The invention relates to an overload clutch comprising a driving and a driven clutch part, between which is interposed an engagement mechanism consisting of a pawl carrying part and a pawl notch part. I n the previously known clutches of this type, the pawls are kept in engagement with the pawl notches by means of springs and the pawl notches are constructed in such a manner that the pawls are capable of slipping out of engagement with the pawl notches, but are prevented from so doing by means of the springs until the torque being transferred exceeds a certain predetermined value at which the springs are no longer capable of keeping the pawls engaged , whereby disengagement takes place. Overload clutches of this kind have the drawback that it is difficult accurately to adjust the torque at which disengagement of the pawls takes place, because both frictional forces and spring forces have to be overcome to cause disengagement. Among prior art that may be pertinent, reference is made to the French patent specification No. 1304082, and to USA patent specifications Nos . 1714105 and 3831724 and the published Western German patent applica¬ tion No. 2805641 . The overload clutch according to the invention is characteriz¬ ed in that one of the clutch parts is connected with one of the parts of the engagement mechanism by means of at least one eiastically yϊeidable element, and that the said one clutch part is rigidly connected with cam members which are adapted upon relative movement of the two clutch parts to disconnect the pawl engagement. Thus, since the pawl disengagement is not effected as a consequence of the reaction forces between pawl and pawl notch , but on the contrary by virtue of the relative turning of the clutch parts as a consequence of the elasticity of the yieldable element, the overload torque will be very well defined , because it will substantially depend on the spring characteristic of the yieldable element, and moreover it is possible to use a positive form of pawl-pawl notch-engagement, i . e. a form of engagement which positively retains the pawl irrespectively of the value of the torque being transferred . Further advantageous features and advantages of the overload clutch according to the instant invention will be apparent from the fol¬ lowing description of two embodiments of the overload clutch shown in the drawing .

In the drawing:

Fig. 1 shows an axial section through a first embodiment of the overload clutch according to the invention along the ;.- : . line 1-1 in Fig. 2,

^" - . ^" Fig. 2 the clutch of Fig. 1, as viewed from the right hand side, some parts having, however, been removed or cut through, Fig. 3 on a larger scale, an axial section through a hub part of the clutch of Figs. 1 and 2 along the line Ill-Ill in 10 Fig. 4,

Fig. 4 an end view of the hub part as seen from the bottom in Fig. 3, Fig. 5 a housing part of the clutch of Figs. 1 and 2 as seen from one end, 15 Fig. 6 an axial section through the housing part of Fig. 5 along the line VI-VI, Fig. 7 a driving element of the clutch as viewed in the axial direction thereof, Fig. 8 the driving element of Fig. 7 as viewed from the left 20 in Fig. 7,

Fig. 9 a spring belonging to the clutch,

Fig. 10 a driving disc of the clutch as seen in the axial di¬ rection thereof, Fig. 11 an axial section of the driving disc of Fig. 10 along 25 the line XI -XI,

Fig. 12 a sectional view of a pawl belonging to the clutch, Fig. 13 the pawl of Fig. 12 as viewed from the left, Fig. 14 an elastϊcally yieldable transmission element of the clutch as viewed in the axial direction thereof, 30 Fig. 15 the transmission element of Fig. 14 as viewed from the bottom, Fig. 16 an axial section of a second embodiment of the over¬ load clutch according to the invention, along the line XVI-XVI in Fig. 17, 35 Fig. 17 the clutch of Fig. 16 as viewed from the right hand side, some parts having, however, been removed and others cut through along the section line XV 11 -XV 11 in Fig. 16,

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Fig . 18 an end view of a hub part of the clutch of Figs . 16 and 17, Fig . 19 a pawl of the clutch of Figs. 16 and 17, partly in section , ' 5 Fig . 20 a side view of the pawl of Fig . 19,

Fig . 21 a sectional view of an end cover of the clutch of

Figs . 16 and 17 along the line XXI -XXI in Fig . 22,

Fig . 22 the cover of Fig . 21 as viewed from the left, and

Fig . 23 a fraction of the cover of Fig . 22 along the sectional

10 line XXI I-XXI I .

