US3325178A

US3325178A - Safety attachment skis

Info

Publication number: US3325178A
Application number: US564169A
Authority: US
Inventors: Reuge Henri; Bonhote Rene; Chevalier Michel
Original assignee: Reuge SA
Current assignee: Reuge SA
Priority date: 1965-07-15
Filing date: 1966-07-11
Publication date: 1967-06-13
Anticipated expiration: 1984-06-13
Also published as: DE1578872A1; AT278610B; NO117788B; CH436069A; FR1486400A

Description

June 13, 1967 REUGE ET AL SAFETY ATTACHMENT SKIS 5 Sheets-Sheet 1 Filed July 11, 1966 June 13, 1967 REUGE ET AL I SAFETY ATTACHMENT SKIS 5 Sheets-Sheet 2 Filed July 11, 1966 June 13, 1967 REUGE ET AL 3,325,178

SAFETY ATTACHMENT sms Filed July 11, 1966 q 5 Sheets-Sheet s 1% him June 13, 1967 G ET AL 3,325,178

SAFETY ATTACHMENT SKI S Filed July 11, 1966 5 Sheets-Sheet 4 June 13, 1967 REUGE ET AL SAFETY ATTACHMENT sKIs 5 Sheets-Sheet 5 Filed July 11, 1966 United States Patent ()fitice 3,325,178 Patented June 13, 1967 3,325,178 SAFETY ATTACHMENT SKIS Henri Reuge and Rene Bonhote, Ste.-Croix, and Michel Chevalier, La Chaux-de-Fonds, Switzerland, assignors to Reuge S.A., Ste.-Croix, Switzerland, a corporation of Switzerland Filed July 11, 1966, Ser. No. 564,169

Claims priority, application Switzerland, July 15, 1965,

9,941/65; Feb. 7, 1966, 1,671/66 18 Claims. (Cl. 280-4135) The present invention relates to a safety attachment for skis comprising a front safety stop against which bears the front of the sole of the shoe and a safety holding device for the heel exerting on the latter in the engaged position a vertical thrust to hold the heel against the ski and an axial thrust applying the boot against the front stop, this device including a stand fixed to the ski and a first support adjustably mounted on the stand corresponding to the size of the boot.

The heel holding devices proposed up to the present invention necessitate the intervention of complicated disengagement mechanisms with hinged levers, requiring a great number of pieces, which renders manufacture costly.

The present invention aims at overcoming this disadvantage and the attachment which is the object thereof is characterized by the fact that the heel holding device includes a rocking element mounted on a cross spindle carried by a second support movable relative to the first to which it is connected, this rocking element having on one side relative to its rocking axis supporting means for the heel as well as a projection adapted to be actuated by the heel, and on the other side two notches for a ratchet mechanism, the cross spindle of the rocking element being stationary relative to the second movable support and disposed in the upper part of the rocking element at the height of the upper notch in the disengaged position, and a pawl mounted on a second cross spindle carried by the said second support, this pawl being urged elastically either into the lower notch in the engaged position to hold the rocking element against the heel with its projection retracted, or into the upper notch when the said element rocks into the disengaged position freeing the boot with the projection ready to be again actuated by the heel when the boot is re-engaged in the attachment.

The accompanying drawing shows, by way of example, several embodiments of the ski attachment object of the present invention.

FIG. 1 is a view in side elevation showing a ski boot with the complete attachment.

FIGS. 2 and 3 are detailed views in section of the heel safety holding device in two operative positions.

FIG. 4- is a section along line 4-4 of FIG. 2.

FIG. 5 is a view in elevation in the disengaged position of this safety attachment according to the second embodiment.

FIG. 6 is an axial section along line 6-6 of FIG. 7, in the engaged position of the attachment.

FIG. 7 is a plan view.

FIG. 8 is an end view from the front of the attachment.

FIG. 9 is a section along line 9-9 of FIG. 6.

FIG. 10 is an axial section similar to FIG. 6 of the third embodiment.

FIG. 11 is a section along line 11-11 of FIG. 10.

FIG. 12 is a view in side elevation of the fourth embodiment.

FIG. 13 is an axial section of this embodiment in another position.

FIG. 14 is a view in side elevation partly in section of the fifth embodiment.

FIG. 15 is an axial section of the sixth embodiment.

FIG. 16 is a sectional view in elevation of the seventh embodiment.

