FORM 2
THE PATENT ACT 1970 (39 of 1970)
&
The Patents Rules, 2 003 COMPLETE SPECIFICATION (See Section 10, and rule 13)
1. TITLE OF INVENTION
SUSPENSION DEVICE HAVING ACTIVE WATT LINKAGE
2. APPLICANT(S)
a) Name : ZF FRIEDRICHSHAFEN AG
b) Nationality : GERMAN Company
C) Address : 88038 FRIEDRICHSHAFEN
GERMANY
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -

The invention relates to a suspension device for the spring or shock-absorbing suspension of a mass body, for example an HGV driver's cab, according to the precharacterising clause of Claim 1.
Suspension devices of the type mentioned at the outset are used for example, but in no way exclusively, in heavy lorries and similar heavy goods vehicles in order to separate the driver's cab from the vehicle chassis in terms or vibrations and movements. Since the spring and damper rates of the spring/damper units of the vehicle turn out to be unavoidably high in heavy goods vehicles owing to the heavy vehicle loads and owing to the high unsprung masses in the undercarriage, irregularities in the road surface and also vibrations from the axles and drive train are still transmitted in considerable measure by way of the axle spring system from the axles and drive train to the chassis and from there to the driver's cab.
To minimise the transmission of such shocks and vibrations to the cab and therefore to the workplace of the driver with the ergonomics and the occupational protection of the driver in mind, cab suspensions have been developed in which the cab or driver's cab is supported on the vehicle chassis using a separate suspension system. Such suspension systems for the driver's cab can be designed with considerably lower spring rates than the axle suspension owing to the mass of the driver's cab being much smaller than that of the vehicle, which is why such cab suspension systems enable irregularities in the road surface or vibrations stemming from the drive train or axles of the vehicle to be isolated or kept away from the workplace of the driver in greatly improved manner.
In order to limit the undesired lateral rolling of the driver's cab relative to the vehicle chassis with resilient cab suspension devices of this type - for example when driving on a slope or turning, but also for example when the surface of the road is irregular on one side - suspension devices have been developed in which a Watt's linkage device is arranged between the driver's cab and the chassis. The Watt's linkage device here ensures that the spring deflection movements between the cab and

chassis are substantially linear, therefore that the degrees of freedom of movement between the cab and chassis are reduced to the vertical spring deflection movement by means of the Watt's linkage device.
A suspension device of this type is known for example from DE10 2005 043 998 Al. This known suspension device comprises, in one embodiment, two parallel-arranged Watt's linkages which ensure that the cab and chassis of the HGV are coupled together in terms of the rolling movements of the HGV about the longitudinal axis, whilst linear spring deflection movements between the cab and the chassis are freely possible along the vertical axis within the spring travel of the chassis.
The substantially fixed coupling in terms of the rolling movements between the cab and chassis in this known suspension device indeed offers the advantage of preventing independent rolling movements of the cab relative to the chassis. On the other hand, however, this means that the cab inevitably follows every rolling excitation from the chassis. Here, the rolling angle of the cab is at least equal to, but -owing to the resilient forces in the cab mounting and in the Watt's linkages - for the most part often even greater than, the angle of the rolling excitation originating from the chassis.
When turning, driving on a slope or in the event of irregularities in the road surface on one side, this can result in the cab tilting as greatly as, or even more so, than the vehicle chassis. However, for reasons of comfort and safety, it would be desirable to prevent or at least reduce lateral tilting of the cab under all driving conditions.
In light of this, it is the object of the present invention to provide a suspension device for the spring suspension of a mass body, in particular for the suspension of a vehicle cab in a heavy goods vehicle, which enables the said disadvantages of the prior art to be overcome. In particular, the suspension device here is intended to enable the prevention of undesired rolling movements of the mass body or the vehicle cab even in the event of rolling excitations of the underbody or the chassis.
- ^ -