In the embodiment shown in Figs . 1 -15, 1 is a driving clutch part in the form of a hub part having inner ribs 2 for engagement with a multi-groove shaft. A pawl notch part 3 with three pawl notches 4 for engagement with three pawls 5 (Fig . 2) is formed in one piece 15 with the hub part 1 . These pawls 5 are approximately in the middle rotatably mounted between two driving discs 7 and 8, Fig . 1 , by means of pins 6, each of said driving discs being mounted on the hub part 1 by means of a ball bearing 9 and 10, respectively. Thus the driving discs 7 and 8 constitute a pawl carrying part of an engagement 20 mechanism which in addition to this pawl carrying part also comprises the pawl notch part 3.

Three driving elements 11 are attached between the driving discs 7 and 8, and each of the driving elements 11 is pierced by two pins 12, 13, the ends of which are attached to the driving discs 7 and 25 8, respectively. Each driving element 11 carries a driving nose 15 pro¬ truding beyond the driving discs 7 and 8. Each of these driving noses engages with an elastically yieldable transmission element 16 and each of these is received in a recess 17 in a housing part 18, which consti¬ tutes the driven clutch part of the clutch illustrated . Cam members 19 30 are formed in the housing part 18 between the recesses 17.

Each pawl 5 is provided at each end with a rotatably mounted .roller 20 and 21 , respectively, of which the rollers 20 serve, in the engaged position of the clutch , for engagement with the pawl notches 4, while the rollers 21 serve to co-operate with the cam members 19 in 35 disengaging the clutch . Each of the rollers 21 additionally serves as an abutment for one end of a spring 22. The other end of each of these springs is held in the adjacent driving element 11 , each of the latter being provided with a slot 23 ( Figs. 7 and 8) for receiving the relevant end of the spring so that this engages with one of ^" the pins 13 of the

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driving element and the inner face of the relevant driving element. The springs 22 have a small bias so that the pawls 5 are loaded by small torque in the clock-wise direction, as seen in Fig . 2, i .e. in direction to urge the rollers 20 into the corresponding pawl notches 4. 7.-5 - The housing part 18 is cup-shaped and has a smooth oute face, and the recesses 17 and the cam members 19 are formed on th inner face of its wall 25. The housing part 18 is closed at one end b means of a cover 26, which is secured by means of a spring ring 2 and is provided with a central opening through which the hub part 1

10 extends. A seal and a ball bearing 28 are provided between the cove 26 and the hub part.

The bottom of the housing part 18 is constituted by a flang 29 with screw holes 30 for the attachment of e.g. a flange of a driven shaft. The opening formed by the flange 29 is closed by means of

15 blank cover 31 . Upon removal of the blank cover 31 the clutch can b used for mounting on a through shaft, and instead of or in addition t the holes 30 the housing may be provided with a toothed ring or lugs for connection with a driven machine element. A ball bearing 32 i provided between the flange 29 and the hub part.

20 Figs. 3 and 4 show the hub part 1 on a larger scale and serve for further illustrating the pawl notches 4. These are cylindrical with the generatrix direction extending in the axial direction of th clutch, and they are shaped as circular arcs along their bottom portion with a radius of curvature which is only slightly greater than th

25 radius of curvature of the pawl engagement rollers 20, viz. corresponding to the engagement conditions of roller chains/chain sprockets. From Fig . 2 it will be seen that a connection line 33, cf. the pawl at the top on the left hand side in Fig . 2, which extends through the center of the pawl roller 20 of the pawl in question and

30 the axis of rotation of the pawl in question, strikes the pawl notch in question below the adjacent terminal edge thereof, which is denoted by 34. The same connection line 33 is shown in Fig . 4, but in this figure the path of this line is inverted as compared to Fig . 2, becaus in Fig . 4 the hub part is shown from the end facing down in the plan

