in order to simplify the understanding , like reference characters have been used in the following in different embodiments for similar or corresponding components but with addition of letters specific to the embodiments . the robot illustrated in fig1 is intended for relative displacement of two elements 1 , 2 . the element 1 is in the example intended to form a base member , relative to which the element 2 is intended to be positioned in space . the element 2 is intended to carry , either directly as indicated in fig1 or , as will be dealt with later , indirectly via a carrying arrangement , a working member 3 . the robot comprises articulated links 4 , 5 provided between the elements 1 , 2 and force - applying arrangements 6 , 7 , 8 for applying force for the relative displacement of the elements . the articulated links 4 , 5 form in addition to two further links 9 , 10 a four - links system fs 1 . the robot comprises further a pivot arm arrangement 11 and a connection arrangement 12 for mutual connection of the four - links system fs 1 and the pivot arm arrangement 11 . the links 4 , 5 ; 9 , 10 are in the example comprised in the four - links system fs 1 parallel in pairs , and accordingly of equal length . thus , the four - links system fs 1 forms parallelogram . a first 6 of the force - applying arrangements is provided to pivot the link 4 and hence also the link 5 of the four - links system in first planes in order to change the form of the four - links system . these planes extend more closely substantially parallel to the planes , in which the links in the four - links system fs 1 are arranged . the force - exerting arrangement 6 comprises a force - exerting member with a stationary portion rigidly connected to the link 9 and a movable portion rotationally rigid connected to the link 4 . the force - exerting member is more closely formed by a rotary means , the stator thereof being connected to the link 9 and the rotor thereof being connected to the link 4 . a second force - applying arrangement 7 is arranged to pivot the four - links system fs 1 in other planes forming an angle , preferably substantially right angle , with the first planes . the force - applying arrangement 7 comprises a force - exerting member with a stationary portion rigidly connected to the element 1 and a movable portion rotationally rigid connected to the link 9 . the force - exerting member is in the example formed by a rotary means with a stator rigidly connected to the element 1 and a rotor connected to the link 9 . the rotary means comprised in the arrangements 6 , 7 are denoted 13 and 14 respectively and their rotation axes are in the example extending with an angle , preferably substantially right angle in relation to each other . it should be noted that the rotary means 13 will follow the link 9 in the example when the four - links system fs 1 is pivoted by means of the rotary means 14 . a third 8 of the force - applying arrangements is arranged to actuate the pivot arm arrangement 11 in order to cause it to pivot . the arrangement 8 comprises a force - exerting member 15 with a stationary portion fixed in relation to the element 1 and a movable portion arranged to actuate the pivot arrangement 11 . more closely , a link arm arrangement 16 is arranged between the movable portion of the force - exerting member 15 and the pivot arm arrangement 11 . this pivot arm arrangement comprises in the example an arm 17 rigidly connected to the movable portion of the force - exerting member 15 and a link arm 18 hingedly connected to the arm 17 and to the pivot arm arrangement 11 via joints 19 and 20 respectively . these joints must allow pivoting of the link arm 18 in all directions in relation to the arm 17 and the pivot arm arrangement 11 respectively , i . e . the joints must allow a relative pivoting movement about pivot axes inclined in relation to each other . thus , the joints could be realised by means of cardan couplings . they could also be realised by means of ball joints , which implies that a further degree of freedom in the form of relative rotation is added . the four - links system fs 1 is in fig1 arranged between the connection arrangement 12 and the element 1 and the pivot arm arrangement 11 is arranged between the second element 2 and the connection arrangement 12 . the pivot arm arrangement 11 is in the example performed by a simple pivot arm 21 . the connection arrangement 12 has the character of a structure , which in a hinged manner connects the pivot arm 21 to the link 10 comprised in the four - links system fs 1 . the pivot arm 21 has two arm parts 22 and 23 respectively located on each side of the pivot axis of the pivot arm denoted 24 , wherein a first arm part 22 is connected to the second element 2 and a second arm part 23 is connected to the link arm arrangement 16 via the joint 20 . the pivot arm 21 is pivotably connected to the connection arrangement 12 and the link 10 with one single degree of freedom . the pivot axis 24 of the pivot arm 21 is in the example directed so that the pivot arm 21 receives pivotability in planes substantially perpendicular to planes , in which the links 4 , 5 of the four - links system are pivotable . it is in fig1 illustrated