This object is achieved by a suspension device having the features of Claim 1. Preferred embodiments are the subject matter of the subclaims.
The suspension device according to the invention serves in known manner for the spring suspension of a mass body relative to an underbody, that is for example the suspension of the driver's cab of a heavy goods vehicle in relation to the vehicle chassis.
In a manner which is likewise known per se, the suspension device comprises a spring/damper arrangement arranged between the mass body and underbody for absorbing shocks and vibrations, and furthermore a Watt's linkage arrangement having two parallel-arranged Watt's linkages connecting the mass body and the underbody in relatively movable manner. The Watt's linkages serve to reduce the degrees of freedom of movement of the mass body in relation to the underbody, in particular the substantially straight-line motion of the mass body in the main direction of momentum of the underbody.
According to the invention, the suspension device is however notable in that.at least one of the connecting rods of a Watt's linkage is constructed to be adjustable in length. The length of the connecting rod of the Watt's linkage is adjusted here by means of an actuator.
The inventive lengthwise adjustability of at least one of the connecting rods of a Watt's linkage of the suspension device enables undesired rolling angles of the mass body, that is for example undesired lateral tilting of the driver's cab of a heavy goods vehicle, to be actively counteracted in that the length of one of the connecting rods of one of the Watt's linkages is adjusted by an actuator.
In other words, this means that the angle between the mass body and the underbody, that is for example between the driver's cab and the chassis, can be actively adjusted in this way so that, for example in the event of lateral tilting of the

chassis, a vertical position of the driver's cab is still maintained, or at least the lateral tilt of the driver's cab is kept smaller than that of the chassis.
The invention can, for a start, be realised irrespective of the manner in which the lengthwise adjustment of the connecting rod takes place as long as an appropriate actuator is able to apply the forces necessary in the particular case of application. It is thus conceivable, for example, to adjust the length of the connecting rod using compressed air or by means of an electric drive. However, according to a particularly preferred embodiment of the invention, the length of the connecting rod is adjusted by a hydraulic actuator. A hydraulic actuator is advantageous in that high actuating forces can be generated in a small space and in that the desired lengthwise adjustment of the connecting rod can be accurately controlled and maintained due to the incompressibility of hydraulic oil.
In terms of the invention, it is for a start immaterial how the two parallel Watt's linkages are structurally designed and arranged between the underbody and the mass body as long as the expected loads can be absorbed and as long as the spacing between the Watt's linkages results in the formation of a lever arm which is suitable for transmitting the rolling moments which occur.
According to a further, preferred embodiment of the invention, the joints of the two Watt's linkages are, however, located substantially in a common movement plane. In other words, this means that the joints of the two Watt's linkages are arranged so that the positions of all the joints span the said movement plane or all the joints of the two Watt's linkages are located substantially in one and the same plane.
This embodiment is advantageous insofar as twisting is thus prevented and the generation of secondary moments, which can occur in the event of any spacing between the movement planes of the two Watt's linkages, are eliminated.

According to a further embodiment of the invention, the two Watt's linkages are arranged laterally offset in relation to their common direction of straight-line motion. This embodiment enables a particularly space-saving and compact arrangement of the Watt's linkages and moreover increases the creative freedom when designing the shape and arrangement of the Watt's linkages.
According to a further, preferred embodiment, the fixing point or bearing point of the central Watt's connecting rod, which belongs to the first Watt's linkage, is connected to the mass body, whereas the fixing point or bearing point of that Watt's connecting rod which belongs to the second Watt's linkage is connected to the underbody.
In this way, the Watt's linkages, or the connecting rods of which the Watt's linkages are composed, are even more compact and can even be arranged such that they nest to a certain extent inside one another. This results in a particularly compact embodiment of the Watt's linkage arrangement with even better use of the installation space available.
A further preferred embodiment of the invention provides for the spacing between the centres of rotation of the two central Watt's connecting rods to be greater than the respective spacings between the outer pivot points, associated with the Watt's linkage transverse thrust bars, of the two Watt's linkages. In other words, this means that the imaginary connecting lines between the six pivot points of the two Watt's linkages no longer form a parallelogram, as in the above embodiments, but are instead closer to a double trapezium shape since the spacings between the outer pivot points of the two Watt's linkages in this embodiment are smaller than the spacings between the two central pivot points.
This embodiment therefore results in an extension of the lever arm formed by the spacing between the centres of rotation of the two central Watt's connecting rods.