FIGS. 17 and 18 are views in side elevation partly in section of the eighth embodiment in two different positions of certain members.

FIGS. 19 and 21 are two views in side elevation of the ninth embodiment in two difi'erent positions.

FIG. 20 is plan view of this embodiment.

The ski safety attachment shown in a general manner in FIG. 1 comprises a front safety stop 1 against which bears the front end of the sole of the shoe A and a safety holding device 2 for the heel exerting on the latter a vertical thrust forcing the heel against the ski 3 and an axial thrust urging the boot against the front stop 1.

The heel holding device shown in FIGS. 2 and 3 comprises a base plate or stand 9 fixed on the ski and a first support 7 mounted on the stand in an adjustable manner corresponding to the length of the boot. To this end, a knurled wheel 5 with a helicoidal screw thread, mounted on a spindle 6 integral with the rear part of the support 7, engages a rack 8 of the sand 9. This first support 7 has side flanges which may slide in slides 11 of the stand 9 (FIG. 4).

A rocking element 12 is carried by a transverse spindle 13 fixed on a second support 4 movable relative to the first support 7 and provided to this end with side flanges 10 sliding in slideways 11 in front of the similar side flanges of the support 7. The rocking element 12 is provided to the fore, that is to say on the side facing the boot, with heel bearing means comprising two rollers 14 disposed on either side of the axis of the ski. Each roller 14 is mounted on a fork-joint 15 adjustable in height by means of a screw 16 and carried by a yoke 17 fixed on the rocking element 12. In the heel holding position (FIG. 3), the yoke 17 is inclined at an angle B of about 10 relative to the vertical.

A curved projection 13 of the element 12 constitutes a downward extension of the latter and extends horizontally under the heel of the boot to serve as a pedal when the attachment is in the disengaged position as shown in FIG. 2.

On the other side of the rocking element 12 relative to the rocking spindle 13 are provided two

notches

19 and 20 of a particular shape for a ratchet mechanism. The bottom of each of these notches is rounded and ends on one side with a straight wall forming an angle and relative to the horizontal when the element 12 is respectively in the disengaged position (FIG. 2) or the engaged position (FIG. 3). In this latter position, the notch 19 is at a radius r from the spindle i3 and at a distance 11 from said spindle. According to the choice of the angle which may vary between 15 and 45, the component of the disengagement force which acts on the element 12 may be modified. In the example shown, the angle is of 30. The rocking spindle 13 which is stationary relative to the support 4 is disposed in the upper part of the rocking element 12 at the height of the upper notch 20 in the disengaged position.

A pawl 21 mounted on a second transverse spindle 22 of the support 4, is urged by a compression spring 23 to engage either the notch 19, or the notch 20 to hold the rocking element 12 in its position engaged against the heel with the projection 18 retracted as shown in FIG. 3 or in thedisengaged position of FIG. 2 with the projection 18 horizontal, ready to be again actuated by the heel when the boot is re-engaged in the attachment. This pawl 21 is constituted by a bent lever one arm of which pivots on the spindle 22, the other arm 24 being free and extending upwardly and rearwardly to serve as a handle or pedal to actuate the pawl against the force of the spring 23. The operative part of the pawl 21 which cooperates with the

notches

19 and 20 consists of a rounded tooth 25 provided outside the bend of the

bent lever

21, 24. The spring 23 is mounted horizontally inside the support 4 to exert a force at the point of contact of the tooth 25 of the pawl with the corresponding notch, tending to pivot the element 12 clockwise when the tooth 25 is engaged in the notch 28* and anticlockwise when this tooth is engaged in the notch 19.

The strength of the spring 23 is adjustable by means of a screw 26 with a knurled head acting on a supporting Washer 27 engaging one end of said spring. A pointer 28 integral with the supporting washer 27 moves in a slot 29 made in one of the webs of the support 4. A scale 30, for example in kg, in front of which moves the pointer 28, gives an indication of the tension of the spring 23.

Instead of a spring, one could utilize any other elastic device,'in particular a pile of rubber rings.