35 of the drawing in Fig . 2. This line 33 forms an angle of about 60 with the radius 35 extending through the center 36 of the relevan pawl notch 4. The portion 37 of the wall of the notch extending fro the point of intersection between this wall and the line 33 to th terminal edge 34 is approximately plane and forms an angle of onl

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very little less than 90° with the connection line 33. It will therefore be understood that when the clutch operates, i .e. when the hub part 1 rotates in the anti-clock-wise direction in Fig . 2, the pawl engagement rollers 20 will be urged inwards towards the bottoms of the engagement notches 4, or in other words a positive force transmission has been established . Nevertheless the forces required for turning the rollers 20 out of engagement are not very great, seeing that the rollers only have to roll on the wall portion 37 which is almost perpendicular to the direction of the force. After each terminal edge 34 follows an inclined run-on track 38 and a circular running track 39 which terminates at the terminal edge 34<a of the next engagement notch .

Figs . 5 and 6 show the housing part 18 on an enlarged scale and it will be seen that the recesses 17 for receiving the elastic transmission elements 16 are delimited at their side edges by arcuate side wails 40, 41 for engagement with the corresponding side edges of the transmission elements, cf. 42, 43 in Fig . 14. From Figs. 14 and 15 it will also be apparent that each transmission element 16 is provided with an axially extending groove 44 for engagement with the correspond¬ ing driving nose 15 of the corresponding driving element 11 so that portions of the elastic transmission elements are present between each side of the driving noses 15 and the side walls 40, 41 of the recesses of the transmission elements. The elastic transmission element shown in Fig . 15 is for economy of space somewhat shortened, but in this connec¬ tion it is to be mentioned that the axial extension of the transmission element substantially corresponds to the axial distance between the inner face of the housing cover 26 and the inner face of the flange 29 of the housing part 18.

The elastic transmission elements consist of an elastomer pla¬ stics material and they are consequently capable of being compressed in the circumferential direction of the clutch . They are preferably in¬ serted in the corresponding recesses 17 at a bias in the circumferential direction . The edge of each transmission element which in the mounted state of the clutch engages the side wall 40 is constituted , as is clear¬ ly apparent from Fig . 14, by a steel pin 46 having a threaded bottom hole 47 so that the transmission elements can easily be extracted from the corresponding recesses 17. As a material for the transmission ele¬ ments one may e. g . use a highly elastic plastics material marketed by E . I . du Pont de Nemours and Company under the registered trademark ADI PRENE.

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Figs. 7 and 8 show one of the driving elements 11 on a lar¬ ger scale. Besides the nose 15 each driving element comprises an arcu¬ ate body 48 integral therewith and through which the two holes extend by means of which the elements are held between the driving discs 7 and 8. The width of the body 48 corresponds to the distance between the driving discs 7 and 8 and the body thus serves as a spacing mem¬ ber. As is apparent from Fig . 8, the nose 15 extends laterally with respect to the body 48 and thus has a length (in the axial direction of the clutch) which is only a little shorter than the distance between the inner face of the cover 26 and the inner face of the flange 29 and thus the driving noses 15 have substantially the same length as the grooves 44 of the transmission elements.

One of the springs 22 is shown on an enlarged scale in Fig . 9, and it will be seen that it is shaped in such a manner as to be sui- table for engaging with the corresponding pawl roller 20, its holding pin 13, and the inner face of the corresponding driving element. Thus, the driving elements 11 , in addition to their driving function , also serve as spacing members and as spring holders.

Figs . 12 and 13 show on a larger scale one of the pawls 5. Each pawl consists of two cheek plates 50, 51 , which are kept at a spacing from one another by means of three spacing sleeves 53, the ends of which are received in corresponding recesses of the cheek plates 50 and 51 . The sleeve 53 in the middle serves to receive the corresponding pin 6, cf. Fig . 2, while the sleeves 53 at the ends receive bolts 54, which at their outer ends are riveted to the cheek plates 50, 51 . The sleeves 53 at the ends of the pawl serve as bearings for the two pawl rollers 20, 21 . The pawl has a width such that it can be received between the driving discs 7 and 8 with a suitable play. The parts 20, 21 , 53, 54 may consist of standard chain parts. As is apparent from Fig . 12, the distance between the sleeve

53 for the pin 6 and the bolt 54 for the pawl engagement roller 20 is greater than the distance between the other roller 21 and the sleeve 53. Consequently, when the clutch rotates, the pawls will be subjected to a torque produced by the centrifugal force and acting in the anti-clock-wise direction , as seen in Fig . 2.

