GB2053415A

GB2053415A - Resilient Shaft Coupling

Info

Publication number: GB2053415A
Application number: GB8019741A
Authority: GB
Original assignee: Balcke Duerr AG
Current assignee: Balcke Duerr AG
Priority date: 1979-06-21
Filing date: 1980-06-17
Publication date: 1981-02-04
Also published as: FR2459405B1; DE2924935A1; JPS5642724A; IN152458B; DD151649A5; DE2924935B2; JPS6237251B2; FR2459405A1; GB2053415B; DE2924935C3

Abstract

Coupling halves (12, 14) comprise plane oblique surfaces (16 and 24), 18 and 26, 20 and 28) which delimit intermediate spaces (34) which open, in wedge-like formation, in the radial direction. Sliding elements (42, 44, 46) are arranged in the spaces (34) and comprise plane sliding surfaces (52, 54, 56, 58, 60, 62) lying with surface- to-surface contact on the oblique surfaces (16, 24, 18, 26, 20, 28) and held in contact by a surrounding, resiliently deformable holding ring (98). When torque is applied the coupling halves (12, 14) turn relative to each other, the intermediate spaces (34) become narrower, and press the sliding elements (42, 44, 46) outwards to deform the holding ring (98) to non-circular shape. The oblique surfaces and/or the sliding surfaces (52, 54, 56, 58, 60, 62) are arranged on hemispherical compensating elements (74, 76, 78, 82, 84, 86), mounted in bearing sockets (96) in the coupling halves (12, 14) and/or in the sliding elements (42, 44, 46) in such a way as to be pivotable in all directions to ensure that the associated surfaces remain in complete mutual contact when the opening angle of the spaces (34) is altered. <IMAGE>

Description

SPECIFICATION Resilient Shaft Coupling The invention relates to a resilient shaft coupling whose coupling halves carry at least two plane oblique surfaces which are orientated transversely of the direction in which force is transmitted, two oblique surfaces of the two coupling halves lying opposite one another in pairs and delimiting a radially opening intermediate space, at least one sliding element being arranged in a radially resilient bearing and engaging in the intermediate space, the said at least one sliding element carrying two plane sliding surfaces which lie remote from one another; and each plane oblique surface abuts against a sliding surface.

A resilient shaft coupling of this kind is disclosed in German Offeniegungsschrift 27 42 442. In this resilient shaft coupling the coupling halves are constituted as externally toothed central wheels which are surrounded by an internally toothed planet wheel. The plane oblique surfaces of the teeth of the central wheels lie opposite each other in pairs and delimit intermediate spaces which open radially outwardly. The wedge-shaped teeth of the planet wheel engage in these intermediate spaces.

When torque is applied to this resilient shaft coupling the two coupling halves (central wheels) rotate relative to each other. The intermediate spaces then narrow, and the teeth of the planet wheel which engage in these intermediate spaces are pressed outwards in opposition to a resiliently inward pressure. This resiliently acting force, which can be produced in various ways, produces the resilience of the shaft coupling of German Offenlegungsschrift 27 42 442. By reason of the sliding action of the wedge-shaped teeth of the planet wheel on the flanks of the intermediate spaces, this resilient shaft coupling is referred to as "sliding wedge coupling".

When the coupling halves (central wheels) are turned, relative to one another, through a certain angle of rotation, the oblique surfaces are not displaced parallel but are pivoted through the same angle of rotation. The result of this is that the opening angle of the intermediate space, included by the two opposed oblique surfaces, decreases by the said angle of rotation.

Accordingly, the greater the angle of rotation the smaller (more acute) will be the opening angle. In the case of the various embodiments of German Offenlegungschrift 27 42 442 the teeth of the planet wheel are accommodated to this alteration in angle of the intermediate space through the individual teeth of the planet wheel being deformable. These teeth of the planet wheel are deformable through their consisting of flank parts which are articulated to one another at the tooth tip. A resilient force presses the flank parts resiliently away from each other. If the tooth flanks are plane, the oblique surfaces and sliding surfaces are continuously exactly parallel; through the surface-to-surface abutting contact high torques can be transmitted without inadmissibly high surface pressures occurring.

It is proposed, in the embodiments of German Offenlegungsschrift 27 42 442 and for the purpose of compensating for an inexact alignment of the coupling shafts, to construct the teeth of the planet wheel and/or the teeth of the central wheels of spherical or cambered shape; the tooth flanks are, in this case, not plane, so that the oblique surfaces and sliding surfaces only abut one another linearly, and the torque which can be transmitted is restricted due to the fact that a certain surface pressure may not be exceeded.

Underlying the present invention is the object of ensuring, in each operating condition of a resilient coupling, that the sliding surfaces and oblique surfaces, which about one another and slide on one another, are exactly parallel.

With regard to compensating for an inexact alignment of the shafts to be coupled together, this object is to be regarded in consisting in eliminating a spherical (cambered) formation of the oblique surfaces or sliding surfaces (a spherical or cambered formation of these surfaces prevents surface-to-surface abutment).

With regard to the problem of compensating for the altering opening angle of the intermediate space, this object is to be regarded as consisting in achieving an exact surface-to-surface contact in spite of the altering opening angle of the intermediate space without using resiliently deformable teeth of the type described at the outset of this specification.

The object underlying this invention can be said to consist in that the coupling, proposed in German Offenlegungsschrift 27 42 442, shall be in the form of a completely metal coupling, in which the sliding surfaces and oblique surfaces are, in each operating condition, exactly parallel, and abut one another in surface-to-surface contact.

Further, the coupling should be simple in construction and therefore inexpensive; the resilience of the coupling should be readily adaptable to the particular practical application intended for the coupling.

Proceeding from a coupling of the kind defined at the outset this object is, according to the invention, achieved by constituting at least one of the plane surfaces, associated with one another, of an intermediate space on a compensating element shaped as a segment of a sphere, this compensating element being mounted in a spherical bearing socket in such a way that it can pivot in all directions; the number of the intermediate spaces, in each of which a sliding element is arranged, amounts to 2 to 12; and the sliding elements are pressed by a holding ring into their associated intermediate spaces, this holding ring being capable of resiliently deforming radially so as to assume non-circular shape.

By the expression "compensating element having the shape of a sphere segment" is to be understood an element which a) is pivotably mounted, by a surface shaped as a sphere segment, in the spherical bearing socket, b) carries a plane surface (sliding surface or oblique surface) of the intermediate space.

It is ensured-through mounting a sliding surface and/or an opposite-lying oblique surface so as to be pivotable about a fulcrum-that the pivotably mounted surface always adjusts so as to assume a position parallel to the other surface. In this way it is possible-without the use of deformable teeth of the type described at the outset, that is to say in particular with a fully nonresilient, hard, metallic sliding element-to compensate for an inexact alignment of the shafts and/or an alteration of the opening angle of the intermediate space.

The coupling can easily accommodate to the particular practical application required for it through the choice of a corresponding number or intermediate spaces or sliding elements.

