the cushion is pressed by the load against the inner circumferential surface 11a or 11b of the ring 2 respectively.

The bearing according to FIG. 4 has a convexly curved inner circumferential surface 11b. The circumferential surface of the pressure cushion 1b is provided with a reinforcement 1a having a higher modulus of elasticity. The reinforcement 1a forms also a ring which in this embodiment rests at the top and bottom side of the pressure cushion 1b against plates 14 and 15 which are large enough to cover the cushion proper as well as the reinforcement 1a. This reinforcement assures that the pressure cushion 1b will not be squeezed out of the gaps 9, 9a between the ring 2 and the upper and lower supporting structure 5 and 6. In addition, the reinforcement 1a further improves the resistance of the bearing against horizontal displacements. In the embodiment of FIG. 4, the reinforcement 1a extends all around the circumferential surface of the pressure cushion 1b. However, these reinforcements may in other embodiments extend only in the area of the gaps 9, 9a. Both types of reinforcements may, to a certain extent, contribute to a transfer of the horizontal force by the bearing. Incidentally, the plates 14, 15 cooperate with the ring 1a in the overall reinforcement of the pressure cushion 1b. These plates 14, 15 may be rigidly attached to the cushion proper or a form-fit may be provided between the cushion and these plates.

FIG. 5 shows an advantageous combination of the bearing according to the present invention with customary structural forms. The pressure cushion 1 is provided with reinforcing plates 21, 22 and 23, 24 in its regions outside of the ring 2. This location of the plates 21 to 24 in regions outside the confinement by the ring 2, permits a displaceability in a direction perpendicularly to the axis of the bearing. On the other hand, the regions outside the ring and particularly the region inside the ring 2 permit for the tilting and rotation. Especially the region within the ring 2 contributes to this movability since no reinforcement plates are provided in this area so that it may be deformed by shearing forces to the fullest extent.

The bearing according to FIG. 5 is further provided with a sliding layer 2a between the inner circumferential surface of the ring 2 and the cushion proper. This sliding layer 2a improves the sliding of the circumferential areas of the pressure cushion on the ring 2, whereby a better shearing deformation of the pressure cushion in these areas is accomplished. Such sliding layer 2a may be provided on all the embodiments shown in the drawings not just in the embodiment of FIG. 5.

A particular advantage of the sliding layer 2a is seen in that it serves as a separating layer during the production of the bearing. If the layer 2a is made of a suitable separating material, the pressure cushion 1 may be directly vulcanized into the ring 2 or it may be hardened directly within the ring 2 without running the risk that the pressure cushion adheres to or becomes glued to the ring 2. The reinforcing plates 22 and 23 may also extend into the ring 2 or rest against the same, however, the arrangement has to be such that they do not interfere appreciably with the tiltability of the bearing. Preferably, the sliding layer 2a is directly secured to the ring 2.

As a modification, instead of providing a sliding layer 2a, the rings may be made of a synthetic material which is preferably reinforced by fibers, such as glass fibers whereby the synthetic material is selected to have the desired sliding characteristics. However, metallic or synthetic material rings may also be used and provided with a metal or other coatings which are formed or selected to provide a corrosion resistant and sliding layer.

In the embodiment according to FIG. 6, an area 1d, which completely envelopes the pressure cushion 1, is reinforced. In such a structure, the interior of the pressure cushion may have plastic characteristics whereby the plastic deformation may change into an elastic deformation toward the outer regions of the cushion.

In view of the foregoing, it will be appreciated that the tiltable bearings according to the present invention may be constructed as sliding bearings. For instance, a sliding plate may be provided which slidably rests against one of the supporting surfaces and which is connected to the pressure cushion in a rigid or a form-fit manner and, if desired, the glide plate or plates may extend into adjacent areas of the ring.

The sliding plate may be guided in the adjacent supporting surface so that it permits a sliding movement in one direction only as is illustrated, for example, in FIG. 7, wherein a portion 31a of a slide plate 31 covering the pressure cushion 1 extends into a recess of the upper supporting structure. The plate 31 reaches with its outer circumference into the ring 2 and rests against the inner circumferential area of the ring. The portion 31a of plate 31 is slidingly guided and rests against guiding surfaces 5b and 5c of said recess in the supporting structure having side walls lined with sliding layers 34a and 34b which act as guiding surfaces and permit the sliding movement only in one direction, namely perpendicularly to the plane of the drawing.