Figs . 10 and 11 show one of the driving discs e. g . the disc 7 on an enlarged scale. Since the two discs 7 and 8 are identical , only one of them is shown on an enlarged scale. The disc is constructed on its inner side with a recess 56 for mounting of the corresponding bear-

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ing 9, and moreover it has fifteen holes 57 which are uniformly distri¬ buted in the circumferential direction and each of which is constructed with an inner shoulder 58, Fig . 11. These holes 57 serve for receiving the ends of the pawl mounting pins 6 and the attachment pins 12 and 13 for the driving elements. By virtue of the shoulders 58 these pins may just be introduced loosely at the mounting, whereby this is facilita¬ ted . From Fig . 2 it will be seen that the holes on either side of a pawl mounting pin 6 are not used, but again for the purpose of facilitating the mounting the holes are nevertheless made, because no predetermin- ed orientation of the driving discs relative to one another is then required, if only the holes are located axϊally opposite one another.

The clutch shown in Figs . 1 -15 operates as follows :

When the driving clutch part or hub part 1 is driven in the direction of the arrow 59 in Fig . 2, the pawl notch part 3 will take along the pawl rollers 20 engaged in the pawl notches, and by virtue of the engagement explained above the pawl rollers will transmit the force to the pawl mounting pins 6 which again by virtue of their con¬ nection with the driving discs 7 and 8 will rotate these and thereby also the driving elements 11 carried by these discs . By virtue of the engagement of the driving noses 15 in the grooves 44 of the elastically yieldable elements 16, the driving elements will take along the elements

16, and these will again drive the driven clutch part or housing part 18 by virtue of the engagement with the side faces 40 of the recess

17. By this transmission of torque the portions of the elastically yield- able elements or transmission elements 16 located between the driving noses 15 and the walls 40 will be compressed in the circumferential direction and in other words a relative displacement of the hub part 1 and the housing part 18 will take place, viz. against the direction of the arrow 59. With respect to the hub part 1 the housing part 18 will consequently move in the clock-wise direction in Fig . 2 corresponding to the degree of compression of the elastic transmission elements, and thereby the cam faces of the cam members 19 will approach the pawl rollers 21 . When this relative turning movement reaches a predetermined size, the cam faces will urge the rollers 21 inwards , whereby the pawls are subjected to a turning movement in the anti-clock-wise direction , as seen in Fig . 2, i .e. in the direction of disengagement of the rollers 20 from the pawl notches 4. By virtue of the conditions of engagement explained above only a small torque on the pawls will be required for disengaging the pawl rollers 20, cf. the wall portion 37 in

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Fig . 4, and this means that the compressibility of the transmission elements 16 will by far be the dominating factor in determining the torque at which the pawls will be disengaged. As soon as the pawl ' rollers 20 have passed the terminal edges 34, the engagement is disrup¬ ted and the rollers 20 move outwards along the adjacent run-on tracks

38 and ^" will continue along the running tracks 39 forming a continuation of the run-on tracks. Depending on the size of the disengagement torque it may happen that a roller 20, when quitting its engagement, may jump more or less outwards, but this will only have the effect that the roller 21 at the opposite end of the pawl 5 will strike a runnin track 39 between two pawl notches. In order to avoid that in this situation the springs 22 may be jammed between these running tracks