The safety attachment described operates in the fol lowing manner:

In order to fix his ski to the boot, the skier engages the front end of the sole against the front stop 1 and after having adjusted the position of the support 7 as a function of the length of the boot, he forces the heel on the projection 18 of the rocking element 12 and causes the latter to rock against the force of the spring 23 until the tooth 25 of the pawl 21 leaves the notch 20 to penetrate into the notch 19 (FIG. 3), the rollers 14 whose height has been previously adjusted corresponding to the height of the heel bearing on the edge of the heel, forcing the latter vertically against the ski. The support 4 is movable longitudinally and permits of forcing elastically, under the action of the spring 23, the rollers 14 against the boot. This support 4 may therefore move relative to the support 7, over a travel of about 6 mm. Satisfactory tests have been effected with a spring developping a vertical force of 80 to 120 kg. and a horizontal force against the front stop of about 20 kg.

In the case of a forward fall for example, if the heel exerts on the rollers 14 a stress exceeding the strength of the spring 23, the element 12 will be rocked in a clockwise direction forcing the rounded rib E between the

notches

19 and 20 against the part of the arm 24 of the pawl 26 adjacent to the tooth 25. The pawl is then forced backwards against the force of the spring 23 until the tooth 25 passes over the rib E and falls into the notch with the element 12 in the disengaged position, thus freeing the boot from the ski.

Instead of the rollers 14, one could provide a single element of plastic material for example, conforming to the shape of the rear part of the heel so as to bear on its edge as with the rollers.

Furthermore, the arched projection 18 of the element 12 could be mounted in a removable manner on this element or adjustably relative to the latter.

The heel holding device shown in FIGS. to 9 comprises the support 4 slidably and longitudinally mounted on the ski 3, the rocking element 12 carried by the trans verse spindle 13 on the support 4 and having, on one side of this spindle a stop 31 for the heel and the projection 18 adapted to be actuated by the heel, and on the other side the two

notches

19, 20 for the ratchet mechanism. The spindle 13 is located in the upper part of the element 12 at the height of the notch 20 in the disengaged position.

The pawl 21 is mounted on the second transverse spindle 22 of the support 4 and is urged by the compression spring 23 to engage either the notch 19 in the engaged position with the projection 18 retracted, or in the notch 20 in the disengaged position with the projection 18 ready to he again actuated by the heel when the boot is re-engaged in the attachment.

The heel holding device shown in FIGS. 5 to 9 comprises a stand 32 fixed on the ski 3, a first support 33 mounted on the stand 32 in an adjustable manner corresponding to the size of the boot and a second movable support constituted by the support 4 connected to the first support 33. This second support 4 comprises two parallel webs held together by the

spindles

13 and 22 carrying respectively the rocking element 12 and the pawl 21. Two transverse holding and guiding

pins

34 and 35 pass through the

supports

33 and 4. These

pins

34 and 35 extend between two side plates 36 provided for the first support 33. The webs of the second support 4 are pierced with lengthened holes 37, 38 through which pass the

pins

34, 35 respectively, so as to permit longitudinal movement of the second support 4 relative to the first.

The stand 32 has on each side a rack 32' cooperating with a corresponding rack 33 of the first support 33 to permit of adjusting the latter according to the size of the boot. Three screws 39 passing through lengthened holes block the support 33 in the desired position on the stand 32, itself fixed on the ski 3 by means of screws 40.

The rocking element 12 is provided with side teeth 41 cooperating with corresponding indented parts of the stop 31 to permit its adjustment on the element 12 according to the height of the heel, a screw 42 blocking the stop 31 in the desired position. A ring '43 is fixed in the upper part of the element 12 and serves to pass a ski holding strap in the case of a fall and the disengagement 0f the attachment.

The operation of the embodiment described with regard to FIGS. 5 to 9 is the following:

When the attachment is in the disengaged position of FIG. 5, the rocking element 12 is held inclined backwardly by the pawl 21 engaged in the notch 20. In order to put on the ski, the skier engages the front end of the boot against the front stop (not shown) and bears downwardly with his heel on the projection 18 of the rocking element 12 so as to cause this element to pivot to the position of FIG. 6. A triangular guide mark R is marked on one of the webs 36 of the support 33 and cooperates with lines T of the movable support 4 so as to render visible the movement of this support relative to the stationary support 33. The boot is applied against the front stop with a force of the order of 20 to 40 kg. by the spring 23 and the

pins

34, 35 moving in the lengthened holes 37, 38 respectively. This force is adjustable by means of the screw 26 which more or less compresses the spring 23. The movement of the screw 26 is located in known manner by a dog E moving in a slot F opposite a scale or by any other visual means.