This extended lever arm can therefore be better used to absorb turning moments, for example rolling moments of a driver's cab.
This has the advantage that only reduced forces - inversely proportional to the increased length of the central lever arm - have to be transmitted by way of the Watt's linkage arrangement in the event of a given turning moment or rolling moment. Thus, a reduced and therefore lower-mass dimensioning of the Watt's linkages is possible whilst, at the same time, the considerable turning moments - for example from the rolling support of a driver's cab - can be transmitted in unchanged measure by way of the Watt's linkage arrangement and introduced into the underbody, for example into the chassis of the heavy goods vehicle. Furthermore, the residual rolling movements resulting from unavoidable resilient forces - for example in the region of the Watt's linkages, in the region of the pivot points of the Watt's linkages on the mass body and on the underbody, or resulting from the flexibility of any elastomer bearings used - are thus reduced owing to the lower forces to be transmitted.
According to a further, particularly preferred embodiment of the invention, it is furthermore provided for the outer pivot points associated with the transverse thrust bars of the two Watt's linkages to each be located in pairs on a swivel axis common to both Watt's linkages. In other words, this means that the spacing between the outer pivot points between the two Watt's linkages in this embodiment is not reduced by only a certain amount, as in the previous embodiment, but that this spacing here is zero. Thus, the outer pivot points of the transverse thrust bars of the two Watt's linkages as a whole share only two joint axes, instead of requiring four joint axes as before.
This saves on structural elements and therefore reduces costs. Furthermore, the design of the Watt's linkage arrangement is thus particularly compact and saves on installation space, and it is only necessary to construct two connecting points on the frame side, instead of the previous four. Since the forces generated by the two Watt's

connecting rods and acting on the frame-side connecting points partially cancel each other out in this arrangement owing to vectorial addition, the frame-side connecting parts can be of a lighter and therefore more economical design. Furthermore, when using elastomer bearings, it is possible to reduce the stiffnesses used for the elastomer bearings, which corresponds to better noise insulation.
This latter is particularly the case when, for a start, the in each case two transverse thrust bars, converging with their outer pivot points, of the two Watt's linkages are -for the purpose of vectorial force addition - non-resiliently mounted on a common swivel axis whilst only the common swivel axis taken by itself is resiliently connected to the corresponding frame-side connecting points.
According to a further embodiment of the invention, it is furthermore provided for the two transverse thrust bars, coupled in the region of their outer pivot points to a common swivel axis, of the two Watt's linkages to each be constructed in a single piece, for example in the form of a V-shaped combination bar. This embodiment, in which two commonly coupled transverse thrust bars each form a component which resembles, for example, a triangular connecting rod, brings about further structural simplifications in that the number of components required is still further reduced.
In particular, instead of four swivel bearings - as in the previous embodiments -only two are now required for connecting the outer pivot points of the transverse thrust bars. Furthermore, it is thus readily possible to arrange both Wart's linkages of the Watt's linkage arrangement composed in this way substantially in one and the same plane, which again saves on installation space. Also, in this embodiment, the forces introduced into the corresponding connecting parts on the vehicle chassis are smaller owing to a partial vectorial cancellation of forces, again resulting in the above-mentioned advantages in terms of weight and cost and in terms of the use of elastomer bearings for possible noise insulation.

According to further embodiments of the invention, it is provided for at least one of the bearing points, although preferably several or all bearing points, of the Watt's linkage arrangement to be constructed as elastomer bearings, and for the swivel axes of commonly coupled or single-piece transverse thrust bar pairs to be resiliently connected to the mass body and underbody.
The construction of one or more of the bearing points, or even all the bearing points, of the Watt's linkage arrangement as elastomer bearings is particularly advantageous in that the suspension device can thus be of a particularly robust and resistant design, whilst at the same time reducing the maintenance requirements to a minimum. Moreover, this also results in additional vibration damping in the microregion, both reducing the bearing and material loads and also further improving the comfort which may be achieved with the suspension device -particularly when used in vehicles.
The resilient connection between the swivel axes of commonly coupled transverse thrust bar pairs has the additional advantage, already outlined above, of thus enabling a partial vectorial cancellation of the tensile and compressive forces prevailing in the transverse thrust bars to take place - by way of the common coupling of the transverse thrust bar pairs - before only the remaining residual forces, which are much weaker in value, are to be resiliently introduced into the underbody or mass body.
Finally, with the use of elastomer bearings, it is also possible to prevent structural stresses from occurring under certain spring deflection conditions in the Watt's linkages, and tolerances in the manufacture or the occurrence of canting during use can be better offset.
According to a further embodiment of the invention, it is provided for the suspension device to comprise not only one, but a plurality of Watt's linkage arrangements. This enables - for a start irrespective of the concrete structural design