39 and the rollers 21 , the running tracks, as is most clearly apparent from Fig . 3, are provided with a circumferentially extending V-shaped recess 49 in which the spring ends can be accomodated . Re-engagement will take place only when the relative speed of rotation of the hub part 1 and the housing part 18 has dropped to a very small value, because a roller 20 in an attempt of being engaged with a pawl notch 4 by its spring 22 will have a considerable tendency to miss the pawl notch by virtue of the high leading edge 34 thereof so that the roller 20 will slip across the pawl notch 4 and strike the run-on track and the running track following thereafter. Renewed engagement will take place only when the relative speed has dropped to approximately zero, and thereby the clutch has fulfilled its purpose. Since only small forces are required for disconnecting the pawl engagement, the disengagement will take place relatively gently without great shock effects, and after the disengagement the clutch parts will rotate smoothly by virtue of the bearings 9, 10, 28, 32, and the pawls will not either produce any substantial friction by virtue of the rollers 20 which will even at moderate numbers of revolutions of the housing part 18 be kept in an elevated position by the centrifugal effect as a consequence of their disequilibrium about their mounting pins 6 and also as a consequence of the weak springs 22.

Seeing that, as explained above, portions of the elastic transmission elements 16 are present on both sides of the engagement grooves 44, this means that the driving noses 15 can be elastically displaced in both circumferential directions with respect to the housing and that during the transmission of torque the clutch is to some degree elastic in both circumferential directions, but it will be understood that

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this is not absolutely necessary for the purposes of the present inven¬ tion .

The forced control of the movement of disengagement by meana of the cam members 19 and the rollers 21 moreover results in a very precise disengagement, and the torque of disengagement is substan¬ tially determined only by the elastic properties of the elastically yieldab¬ le elements 16. Therefore, the overload torque of the clutch can also easily be changed, viz. by replacing a set of elements by other sets having different elastic properties. In Figs. 1 -15 a one-way clutch is illustrated by way of example. There is, however, nothing to prevent that the clutch may be constructed as a two-way clutch , seeing that it may be provided with two sets of pawls, one set of which is inclined in the opposite direction of the other, the corresponding disengaging cam members likewise being inversely oriented so that the disengagement of both sets of pawls may take place by relative turning of the housing part and the hub part.

The clutch of Figs. 1 -15 also distinguishes itself by being capable of transmitting high torques at small dimensions owing to the positive pawl engagement referred to, so that the clutch according to the invention may be made small in relation to the driving shaft or other driving machine element.

In the embodiment shown in Figs. 16-23, 61 is a driving clutch part in the form of a hub part having internal ribs 62 for engagement with a multi-groove shaft. A pawl notch part 63, which is integral with the hub part 61 , is constructed with three pawl notches 64 for engagement with three pawls 65 (Fig . 17) . These pawls 65 are approximately in the middle rotatably mounted between two driving discs 67 and 68, Fig . 16, by means of pins 66, the driving discs 67 and 68 being mounted on the hub part 61 by means of journal bearings 69 and 70, respectively. Thus the driving discs 67 and 68 constitute a pawl carrying part of an engagement mechanism which in addition to this pawl carrying part also comprises the pawl notch part 63.

Between the driving discs 67 and 68 three driving elements 71 are attached, each being pierced by two pins 72, 73, the ends of which are attached to the respective driving discs 67, 68. Each driving element 71 carries a driving nose 75 protruding beyond the driving discs 67 and 68. Each of these driving noses engages with an elastically yieldable transmission element 76 and each of these is receiv-

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ed in a recess 77 of a housing part 78 constituting the driven clutch part of the clutch illustrated. Between the recesses 77 cam members 79 are formed in the housing part 78. Each pawl 65 is provided at each end with a rotatably mounte - roller 80 and 81 , respectively, of which the rollers 80 serve, in the engaged position of the clutch, for engagement with the pawl notches 64, while the rollers 81 serve to co-operate with the cam members 79 in disengaging the clutch. Each of the rollers 81 additionally serves as an abutment for one end of a spring 82. The other end of each of 0 these springs is held in the adjacent driving element 71 . The springs 82 have a small bias so that the pawls 65 are loaded by a small torque in the clock-wise direction, as seen in Fig . 17, i . e. in a direction to urge the rollers 80 into the corresponding pawl notches 64. .

