FR2612587A1 - IMPROVEMENT TO BRAKE LEVERS WITH ADJUSTMENT DEVICE FOR WEARING TRIMS - Google Patents

Abstract

THE INVENTION CONCERNS A BRAKE WHOSE BRAKE LININGS ARE CONTROLLED BY A LEVER 2. BETWEEN THE SPACING CAM 30 AND THE LEVER 2 ARE INTERCALED THE AUGER 5 AND THE CROWN 6. THE GAP OF THE PADS AND THE STROKE. BRAKE GUARDS ARE ADJUSTABLE BY ROTATION OF SCREW 5. APPLICATION: ADJUSTMENT TO COMPENSATE BRAKE LINING WEAR.

Description

The subject of the invention applies to

  drum brakes and more particularly to the

  which adjust the approximation of the linings to the drum due to the wear caused by the use and which, for this purpose, comprise a worm / crown gearing mechanism, with, in the the axis of the crown, the lever for acting simultaneously on the two fittings by bringing them closer to the drum, simultaneously, the shaft of the worm is provided with means that can print a rotation which, through the crown , will be transmitted to the lever, this one varying at any moment its angular position

  of rest, which amounts to compensating for the wear produced by

  smoothing the initial gap between brakes

  and the drum; this setting can be done automatically by

  part of the angular displacement of the braking lever

  braking; also, the braking can be manual by

  direct action on the worm shaft when

  the level of wear of the linings has reached a certain

some value.

  In what follows, we will call "initial spacing"

  "the brake gauge", the distance set for the normal operation of the device in the absence of wear of the gaskets, the term "initial braking stroke" shall be referred to as the path required to brake, corresponding to "the initial braking distance"

  and "braking stroke" means the braking distance

  swims generally, with or without wear of the pads.

  Similarly, the term "excess wear stroke" means the additional displacement necessary caused by the wear

  undergone by the linings and by "elastic deformation

  "additional movement due to the ability to

  elastic training authorized by all the elements that

  intervene in the braking action. The race of excess of

  sure will only occur in cases where there is wear and tear

  fective trims. On the other hand, the race of elastic deformation will be present in all the braking, that there is or

  not an appreciable wear of the fittings.

  In the present description, the term "lever

  brake which directly receives the braking pressure of the control rod, which will usually be the rod

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  a fluid cylinder belonging to the braking device.

  In the field of the invention, there are known devices in which the adjustment is obtained by exclusively manual means by direct action on the stem of the screw and to do this, it will have for example a hexagonal head,

  accessible from outside the lever.

  Automatic devices are also known

  in which we implement more or less complex means of transmission, clutch etc .. which take advantage of

  course of the lever in the braking action for

  some rotation of the worm shaft when

  said travel of the lever exceeds the angular value which

  would correspond to the specified normal spacing between the

and the drum.

  In these devices, the control mechanism of the worm is integrated within the body of the lever, and it has a locking position which must be released for the said mechanism to act. The unlocking of the mechanism comprises

  the axial displacement of the worm in opposition to a res-

  relatively robust fate and the displacement is obtained by the torsional antagonistic torque generated when the lever acts on the fittings against-effort when there is some

brake lining wear.

  On the other hand, the rotation of the

  The end of the worm is obtained by a rack / pinion gear in which the pinion is mounted on the shaft of the worm and the rack is controlled inside the body of the lever, creating a relative movement of the lever.

  general with respect to an internal fixed seat whose

  lity is obtained by an external anchorage to the adjustment device.

  Among the main disadvantages of these

  In the first place, it should be noted that the lever and

  its shaft are subjected to the exceptionally

  necessary to unblock the worm shaft as well as the subsequent movement of the rack which

  also means that a perfect perfect synchronization

  to be made to prevent tensions from appearing

  in the rack / pinion assembly, tensions that occur

  -3- when the rack will be moved without the worm shaft being unlocked. Ultimately, in these devices as well the worm mechanism / crown that reflects the variation, that the elements involved in the creation of this variation, are permanently subject to adverse efforts. In these automatic devices we also have

  the disadvantage that what is discerned is the value of the

  operation, but not its quality; this implies that the position of the lever will be changed each time the course of the

  the lever will sufficiently exceed the braking stroke which means

  that the fact of the setting is affected by the

  elastic formation of materials which is undesirable since this may give rise to approximations of the fittings

  not justified by sufficient wear thereof; consequently

  when the materials will elastically resume, the

  between the packings and the drum will be lower than normal and during subsequent braking we may have a

brake lock.