and arrangement of the Watt's linkages - further improved guiding accuracy, greater strength and increased safety, particularly when used in vehicle construction.
Here, the movement planes spanned by the joints of one of the Watt's linkage arrangements are preferably arranged perpendicularly to the movement planes spanned by the joints of a further Watt's linkage arrangement. In other words, this means that at least two Watt's linkage arrangements are used, whereof the respective Watt's linkages are arranged in planes which are perpendicular to one another. It is thus possible to effectively limit the degree of freedom of movement of the mass body - for example a vehicle cab - to movements along only one spatial direction (for example along the vertical main direction of momentum of the chassis), whilst movements along the two other spatial directions are eliminated. Undesired rotations of the mass body about at least two axes of the Cartesian coordinate system, that is for example both rolling movements and pitching movements of a vehicle cab, can also be reliably prevented in this way.
The invention is explained in more detail below with reference to drawings merely illustrating exemplary embodiments, which show
Fig, 1 a schematic illustration of an embodiment of a suspension arrangement according to the present invention in a neutral position;
Fig. 2 an illustration, corresponding to Fig. 1, of the suspension device according to Fig. 1 in an activation position in the event of a rolling movement;
Fig. 3 an illustration and view, corresponding to Figs. 1 and 2, of a suspension device according to a further embodiment;
Fig. 4 an illustration and view, corresponding to Figs. 1 to 3, of a suspension device according to a third embodiment;

Fig. 5 an illustration and view, corresponding to Figs. 1 to 4, of a suspension device according to a fourth embodiment of the invention; and
Fig. 6 an illustration and view, corresponding to Figs. 1 to 5, of a suspension device according to a fifth embodiment, with single-piece transverse thrust bar pairs.
Fig. 1 shows, in a highly schematic illustration, an embodiment of a suspension device according to the present invention. It is firstly possible to see an underbody 1 and a schematically indicated mass body 3 connected to the underbody 1 by way of a spring/damper arrangement 2. Here, the underbody in the illustrated embodiment is intended to represent the front region of the chassis 1 of a heavy goods vehicle, whilst the indicated mass body represents the cab 3 of the heavy goods vehicle. The direction of travel extends perpendicular to the plane of the drawing here.
It is possible to see in Fig. 1 that the connection between the cab 3 and chassis 1 comprises two Watt's linkages 4, 5 in addition to two spring/damper devices 2. It is shown that each of the Watt's linkages 4, 5 comprises five joints, which are denoted by the letters A, B, C, D, E. Of the joints A to E, in the illustrated embodiment A and E are fixed to the frame whilst C is fixed in each case to the cab. The pivot points A to E of each Watt's linkage are mutually connected here by an arrangement of two transverse thrust bars 6, 7,8 and a central Watt's connecting rod 9.
Owing to the particular (in themselves known) kinematics of the Watt's linkages 4 and 5 according to Fig. 1, the lateral transverse movements of the cab 3 relative to the chassis 1 are each supported by way of the joints A, C and E of the two Watt's linkages 4, 5, whilst, on the other hand, the Watt's linkages 4, 5 freely allow relative movements of the cab 3 and chassis 1 along the vertical.
This is linked to the fact that the central centre of rotation C of the respective Watt's connecting rod 9 is unable to leave its vertical movement path (indicated by the