The holding ring is resiliently deformed by the sliding elements which exert radial pressure (outwardly or inwardly); this holding ring deforms oppositely (inwardly or outwardly) between the areas in which it abuts the sliding elements.

The resilience of the coupling can therefore be affected by the particular form of construction of the resiliently deformable holding ring. If the wall thickness of the holding ring is very small in relation to the diameter, and thus the holding ring is easily deformable, this means a greater elasticity of the coupling in comparison with an embodiment with a holding ring of greater wall thickness. The resilience of the coupling can be additionally affected by the opening angle of the intermediate spaces. When the opening angle of the intermediate spaces is small, e.g. 300 to 600 when no torque has been applied to the coupling, the radial force acting on the sliding element is, for a predetermined torque to be transmitted, smaller than in the case of a greater opening angle.For this reason the effect of the resilient holding ring on the resilience of the coupling is smaller than in the case of a larger opening angle of the intermediate spaces.

Thus, as a whole, the resilient shaft coupling according to the present invention fulfils the requirements, expected of such a coupling, in respect of its construction, adaptability to different operating conditions, simple and reliable mechanism for transmitting the torque, and also the ease with which the resilience of turning movement can be affected.

With regard to the opening angle of the intermediate spaces it should be noted that this opening angle must be at least so great that a satisfactory sliding movement of the sliding surfaces on the oblique surfaces is rendered possible so that, when the coupling halves turn relative to each other, the friction of the surfaces in mutual abutment is overcome, and a radial movement of the sliding elements is possible.

In order to permit, if required, the damping characteristic to be subsequently altered, it will be found advantageous if a radial stop for the holding ring is arranged between each pair of adjacent intermediate spaces on the periphery of at least one coupling half, this stop being adjustable or resilient in the radial direction.

One particularly satisfactory modification of the invention may reside in the provision of an even number of sliding elements; each pair of oblique surfaces lying adjacent one another in the peripheral direction-these oblique surfaces being formed on different sliding elements-are arranged on the same coupling halt In this way the resilient shaft coupling can be constructed on the principle of a jaw coupling, which is resilient in both directions of rotation, the intermediate spaces being formed between the individual jaws.

Conveniently, the holding ring surrounds the sliding elements in most practical applications, and the intermediate spaces widen radially outwardly. It is to be recommended, in the case of couplings which rotate with high speed, to arrange for the sliding elements to surround the holding ring, that is to say for the holding ring to be positioned on the inside, and for the intermediate spaces to widen radially inwardly.

A further, advanageous modification of the invention may consist in mounting the compensating elements in the couling halves, the sliding elements consisting of sliding wedges which comprise the sliding surfaces. This embodiment is particularly intended for couplings which are only intended to transmit a small torque, e.g. a torque smaller than 100 kpm. This is because, in the case of couplings of this kind, the individual parts are correspondingly small, and adequate mounting means for the sliding elements are only provided in the coupling halves.

However, where a coupling is intended for transmitting relatively large torques, e.g. torques greater than 100 kpm, and, accordingly, where the individual components are of relatively large dimensions, it is to be recommended to mount the compensating elements in the sliding elements and for the compensating elements to comprise the sliding surfaces. The oblique surfaces may be constituted in various ways. If the offset of the shafts to be coupled together is small, e.g. if this offset amounts to a maximum of' 1/100th to 1/75th of the shaft diameter, and/or if the angle offset of the shafts is small (e.g. is a maximum of 20), then it will suffice, in most cases, if the oblique surfaces are directly formed on the coupling halves, if the compensating elements are mounted in the sliding elements.

In other cases, in which the above-stated conditions do not apply, it will be preferable to form the oblique surfaces on other compensating elements shaped as sphere segments, which are mounted in the coupling halves, that is to say compensating elements are mounted both in the sliding elements and also in the coupling halves.

Further advantages and features, and also the mode of operation of the different shaft couplings proposed according to the invention, are explained below with reference to embodiments shown in the drawings. In these drawings: Figure 1 is a view taken in the direction of the axis of a coupling according to the invention; in this view no torque is applied to the coupling; Figure 2 is a cross-section taken along the line Il-Il of the subject matter of Figure 1; Figures 3 and 4 illustrate different pivot mountings of compensation elements in the coupling halves and/or slider elements; Figure 5 is a view in the direction of the axis of the coupling of Figure 1, whose coupling halves have been rotated relative to one another by the application of torque; the holding ring is illustrated in cross-section; Figure 6 is a cross-section taken along the line VI--VI of the subject matter of Figure 5; Figure 7 is in the form of a cross-section taken along VIl-VIl of the subject matter of Figure 6 and also of the detail VII indicated in Figures 1 and 5, and serves to explain the sequence of movements which take place; Figure 8 is a cross-sectional view taken along the line VIll-VIll of the subject matter of Figure 1; Figure 9 is a view taken in the direction of the axis (cross-section taken along the line IX-IX of Figure 10 of a further coupling constituted as a jaw coupling; in the view of Figure 9 no torque is applied to the coupling; Figure 10 is a plan view, corresponding to the view indicated by the arrow X in Figure 9, of the subject matter of the latter Figure; the holding ring is shown in cross-section; Figure 11 is a cross-section taken along line Xl-Xl on the subject matter of Figure 10; the sliding element is shown at a distance from the intermediate space; Figure 12 is a radially outward, developed view of the two coupling halves of Figure 9, and extends over the area Xll-Xll of Figure 9; Figure 1 3 is a view taken in the direction of the axis of a coupling half, which carries four compensating bodies on the individual inserts, which have been introduced into slots of the coupling half; Figure 14 is a cross-sectional view taken along line XIV--XIV of the subject matter of Figure 13; parts lying behind the section plane are not shown; Figure 1 5 is a cross-sectional view, taken along line XV-XV of of Figure 16, of a coupling constituted as a jaw coupling and having four intermediate spaces; in this view no torque has been applied to the coupling; Figure 1 6 is a cross-section taken along line XVl-XVl of the subject matter of Figure 1 5; Figure 1 7 is a developed view, as seen radially inwardly, of the whole of the two coupling halves of Figure 1 5, and is shown on a different scale; Figure 1 8 is a cross-sectional view taken perpendicularly of the axis of the coupling; this sectional view is taken through the coupling of Figure 15, whose coupling halves have been turned, relative to each other, by the application of torque; this cross-section is taken through line XV-XV; Figures 1 9 to 22 illustrate the provision of a flat needle cage between an oblique surface and a sliding surface; Figure 23 illustrates a modification of the coupling according to the invention, and has an internally positioned holding ring; this modified embodiment is illustrated in the form of a crosssection taken along the line XXlll-Xlll of Figure 24 (in this view no torque has been applied to the coupling); Figure 24 is a cross-section taken along line XXIV--XXIV of the coupling shown in Figure 23; Figure 25 is a longitudinal cross-section, taken along the line XXV-XXV of Figure 24, through the upper half of the coupling; and Figure 26 is a cross-section, taken along line XXIII--XXIII, through the coupling shown in Figure 23; no torque has been applied to the coupling in this Figure.