The housing part 78 is cup-shaped and has a smooth outer face, and the recesses 77 and the cam members 79 are formed on the inner face of its wall 85. The housing part 78 is closed at one end by means of a cover 86, which is secured by means of a spring ring 87 and is provided with a central opening through which the hub part 61 extends. A seal and a journal bearing 88 are provided between the co- ver 86 and the hub part.

The bottom of the housing part 78 is constituted by a flange 89 with screw holes 90 for the attachment of e.g. a flange of a driven shaft. The opening formed by the flange 89 is closed by means of a cover 91 , through which the hub part 61 extends, so that the clutch can be used for mounting on a through shaft, and instead of or in ad¬ dition to the holes 90 the housing may be provided with a toothed ring or lugs for connection with a driven machine element. A journal bearing 92 is provided between the cover 91 and the hub part 61 . Fig . 18 shows the hub part 61 in end view and serves for further illustrating the pawl notches 64. These are cylindrical with the generatrix direction extending in the axial direction of the clutch, and they are shaped as circular arcs with a radius of curvature which is only slightly greater than the radius of curvature of the pawl engage¬ ment rollers 80, viz. substantially corresponding to the engagement conditions of roller chains/chain sprockets . From Fig . 17 it will be seen that a connection line 93, cf. the pawl at the top on the left hand side in Fig . 17, which extends through the center of the pawl roller 80 of the pawl in question and the axis of rotation of the pawl in question , strikes the pawl notch 64 in question slightly below the

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adjacent terminal edge 94 thereof. It will therefore be understood that when the clutch operates, i.e. when the hub part 61 rotates in the anti-clock-wise direction in Fig . 17, the pawl engagement rollers 80 will be urged inwards towards the bottoms of the engagement notches 64, or in other words a positive force transmission has been established. Nevertheless, the forces required for turning the rollers 80 out of engagement are not very great, seeing that the rollers only have to roll almost perpendicularly to the direction of the force to the terminal edge 94. After each terminal edge 94 follows a circular running track 99 which terminates at the terminal edge 94 of the next engagement notch . As will be apparent from Fig . 18, the terminal edges are slightly rounded .

From Fig . 17 it will be seen that the recesses 77 for receiv¬ ing the elastic transmission elements 76 are delimited at their side edges by rectilinear side walls 100, 101 for engagement with- the corre¬ sponding side edges of the transmission elements. From Fig . 17 it will also be apparent that each transmission element 76 is provided with an axial ly extending groove 104 for engagement with the corresponding driving nose 75 of the corresponding driving element 71 so that portions of the elastic transmission elements are present between each side of the driving noses 75 and the side walls 100, 101 of the recesses of the transmission elements.

The elastic transmission elements consist of an elastomer pla¬ stics material and they are consequently capable of being compressed in the circumferential direction of the clutch . They are preferably inserted in the corresponding recesses 77 at a bias in the circumferential direction . As a material for the transmission elements one may e. g . use a highly elastic plastics material marketed by E. I . du Pont de Nemours and Company under the registered trademark ADI PRENE.

Figs. 19 and 20 show on a larger scale one of the pawls 65. Each pawl consists of two cheek plates 110, 111 , which are kept at a spacing from one another by means of a middle sleeve 113, the ends of which are received in corresponding recesses of the cheek plates 110 and 111 . The middle sleeve 113 serves to receive the corresponding pin 66, cf. Figs. 16 and 17. The middle sleeve 113 is lined with a liner 114 in order to obtain a certain elasticity.

Each pawl 65 has a width such that it can be received between the driving discs 67 and 68, and widened collars 115 of the

form journalling collars between the pawl 65 and the driving discs 67 and 68.