  On the other hand, the design of these mechanisms

  with an integrated whole in the body that envelops the lever im-

  plicates a complexity of execution, makes the absolute

  dependent on its execution and requires the provision of

  yen passable, such as screw caps to access

  inside for repairs or maintenance.

  The present invention is a device for

  the automatic adjustment of the brake gap, which pre-

  feels the peculiarity that the rotation of the worm, which through the crown, changes the angular position

  the lever, is done by means of a double ratchet mechanism, de-

  finished outside the shaft on an axial extension of the worm shaft and which consists in that said extension of the shaft of the worm has a diametrical through hole, with two diametrical teeth in mounting floating on an intermediate spring that pushes them out, exerting permanent pressure on the grooved interior

  axially of a detachable socket that maintains said extension

  The outer diameter of the worm and the grooves of the detachable sleeve define grooves whose profile corresponds to that of the diametral teeth, these striations are in odd number.

  so that for the relative position of one of the teeth

  in one streak, the other tooth will be constantly

  center of the step separating two consecutive streaks, the amo

  Vible having a solidarity side lug united by a double joint at the end of a tie rod which articulates at its other end to the front extension of the control rod and for its control the removable sleeve receives at each stroke a tangential actuation back and forth by means of

  tie rods, ear and double joint.

  According to the invention, the conjugated profile of the streaks

  defines two slopes of distinct value, the slope with the least

  being a substantially tangential ramp capable of producing the withdrawal of the tooth in the braking stroke and the steepest slope is a substantially radial wall, so that when the braking gap has its initial value, the action of braking produces the removal and extension of the teeth without changing their relative position of attachment, while,

  when as a result of wear, the course of the. brake course-

  age becomes larger, it occurs that the tooth which is at rest between two streaks, is to be hooked by the streak receding the nearest and when this streak returns to its rest position at the return of braking, the new hooking determines a rotation on the shaft of the worm, and consequently the lever, whose size is equivalent to

half-step streaking.

  This provision has inherent advantages

  The following are the following:

  The worm / rack mechanism is

  to its own function of transmitting or transferring to the

  the angular variation created and measured by a

  dependent so that the lever shaft is not subjected to

  no abnormal effort, nor the teeth of the gear.

  Inside the lever there will be nothing but the worm / rack mechanism, so that the realization is much simpler,

  The implementation and the procedure of the

  Tif in themselves are also simpler Given that in addition to the removal of the aforementioned spring, the assembly recommended with - 5 - bushing, double ratchet and pulling traction of a construction, operation and maintenance easier and it does not create abnormal forces on the rest of the device, that it does not require a very great synchronization of operation, nor an external anchorage of high precision, in comparison with the mechanism of pinion rack and the assembly which can be blocked from the known device that are done inside the body

of the lever.

  Without modification of the lever or the mechanism

  Worm gear / rack mechanism The device can be converted from automatic system to manual only system, with no change other than the removal of the double ratchet and pulling pull, so that the device has a very great flexibility of application; in any case, when the device is controlled manually only, it can be provided that the shaft of the

  worm is shorter on its outer portion.

  As there is, inside the body of the lever, the worm / crown mechanism and the worm can be extracted axially, it is not necessary to extract the crown and it does not need to be removed. It is not necessary that the side covers which are used for the assembly are practicable, one can adopt the solution of the riveting like the recommended mounting, which is more

  simple and more economical than screw fixing.

  The odd number of streaks that produce

  closer to the fittings for each half-step between streaks

  puts a fine adjustment without these streaks are finesse

  extreme, or in other words, with a streak dimension de-

  finished, it is possible to adjust the wear by half-streak.

  Another important feature of the invention lies in the fact that, when the adjustment of the wear is done automatically by the double ratchet mechanism described, it happens that the shaft of the worm is housed, with axial play, in a blind hole at the bottom of which, put in place before the shaft, there is a set of elastic washers, and, at the same time, the doubly articulated arm has means that allow the elastic extension of its length so that it's only

  when, in the braking maneuver, the

  elastic deformation of the materials, and that the

  applied force reaches a sufficient modulus to balance the ef-

  -6 - strong deformation antagonist, that the shaft of the worm

  moves to the bottom of his blind hole, causing the

  axial locking and locking in rotation of the dou-

  ratchet, preventing it from making adjustments that would not be due to wear and, during the blocking of the sleeve integrity of the arm is guaranteed by its means of elastic extension.