Figure 1 illustrates a coupling according to the invention, whose two coupling halves are free of applied torque, that is to say the coupling is in its loadfree condition.

Figure 2 is a cross-section taken along line 11- 11 of the subject matter of Figure 1. In Figure 2 arrow I indicates the direction in which the subject matter of Figure 1 is viewed.

Of the two coupling halves 12 and 14 shown in Figure 2 only the front coupling half 12 is visible in Figure 1. This front coupling half 12 is provided with a central bore 102, while the rear coupling half 14 has a central bore 104. Bore 102 is intended to receive a drive shaft, and the bore 104 is intended to receive the driven shaft. The shafts are secured in place by means of keys.

Each of the coupling halves has a circular coupling disc with a central hub.

The front coupling half 12, which can be seen in Figure 1, has three spherical bearing sockets 96, which are distributed at regular angular intervals along the periphery and are disposed in planes lying perpendicularly of the plane of the drawing of Figure 1. Three compensation elements 74, 76 and 78, which the shape of segments of a sphere (e.g. are hemispherical) are mounted in these three spherical bearing sockets 96. The three compensation bodies each define a plane oblique surface 16, 18 and 20. These three plane oblique surfaces extend transversely of the direction in which force is transmitted and include an angle with one another. Figure 2 shows, in the front coupling half 12, the spherical bearing socket 96, the compensation body 74, and also the plane oblique surface 16, these parts being shown in cross-section.For the sake of simplicity reference is made to "hemispherical" compensation bodies. However, these compensation elements do not have to be exactly formed as "half" spheres, as is apparent from the drawings. The compensation elements may be smaller than or, if necessary, larger than, hemispherical bodies. What is essential is that these compensation bodies are mounted, by a spherical surface, in the spherical bearing socket, and are therefore pivotable in all directions.

The rear coupling half 14 carries, in spherical bearing sockets 96, compensation elements 82, 84 and 86; this is similar to the arrangement in coupling half 12, but the orientation of the compensation elements 82, 84 and 86 is opposite. Each of these compensation elements 82,84 and 86 has an oblique surface 24, 26 and 28. A sliding element 42, 44, 46 is arranged between the oblique surfaces 16, 18,20 of the front coupling half 12 and the oblique surfaces 24, 26, 28 of the rear coupling half. This arrangement is particularly clear from Figure 2.

The sliding elements extend axially the whole length of the coupling halves 12, 14.

As is clear from Figure 1: a) the plane oblique surfaces 16 and 24 of the compensation elements 74 and 82 lie opposite one another and are mounted in spherical bearing sockets 96 of the front coupling half 12 and of the rear coupling half 14, so that the surfaces 16 and 24 lie opposite one another in offset relationship (see Figure 2), b) the plane oblique surfaces 18 and 26 of the compensation elements 76 and 84 lie opposite one another, and are mounted in spherical bearing sockets 96 of the front coupling half 12 and of the rear coupling half 14, and c) the plane oblique surfaces 20 and 28 of the compensation elements 78 and 86 lie opposite one another, so as to form a pair, and are mounted in spherical bearing sockets 96 of the front coupling half 12 and of the rear coupling half 14.

In each case a plane oblique surface of the front coupling half 12 includes, with a plane oblique surface of the rear coupling half 14, a radially outwardly opening intermediate space 34 (see Figure 11). A sliding element in the form of a sliding wedge 42, 44 and 46 are arranged in each intermediate space. Each sliding element 42, 44, 46 has plane sliding surfaces 52, 54 or 56, 58 or 60, 62, each of which abuts against a plane oblique surface of one of the six compensation elements 74, 76, 78, 82, 84 and 86.

The sliding elements are triangular in crosssection.

The three sliding elements 42, 44 and 46 are held in the position shown in the drawing by an enclosing holding ring 98 and act, analogously to the resilient shaft coupling of the German Offenlegungsschrift 27 42 442 referred to at the outset, in the manner of the teeth of a planet wheel which surrounds two central wheels (comparable to the coupling halves 12 and 14).

The holding ring 98 surrounds the coupling halves, the distance a lying between this ring 98 and the coupling halves, thereby defining an annular gap 122.

When the front coupling half 12, which is fast in rotation with the drive shaft, rotates in the direction 100, the plane oblique surfaces 16, 18 and 20 press against the plane sliding surfaces 52, 56 and 60 of the three sliding elements 42, 44 and 46. A component of force acts in the radial outwards direction on the sliding elements. The latter bear against the holding ring 98, and transmit the torque to the plane oblique surfaces 24,26, 28 of the three compensating elements 82, 84 and 86, which are mounted in spherical bearing sockets 96 of the rear coupling half 14.

When torque is thus transmitted pressure and shearing force are applied to the individual, substantially wedge-shaped sliding elements 42, 44 and 46. In order to ensure that, when such shearing load is applied between the two coupling halves, the sliding elements 42, 44 and 46 will not tilt, the holding ring comprises two continuous guide beads 99, 101. The sliding elements lie between the radially inwardly extending, mutually facing guide surfaces 103, 105 of the guide beads, and can move in the circumferential direction, but not in the axial direction (e.g. sliding element 46 on the left-hand side of Figure 2).

In its circular coupling disc each of the coupling halves 12, 14 has three V-shaped openings, which are uniformly distributed round the periphery. These openings are radially directed and widen in the outward direction. These openings serve to receive the wedge-shaped sliding elements 42, 44, 46. For this purpose each opening of the front coupling half defines a V surface 11,113, and a counter surface 112, 114, 11 6; both surfaces intersect at the base of the opening. The rear coupling half 14 has corresponding V-shaped openings. In Figure 2 the V-surface 311 and the counter surface 312 of the rear coupling half 14 can be seen. A respective one of the spherical bearing sockets 96 is arranged in each V-surface of the two coupling halves.The inclination of each of the counter surfaces 112,114,116,312 matches the inclination of the sliding surface of the associated sliding element. In the "unloaded position" of Figure 1, in which no torque has been applied to the coupling, the three sliding elements 42, 44 and 46 lie, on their two plane sliding surfaces 52, 54, 56, 58, 60, 62, on a respective plane oblique surface 1 6, 1 8, 20 and a respective counter surface 112, 114, 11 6 of the front coupling half.

The same is true of the rear coupling half 14 (cf.

Figure 2).

As is apparent from Figures 1 and 2, three spherical bearing sockets 96 are provided in each coupling half; a compensating element is mounted, for rotation about a fulcrum 72 (cf.

Figure 7) in each of these sockets 96. In each case the compensating element is in the form of a segment of a sphere and has a rotational surface 94 which lies concentrically of the fulcrum 72 and is mounted in a spherical bearing socket 96 which is concentric with the fulcrum 72 (cf. Figure 2).

The compensation element is therefore pivotable in all directions. As the compensating elements, mounted in spherical bearing sockets 96, are usually of lesser height than hemispherical elements the fulcrum 72 usually lies inside the sliding element, as is depicted in Figures 1 and 2.