a third link 25 forming other four - links systems together with each of the other links 4 , 5 . this third link is connected to the element 1 by means of a joint 26 and to the link element 28 via a joint 27 , said link element 28 being connected to the link 10 in the four - links system fs 1 via joint 29 . since the form of fs 1 may be changed in its own plane by pivoting the links 4 , 5 and besides may be rotated in a rotation plane perpendicular to said pivoting plane , it is required that the joints 26 , 27 of the link 25 are so arranged that the link 25 may pivot in all directions in relation to the element 1 and the link element 28 respectively . joints with at least two non - parallel pivot axes or ball joints will thus be of interest . the link element 28 is however pivotably connected to the link 10 of the four - links system fs 1 with one single degree of freedom , i . e . the joint 29 allows pure pivoting about an axis . this axis must run perpendicularly to the adjacent joint axes of the four - links system in order to cause a parallelogram - function . this requires in addition that the link 25 is substantially parallel to the links 4 , 5 and has substantially the same length as they have . thus , the working member 3 may by means of the robot illustrated in fig1 be adjusted in z - direction by means of the rotary means 13 . the working member 3 may further be adjusted in the xy - plane by means of a suitable operation of at least one of and suitably both of the rotary means 14 , 15 . the alternative illustrated in fig2 corresponds regarding the substantial parts with the previous embodiment . the difference is in the first place that the link / link element denoted 25 and 28 respectively in fig1 are not present in this case . these components are thus not necessary but may be added when there is a need for further stability of the four - links system fs 1 . the robot has in absence of those components a more slender design and besides a greater working area . the alternative in fig3 is closely related to the embodiment according to fig2 . there are mainly only two differences ; the first difference is that the pivot arm 21 a is connected to the link arm 18 a in the area between the ends of the pivot arm , i . e . the pivot arm 21 a is connected to the connection arrangement 12 a with one of its ends and its other end carries the working member 3 a . the second difference is that also the force - exerting member 13 a is fixed with the stationary portion thereof in relation to the first element 1 a . the movable portion ( drive axis ) of the member 13 a has instead a gear wheel 30 , which drives a further gear wheel 31 rigidly connected to one 4 a of the links in the four - links system fs 1 in an inclined relation thereto . the gear wheels 30 , 31 form in other words an angular gear , which permits this rotation when the links 4 a and 5 a are rotated about the rotation axis denoted 32 by means of the force - exerting member 14 a provided that the force - exerting member 13 a by rotation by means of the member 14 a is driven to follow with the same angular velocity . the movable portion of the force - exerting member 14 a is rotationally rigid connected to the link 9 a as previously , said link 9 a being hingedly connected to the links 4 a , 5 a . it should hereby be noted that the gear wheel 31 suitably is rotationally mounted in relation to the link 9 a . the alternative illustrated in fig4 differs from the embodiment according to fig1 by means of that each of the articulated links 4 b , 5 b and 25 b is connected to the first element 1 b and the connection arrangement 12 b respectively , which in this case , and also in the previous embodiment , may be regarded comprising the link 10 b , by means of joints permitting the links to pivot in all directions in relation to the first element 1 b and the connection arrangement 12 b . it should also be noted that the component 28 b , which in the embodiment according to fig1 had the character of a link element hinged in relation to the link 10 , in this case forms a rigid component of the connection arrangement 12 b . it is however within the scope of the embodiment according to fig4 to also utilise the embodiment shown there . it has already been mentioned that the joints 26 b , 27 b are arranged so that they permit pivoting of the link 25 b in all directions in relation to the element 1 b and the connection arrangement 12 b . thus , it is here referred to joints with double , angularly disposed pivot axes , for example cardan joints , or ball joints . corresponding considerations are valid for the joints denoted 33 between the links 4 b , 5 b and the element 1 b and the connection arrangement 12 b respectively . the articulated connection of the link 4 b to the element 1 b is however somewhat special as a consequence of that the articulated connection takes place via the force - exerting members 13 b , 14 b in on principle the same way as already have been discussed . thus , the link 4 b will be connected to the element 1 b via the rotation axes of the two force - exerting members 13 b , 14 b , which extend substantially perpendicularly to each other . thus , the rotation axes of the members 13 b , 14 