At the side of each cheek piate 110 and 111 facing the center line of the clutch a toothed sector 116 is provided, and about

ST- the hub part 61 a synchronizing ring 117 is rotatably mounted at each side of ^" the pawl notch part 63. These synchronizing rings 117, 117 are mounted on lateral extensions of the journal bearings 69 and 70 of the driving discs 67 and 68. Each synchronizing ring 117 is provided with three toothed sectors 118, which are distributed at a mutual spacing of

10 120°. Each toothed sector 118 of a ring engages a toothed sector 116 of a pawl 65. Thus, the ring 117 at one side of the pawl notch part 63 engages with each of the cheek plates 110 which extend into a spacing between the driving disc 67 and the pawl notch part 63, and the ring 117 at the other side of the pawl notch part 63 engages with the cheek

15 plates 111 which extend into a space between the driving disc 68 and the pawl notch part 63, cf. Fig . 16. In order to secure the required play for the rings 117 and the cheek plates 110, 111 slide blocks 119 of bearing metal are inserted between each of the driving discs 67 and 68 and the pawl notch part 63. These blocks 119 are secured to the

20 driving discs 67 and 68 by means of laterally extending pins 120, Fig . 17, in the spaces between the toothed sectors 118 of the rings and in the spaces between the pawls 65. Moreover, the driving discs 67 and 68 are guided externally by means of collars of the bearing liners 88 and 92 of the covers 86 and 91 .

25 As shown in Figs. 21 and 22, the end cover 86 is construct¬ ed on its inner side with three plateaus 121 which are uniformly distri¬ buted in the circumferential direction . The radial width of these pla¬ teaus corresponds to the radial width of the elastically yieldable element 76 and they are located at the same radial distance from the axis of

30 the clutch as the elements 76. The plateaus 121 protrude from an axially directed collar 122 of the cover. In the outer face of the cover 86 a bottom hole 123 is provided, as shown in Fig . 23 for engagement by a tool so that the cover 86 can be turned in the circumferential direction whereby the plateaus 121 can be turned between positions in which the

35 plateaus are located opposite to the spaces between the elastic elements, or directly opposite the said elements 76, or assume intermediate posi¬ tions . Thereby it is possible to adjust a space 124, Fig . 16, between the elastically yieldable elements 76 and the collar 122 of the cover 86, whereby the possibility of the elastically yieldable element 76 to expand

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in the axial direction can be adjusted .

The clutch shown in Figs. 16-23 operates as follows : When the driving clutch part or hub part 61 is driven in the direction of the arrow 125 in Fig. 17, the pawl notch part 63 will take L . along the pawl rollers 80 engaged in the pawl notches, and by virtue of the engagement explained above the pawl rollers will transmit the force to the pawl mounting pins 66 which again by virtue of their connection with the driving discs 67 and 68 will rotate these and thereby also the driving elements 71 carried by .these discs. By virtue 0 of the engagement of the driving noses 75 in the grooves 104 of the elastically yieldable elements 76, the driving elements will take along the elements 76, and these will again drive the driven clutch part or housing part 78. By this transmission of torς e the portions of the elastically yieldable elements or transmission elements 76 located in 5 front of the driving noses 75, as viewed in the direction of the arrow 125, will be compressed in the circumferential direction and in other words a relative displacement of the hub part 61 and the housing part 78 will take place, viz. against the direction of the arrow 125. With respect to the hub part 61 the housing part 78 will consequently move 0 in the clock-wise direction in Fig . 17 corresponding to the degree of compression of the elastic transmission elements 76, and thereby the cam faces of the cam members 79 will approach the pawl rollers 81 . When this relative turning movement reaches a predetermined size, the cam faces will urge the rollers 81 inwards, whereby the pawls 65 are 5 subjected to a turning movement in the anti-clock-wise direction, as seen in Fig. 17, i . e. in the direction of disengagement of the pawl rollers 80 from the pawl notches 64. By virtue of the conditions of engagement explained above only a small torque on the pawls will be required for disengaging the pawl rollers 80, and this means that the 0 compressibility of the transmission elements 76 will by far be the dominating factor in determining the torque at which the pawls will be disengaged . As soon as the pawl rollers 80 have passed the terminal edges 94, the engagement is disrupted and the rollers 80 move outwards and will run along the running tracks 99. As is apparent from Fig . 5 17, each spring 82 is provided with a bend 126, and the cheek plates of the pawls are provided with a nose 127 partly engaging the spring bend 126. When a roller 80 skips its engagement, it may jump more or less outwards, which , however, will only have the effect that the spring bend 126 will strike a running track 99 between two pawl