dotted line 12 in Fig. 1) owing to its guidance by the two transverse thrust bars 6 or 7 and 8 associated with it - which have to be the same length for this purpose, and whereof the outer pivot points A and E have to have a vertical spacing 11 which corresponds to the length of the Watt's connecting rod 9. As a result, the cab 3 and chassis 1 are, for a start, always held in the illustrated mutually centred position above one another. There is no relative transverse movement of the cab 3 in relation to the chassis 1.
Static or dynamic transverse forces which occur are therefore transmitted directly by way of the transverse thrust bars 6 or 7 and 8, by way of the Watt's connecting rod 9 and by way of the joints A to E between the cab 3 and chassis 1 so that - in each case in the region of the Watt's linkages 4 and 5 in the present embodiment, that is for example in the rear region of the cab 3 - a further lateral guidance or support of the cab 3 is unnecessary. The vertical movement between the cab 3 and chassis 1 therefore remains completely unhindered owing to the free vertical movability of the respective Watt's connecting rod 9 and is, as provided, merely accommodated or absorbed by the spring/damper arrangements 2.
The Watt's linkage arrangements illustrated in the Figs, here comprise in each case two separate Watt's linkages 4 and 5 whereof the respective directions of straight-line motion 12 (dotted line in Fig. 1) correspond and whereof the two movement planes determined by the position of the respective connecting rods 6, 7, 8 or the pivot points A to E extend parallel to one another, and in the embodiments shown therefore coincide approximately with the plane of the drawing.
Such Watt's linkage arrangements with two Watt's linkages 4 and 5 arranged at a vertical spacing are particularly advantageous in that they not only enable a straight-line motion of the cab 3 relative to the chassis 1, but also provide for a stabilisation against rotational movements - that is against rolling movements W according to Fig. 2.

This is due to the fact that the two Watt's linkages 4 and 5 arranged according to Figs. 1 to 5 with a mutual vertical spacing 10 between the chassis 1 and cab 3 can not only transmit transverse forces - as is the case with a single Watt's linkage. Instead, owing to the vertical spacing 10 (acting as a lever arm) between the two Watt's linkages 4 and 5, it is thus also possible to transmit turning moments that act about the longitudinal axis of the vehicle, which therefore refer to rolling moments W according to Figs. 2 to 5.
In other words, this means that the cab 3 in the exemplary embodiments shown can first of all still only execute the (desired) vertical compensating movements along the dotted line 12 relative to the chassis 1, whilst lateral relative movements or rotations W of the cab 3 with respect to the chassis 1 are prevented thanks to the Watt's linkage arrangement 4,5 shown.
As described at the outset, this means that the chassis 1 and cab 3 are substantially rigidly coupled together in terms of the rolling moments or rolling movements W, so that, when the chassis is tilted, this tilted position is (possibly undesirably) also transferred to the cab.
According to the invention, this problem is however solved in that at least one of the connecting rods of the Watt's linkage arrangement is constructed to be adjustable in length by means of an actuator. In the embodiment shown, this is the connecting rod 6 of the upper Watt's linkage 4 in each case. The schematic illustration of Figures 1 to 5 shows that the lengthwise adjustable connecting rod 6 contains a hydraulic element which enables the effective length of the connecting rod 6 to be adjusted.
Fig. 2 shows the effect that the lengthwise adjustment of the connecting rod 6 has on the arrangement of the chassis 1 and cab 3. In Fig. 2, the chassis 1 is in a tilted position, for example as a result of driving on a slope or turning. To keep the cab 3 in an upright horizontal position in spite of the tilted position of the chassis 1, the hydraulic lengthwise adjustable connecting rod 6 of the upper Watt's linkage 4 is

driven accordingly and the active length of the lengthwise adjustable connecting rod 6 is correspondingly increased. This results in the situation shown in Fig. 2, in which the parallel guidance between the chassis 1 and cab 3, which is produced by the two Watt's linkages 4 and 5, is followed through an angle corresponding to the tilted position of the chassis 1.
It is thus possible to ensure that the cab 3 maintains its horizontal position, even when the chassis is tilted, since the central pivot points C of the Watt's connecting rods in this case are also able to maintain their vertical position above one another, even when the chassis 1 is in a tilted position, c.f. dashed line 12 in Fig. 2.
Fig. 3 shows a further embodiment of an inventive suspension device with two Watt's linkages. The suspension device according to Fig. 3 differs from the suspension device according to Figs. 1 and 2 for a start in that the two Watt's linkages 4 and 5 in the embodiment according to Fig. 3 are arranged laterally offset or offset in the transverse direction of the vehicle. Furthermore, in the embodiment according to Fig. 3, the Watt's connecting rod 9 of the upper Watt's linkage 4 (as seen in the drawing) - as is firstly also the case in the embodiment according to Figs. 1 and 2 - is connected at its centre of rotation C to the cab 3, whilst the Watt's connecting rod 9 of the lower Watt's linkage 5 here is connected to the chassis 1. In the embodiment according to Fig. 3, these two differences from the embodiment according to Figs. 1 and 2 mean that the Watt's linkages can be arranged nesting inside one another and therefore in particularly space-saving manner.
Further embodiments of suspension devices for example for driver's cabs are shown in Figs. 4 and 5. The embodiments illustrated here revert in principle to the embodiment according to Figs. 1 and 2. However, the embodiments according to Figs. 4 and 5 differ from the embodiment according to Figs. 1 and 2 in that the spacing 10 between the centres of rotation C of the two Watt's connecting rods 9 in the embodiments according to Figs. 4 and 5 is greater than the spacings 11 (Fig. 4)