b will provide the universal pivotability of the link 4 b in relation to the element 1 b provided of course that the members 13 b , 14 b permit the pivoting movements in question . thus , the discussion above implies that the link 9 present in the embodiments according to fig1 and comprised in the four - links system fs 1 in the embodiment according to fig4 will be formed by the element 1 b itself in combination with the force - exerting members 13 b , 14 b . two degrees of freedom are obtained in fig1 between the link 5 and the first element 1 by the link between 5 and 9 in combination with the rotation axis of the member 14 . two degrees of freedom are obtained in fig4 for the link 5 b by the joint 33 . the alternative illustrated in fig5 differs from the preceding alternatives by way of not only the force - applying arrangement 8 c but also the force - applying arrangements 6 c and 7 c comprise link arm arrangements 16 c , 34 and 35 respectively , through which the force - exerting members 13 c , 14 c and 15 c respectively actuate the second element 2 c . the link arm arrangements 34 , 35 comprise respective arms 36 , 37 in similarity to what is valid for the link arm arrangement 16 c , said arms being rotationally rigid connected to movable portions of the respective force - exerting members 13 c , 14 c and links 38 and 39 respectively connected between these arms 36 , 37 and the second element 2 c . from what has already been described regarding the link arm 18 c , the link arms 38 , 39 are also hingedly connected in relation to the arms 36 and 37 respectively and the element 2 c ( the pivot arm 21 c ) via joints permitting pivoting of the link arms in all directions . it is once again concerning ball joints or other joint constructions , such as cardan joints , permitting pivoting about two pivot axes angularly displaced in relation to each other . it is in the embodiment according to fig5 in the first place the force - applying arrangement 6 c , which effects movement of the second element 2 c in z - direction . the arrangement 7 c effects movement in y - direction while the arrangement 8 c effects movement in x - direction . it is in fig5 illustrated how the pivot arm 21 c is provided with a stabilising bar 40 causing the articulated base of the pivot arm 21 c becoming comparatively wide and therefor stabile in relation to the connection element 12 c . the four - links system fs 1 is in the alternative according to fig6 arranged between the connection arrangement 12 d and the second element 1 d . the pivot arm arrangement 11 d is pivotable in relation to the connection arrangement 12 d about a pivot axis denoted 41 , which in this case , although it is not necessary , is substantially parallel to the pivot plane of the four - links system fs 1 . the latter may be pivoted by means of the force - exerting member 13 d . the pivot arm arrangement 11 d is in this case pivotable in relation to the connection arrangement 12 d by means of a joint arrangement generally denoted 42 permitting pivoting of the pivot arm arrangement 11 d in all directions in relation to the connection arrangement 12 d . the pivot arm arrangement 11 d is in this embodiment in reality formed as a further four - links system comprising a further link 43 , except for the link 21 d , which corresponds to the previously mentioned pivot arm 21 , said link 43 in addition to two further links 44 , 45 forming a four - links system in said way . it is thereby pointed out that the links 21 d and 43 are pivotable in relation to the link 45 , which is the one to be rotatable about the previously mentioned axis 41 . by means of the pivotability of the links 21 d and 43 in relation to the link 45 and the rotatability thereof about the axis 41 , the pivoting freedom of the pivot arm arrangement 11 d in relation to the connection arrangement 12 d is thereby provided in all directions . the second element 2 d is not arranged directly on the pivot arm 21 d in this embodiment , but instead on the link denoted 44 , which is partly carried by the arm 21 d . this implies that the direction of the elements 2 d in space will be maintained as a consequence of that two four - links systems in reality will be coupled in series , but by a relative pivoting movement of the four - links systems about the axis 41 , the rotation position of the second element 2 d will on the other hand be displaced . force - applying arrangements 7 d and 8 d respectively with force - exerting members 14 d and 15 d are in this case , just as in the previous case according to fig5 prevailing , which are connected to the second element 2 d , here the link 44 , via link arm arrangements 35 d and 16 d respectively in order to operate the same . it is in the first place the force - applying arrangement 8 d operating the second element 2 d in z - direction in the figure while the arrangement 7 d is pivoting the pivot arm arrangement 11 d about the axis 41 , which in fig6 is substantially vertical so that the element 2 d is displaced in x - direction . the force - applying arrangement 7 d is finally displaceable via the element 2 d of the fs 1 in y - direction . the four - links system fs 1 is provided between the connection arrangement 12 