In addition, the top surface of plate 31 which forms an annular area around the portion 31a is covered with a sliding layer 33 which rests against the supporting surface 3 of the structure 5. The bottom side of the bearing cushion 1 is provided with a plate 32 which likewise extends into and engages the inner circumferential surface of the ring 2. Plate 32 may be connected to the supporting structure 6 in a form-fit manner. This bearing is capable of transmitting horizontal forces in one direction and to yield in a direction extending perpendicularly to said one direction because of the rail-like guiding surfaces 5b and 5c. If the bearing is to be rotatable about a central axis only, the portion 31a of the plate 31 and the guiding surfaces 34 will be cylindrical.

In another embodiment of the present invention shown in FIG. 8, the pressure cushion has an annular shape, the inner circumference of which may be supported by one ring or by two rings extending over a part of the height of the ring 2. One or two holding bolts connected to the supporting structure may reach into the inner ring or rings supporting the inner circumference of the annulus for securing the bearing in a fixed position. If in these embodiments only one holding bolt extending from one bearing surface is provided, this one bolt may be held in a guiding means in the supporting structure for permitting a shift or displacement of the bearing.

Referring further to FIG. 8, the annular pressure cushion 35 is in sliding contact at its inner circumferential surface with an inner ring 36. Thus the bearing of FIG. 8 is constructed as a fixed bearing. The inner ring 36 is held by the pressure cushion in a form fitting manner in the same way as the ring 2 carried by the outer circumferential surface of the pressure cushion 35. Bolts 37 and 38 secured to the supporting sructures 5 and 6 extend from both sides into the inner ring 36 thereby leaving a gap 39 between the ring 36 and bolts 37, 38 for permitting the free movability of the ring 36. A gap 40 is further left between the end faces of the bolts 37 and 38 so that the bearing may also be vertically displaced. The bolts may be made of an elastically yielding material or elastically yielding intermediate layers may be placed into the gap 38 between the bolts and the inner ring.

The bearing of FIG. 9 is constructed as a sliding bearing in a manner similar to that of the bearing illustrated in FIG. 7 to permit a sliding movement of the upper structure with respect to the lower structure but in one direction only. An annular pressure cushion 35 is provided which is supported at its inner circumference by an inner ring 36. A bolt 38 extends into the inner ring 36. The bolt 38 is provided adjacent to its upper portion 41 with two parallel guiding surfaces which extend into a guiding groove 42 in the upper structure 5. Between the guiding surfaces of the bolt 38 and the side walls of the groove 42 there are located sliding layers 34a and 34b. The guiding groove 42 extends perpendicularly to the plane of the drawing and has a depth sufficient to leave a gap above guiding portion 41 of bolt 38 to permit the inner ring 36 to adjust itself freely in the vertical direction.

In still another embodiment of the invention two confining rings may be used. One of the advantages of this embodiment is that the two rings engage the bearing surfaces of the supporting structures and are secured to these structures to permit a better connection of the bearing to these supporting surfaces. At least the inner surface of the upper ring which faces the pressure cushion may flare outwardly but toward a center extending horizontally through the pressure cushion to thereby describe, for instance, a frusto-conical-circumferential surface. Such a shape of the inner surface of the rings provides a good hold of the rings on the pressure cushion and accommodates the deformation behavior of the pressure cushion under a load.

Referring to FIG. 10, the tilting bearing shown therein comprises again a pressure cushion 1 which is supported on its outside by an upper ring 16 and by a lower ring 17 which rest against the upper and lower supporting surface of the supporting structures 5 and 6 respectively. A gap 18 is left between the rings 16 and 17 to permit tilting movements and corresponding small horizontal displacements of the bearing when the pressure cushion is deformed. In the vicinity of the gap, the pressure cushion has a circumferential groove which becomes narrower in the vertical direction when a load is applied to the bearing. In order to control the deformation of the cushion in the area of the rings 16 and 17, the interior ring surfaces which contact the pressure cushion are inclined outwardly and widened in the direction toward the gap 18.

At least one of the two rings 16 or 17 may be rigidly connected to the respective supporting surface, for instance, by a form-fit between the ring and said supporting surface. Such a form-fit may be achieved by a plate or shoulder which is anchored in the supporting surface and which extends into the ring while resting against the inner surface of the ring. Advantageously, the plate or shoulder may be rigidly connected to the ring. Various modifications are available for rigidly connecting one or both rings to the supporting surface, depending on the type of bearing and the type of load to which the bearing will be subjected.