By virtue of the fact that the compensation elements are shaped as segments of a sphere the coupling according to the invention can also be used when the axis 70 of the coupling in the vicinity of the drive shaft includes an angle with the axis 70 of the coupling in the vicinity of the driven shaft. The fact that the compensation elements can pivot enables such an angular difference to be compensated for.

As is clear from Figures 1 and 2, the plane oblique surfaces of the coupling halves 12 and 14 are arranged on pivotable compensating elements, which are mounted in spherical bearing sockets 96 of the V-surfaces. Other arrangements of compensating elements are illustrated in Figures 3 and 4; both of these Figures 3 and 4 show views similar to that of Figure 2, although in the case of Figures 3 and 4, only the area around the sliding element 42 is shown.

As is clear from Figures 3 and 4 it is possible to arrange the plane sliding surfaces of the three sliding elements on pivotable compensating elements, which are mounted in spherical bearing sockets, which are formed in the sliding elements.

Figure 3 shows an embodiment of this kind in which the compensating elements 74, 82, which are held in the sliding element 42, are mounted in spherical bearing sockets. In this case the corresponding plane oblique surfaces 1 6 and 24 of the coupling halves 12 and 14 are directly arranged on the coupling halves 12, 14. In this case it is not necessary to constitute the sliding elements 42, 44, 46, 48 in the form of sliding wedges of triangular cross-section. The shape of the sliding elements can be selected as required with the sole proviso that the compensation elements are held in the correct position by the sliding elements. However, the sliding elements will usually be given the wedge shape, as this is the simplest possible form of construction.

Figure 4 illustrates a further modification. In the case of the embodiment shown in Figure 4, and in contradistinction to that shown in the previous embodiment (Figure 3), the plane oblique surfaces 16, 24 of the two coupling halves are arranged on further compensating elements 274 and 282. These compensating elements 274, 282 are also approximately hemispherical, and are pivotably arranged in bearing sockets of the coupling halves, as is very clearly shown in Figure 4. The arrangement illustrated in Figure 4 affords the dvantage of a greater pivoting movement.

When a torque is transmitted, by the coupling shown in Figure 1, from the front coupling half 12 to the rear coupling half 14, the three sliding elements 42, 44 and 46 are outwardly radially pressed against the enclosing holding ring 98.

These sliding elements 42, 44 and 46 cause the holding ring to be deformed to a non-circular shape, as is illustrated in Figure 5. The points at which the surfaces of the three sliding elements 42, 44 and 46 press against the holding ring 98 (which is shown in cross-section and without guide beads 99, 101) act as radially resilient bearings 50. As is shown in Figure 5, the three sliding elements 42, 44 and 46 are radially outwardly pressed in opposition to this radially resilient movement, which derives from the deformation of the holding ring 98 to a noncircular shape; the plane sliding surfaces of these sliding elements 42, 44 and 46 slide on the plane oblique surfaces, which abut these sliding surfaces of the sliding elements, of the two coupling halves.

The cross-section, taken along line VI--VI of Figure 6, substantially resembles that of Figure 2.

One difference resides in the fact that, as show in Figure 6, the plane sliding surfaces 52 and 54 of the radially outwardly pressed sliding element 42 have lifted away from the counter surfaces 312 and 112. In this position, in which pressure has been applied to the sliding element 42, the latter lies with the front half of its plane sliding surface 52 on the plane oblique surface 1 6 of the compensating element 74 of the front coupling half 12, whereas the rear half of its plane sliding surface 54 abuts the plane oblique surface 24 of the compensating element 82 of the rear coupling half. These two halves, to which pressure has been applied, of the plane sliding surfaces 42 and 54 are so offset relative to one another that a shearing force is applied to the sliding elements.It was stated above that continuous guide beads 99, 101 are provided on the holding ring 98 for preventing tilting of the three sliding elements between the coupling halves. For this purpose the end surfaces 73 of the sliding elements are guided on the guide surfaces 103, 105 (Figure 2).

The holding ring 98 deforms resiliently until it abuts against the coupling discs in the three areas between the three sliding elements. The torque at which this position of abutment occurs is adjustable if adjustable or spring-loaded stops are provided between the three sliding elements. As shown in Figures 1 and 5, these adjustable stops are in the form of radial screws 127, 128, 130 or (right-hand upper quadrant of Figure 1) of pins 132, which are arranged on the periphery of at least one coupling half. The pins 132 are radially outwardly biased by springs, e.g. cup springs 205.

The damping characteristic of the resilient shaft coupling according to the invention can be set by adjusting the screws or by appropriate selection of the springs, before the holding ring 98 has been pushed into position. Aiso, the damping characteristic can be additionally or solely affected by selection of the resilience of the holding ring 98. Naturally, only one type of stop will be selected in a coupling, that is to say either screws 127, 128, 130 or spring-loaded pins 132.

It is clear from a comparison of Figures 1 and 5 that the resilient deformation of the holding ring 98 permits a radial movement of the three sliding elements 42, 44 and 46. Figure 7, which is in the form of a detail VII of Figures 1 and 5, and the cross-sectional view taken along line VIl-VIl of Figure 6, elucidate the pivotal movements of the compensating elements which occur on the occasion of this radial movement of a sliding element and, for this purpose are shown on a greatly enlarged scale. Continuous lines indicate the position of Figure 1, in which no torque has been applied, and dashed lines indicate the position of Figure 5, where torque has been applied. Further, in the right-hand half of Figure 7 part of the frqnt coupling half 12 is shown broken away along line 140.Consequently, only a short section of the counter surface 112 of the front coupling half 12 is visible in this Figure; the line which continues the interrupted line of counter surface 112 indicates the V-surface 311 of the Vshaped opening of the rear coupling half 14. The spherical bearing socket 96 is provided in this Vsurface 311, the compensating element 82, shaped as a segment of a sphere, is pivotably mounted in this socket 96.

The V-surface 111 of the front coupling half 12 is formed with the spherical bearing socket 96, in which the compensating element 74 is pivotably mounted.

The V-surfaces 111 and 311, in each of which a corresponding compensating element is pivotably mounted, include with each other an angle .

The plane sliding surfaces 52 and 54 of the wedge-shaped sliding element 42 include with each other the same angle a included by the Vsurfaces 111 and 311 of the coupling halves 12 and 14. Thus, in the position shown in Figure 7, which is drawn in continuous line and corresponds to the position of Figure 1 in which no torque has been applied to the coupling, the plane oblique surfaces 16 and 24 of the compensating elements 74 and 82 also include this angle a with each other.