e and the second element 2 e in the alternative according to fig7 and the pivot arm arrangement 11 e is provided between the first element 1 e and the connection arrangement 12 e . the force - exerting member 15 e effects pivoting of the pivot arm 21 e about the axis denoted 46 and it causes the force - exerting member 13 e to follow due to that the stator thereof is rotatably rigid connected to the rotor of the member 15 e . the force - exerting member 14 e has on the other hand its stator connected to the first element 1 e . thus , the four - links system fs 1 may be relocated by the pivot arm 21 e so that the element 2 e is displaced in y - direction . the member 13 e causes a pivoting movement in z - direction of fs 1 and the element 2 e via the associated link arm arrangement . the force member 14 e causing fs 1 to pivot in horizontal direction via the associated link arm arrangement , i . e . substantially parallel to the pivoting plane of the pivot arm 21 e so that the element 2 e is displaced in x - direction . the alternative in fig8 mainly corresponds to the alternative in fig2 and 3 except for that the pivot arm 21 f of the pivot arm arrangement is connected to the connection arrangement 12 f by means of a joint 47 allowing pivoting of the pivot arm 21 f in all directions in relation to the connection arrangement 12 f . the force - applying arrangement 8 f with the force - exerting member 15 f and the associated link arm arrangement 16 f serve for operating the pivot arm 21 f in the horizontal plane . a further moment is in this case that the pivot arm 21 f also may be pivoted in the vertical plane and more closely with the aid of the force - exerting member 14 f , which is connected to the second element 1 f with a stationary portion thereof and carrying the force - exerting member 15 f with a movable portion thereof . the members 14 f and 15 f have their respective rotation axes running in an angle in relation to each other , more closely in a substantially right angle so that the pivot arm 21 f thus may be pivoted as desired in space . this requires that the joint 19 f between the arm 17 f of the link arm arrangement 16 f and the link arm 18 f is arranged with only one degree of freedom , namely pivotability about one single axis . this axis should be substantially parallel to the pivoting axis of the member 15 f , but inclined , suitably with substantially right angle , to the rotation axis of the member 14 f . the four - links system fs 1 may with the aid of the force - exerting member 13 f also be pivoted vertically in order to change the vertical position of the pivot arm 21 f . in an embodiment illustrated in fig9 a four - links system fs 1 is vertically pivotable by means of the force - exerting member 13 g and a pivot arm 21 g is horizontally pivotable in relation to the connection arrangement 12 g with the aid of the force - exerting member 15 g . a transmission 49 for rotation of the working member 3 g arranged on the link 9 g and driven by a drive motor 48 comprises force transmitting members in the form of shafts 51 and / or traction transmitting elements 52 placed around diverting wheels 53 , 54 extending along the four - links system fs 1 ( the link 5 g thereof ) and the pivot arm 21 g and angular gear members 55 provided between these shafts / diverting wheels for force transmission without effecting the relative movement between the pivot arm 21 g and fs 1 . a shaft 51 is in the example extending along the link 5 g , said shaft having a gear wheel driven by the motor 48 at one end thereof . the device is suitably arranged so that a gear wheel of the motor 48 and the shaft 51 respectively form a first angular gear . a gear wheel 56 at the other end of the shaft 51 is arranged in driving connection to a gear wheel 57 , in the example via third gear wheel 58 forming an angular gear with each of the other gear wheels 56 , 57 . a shaft rigidly fixed to the gear wheel 57 is rotationally rigid connected to the break wheel denoted 53 so that by rotation thereof the traction transmitting element 52 will cause the diverting wheel 54 to rotate and thereby the working member 3 g to turn . the working member may thereby be adjusted as desired . it is to be noted that naturally the diverting wheels 53 , 54 and the traction - transmitting element 52 could be replaced by a gear arrangement with required shafts . the shaft 51 could similarly besides associated gear wheels be replaced by diverting wheels with traction transmitting elements . the force - exerting member 14 g is in the example arranged to turn the fs 1 around via the link 9 g . the motor 48 arranged on the link 9 g will thereby follow . the member 15 g is suitably arranged substantially coaxially with the member 14 g . it is to be noted that the solution illustrated in fig9 naturally is applicable on the embodiments according to all the described alternatives according to fig1 - 8 . it is in fig1 illustrated a further embodiment suitable to obtain turning of the working member 3 h on the basis of the first element 1 h so that its adequate turning position may be adjusted . such an adjustment of turning position may also be required for different manipulative tasks which the working member