  That is to say that this mechanism presents the

  it is important to know if the path that goes beyond

  the braking stroke is due to the wear of the linings or to the de-

  elastic formation of materials because in the latter case, the

  excessive torque antagonistic torque produces a grip-

  page of the double ratchet socket which is thus prevented from ef-

perform its adjustment function.

  When the adjustment of the wear occurs by manual control means only, the mounting of the

  the worm in the lever body is made

  of a sleeve whose core has semi-axial

  circular and diametrical pairs, sleeve which covers a longitudinal section of the shaft in which this

  shaft has a diametral bore housing extreme balls associated

  by an intermediate state which forces them to go out and

  to mate with respect to a diametrical wall of channels.

  The advantage of this device is that the coupling

  obtained ensures that the operating vibrations do not

  will not change the relative angular position of the engrene-

  between the worm shaft and the crown, which is the position which ultimately marks the adjustable connection of the gaskets to the drum. However, this coupling can be overcome if deliberate manual adjustment is made. The accompanying drawings, given as an example

  non-exhaustive, will help to better understand the characteristics

of the invention.

  Fig.1 is a schematic view of a system

  brake system containing the recommended device,

  Fig.2 is an elevational view of the encir-

  key in Fig.l; after removal of the drum 14 and the packing

  15 and corresponding section, it represents the structure

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  interior of the double ratchet and rack / pinion, the silencing

  hoop of the cam 3 being drawn in discontinuous line.

  Fig.3 is a side elevation view corresponding to

  FIG. 2 and in partial section according to the reference 25.

  FIG. 4 is an enlarged view of the detail circled in FIG. 3, relating to the riveting of the covers 13,

  Fig.5 is a view showing the mounting for

  manual setting only, on which we see only a small part of the lever 2 Fig.6 is a perspective view of the device limiting the operating stroke of the shaft 8, Figures 7, 8 and 9 are enlarged views which represent a cross section of the sleeve 4 by the axis of the diametral hole 9, showing different situations

  illustrating the operation. Figure 7 corresponds to the posi-

  8, corresponds to a state in which there has been progress in the attachment of the teeth 11 and the brake is still actuated, and FIG.

  in which there has been a progress of the adjustment to the position

  angular displacement of the cam 3, FIG. 10 is a side elevational view of the self-adjusting brake lever 2, which

  represents partial cuts affecting the device of ex-

  elastic tension of the arm 35 and the lower half of the arm

  7 is a front view corresponding to FIG. 10 and shows partial sections on the double ratchet adjustment mechanism and the lower half

  of the shaft 8 of the crown 6, drawn in a discontinuous line.

  FIGS. 12 and 12 are views corresponding to FIGS. 10 and 11 and which show only the portion of the

  the lather concerned by the wear adjustment device, the

  which, in this case, is manual control only. FIG. 13 is given by reference numeral 49 of FIG. 12, FIGS. 14 and 15 are enlarged views

  circled details of Figures 12 and 13.

  Figures 16 and 17 show the lever of Figures 10 and 11 in two working positions: the first,

  whereas the angular zone of the elastic deformation of the

  - 8 - is not yet reached, and the second, when

  has already entered the zone and the effect of

  FIGS. 18 and 19 are enlarged views of the encircled details of FIGS. 16 and 17, relating to the shaft 7 of the worm 5. FIG. 20 is an enlarged view of the detail "Y" of the