When the boot is subjected to a vertical stress in the case of a forward fall, for example, the rocking element pivots clockwise pushing the pawl 21 against the action of the spring 23, from the notch 19 (FIG. 6) to the notch 20 (FIG. 5), thus disengaging the boot from the heel holding device.

In the second embodiment shown in FIGS. 10 and 11, the stand has a U-shaped section with flanges 44 at the base, the bed 45 and these flanges being fixed on the ski and the legs 46 having lengthened openings 47 to receive the holding and guiding

pins

34, 35. An adjustment screw 48 with a knurled head bears on a transverse wall 49 of the stand and screws in a tapped hole, made in the vertical wall 50 of the first support 51 adjustable to permit moving this support on the stand. The second support 52 is disposed between the legs 46 of the stand and the first support 51 between the webs of the second. The first support 51 carries the

pins

34, 35 Which project on each side to pass through lengthened holes 53 made in the webs of the support 52 and the lengthened openings 47 of the vertical legs of the stand to permit longitudinal movement of the support 52 relative to the support 51.

The operation of this embodiment is in all points similar to that of the first embodiment. In order that the support 52 may slide on the support 51, this latter has on each side a lengthened hole 22' receiving the spindle 22 of the pawl 21.

The embodiment of FIGS. 12 and 13 differs from that of FIGS. 5 to 9 above all by the pawl 21' whose actuating lever 24' passes below the pin 34 and beyond the stationary support 36. This arrangement permits in particular of actuating more easily the lever, in particular to remove the attachment, the arm of the lever being longer than in the case of the lever 24 of FIG. 2. Further the support 36 may be closed at the top to prevent snow from penetrating into the device.

In the embodiment of FIG. 14, the support of the rocking element 12 and of the pawl 21 is designated by the reference number 54. This support 54 pivots about a transverse spindle 55 fixed on the support 56. The support 54 is guided and limited in its pivoting by a transverse spindle 57 also fixed on the support 56 and a lengthened hole 58 made to this end in said support 54.

The operation of this embodiment differs from that of the preceding examples by the fact that in the case of a disengagement of the holding device, the rocking element 12 pivots against the action of the spring 23 and frees it self from the boot by causing its support 54 to pivot about the spindle 55, the lengthened hole 58 moving on the spindle 57.

In the embodiment of FIG. 15, the pawl is replaced by a ball 59 urged by a spring 60 the tension of which is adjusted by a screw 61. The rocking element 12 is always the same as in the preceding examples and its pivoting spindle 13 is fixed on a movable support 62 playing the same role as the support 4 of FIGS. 5 to 9. This support 62 is guided by two

pins

34, 35 fixed to a support 63 and passing through lengthened holes 62 in the support 63. The spring 23 is mounted between these two supports and its compression is adjusted by the screw 26 as previously.

The operation of this embodiment is identical to that of FIGS. 5 to 9. While it has not been shown, a lever could be provided to disengage the attachment by hand acting for example on the ball to withdraw it from the notch of the ratchet mechanism.

The holding device shown in FIG. 16 comprises an auxiliary lever 66 pivoting at 67 on the support 51 identical to that of FIG. 6. This lever 66 is connected to the pawl 68 by a rod 62 to permit of disengaging the latter from the outside of the device, against the action of a re turn spring 70. By bearing on the lever 66, the pawl 68 is disengaged from the corresponding ratchet mechanism notch and the boot may be disengaged from the attachment.

The embodiment shown in FIGS. 17 and 18 is similar to the one of FIG. 14 as regards the pivoting support 54. The holding pawl 71 of the rocking element is however not provided with an operating lever. To disengage this pawl 71 from the notch 19, it is possible to act on the screw 26 for the adjustment of the tension of the spring 23. To this end, this screw 26 is mounted on a bracket 72 pivoting on a transverse spindle 73 and held in the vertical position by a lever 74 with an eccentric 75. A boss 72 is made on the bracket 72 and cooperates with hollows of the eccentric. In the position of FIG. 13, the lever 74 holds the pawl 71 in the notch 19 in the engaged position. By lowering the lever 74 into the position of FIG. 14, the bracket 72 pivots about its spindle 73, the pawl 71 is freed from the tension of the spring 23 and the rocking element 12 may pivot into the disengaged position to free the boot.

In all the embodiments described up to the present, the heel holding device applies the latter against the ski in such a way so that it is not possible to walk on skis.