is to carry out , which should be apparent from the discussion above , but the adjustment is usually also desirable by that the pivotable embodiment of the robot means that the working member 3 h will change turning positions in space by such a pivoting movement . it is in fig1 illustrated how a force - exerting member 59 has a stationary portion fixed by the first element 1 h and a movable portion connected to an arm 60 . an arm pivotable in relation to the same is denoted 61 . an arm or a link pivotable in relation to the same is denoted 62 . by suitable driving of the force - exerting member 59 , the working member 3 h may thus be displaced via the arms 60 , 61 . a drive motor 114 is located on the first element 1 h in order to generate energy for turning the working member 3 h . the drive motor 114 has a stationary portion connected to the element 1 h and a movable portion , here in the form of a drive shaft , arranged to cause the drive wheel 115 to rotate . a further wheel 116 is rotatably mounted on the outer end of the arm 60 and a traction - transmitting element 117 is placed around these two wheels 115 , 116 in the form of a loop . the wheel 116 is connected to a shaft 118 and a conical gear wheel 119 is fixed thereon . the shaft 118 is rotatable in relation to the outer end of the arm 60 . a support element 120 is also mounted round the shaft 118 , which is movable around the shaft 118 with one degree of freedom , i . e . pure turning . this support member 120 is with one degree of freedom pivotably connected to a shaft 121 , which is also rotatable in relation to the arm 61 . a conical gear wheel 122 and a wheel 123 are rotationally rigid connected to the shaft 121 , wherein a traction transmitting element 124 in the form of a loop is placed round the wheel 123 , said element 124 also being placed round a further wheel 125 being rotationally rigid connected to a shaft 126 mounted in the arm 61 at an outer end thereof . the gear wheels 119 and 122 form together an angular gear in that the shafts 118 and 121 extend substantially perpendicularly in relation to each other . the shaft 126 carries a rotationally rigid connected conical gear wheel 127 , which is in engagement with a conical gear wheel 128 forming a further angular gear , said conical gear wheel 128 being rotationally rigid connected to the working member 3 h . the gear wheel 128 is rotationally rigid arranged on a shaft 129 . the shaft extends perpendicularly in relation to the shaft 126 . a further support element 130 is mounted to the two shafts 126 and 129 with a single degree of freedom , i . e . pure turning . the embodiment according to fig1 operates in the following way : the arm 60 may be turned by actuating the force - exerting member 59 and the arm 61 may thereby be caused to turn . the described connections / force transmissions via the angular gears and the support elements 120 and 130 pivotably connected to the gear wheel shafts implies that the transition between the arm 60 and the arm 61 on one hand and between the arm 61 and the arm 62 on the other hand , there is obtained movability in two degrees of freedom , namely turning in two in relation to each other perpendicular axes . this implies that the arm 60 rotatable in a plane may be caused to operate the arm 62 also when the latter is disposed away from the rotation plane for the arm 60 , which is indicated in fig1 . the drive wheel 115 will be caused to rotate by driving of the drive motor 114 . the drive wheel 115 drives the traction - transmitting element 117 in the form of a belt , line , wire or chain around so that also the wheel 116 is caused to rotate . the shaft 121 is caused to rotate via the angular gear 119 / 122 and this also leads to rotation of the wheel 123 , which will drive the wheel 125 via the element 124 so that the shaft 126 is caused to rotate . this will cause turning of the working member 3 h via the angular gear 127 , 128 . it is to be noted that the embodiment according to fig1 is applicable by all the embodiments according to fig1 - 9 . the arm denoted 60 in fig1 may for example thereby be formed by the arm denoted 17 in earlier figures while the arm denoted 61 in fig1 could be formed by the link arm 18 . the arm denoted 62 could thereby be formed by the pivot arm 21 itself or possibly by the link denoted 44 . the force member 59 should then correspond to the member denoted 17 . a fundamental solution for achieving double force transmission between two parts of the device pivotable round double , non - parallel shafts in relation to each other is illustrated in fig1 . force transmission could in comparison with the force transmission between the arm 60 and the arm 61 illustrated in fig1 with guidance of the embodiment according to fig1 take place twice . the explanation thereto is that double sets of traction - transmitting elements 131 , 132 driven by separate drive motors and placed over a respective drive wheel 133 , 134 are arranged in fig1 . the shaft 135 at the wheel 134 is formed as a tube shaft while the shaft 136 of the other wheel 133 extends through the tube shaft 135 . the tube shaft 135 is provided with a first conical gear wheel 137 and the shaft 136 is provided with a second