notches and will thereby alleviate possible knocks between the pawls and the pawl notch part. Re-engagement will take place only when the relative speed of rotation of the hub part 61 and the housing part 78 has dropped to a very small value, seeing that a roller 80 in an attemp ≠ of being engaged with a pawl notch 64 by its spring 82 will have a great tendency to slip across the pawl notches. Renewed engagement will take place only when the relative speed has dropped to approximately 0.

As soon as a pawl commences to move as a consequence of

10 abutment between its roller 81 and the corresponding cam face 79, this movement will be transferred via the synchronizing rings 117 to a cor¬ responding movement of the other pawls. Thus, ^ven if, owing to una¬ voidable manufacturing tolerances, abutment should not take place si¬ multaneously between all the pawl rollers 81 and the corresponding cam

15 faces 79, the synchronizing rings will ensure that all the pawls are disengaged simultaneously, whereby it is avoided with certainty that during the disengagement movement a single pawl might be called upon momentanously to transmit the whole of the torque prevailing between the hub part 81 and the housing part 78 in the moment of disengage-

20 ment.

As is apparent from Fig. 17, the cam faces 79 are construct¬ ed symmetrically about a radially extending axis. This means that the . clutch may in a simple manner be re-set from one direction of rotation to the other, because the pawls 65 may, after their mounting pins 66

25 have been dismounted, be inverted and mounted again , whereby the rollers 81 of the pawls will co-operate with the cam faces 79 in exactly the same manner as above described, the pawl notches 64, too, being symmetrical about radially extending central axes, as will be seen from Fig. 18.

30 The elastic liners 114, Fig . 19, of the pawls also contribute to compensate for possible manufacturing tolerances.

The forced control of the disengagement movement by means of both the cam faces 79 and the synchronizing rings 117 results in a very precise disengagement, and the disengagement torque is determine

35 substantially solely by the elastic properties of the elastically yieldable element 76. it will be understood that during the transmission of torque, the elastically yieldable elements 76 are compressed in the cir¬ cumferential direction which again means that at the same time they expand perpendicularly thereto, i . e. radially and axially. By turning

the cover 86, as explained above, the play 124 may be adjusted and, if desired, entirely removed, whereby the freedom of the elastic elements 76 to expand in the axial direction is limited so that the elements when being compressed in the circumferential direction must look out for ^" Sr- other places in order to obtain space for the required lateral expansion . Consequently, a turning of the end cover 86 will cause a change of the torque, at which the elements 76 will yield to a degree sufficient to establish the disengagement movement. In brief, the maximum torque that may be transmitted by the clutch may be adjusted

10 by turning the cover 86. If this possibility of adjustment should not be sufficient, the elastically yieldable elements 76 may be replaced by elements having different elastic properties.

The clutch of Figs. 16-23 also distinguishes itself by being capable of transmitting high torques at small dimensions, owing to the

15 positive pawl engagement mentioned above, so that the clutch according to the invention can be made small in relation to the driving shaft or other driving machine element.

In the beforegoing , the hub part has been referred to as the driving part of the clutch, and the housing as the driven part. It

20 will , however, easily be seen that the housing may constitute the driving part,_ and the hub part the driven part. Moreover, the pawl engagement part has been described above as being rigidly connected with the hub part, and the elastically yieldable elements have been described as being connected with the housing . It will, however, also

25 easily be seen that the inverse arrangement can also be used, meaning that the pawl engagement part is rigidly connected with the housing and the elastically yieldable elements may be connected with the hub part.

30

35

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