In order to avoid this disadvantage, the heel holding device of the embodiment shown in FIGS. 19 to 21 comprises a lever 76 with a cam 77 mounted at the rear of the device on a pivoting spindle 78. In the full line position shown in FIG. 16, the cam 77 of the lever 76 bears against a U-shaped element 79 adjustably fixed by a screw 80 to the inner support 51 provided With the holding and guiding

pins

34 and 35 of the movable support 52.

The attachment described is completed in this embodiment by a cable 81 surrounding the heel of the boot guiding A and hooked to a stretcher device B. When the lever 76 is placed in the position of FIG. 20, the heel holding device is in the position of use, the stop 31 hearing against the heel over the cable 81. By pivoting the lever 76 into the position in dot and dash lines in FIG. 20, the heel holding device is put out of service, that is to say that the element 79 slides backwards with the supports '51 and '52, thus separating the stop 31 from the heel as shown in FIG. 21. In this position, the heel is only held by the cable 81 and the ski may thus be used for walking.

The safety attachment described has the advantage of being of safe operation and of particularly simple construction comprising only two main elements, that is to say the rocking element and the pawl.

What we claim is:

1. Safety attachment for skis, comprising a front safety stop against which bears the front end of the sole of the boot and a safety holding device for the heel exerting on the latter in the engaged position a vertical thrust to hold the heel against the ski and an exial thrust applying the boot against the front stop, this device comprising a stand fixed on the ski and a first support adjust-ably mounted on the stand corresponding to the size of the boot, characterized by the fact that the heel holding device further comprises a rocking element mounted on a transverse spindle carried by a second support movable relative to the first to which it is connected, this rocking element having on one side relative to its rocking axis supporting means for the heel as well as a projection adapted to be actuated by the heel, and on the other side two notches for a ratchet mechanism, the transverse spindle of the rocking element being stationary relative to the said second movable support and disposed in the upper part of the rocking element at the height of the upper notch in the disengaged position, and -a pawl mounted on a second transverse spindle carried by the said second support, this pawl being urged elastically either into the lower notch in the engaged position to hold the rocking element against the heel with its projection retracted, or into the upper notch when the said element rocks into the disengaged position freeing the boot wit-h the projection ready to be again actuated by the heel when the boot is re-engaged in the attachment.

2. Ski attachment according to claim 1, characterized by the fact that the second movable support connected to the first and urged elastically comprises two parallel webs held together by the spindles carrying the rocking element and the pawl, and that transverse holding and pins pass through the two supports.

3. Ski attachment according to claim 1, characterized by the fact that the said second movable support is slidably and longitudinally mounted on the ski.

4. Attachment according to claim 1, characterized by the fact that the said projection constitutes a downward extension of the rocking element, this projection being arched so as to come horizontally under the heel in the disengaged position to serve as a pedal.

5. Attachment according to claim 1, characterized by the fact that the notch serving to retain the element in the engagement position of the heel of the boot has an upper wall inclined to the horizontal by an angle included between 15 and 45, the bed of this notch being located at a definite distance from the rocking spindle of the element and below the latter.

6. Attachment according to claim 1, characterized by the fact that the pawl is constituted by a bent lever pivoting at the end of one of its arms about a spindle stationary relative to said support, the other arm being free and extending backwardly to serve as an actuating handle or pedal, the operative part of the pawl which cooperates with the notches consisting of a tooth made on the outside of the bend of said lever, and the elastic means urging the pawl being constituted by a spring mounted horizontally inside the support to exert a force at the point 7 of contact of the tooth of the pawl with the corresponding notch tending to cause the element to pivot in a counterclockwise direction.

7. Attachment according to claim 1, characterized by the fact that the support has on one side an opening provided with a scale, and by the fact that the elastic means urging the pawl are adjustable and include a pointer movable opposite the said scale.

8. Ski attachment according to claim 2, characterized by the fact that the first support comprises two side plates between which extend the said pins, and that the webs of the second movable support are pierced with lengthened holes through which pass these transverse pins fixed to the legs of the first support so as to permit a longitudinal movement of the second support relative to the first.

9. Ski attachment according to claim 8, characterized by the fact that the stand has at least one rack cooperating with a corresponding rack of the firs-t support for the adjustment of the latter.