conical gear wheel 138 on its end extending through the tube shaft 135 . the gear wheel 137 connected to the tube shaft 135 is in engagement with a conical gear wheel 139 placed on a tube shaft 140 forming an angular gear . a wheel 141 is rigidly connected to the tube shaft 140 and a traction - transmitting element 142 is placed over the wheel 141 and driven by the same . a further conical gear wheel 143 is in engagement with the gear wheel 138 , the gear wheel 143 being fixed to a shaft 144 extending through the tube shaft 140 and being connected to a wheel 145 driving a traction - transmitting element 146 , which runs further to a wheel ( not shown ) driven thereby , which is also the question for the element 142 . the transmission shown in fig1 thereby permits double force transmission and a joint with two degrees of freedom is simultaneously formed , i . e . a joint permitting turning around two angularly disposed shafts . the transmission may be utilised for providing the associated robot structure with two degrees of freedom . the components 131 , 133 , 136 , 138 , 143 , 144 , 145 and 146 may for example be utilised for turning the working member 3 around and the other components may be utilised for another degree of freedom of the robot , for example displacing a part carrying the working member 3 . it is to be noted that the shafts 135 , 136 and 140 , 144 respectively naturally not need to be driven by and drive respectively diverting wheels for traction - transmitting elements . gear wheels may instead of the diverting wheels be arranged on said shafts 135 , 136 and 140 , 144 , which via corresponding gear wheels arranged on rotatable shafts could be capable of effecting the corresponding driving function and driven function respectively . it is in fig1 illustrated an alternative to the embodiment discussed by guidance of fig1 . shaft transmissions 146 , 147 arranged along the arms 60 i and 61 i are utilised instead of traction transmitting elements and them driving wheels and wheels driven by them respectively for force transmission . this implies that further angular gear functions have to be arranged in the joint transitions in ways apparent from fig1 . the alternative illustrated in fig1 is similar to the one in fig8 except for that the pivot arm arrangement 11 j is of a more complex nature in similarity to what is the case for example in the embodiment according to fig6 . the pivot arm arrangement 11 j in fig1 forms more closely an articulated four - links system where the pivot arm 21 j forms one of the links . the connection arrangement 12 j is in this case connected to the pivot arm arrangement 11 j by means of a joint arrangement 47 j formed by two in relation to each other angularly disposed pivot axes 47 ja and 47 jb . the pivot axis 47 jb thereby connects a link 45 j comprised in the four - links system 11 j so that said link may be turned in relation to the connection arrangement 12 j with only one degree of freedom . the pivot axis 47 ja connects the pivot arm 21 j to the link 45 j , also here with only one degree of freedom . the remaining links in the four - links system are denoted 43 j and 44 j respectively . the working member 3 j is in the example connected to the link 44 j in the four links system 11 j . it suitably forms a parallelo - gram . the pivot axis 47 jb is in the example substantially parallel to the pivot plane for fs 1 . this is however not required . the axes 47 ja and 47 jb are suitably perpendicular in relation to each other . thus , the four - links system 11 j is pivotable around the axis 47 jb in relation to the connection arrangement 12 j by means of the force member 14 j in a way similar to what has been discussed regarding fig8 and the pivot arm 21 f illustrated there . the pivot arm 21 j is by means of the force member 15 j pivotable in relation to the link 45 j around the axis 47 ja . the force transmission in fig1 between the force member 14 j and the pivot arm 21 j is arranged in on principle the same way as what has been described regarding fig8 . in common for all the described embodiments is that a suitable control unit , especially in the form of a computer , is arranged to control the force - exerting members of the different robot embodiments in order to cause the second element 2 or thereto directly or indirectly connected members 3 in desired movement paths . it is evident that the invention is not only restricted to the embodiments discussed hereinabove . thus , detailed adaptations of the embodiments may be carried out depending on the circumstances without leaving the inventive concept appearing from claim 1 . it is further noted that the idea illustrated in fig3 to cause the four - links system fs 1 to pivot by means of an angular gear function between one of the links in the four - links system and the associated force - exerting member 13 a of course is applicable on the embodiments according to fig1 and 4 . the primary advantage with such an arrangement is that the force - exerting member 13 no longer needs to follow when the four - links system is turned around by means of the force - exerting member 14 . thus , the mass needed to be caused to move and thereto related inertias will be reduced .