In the tiltable bearing shown in FIG. 11, the pressure cushion 1 has a surface layer 1d which completely envelopes the pressure cushion and is harder than its core 1b. In the vicinity of the gap 18 between rings 16 and 17, there is again provided a groove 19 formed in the surface layer 1d. The structure members 5 and 6 on the supporting structure have shoulders 5a and 6a respectively which engage the rings 16 and 17 in a form fitting manner. These shoulders, or one of them, may be plates rigidly secured to the respective structural member and reaching into the respective ring or being secured thereto. However, the rings may also be directly secured, as by welding, to the supporting structure. The embodiment wherein a plate or plates supported by the respective structural member reaches into the confining ring to which it is also secured is especially suitable for constructing a gliding bearing, whereby a glide layer may be embedded in the plate or in the plate and in the ring which glide layer cooperates with a glide plate of the respective supporting surface.

The horizontal movability of the tiltable bearing according to the invention may be restricted further by increasing its resistance to shearing forces in the area of areas of the pressure cushion which are not surrounded by the ring or rings as compared to the enclosed areas of the pressure cushion. This may be done,for instance, by reinforcement layers or by reinforcing the circumferential zones of the pressure cushion that are not enclosed by the rings.

Such an arrangement is shown in FIG. 12 in which reinforcement layers 20 are provided within the pressure cushion 1 in the area between the rings 16 and 17, opposite the gap 18. These reinforcements may be plates extending parallel to the bearing surfaces 3 and 4. These reinforcement layers 20 in the area of gap 18 control the shear deformation of pressure cushion 1 depending on the load, whereas the areas outside ring 16 and 17 permit a tilting or rotating about horizontal axes.

FIG. 13 shows a slidable bearing in which a plate 31 of a sliding material, such as polytetrafluorethylene (PTFE), is inserted in the upper ring 16 which itself is convered by a layer 25 of the same material. A sliding plate 13 is provided at the bearing surface 3 and cooperates with the layer 25 and with the plate 31. The lower ring 17 rests against the other bearing surface 4 through a layer 26 made of a material having only a relatively low elastic deformability. A plate 34 is inserted into the ring 17 and rests on the bearing surface of the support structure 6. The glide plate 32 is anchored in the bearing surface of the supporting structure 6 by bolts 27. In addition to the groove 19 in the pressure cushion 1 in the area of the gap 18 there are further grooves 26' provided in the area of the upper and lower edge of the pressure cushion.

FIG. 14 shows a slidable and tiltable bearing which is slidable only in one preferred direction, in this instance, the direction extending perpendicularly to the plane of the drawing. For this purpose, the upper supporting surface 28 is extended to form a channel with supporting side walls 30 which confine the rings 16a and 17a for movement only in said one direction. Between the rings 16a and 17a there are arranged sliding layers 29 against which the rings 16a and 17a rest in a sliding manner. A sliding plate 31a extends into the upper ring 16a. The plate 31a extends over the top of the ring 16a and rests slidably against the supporting surface 28. Similar to the arrangement according to FIG. 13, the lower ring 17a is provided with a plate 32 extending into the lower ring and fixed with respect to the lower supporting surface 4. Preferably, rings 16a and 17a have a straight or cylindrical outer contour.

FIG. 15 illustrates a fixed bearing with an annular cushion 1c as in FIGS. 8 or 9. In addition to the outer rings 16 and 17, inner rings 43 and 44 are provided in the annular pressure cushion 1c so that the cushion rests laterally against the inner and outer rings. A bolt 45 extends with play into the inner rings 43 and 44. Bolt 45 is supported by the structural members 5 and 6 by means of elastic layers 46 and 47 respectively. If said play between bolt 45 and the inner rings 43, 44 is sufficiently small horizontal forces may be transmitted by the bolt 45 from inner ring 44 to inner ring 43.

The features of the bearings of FIGS. 14 and 15 may be combined to construct a bearing for permitting displacement in one direction only in which the inner bolt 45 transmits horizontal forces from the inner ring 43 to the other inner ring 44. In this arrangement, the displacement of the structural members 5 and 6 with respect to each other is limited to said one direction and in addition the tilting movement is controlled to take place solely in a direction extending parallel to said one direction.

The bearing according to FIG. 15 may also be constructed in accordance with the features mentioned in connection with FIG. 9 whereby the bolt 45 would be guided in one or the other of the members 5, 6 so as to slide in a preferred direction.