10. Ski attachment according to claim 2, characterized by the fact that the stand has a U-shaped section the bed of which is fixed on the ski and the legs of which have lengthened openings, that an adjusting screw connects the stand to the first support so as to be able to move the latter on the stand according to the length of the boot, that the second movable support is disposed between the legs of the stand, that the first support is disposed between the webs of the second movable support and carries the pins projecting from each side to pass through lengthened holes provided in the Webs of the second Support and the elongated openings of the legs of the stand so as to permit longitudinal movement of the second movable support relative to the first.

11. Ski attachment according to claim 2, characterized by the fact that the stand has a U-shaped section the bed of which is fixed on the ski and the legs of which have elongated openings, that an adjusting screw connects the stand to the first support so as to be able to move the latter on the stand according to the length of the boot, that the first support is dis-posed between the legs of the stand, that the second movable support is disposed between the webs of the first support, the pins being carried by the second movable support and passing through elongated holes provided in the webs of the first support and the elongated openings of the stand to permit relative longitudinal movement between said supports.

12. Ski attachment according to claim 8, characterized by the fact that the pawl comprises a lever extending backwards below the rear pin and beyond the first support so. as to be operated fromthe outside of the heel holding device.

13. Ski attachment according to claim 2, characterized by the fact that the second movable support is mounted to pivot on the first support, that the transverse pins are fixed to said first support, the one serving as a pivoting spindle and the other as a guiding axis for the second support which is provided to this end with an arched elongated hole.

14. Ski attachment according to claim 8, characterized by the fact that the rocking element mounted on the second support is held by a ball subjected to the action of a spring, and that another spring bearing on the first support urges the second movable support through the agency of the rocking element against the heel.

15. Ski attachment according to claim 10, characterized, by the fact that it comprises an auxiliary lever pivoting on the first support and connected to the pawl to permit of disengaging the latter from the outside of the heel holding device.

16. Ski attachment according to claim 13, characterized by a pivoting bracket for the spring tension adjusting screw urging the pawl and by a cam lever pivoted on the first support in the neighbourhood of the pivoting axis of the bracket with the cam bearing against this bracket in such a way that in one position of said lever, the bracket with the screw hold the spring stretched and in another position the bracket pivots with the screw, releasing the said spring.

17. Ski attachment according to claim 2, characterized by the fact that the rocking element carries a V-shaped stop adjustable in height so as to engage the heel of the boot.

18. Ski attachment according to claim 2, characterized by a cam lever pivotally mounted behind the heel holding device to move as a whole the two supports from a position of use to a position of non use in which the boot is only held in known manner by a cable passing around the heel so as to be able to walk with the ski.

References Cited UNITED STATES PATENTS 4/1961 Ta ggart 280-4135 6/1965 Hatlapa 280-4135

Claims

1. SAFETY ATTACHMENT FOR SKIS, COMPRISING A FRONT SAFETY STOP AGAINST WHICH BEARS THE FRONT END OF THE SOLE OF THE BOOT AND A SAFETY HOLDING DEVICE FOR THE HEEL EXERTING ON THE LATTER IN THE ENGAGED POSITION A VERTICAL THRUST TO HOLD THE HEEL AGAINST THE SKI AND AN EXIAL THRUST APPLYING THE BOOT AGAINST THE FRONT STOP, THIS DEVICE COMPRISING A STAND FIXED ON THE SKI AND A FIRST SUPPORT ADJUSTABLY MOUNTED ON THE STAND CORRESPONDING TO THE SIZE OF THE BOOT,CHARACTERIZED BY THE FACT THAT THE HEEL HOLDING DEVICE FURTHER COMPRISES A ROCKING ELEMENT MOUNTED ON A TRANSVERSE SPINDLE CARRIED BY A SECOND SUPPORT MOVABLE RELATIVE TO THE FIRST TO WHICH IT IS CONNECTED, THIS ROCKING ELEMENT HAVING ON ONE SIDE RELATIVE TO ITS ROCKING AXIS SUPPORTING MEANS FOR THE HEEL AS WELL AS A PROJECTION ADAPTED TO BE ACTUATED BY THE HEEL, AND ON THE OTHER SIDE TWO NOTCHES FOR A RATCHET MECHANISM, THE TRANSVERSE SPINDLE OF THE ROCKING ELEMENT BEING STATIONARY RELATIVE TO THE SAID SECOND MOVABLE SUPPORT AND DISPOSED IN THE UPPER PART OF THE ROCKING ELEMENT AT THE HEIGHT OF THE UPPER NOTCH IN THE DISENGAGED POSITION, AND A PAWL MOUNTED ON A SECOND TRANS-