As has already been explained, when torque is applied to the resilient shaft coupling according to the invention, the sliding element 42 is radially outwardly pressed in opposition to the resilient force of the surrounding holding ring 98 not shown in Figure 7. In this position the sliding element 42 is in the position shown in dashed line in Figure 7. This position, shown in dashed line and assumed when torque has been applied to the coupling, is-as is also the position which is shown in discontinuous line and which is assumed when no torque has been applied to the coupling--drawn symmetrically of the radial plane 134, although this radial plane has already rotated while torque was being applied to the coupling; this rotation may amount to a number of revolutions about the coupling axis.However, Figure 7 is clear if the position assumed when no torque has been applied, and the position assumed when torque has been applied, are drawn symmetrically of a single radial plane 134, which extends perpendicularly on the plane of the drawing and is shown as a line.

The plane sliding surfaces 52 and 54 continue, after a torque has been applied, to include with one another the angle m, as the sliding element 42 is intrinsically non-deformable. as the sliding element 42 maintains its symmetrical position to the radial plane 134, rotation of the two coupling halves through the angle relative to one another causes: 1) the V-surface 111 of the front coupling half 12 to pivot through an angle /2; 2) the V-surface 311 of the rear coupling half 14 to pivot through (p/2.

These pivotal angles nod/2 are both shown on the right and left-hand sides. As we are concerned here with pivotal movements, the V-surfaces 111 and 311 do not move parallel but are pivoted in relation to one another, so that the angle which they include with one another decreases from a to a-(p. This angle a-(p is shown in the upper part of Figure 7.

If the plane sliding surfaces 52 and 54 directly (as in the case of the prior art) abutted the Vsurfaces 111 and 311, there would be, on the occasion of rotation of the two coupling halves through the angle (p, no surface abutment of the plane sliding surfaces 52 and 54 on the V surfaces 111 1 1 and 31 1. 111and311.Forthisreasonthe invention provides the compensating elements 74 and 82, which so pivot in the spherical bearing socket 96, that their plane oblique surfaces 16 and 24 lie in complete surface-to-surface abutting contact with the plane sliding surfaces 52 and 54 of the sliding element 42 in each position of the latter In the case of the embodiment illustrated the plane oblique surfaces 1 6 and 24 are pivoted through an angle /2.

In the embodiment shown in Figure 7 the two compensating elements are mounted in spherical bearing sockets 96. The fulcrum 72 lies exactly in the plane sliding surface 52 or 54. However, in general it is preferred if the height of the compensating elements is less than that corresponding to hemispherical shape, so that the fulcra 72 assume a position within the sliding element 42.

The two coupling halves 12, may be formed with opposed radial surfaces 133, 135 which extend radially and, relative to one another, axially inwardly. The maximum possible angle P of rotation is reached when these radial surfaces abut each other. When a higher torque is exerted the coupling acts as a rigid, non-resilient coupling without any danger of damage or overload existing.

An embodiment in which the angle P of rotation is limited in this way is illustrated in Fig.

8, which is in the form of a cross-section taken along line VIll-Vill of Figure 1. As shown in this Figure the front coupling half 12 has an axial projection 240 which comprises the radial surface 133. This projection 240 engages in a recess 242, which lies in the rear coupling 14 and has the radial surface 135. The arrangement is such that, when no torque is applied to the coupling, the two radial surfaces 133, 135 lie opposite one another and are mutually spaced. When torque is applied, that is to say when the two coupling halves turn relative to each other, the two radial surfaces 1 33, 1 35 approach one another, and abut one another at a maximum turning angle q) max. The coupling then acts as a rigid coupling, the radial surfaces 133, 135 delimiting the elasticity range of the coupling.The projection 240 may possibly be constituted by a pin, which has been screwed into place, and the recess 242 by a bore. This is also advantageous if a number of radial surfaces 133, 135 are provided, and are distributed round the periphery.

When, as shown in Figure 7, the sliding element 42 moves radially, the inner tip 142 of the sliding element 42 moves from radius r1 to radius r2. The size a of the annular gap 122 between the outer periphery 144, 146 of the coupling discs and the holding ring 98 (not shown) alters by the differences r2-r1=Ar. In the vicinity of the sliding elements the size a of the annular gap 122 increases by this value Ar, while at the three points of the outer periphery 144, 1 46 lying between these sliding bodies the size a of the annular gap decreases. The screws 127, 128, 130 or pins 132 of Figures 1 and 5 are so set that the damping characteristic of the coupling is given the required pattern; from the instant at which the holding ring 98 touches the stops 127, 128, 130, 132 this characteristic steepens (cf. Figure 5).

Figures 9 to 12 illustrate a resilient shaft coupling according to the invention which differs from the embodiments shown in Figures 1 and 5 in that the coupling is constituted as a jaw coupling.

Figure 9 is a view corresponding to that of Figure 1; more specifically, Figure 9 is in the form of a cross-section taken along line IX-IX of the subject matter of Figure 10. Figure 10 is a view in the direction X of the subject matter of Figure 9; the upper half of the holding ring 98 is omitted from the drawing. Further, Figure 11 is a schematic cross-section through line Xl-Xl of Figure 10, and Figure 12 is a developed crosssection taken along line Xll-XlI. In Figure 10 elastic sealing washers 124, 126 are provided between the holding ring 98 and the coupling halves.

It is clear from the developed view of Figure 12, and also from Figure 9, that the rear coupling half 14 carries three jaws 166 (not visible in Figure 12), 1 68 and 180 which are distributed at regular intervals and project perpendicularly from the plane of the coupling half 14; these jaws 166, 168 and 180 extend almost to the front coupling half 12.

In its turn, this front coupling half 12 carries three jaws 1 70, 1 72 and 174, which are distributed at regular intervals and extend from, and perpendicularly of, the front coupling half 12; these jaws 170, 1 72 and 1 74 reach almost to the rear coupling half 14. The opposed surfaces a) of the jaws 172,180 b) of the jaws 174,166 and c) of the jaws 170,168 correspond to the V-surfaces 111,113,115 and 311 referred to with reference to Figures 1 to 8 and carry, in spherical bearing sockets, the compensation elements which are pivotable about a fulcrum. These compensation elements carry plane oblique surfaces which, as in the case of Figures 1 to 8, abut against plane sliding surfaces of the sliding elements 42,44 and 46.

The sliding elements are formed as sliding wedges with triangular cross-section.

As in the case of the coupling shown in Figures 1 to 8, the application of torque causes the sliding g elements 42, 44 and 46 to move outwardly.

However, no shearing forces act on these sliding elements 42, 44 and 46 as the opposed Vsurfaces of the jaws, which comprise the spherical bearing sockets, lie directly opposite one another and support the plane sliding surfaces of the sliding elements along their whole axial extent. This form of construction of the resilient shaft coupling according to the invention as jaw coupling thus renders superfluous the provision of guide beads 99, 101 on the holding ring 98, and enables particularly high torques to be transmitted since a compensation element with a larger sliding surface can be used.

The compensation elements of Figures 9 to 12 are shaped as segments of spheres, as is particularly clear in Figure 11. That Figure shows a sliding element 42 with its two plane sliding surfaces 52 and 54. Parallel to these two plane sliding surfaces are the plane oblique surfaces 16 and 24 of the compensation elements 74 and 82, shaped as segments of a sphere, which are pivotably mounted in circle bearing sockets 96 of the jaws 172 and 180.