As will be evident from the above, various modifications of the present tiltable bearings are possible. For example, the features of the bearings described in connection with FIGS. 1 to 9 may be employed singly or in combination with the bearings according to FIGS. 10 to 15 and vice versa.

The features of the tiltable bearing according to the present invention may also be advantageously combined with heretofore known bearings and the principles on which they are based. The circumferential area enclosed by the ring or rings may also be smaller than half the height of the pressure cushion. The present bearings may be easily adapted to the various requirements of a supporting structure, i.e., the present bearings may be used either as a pure tilting bearing or as a fixed bearing or as a slidable bearing. Where reinforcements are embedded in the cushion regions not confined by said ring or rings, the gaps 9, 9a or 18 may generally be larger than without these reinforcements.

In view of the foregoing, it is to be understood that it is intended to cover all modifications and equivalents within the scope of the appended claims.

Claims

What is claimed is:

1. In a tiltable bearing for heavy structures wherein a pressure cushion is arranged between an upper bearing surface forming part of said heavy structure and a lower bearing surface forming part of a supporting structure, whereby a given spacing is provided between said bearing surfaces, said pressure cushion having a circumferential surface, an upper wall facing said upper bearing surface, and a lower wall facing said lower bearing surface, said circumferential surface of the pressure cushion connecting said upper and lower walls of the cushion; the improvement comprising cushion confining upper and lower ring members each having an inner surface surrounding at least a portion of said circumferential cushion surface, said upper and lower ring members having a combined height less than said given spacing to provide a gap therebetween of sufficient height to permit a tilting movement, said gap being simultaneously sufficiently small in height for controlling horizontal displacements of the bearing, and means for providing a form-fit between said inner surfaces of the ring members and said circumferential surface of said pressure cushion, said form-fit means permitting a relative gliding movement between the inner surfaces of the ring members and the circumferential cushion surface.

2. The tiltable bearing according to claim 1, wherein said circumferential cushion surface has a given height, said ring members having a total height corresponding to more than one half of said given cushion height.

3. The tiltable bearing according to claim 1, wherein at least said upper ring member comprises an inner surface facing the pressure cushion, which surface widens toward the gap.

4. The tiltable bearing according to claim 1, wherein said means for securing said ring members comprise means for rigidly connecting at least one ring member to its respective bearing surface.

5. The tiltable bearing according to claim 1, wherein at least one of said bearing surfaces comprises means for reaching with a form-fit into the respective ring menber.

6. The tiltable bearing according to claim 15, further comprising plate means, means for anchoring said plate means to the respective bearing surface, said plate means reaching into the respective ring and resting against the inner surface of the ring.

7. The tiltable bearing according to claim 6, further comprising means for rigidly connecting said plate means to the respective ring.

8. The tiltable bearing according to claim 1, wherein the pressure cushion comprises groove means in its circumferential surface.

9. The tiltable bearing according to claim 1, wherein the pressure cushion is annular and wherein said ring means comprise an upper outer ring, an inner outer ring, an upper inner ring, and a lower inner ring, said annular pressure cushion having an inner circumferential surface against which the inner rings rest to provide a further gap therebetweeen, said further gap substantially registering with said first mentioned gap.

10. The tiltable bearing according to claim 9, further comprising means for rigidly connecting at least one of said rings to the respective bearing surface, a bolt, means for elastically supporting said bolt at its top and bottom sides against the respective bearing surface, said bolt being located with play within said inner rings.

11. The tiltable bearing according to claim 1, further comprising means for slidably supporting the bearing relative to one bearing surface, said slidable supporting means comprising a layer preferably made of polytetrafluorethylene.

12. The tiltable bearing according to claim 1, comprising a bearing surface having two opposite parallel side walls, said pressure cushion and rings being slidably supported with respect to said side walls.

13. The tiltable bearing according to claim 1, further comprising reinforcing plate means in said pressure cushion, said plate means being located in a region of the pressure cushion registering with said gap.

14. The tiltable bearing according to claim 1, further comprising sliding surface means located between the ring means and the adjacent circumferential surface of the pressure cushion, said sliding surface means being connected to the ring or rings.

15. The tiltable bearing of claim 1, wherein said upper and lower ring members have a total height, as viewed in a direction perpendicular to said bearing surfaces, corresponding to at least one half of said given height of said pressure cushion.

16. The tiltable bearing of claim 1, further comprising means for securing said upper and lower ring members to the respective bearing surfaces.