between the outer pivot points A, E - associated with the transverse thrust bars 6, 7,8 - of the two Watt's linkages 4 and 5.
As the applicant has discovered, these particular geometrical relationships in the embodiments according to Figs. 5 and 6 do not impair the function of the Watt's linkages in any way. This means, in particular, that the desired straight-line motion of the Watt's connecting rods or the straight-line motion of the central pivot points C of the Watt's connecting rods is also fully maintained in these embodiments.
On the other hand, however, it is advantageous that the lever arm 10 formed by the increased spacing 10 here between the central pivot points C of the two Watt's connecting rods 9 is extended proportionally to the increase in the spacing 10 between these two pivot points C. This means that rolling moments W which are introduced by way of the chassis 1 or driver's cab 3 likewise only result in proportionally reduced reaction forces, which is true both for the forces acting within the Watt's linkages 4 and 5 and for the forces introduced into the driver's cab 3 by way of pivot point C.
In other words, thanks to the embodiments according to Figs. 4 and 5, it is therefore possible for the dimensions of both the Watt's linkages 4 and 5 and their suspension C on the vehicle cab 3 to be reduced and therefore lower in mass.
The Watt's linkage arrangement according to Fig. 5 further differs from the embodiment according to Fig. 4 in that the outer pivot points, associated with the transverse thrust bars 6, 7, 8 of the two Watt's linkages 4, 5, are each located in pairs at A' and E' on a swivel axis common to both Watt's linkages 4 and 5. In other words, this means that the spacing of the outer pivot point pairs A and E between the two Watt's linkages 4 and 5 in this embodiment is not reduced only by a certain amount - to the spacing 11 there - as in the previous embodiment according to Fig. 4, but that this spacing in the embodiment according to Fig. 5 is zero. In this way, the outer pivot point pairs A and E of the transverse thrust bars 6, 7 and 8 of the two

Watt's linkages 4, 5 as a whole share only two swivel axes at A' and E' instead of requiring four swivel axes (twice A, twice E) as in the exemplary embodiments according to Figs. 1 to 4.
This therefore saves on structural elements, in particular frame-side or chassis-side couplings and bearing axes here, and thereby also reduces costs. Furthermore, the Watt's linkage arrangement can thus be of a particularly small construction and therefore saves on valuable installation space.
Fig. 6 finally shows a further embodiment of an inventive suspension device with a Watt's linkage arrangement 4,5. The Watt's linkage arrangement illustrated in Fig. 6 reverts substantially to the Wart's linkage arrangement according to Fig. 5. However, the embodiment according to Fig. 6 differs from the embodiment according to Fig. 5 in that, in the Watt's linkage arrangement according to Fig. 6, in each case the two transverse thrust bars 6, 7,8 of the two Watt's linkages 4, 5, which according to Fig. 5 were previously separate but still coupled to a common swivel axis at A' and at E', are now constructed in pairs in a single piece in the form of a combination bar 13 and 14 in each case.
This embodiment, in which the commonly coupled transverse thrust bars thus in each case form a V-shaped component which here resembles a triangular connecting rod 13,14 brings with it further structural simplifications and additional advantages. For a start, the number of necessary components is again considerably reduced. In particular, instead of requiring four outer swivel bearings for four transverse thrust bars here, now only two bearings are required to connect the outer pivot points A', E' of the two combination bars 13, 14. Furthermore, the two Watt's linkages 4, 5 which are combined in this way are arranged substantially in one and the same spatial plane, which again saves on installation space. Finally, the tensile and compressive forces prevailing within the Watt's linkage arrangement thus also partially cancel each other out without these forces firstly having to circuit the connection at the chassis or driver's cab.