  FIG. 17, referring to the extensible arm 3 which is

  produced again for better understanding,

  In these figures are shown the reference points

  after: 1. Control rod 2. Brake lever 3. Cam 4. Removable grooved bushing 5. Worm gear 6. Crown 7. Worm shaft (5) 8. Cam shaft (3) 9. Diameter hole of the shaft (7) 10. Generic strip of the socket (4) 11. Diametral tooth 12. Intermediate spring 13. Cover 14. Drum 15. Packing 16. Lateral ear 17. Pulling 18. Tangential ramp 19. Wall radial 20. Window 21. Collar 22. Gasket 23. Sector Girder 24. Manual Control Head 25. Cutting Mark 26. Reference Stripe 27. Straight Strike 28. Fluid Cylinder 29. Double Hinge 30. Peripheral Flange on cam 31. Limit stop 35. Elastic stretching arm 36 Elastic washers 37. Axial shaft trunnion (7) 38. Shaft blind hole (7) 39. Coupling sleeve 40. Sleeve ducts (39) 41. Diamond drilling 42. Balls 43. Intermediate spring 44. Angle of braking and excess wear strokes 45. Stroke angle of deformation Elastic 46. Traction spring 47. Tube 48. Head 49. Section mark Our automatic brake adjustment device is applied to a drum brake system in which the control of the packings 15 on the drum 14 is effected by means of a cam 3 which, at the time of braking, rotates solidly with the brake rod 2, which in turn is moved by the rod 1 of the fluid cylinder 28 and at the same time the cam 3 is mounted in extension of the shaft 8 on which is keyed the crown 6 of a worm gear / crown 5, 6, which, associated with the shaft 7 of the worm 5 has a mechanism

  may, in specified circumstances, modify the

  Relative locking of the auger / crown 5.6,

  by rotating the auger 5 which is

  by rotation of the ring gear 6 and, consequently, of the rest position of the cam 3, with the result that the packings 15 are brought into the drum 14,

  with compensation for the wear on the linings.

  One of the particular features of this invention relates to a novel and advantageous device for generating the gyratory movement of the worm 5 which will ultimately result in a change in the position

- 10 -

  3. As is shown in FIGS. 2 and 3, this device consists in that the body of the lever 2 only has the worm / crown mechanism 5.6 and

  the shaft 7 of the worm 5 extends axially to the ex-

  the interior of said body where it has a diametrical hole 9 in which are placed the two diametrical teeth 11 as well as the

  intermediate spring 12; this extension of the shaft 7 is

  tightened by the removable sleeve 4 whose interior is grooved by defining an odd number (preferably nineteen) of grooves 10 equal to each other and whose profile corresponds to that of diametrical teeth 11; outside, this removable sleeve 4 has a side lug 16 on which articulates the double joint 29 in the tangential direction

  compared to the sleeve 4, and in turn, this double

  culation 29 receives the articulated connection of the end of the rod 17 whose particular configuration (Figure 3) allows it to articulate its other end in the extension of

the control rod 1 (Figure 2).

  Thanks to this construction, the axes of articulation

  drawbar 17, the shaft 8 of the crown 6 and the axis

  articulation between the rod 1 and the lever 2 are placed at the vertices of an articulated trapezoid whose configuration is such that, when at the moment of braking, the rod 1 moves

  in a linear fashion in the direction of the arrow (

  the lever 2 around the shaft 8, the tie rod 17 performs

  simultaneously an angular displacement around its articu-

  lower section and a linear upward movement (according to the arrows shown in Figure 2) whose direction is tangent to the sleeve 4 and whose point of application is on the side lug 16, so as to produce a rotation

  on the removable bushing 4, in accordance with the arrows of the

gure 3.

  The operation of the device recommended is illustrated in Figures 7, 8 and 9 which show enlarged sections in which we see only the shaft 7 of the worm 5, the diametrical teeth 11, the intermediate spring 12 and the inside. grooved from the removable sleeve 4. The figure

  7 corresponds to the resting position and we can see the tooth dia-

  Metale 11 upper, in hooking position and tooth

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- he -

- ll # -

  lower 11 in the center, between the reference streaks 26 and

  consecutive 27 (indented, depending on the direction of rotation

  swimming). When the brake is actuated, the bushing 4 rotates in the direction of the arrows (FIG. 8) by a value such that, if there is no wear on the packings 15 (initial clearance

  of braking), it would be insufficient for the

  cutive 27 exceeds the position of the tooth 11 and can

  and then, when the brake is released, the bushing 4 will reverse the rotation and return to the starting position (figure

  7); on the other hand, if there was sufficient wear on the

  15, the braking stroke would exceed the value of the

  initial braking stroke and socket 4 would turn a year

  It is larger enough that this time there is attachment of the lower tooth 11 in the consecutive streak 27. Then, when the brake is loosened, as the removable sleeve 4 must always return to its initial angular position, it will follow ( 9) that the diametral axis of the teeth 11 and therefore the shaft 7 of the worm 5 will be brought to a new angular position of rest which will be retained until a new wear of magnitude

  sufficient; the rotation of the worm 5 will cause the rotation

  the crown 6 and consequently the cam 3, so that the latter will also adopt a new angular rest position according to which the packings 15 will be brought closer together

  drum 14 until the initial braking distance is restored.