In order to show, on the one hand, the sliding surfaces 52 and 54 and, on the other hand, the plane oblique surfaces 1 6 and 24, separately from one another, the sliding element 42 is shown, in Figure 11, positioned a short distance radially outwardly. Naturally, in actual operation of the coupling, such a position is never assumed, as the holding ring 98 continuously inwardly radially presses on the sliding element.

As is apparent from Figures 9 to 12, the jaw coupling is conventionally constructed in the sense that the long arms of the angled jaws are welded or screwed to the associated coupling disc and the short arm of the jaws extends into the space between the coupling halves. In the case of the embodiment of Figures 13 and 14 the long arm of the jaws is superfluous.

Figure 13 is an axial view, seen from the drive shaft towards the driven shaft, of a rear coupling half 14. The associated front coupling half is constituted analogously to the rear coupling half 14.

As is clear from Figure 13, axially extended slots 194, 196, 197 and 198 are distributed at regular angular intervals in the coupling half 14.

Inserts 200 are placed in these slots. The orientation or attitude of these inserts is similar to that of the jaws of the jaw coupling of Figures 9 to 12; accordingly, the orientation or attitude of these slots 194, 196, 197 and 198 is determined.

After the inserts have been introduced into their associated slots, they can be locked in place by means of locking screws 204, which are arranged in bores which extend from the inside of the coupling half 1 4 as far as the slot. The inserts 200 carry, in spherical bearinq sockets, the compensation elements which are shaped as segments of a sphere, as do the jaws of the jaw coupling of Figures 9 to 12. The advantage of the arrangement of Figures 13 and 14 compared with the jaw coupling of Figures 9 to 12 resides in the fact that it can more easily be manufactured and can be assembled simply. In Figure 14 parts lying behind the section plane are not shown. The inserts are parallelepipedic.

Figure 1 5 is in the form of a cross-section taken through a further jaw coupling according to the invention, which differs from the jaw coupling shown in Figure 9 in that four sliding elements are provided instead of only three sliding elements.

The cross-section is taken along the line XV-XV of Figure 1 6.

Figure 1 6 is a cross-section taken along the line XVl-XVl of the subject matter of Figure 15.

Further, Figure 17 is a developed view similar to that of Figure 12, although the developed view of Figure 17 extends along the whole periphery of the two coupling halves without showing the surrounding holding ring 98. The length of the developed view is not drawn to scale.

Figures 1 5, 1 6 and 17 show the jaw coupling in a position in which no torque is applied for causing relative turning movement between the coupling halves.

Figure 1 8 is a cross-sectional view corresponding to that of Figure 15, the coupling halves having been turned through the angle q of rotation relative to each other.

In Figure 1 5 the legend XVIIA--XVIIB indicates that the lower half of Figure 1 7 is associated with the left-hand circumferential part of Figure 15, and that the upper half of Figure 1 7 is associated with the right-hand circumferential part of Figure 15.

The provision of an even number of sliding elements enables two plane oblique surfaces to be alternately provided on a jaw of one of the coupling halves, and two plane oblique surfaces to be provided on a jaw of the other coupling half, whereas in the case of the embodiment of Figures 9 to 12, it is only possible to alternately provide one plane oblique surface on a jaw of one coupling half and a plane oblique surface on a jaw of the other coupling half.

As shown in Figure 17, the two jaws 166, 168 are arranged on the rear coupling half 14, and the two jaws 178, 180 on the front coupling half 12.

The arrangement is such that: 1) sliding element 42 lies between jaws 166 and 180, 2) sliding element 48 lies between jaws 1 80 and 168, 3) sliding element 46 lies between jaws 1 68 and 178, and 4) sliding element 44 lies between jaws 178 and 166 (cf. Figures 1 5 and 17).

When torque is applied to the drive shaft and, hence, to the front coupling half 12, the two coupling halves 12 and 14 rotate relative to each other in the direction of arrows 220 and 22 of Figure 1 7. This causes: 1) jaws 1 66 and 180 to move closer to each other, 2) the distance to increase between the jaws 180 and 168, 3) the jaws 168 and 178 to move closer to each other, and also 4) the distance between the jaws 178 and 166 to increase.

The effect of these decreases and increases of the distances between the four jaws on the four sliding elements can be seen in Figure 18: a) the diametrically opposite-lying sliding elements 42 and 46 are radially outwardly displaced, and deform the holding ring 98 so that the latter assumes a non-circular shape.

b) the holding ring, which has assumed noncircular shape, thrusts the two other opposed sliding elements 44 and 48 radially inwardly; this radial inward movement can take place through the increase in the distance of the associated jaws.

The jaw couplings shown in Figures 1 and 9 only have a damping effect in one direction of rotation, while they are rigid and non-resilient in the other direction of rotation. The embodiment of Figures 15 to 1 8 has a damping effect in both directions of rotation due to the fact that further sliding elements (44 and 48 in Figure 19) are arranged on the points of the holding ring 98 which lie between two outwardly-pressing sliding elements (42 and 46 in Figure 18) and which move correspondingly radially inwardly, these further sliding elements (44 and 48) in Figure 18) being, accordingly, able to slide radially inwardly.

Thus, the holding ring 98 is clamped, reliably and in clearance-free manner, in each position between, on the one hand, the two outwardly moving sliding elements (in Figure 18: 42 and 46) and, on the other hand, the two inwardly moving sliding elements (in Figure 18: 44 and 48).

If the direction of the arrows 220 and 222 (Figure 1 7) is reversed, this results in a reversal in the direction of torque The two sliding elements 44 and 48 are then radially outwardly pressed and, accordingly, the two other sliding elements 42 and 46 are radially inwardly pressed. As the coupling shown in Figures 1 5 to 1 8 is clearancefree, this reversal in torque occurs without the socalled "speed thrust" occurring that is to say without the sliding surfaces lifting away from the oblique surfaces. As is particularly clear from Figure 17, the jaws in the present example are formed from projections, arranged in pairs, of the coupling halves. However, the jaws may also be angled, as is shown in the example of Figures 9 to 12.The sliding elements consist of sliding wedges of triangular cross-section, and are distributed at regular angular intervals along the periphery.

When the holding ring 98 is deformed to noncircular shape through the sliding elements which are outwardly thrust (in Figures 1 and 5: sliding elements 42, 44 and 46; in Figures 1 5 and 18: sliding elements 42 and 46), the radius of curvature of the holding ring 98 is reduced in the pressure points in which the sliding elements are inwardly pressed on to the holding ring 98.If the radius of curvature of the outer contact surfaces 182,184,186 and 187 of sliding elements 42, 48, 46 and 44 of Figure 1 5 coincides with the radius of curvature of the holding ring 98, to which no torque has been applied, these contact surfaces of the sliding elements only lie, in the position in which torque has been applied, in two lateral edge areas; a hollow space is created, in the centre of the sliding elements, between the holding ring 98 and the sliding element. This entails the risk that a high surface pressure will occur between the edges of the contact surfaces of the sliding elements and the holding ring (this high surface pressure may lead to wear).