The active rolling suppression resulting from the lengthwise adjustable connecting rod 6 is also maintained unaltered here in the embodiments according to Figs. 3 to 6, as described with reference to Figs. 1 and 2.
As a result, it is therefore clear that the invention results in a suspension device for the spring suspension of a mass body, for example an HGV driver's cab, with which the desired, particularly vertical degree of freedom of movement of the driver's cab can be defined in space-saving and structurally robust manner. At the same time, it is possible to prevent undesired rolling movements of the mass body or driver's cab - even in the event of rolling excitations of the underbody or chassis. The invention therefore enables structurally simple active rolling suppression, in particular for vehicle cabs and the like.
List of reference characters
1 Underbody, chassis
2 Spring/ damper arrangement
3 Mass body, cab
4,5 Watt's linkage
6 Transverse thrust bar, actuator-adjustable connecting rod
7,8 Transverse thrust bars
9 Watt's connecting rod
A to E Joints, pivot points
A', E' Pivot points, swivel axes
■ W Rolling movement, rolling moment
10 Spacing, lever arm
11 Spacing
12 Direction of straight-line motion
13,14 Combination bar, triangular connecting rod

WE CLAIM:
1. A suspension device for the spring suspension of a mass body (3), in
particular a driver's cab of a heavy goods vehicle, relative to an underbody
(1), in particular relative to a vehicle chassis, the suspension device having a
spring/damper arrangement (2) arranged between the mass body (3) and
underbody (1) to absorb shocks and vibrations, wherein the suspension
device comprises a Watt's linkage arrangement having two parallel-arranged
Watt's linkages (4, 5) which connect the mass body (3) and the underbody (1)
in relatively movable manner to reduce the degree of freedom of movement
of the mass body (3) in relation to the underbody (1),
characterised in that
at least one of the connecting rods (6) of a Watt's linkage (4) is adjustable in
length, wherein the length is adjusted by means of an actuator.
2. A suspension device according to Claim 1,
characterised in that
the actuator is a hydraulic actuator.
3. A suspension device according to Claim 1,
characterised in that
the actuator is a pneumatic actuator.
4. A suspension device according to Claim 1,
characterised in that
the actuator is an electrically driven actuator.
5. A suspension device according to one of Claims 1 to 4,
characterised in that
the joints (A, B, C, D, E) of the Watt's linkages (4, 5) are located substantially in a movement plane common to the Watt's linkages (4, 5).

6. A suspension device according to one of Claims 1 to 5,
characterised in that
the Watt's linkages (4, 5) are arranged offset in relation to their common direction of straight-line motion in the transverse direction of the vehicle.
7. A suspension device according to one of Claims 1 to 6,
characterised in that
the fixing point of the Watt's connecting rod (9) of the first Watt's linkage is connected to the mass body (3), and the fixing point of the Watt's connecting rod (9) of the second Watt's linkage (5) is connected to the underbody (1).
8. A suspension device according to one of Claims 1 to 7,
characterised in that
the spacing (1) between the centres of rotation (C) of the two Watt's connecting rods (9) is greater than the spacing (11) between the outer pivot points (A, E), associated with the transverse thrust bars (6, 7, 8), of the two Watt's linkages (4,5).
9. A suspension device according to one of Claims 1 to 8,
characterised in that
the outer pivot points associated with the transverse thrust bars (6, 7, 8) of the two Watt's linkages (4, 5) are each located in pairs on a swivel axis (A', E') common to the two Watt's linkages (4, 5).
10. A suspension device according to Claim 9,
characterised in that
the transverse thrust bars, coupled to a common swivel axis, of the two Watt's linkages (4, 5) are each constructed in pairs in a single piece in the form of a combination bar (13,14).

11. A suspension device according to one of Claims 1 to 10,
characterised in that
at least one of the bearing points (A, B, C, D, E) of the Watt's linkage arrangement is constructed as an elastomer bearing.
12. A suspension device according to Claim 10 or 11,
characterised in that
the pivot axes (A', E') of commonly coupled or single-piece transverse thrust bar pairs are resiliently attached to the mass body (3) and under body (1).
13. A suspension device according to one of Claims 1 to 12,
characterised in that
the suspension device comprises a plurality of Watt's linkage arrangements, wherein the movement planes of one Watt's linkage arrangement are arranged perpendicularly to the movement planes of a further Watt's linkage arrangement.