  This phenomenon of successive approximation of the

  Nitures 15 has a limitation to avoid causing damage to the device when the wear is already too great and this limitation results in joint control

  end stop 31 of the lever 2 and the peripheral flange

  on the cam 30 secured to the ring 6 (FIGS. 6 and

  Another important feature of the invention

  This is achieved by the location of the shaft 7 of the worm 5 in the blind hole 38 so that there are axial treads 37 while the ribbed sleeve 4 with double ratchet is recessed with the possibility of rotation. between the flared end of its shaft 7 and the body of the lever 2, and, on the other hand,

  part, in the bottom of the blind hole 38, it is possible to

- 12 -

  before the shaft 7, a pile of elastic washers 36. The improvement is completed by the installation of an arm 35

  elastic extension (Figures 1 and 11) to protect

  manage its integrity when it is solicited by considerable traction efforts; the elastic extension is obtained by a known mechanism which consists in producing an arm in two parts: one with an axial orifice in which a pulling spring 46 is screwed under pressure and the other formed of a head 48 provided with a tube 47 with a bulging section which, when assembled, will be

  firmly held within the interior of said spring 46.

  Figures 16 to 20 illustrate the func-

  recommended development. Figures 16 and 18 correspond to the known operating situation up to

  present, in which angle 44 represents the initial race

  the excess wear stroke (when it exists) so that, if the excess wear is sufficient, there will be a corresponding adjustment, as indicated, without the arm 35 supporting any extension and without the tree

  7 is subjected to any abnormal axial force.

  Figures 17, 19 and 20 correspond to a

  in which braking has determined an

  additional wing of the lever, or angle 45, which is not due to the wear of the linings, but to the elastic deformation of the materials involved in the braking action. Then, the antagonistic torsion torque on the shaft 8 of the ring 6 croft enough for the shaft 7 of the screw without end 5, thanks to the existence of the axial treads 37, to press towards the bottom of the blind hole 38, in opposition to the washers 36, thereby blocking the rotation of the sleeve 4, by compressing it between the flared end of the shaft 7 and the body of the lever 2, and thus ensuring that there can be no eventual additional adjustment (closer fitting of the fittings

  to the drum) which would not be caused by wear; in de fi

  nitive, it eliminates the possibility of jamming brakes as a result of successive unjustified adjustments caused by the elastic deformation of materials. When there is blocking of the sleeve 4 (at the beginning of the stroke represented by the angle 45), it is when the arm 35, being constantly solicited by the

  control rod 1 is subjected to an abnormal effort of trac-

  -13 - which causes its extension (Figure 20) to avoid possible breakage.

  The transformation of the automatic device into dis -

  only positive manual appears by comparing Figures 2 and 5 and it consists in removing the removable sleeve 4 and the pulling 17, possibly replacing the shaft 7 of the worm 5 by another shorter shaft and provided with a head 24 for mounting a manual control tool; this head 24 will also exist in the automatic device to be able to

  also do the manual adjustment if desired.

  The improvement concerning the case of adjustment

  manual only is illustrated in Figures 12 to 15 and it is

  is essentially in the fact that the shaft 7 of the worm 5 has the diametrical bore 41 in which are housed the balls 42, with the intermediate spring 43 which forces them to go out by meeting in the channels 40 which form diametrical pairs in the core of the sleeve 39 through which is mounted the shaft 7 relative to the body of the lever 2. Thus, the angular position adjusted for the shaft 7 is not altered by vibrations or the like, while this blocking can be overcome when, deliberately one wishes to change the setting, by acting on the outer hexagonal head of this

tree 7.