In the case of the jaw coupling of Figures 1 5 to 18, in which only two sliding bodies are radially outwardly thrust, the alteration of the radius of curvature of the holding ring 98 in the pressure points is appreciably greater than in the case of the previously-described forms of construction, which comprise three pressure points. For this reason the radii of curvature of the contact surfaces 182, 184, 186, 187 are only in the case of the embodiment of Figures 15 to 18 so selected that, in the position shown in Figure 1 8 in which torque has been applied (maximum predetermined angle v of rotation), at the pressure points the radii of curvature of the contact surfaces of the sliding elements 42 and 46 coincide in a large measure with the radius of curvature of the holding ring 98 at the pressure points.At these pressure points, in which the greatest radial force is transmitted, a surface-tosurface abutting contact is therefore ensured between the contact surfaces and the inner surface of the holding ring; these contact surfaces 182, 186 and the inner surface of the holding ring have a corresponding radius of curvature in the case of the maximum angle (p of rotation.

Correspondingly smaller is the force-transmitting surface between the sliding elements and the holding ring, on the one hand, in the rest position (Figure 15) and, on the other hand, in the areas lying between the pressure points, where the sliding elements 44 and 48 abut, subject to the applied load, on the holding ring 98 which has been deformed to a flatter shape (i.e. reduced radius of curvature).

For the purpose of affecting the characteristic of the coupling, radially projecting screws or spring-loaded pins can be installed on the jaws (cf. screws or pins 127, 128, 130, 132 of Figure 1).

In Figures 19 to 22 two flat needle cages are provided between each oblique surface and a sliding surface.

Figure 19 only shows the sliding element 42, in whose spherical bearing sockets 96 (with concentric rotating surfaces 94) the compensating elements 74, 82 are pivotably mounted. Figure 20 shows, in plan view, the sliding element and the plane sliding surface 54.

As shown in Figure 21, the plane oblique surface 24 lies opposite the plane sliding surface 54 of the compensating element 82. However, in the embodiment of Figure 21, these surfaces do not directly abut one another, but a needle cage 206 lies between them. In Figure 22 this needle cage 206 is shown in plan view. It can be seen that the axes of the individual rollers 224, 226, 228,230 and 232 of the needle cage 206 lie in the plane of the opposed sliding and oblique surfaces and are so orientated that they extend perpendicularly of the direction of the axis 70 of the coupling.This provision of a needle cage 206 has the following purpose: When the drive shaft and the driven shaft, which are interconnected by the coupling according to the invention, include a large angle with each other, i.e. when the axes of the coupling halves intersect one another, the coupling halves are moved, in the axial direction, relative to one another during the rotation of the coupling halves.

This shift in the axial direction occurs between the plane sliding surfaces and oblique surfaces which abut one another. This shift in the axial direction may, under certain circumstances, amount to a few millimetres. The provision according to the invention of a needle cage between the sliding surfaces and oblique surfaces reduces the effect of forces acting on the shaft (longitudinal forces, transverse forces), and facilitates the movement of the coupling halves relative to each other.

If a radial angle, which the shafts include with one another, is to be compensated for by means of a needle cage arranged between the sliding surfaces and oblique surfaces, this needle cage is turned through 90 relative to the arrangement shown in Figure 22. This needle cage can compensate for radial displacements of the shaft relative to each other, which occur during rotation, and possibly also facilitates the radial movement of the sliding elements.

The embodiments described with reference to Figures 1 to 22 show couplings in which the intermediate spaces 34 widen radially outwardly, and in which the sliding elements, arranged in the intermediate spaces, are supported by an outer holding ring 98. However, the inventive concept also includes an inverse arrangement, i.e. in which the intermediate spaces widen radially inwardly, and in which the sliding elements, arranged in the intermediate spaces, are supported by a holding ring lying within the coupling.

An embodiment of a coupling of this kind is illustrated in Figures 23 to 25.

As is particularly clear from the vertical crosssectional view of Figure 23 (taken along line XXlll-XXIll of Figure 24), and from the horizontal cross-sectional view taken along line XXIV- XXIV, the front coupling half 1 2 has, on its circular coupling disc, three jaws 370, 372, 374 which are uniformly distributed round the periphery and which axially project, gaps being defined between the jaws. Into these gaps engage corresponding jaws 366, 368, 380 of the rear coupling half 14.Opposed, force-transmitting areas of the jaws widen in the radially inward direction, form the intermediate spaces 334, and comprise the plane oblique surfaces 31 6, 318, 320 of the front coupling half 12, and the plane oblique surfaces 324, 326 and 328 of the rear coupling half 14, as is very clearly shown in Figure 23. However, these oblique surfaces do not extend as far as the outer periphery 144, 146 of the coupling halves, but merge into radial surfaces 333 and 335, which lie opposite one another with a circumferential (peripheral) distance therebetween, and serve to delimit the elasticity range of the coupling. The radial length of the radial surfaces 333, 335 amounts, in each instance, to about a third to one-fifth of the radial thickness of the jaws.

As can also be seen from Figure 23, the jaws are in the form of sections of a circular ring A radially extending gap 351 lies between those areas of the jaws which do not comprise oblique surfaces, the size of this gap being approximately equal to the peripheral distance between the radial surfaces 333 and 335.

The sliding elements 342, 344 and 346 are arranged in the intermediate spaces 334, the cross-section of these elements 342, 344 and 346 being approximately triangular. Spherical bearing sockets 96 are provided in peripherally adjacent surfaces of each of these sliding elements. Compensating elements 74, 76, 78, 82, 84, 86, which have the shape of segments of a sphere (e.g. hemispherical elements), are mounted in these sockets 96 so as to be pivotable in all directions. The compensating elements 74, 76, 78 each have a plane sliding surface 352, 356 and 360 respectively, each of which abuts against a plane oblique surface 316, 318 and 320 respectively.Each of the compensating elements 82, 84, 86, which are orientated in opposite directions to one another, has a plane sliding surface 354,358 and 362 respectively; each of these sliding surfaces abuts against a respective plane oblique surface 324, 326, 328. The compensating elements project a sufficient distance from the sliding elements to ensure that, on the occasion of pivotal movement of the compensating elements, no contact can take place between the jaws and the sliding elements.

The resiliently deformable, cylindrically annular holding ring 398 is arranged within the jaws, and forms the radially resilient bearing or support for the sliding elements. The sliding elements 342, 344 and 346 are supported by this ring 398 by one of their triangular faces, and the outer diameter of the holding ring 398 is so selected that when no torque is being applied to the coupling, the sliding elements are so pressed into the intermediate spaces 334 that the sliding surfaces abut against the oblique surfaces.

The radii r4 of the contact (abutment) surfaces 182, 184, 186, on which the sliding elements 342,344,346 abut against the holding ring 398 when no torque is being applied to the coupling, are in each case greater than the outer radius r3 of the holding ring. Coincidence of these radii r3, R4 only occurs, when torque is applied to the coupling, in the vicinity of the sliding elements, when the holding ring 398 is resiliently deformed (cf. Figure 25). In this way it is ensured that surface pressure between holding ring and sliding elements is low when torque is applied to the coupling.

As is clearly apparent from Figure 25, the holding ring 398 is guided axially between the two coupling discs.

In order that the damping characteristic of the proposed coupling can be adjusted, a radially extending screw 327, 328, 330 is arranged on each jaw 366, 368 and 380 respectively (and/or 370, 372, 374) in the area between the sliding elements in the vicinity of the gaps 351. These screws 327, 328, 330 extend radially into the interior of the coupling, and thus form an abutment for the holding ring when the latter resiliently deforms. The characteristic of the coupling can be acted on by adjustment of the screws. Spring-loaded pins may also be used instead of the screws.

If, during operation, a torque is transmitted, in the direction of the arrow 32, from the front coupling half 12 to the rear coupling half 14, the sliding elements 342, 344, 346 are inwardly pressed in opposition to the resilient resistance of the holding ring 398, the holding ring resiliently deforming (cf. Figure 26). The peripheral distance between the jaws 366 and 370, between jaws 368 and 372, and between jaws 380 and 374, decreases, while the peripheral distance between the jaws 370 and 368, between jaws 372 and 380, and between jaws 374 and 366, increases, that is to say the two coupling halves are turned relative to each other. This turning movement can continue until the radial surfaces 333 and 335 abut against one another. The coupling is then rigid for the transmission of torque.

In the present embodiment the compensation elements are niounted in the sliding elements, and the plane sliding surfaces are formed on the compensating elements. In this case it is not necessary for the sliding elements to each have a triangular profile. It is merely essential to ensure that each sliding element has a sufficient abutment or contact surface with the holding ring and also that each sliding element can adequately support and accommodate the compensating elements, which are in the shape of segments of a sphere (e.g. hemispherical). For the sake of simplicity the sliding element will usually be given a triangular profile shape.

Instead of arranging the compensating elements in the sliding elements, they may be provided in the jaws. The sliding elements are then provided with the plane sliding surfaces.

Also possible is an arrangement such as is shown in Figure 4, in which both the sliding elements and also the jaws are provided with compensating elements.

Finally, it is also possible to provide couplings, which are constructed in the manner shown in Figures 1 to 22, with an internally positioned holding ring, if the shape of the intermediate spaes 34 is modified in the manner described above.

Figure 25 shows one way in which the inner space of the coupling can be sealed off, for the purpose of keeping dust and dirt from the sliding surfaces and oblique surfaces. To this end the two coupling halves 12, 14 are surrounded by a cylindrically annular bellows 246 made from a resilient material, such as rubber or plastics material. At its ends this bellows comprises radial flanges 248, each of which is attached by a clamping ring 250 to the hubs of the coupling.

This type of seal can also be used with the other embodiments of coupling described above.

The foliowing guidelines are applicable for dimensioning the couplings according to the invention: the size of the sliding surfaces and, hence, the size of the hemispherical compensating elements is determined by the torque to be transmitted and by the permissible surface pressure between the sliding surfaces and the oblique surfaces. If the sliding surfaces and the oblique surfaces consist of tempered steel, a surface pressure of up to 10,000 kp/cm2 is permissible. The thickness of the coupling discs and the axial length of the jaws are so selected that the spherical bearing sockets 96 for the compensating elements can be machined. The situation is analogous when the compensating elements are mounted in the sliding elements.

The cross-section of the sliding elements is to be so selected that sufficient resistance is presented to shearing force and pressure. The number of sliding bodies is related to the particular application required for the coupling.

Thus, the greatest possible number of sliding elements will be used for constructing a compact coupling which is required to transmit large torque; the same is true of couplings which must compensate for a large angle which the shafts include with each other.

The opening angle of the intermediate space between oblique surfaces, which are associated with each other, of the two coupling halves when no torque is applied to the coupling is to be so selected that a radial movement of the sliding element is possible when there is relative rotation between the two coupling halves. The resilience of the coupling can be affected by the choice of this opening angle. In the case of a small opening angle (about 300) the resilience of the coupling is low, while the resilience is very large in the case of a large opening angle (about 1300). For the other requirements of machine construction an intermediate opening angle of between 600 and 900 will suffice.

The holding rings are preferably made of steel with a wall thickness which permits the required resilient deformation. If necessary, a holding ring can be constructed from a number of rings of different diameter. For this purpose the rings are concentrically pushed into one another, rigidly or loosely.

Claims

1. A resilient shaft coupling, comprising coupling halves each carrying at least two plane oblique surfaces which are orientated transversely of the direction in which forces is transmitted, in which two oblique surfaces of the two coupling halves face one another in pairs and together delimit a radially opening intermediate space, at least one sliding element being arranged in a radially resilient bearing, which sliding element engages in the intermediate space, and carries two plane sliding surfaces which lie remote from one another, each plane oblique surface abutting against a sliding surface, at least one of the mutually associated plane surfaces of an intermediate space being formed on a compensating element which is in the form of a sphere segment and is mounted in a spherical bearing socket in such a way as to be pivotable in all directions; the number of the intermediate spaces, in each of which a respective sliding element is arranged, amounting to 2 to 12; and the sliding elements being pressed into their associated intermediate spaces by a holding ring, which can radially resiliently deform to noncircular shape.

2. A coupling as claimed in Claim 1, comprising at least one radial stop or abutment arranged, between two intermediate spaces, on at least one coupling half to delimit the deformation of the holding ring.

3. A coupling as claimed in Claim 2, wherein the stop is radially adjustable.

4. A coupling as claimed in Claim 2 or Claim 3, wherein the stop is resilient in the radial direction.

5. A coupling as claimed in any one of Claims 1 to 4 comprising an even number of sliding elements; in each instance, two adjacent oblique surfaces, which are associated with different sliding elements, being arranged on the same coupling half.

6. A coupling as claimed in any one of Claims 1 to 5, wherein the holding ring surrounds the sliding elements, and the intermediate spaces become wider in the radially outward direction.

7. A coupling as claimed in any one of Claims 1 to 5, wherein the holding ring is surrounded by the sliding elements, and the intermediate spaces become wider in the radially inward direction.

8. A coupling as claimed in any one of Claims 1 to 7, wherein the compensating elements are mounted in the coupling halves; and the sliding elements consist of sliding wedges which define the sliding surfaces.

9. A coupling as claimed in any one of Claims 1 to 7, wherein the compensating elements are mounted in the sliding elements, and comprise the sliding surfaces.

10. A coupling as claimed in Claim 9, wherein the oblique surfaces are formed directly on the coupling halves.

11. A coupling as claimed in claim 9, wherein the oblique surfaces are formed on other compensating elements which are shaped as segments of a sphere and are mounted in the coupling halves.

12. A resilient shaft coupling substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.