  As can be seen, not only does the mechanis-

* Me of adjustment presents a great simplicity of construction

  and functioning, but it also translates into a

  simple truction for the lever 2 which only houses the worm gear / crown 5,6 and which removes the worm 5 axially, with its shaft 7, so that it is no longer necessary to extract the crown 6, not even for the works

  maintenance. As a result, the covers 13 can be

  riveted, as shown in Figure 4, and for this purpose, these covers have a flange 21 within which is mounted a seal 22 and on the perimeter of which they are tightened by the deformations of the material constituting the lever 2 according to sectoral treads 23

  Nature, as well as the indus-

  triele of the invention being sufficiently described, it suffices to add that, both on the whole of the invention and on its

  parts, it is possible to introduce amendments

  fications of form, material, disposition, while remaining

  within the scope of the invention, these amendments do not

Naturant not the foundation.

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Claims (8)

  1. Improvements to brake levers, with adjustment device for wear of the linings, for brakes in which the cam (3) of spacing of the linings (15) is actuated by the lever (2) via 'a   transmission worm / crown (5,6), in which,   that as a result of wear resulting from the use of the brake on the wheel   a game that goes beyond the game corresponding to the   initial braking force between the linings (15) and the drum (14), the gap and the initial braking stroke   are restored by changing the angular position of   pos of the cam (3) by a relative meshing movement between the worm (5) and the ring (6) of the transmission and in which, for the automatic generation of this movement   relative one takes advantage of the braking stroke itself, cara-   characterized by the fact that the mechanism which produces the relative movement in the auger / crown gear (5,6) is a   double ratchet defined outside the lever (2) on a prolongation   axial arrangement of the shaft (7) of the worm (5) and which consists in that the extension of the shaft (7) of the worm   (5) has a diametrical hole (9) passing through, with two diameters   trales (11) floating on an intermediate spring (12) which forces them out, with permanent pressure against the axially grooved interior of a removable sleeve (4) which encloses the outer extension of the shaft (7) of the worm and the splines of the detachable sleeve (4) define   striations (10) whose profile corresponds to that of the teeth   trales (11) and which are in odd number, so that in the relative position of one of the teeth (11) being hooked in a groove (10) the other tooth (11) will be in the center of the step separating two consecutive streaks, the detachable sleeve (4) having a lateral lug (16) integral and united by a double articulation (29) at one end of a tie rod (17) whose other end articulates with the prior extension of the control rod (1) and for its control, this removable sleeve (4) receives at each braking stroke a tangential back and forth operation by means of the tie rod (17), the ear (16). ) and double articulation (29) 2,612 58 7   -16- 2. Improvements to brake levers with device   of adjustment for the wear of the gaskets, according to the   1, characterized by the associated profile of the ridges (10) which defines two slopes of different inclination, the least inclined slope being an almost tangential ramp (18) capable of producing the removal of the tooth (11) at the braking stroke , and the most inclined slope being a wall (19) almost radial, capable of producing an attachment for   a tooth, so that when the brake spacing   the initial value, the action of braking   the removal and extension of the teeth (11) without modifying their relative latching position, whereas, when as a result of wear of the linings (15), the path of the braking stroke is greater, the tooth (11 ) that can be found   in the rest position between two striations (10) is to be ac-   crooked by the nearest recessed strip and, when this strip (10) returns to its rest position during the braking return stroke, the new meshing causes a rotation on the shaft (7) of the worm (5) and by   cam (3) of a value equivalent to half no streaking.   3. Improvements to brake levers with device   adjusting the wear of the linings, according to the   1 and 2 of the type in which the compensation of the wear is done by means of a worm gear (5) /   crown (6), with cam (3) mounted on the axis (8) of the neck   (6) to bring the gaskets (15) closer to the drum (14) and on the shaft (7) of the worm (5) within the   the brake lever body (2) are provided with rotation means   which determine on the cam (3) the rotation which will bring together the linings (15), characterized by the fact that   only when the adjustment is done automatically by a   double ratchet mechanism consisting of a sleeve (4) enclosing the shaft (7) of the worm (5) between an extreme projection   of the latter and the lever body (2), the bushing (4) accom-   pleating a back and forth rotation given by an arm (35) articulated on the sleeve (4) on the one hand and on the rod of   control (1) on the other hand, at a point placed in front of the   With the lever (2), the shaft (7) of the worm (5) is housed with axial clearance in a blind hole (38) at the bottom.   from which a pile of   the elastics (36), and at the same time the arm (35)   articulated means, comprises means which allow an elastic extension of its length, so that, when   braking maneuver we reach the angular zone of de-   elastic formation of materials and that applied force   reaches a sufficient module to balance the antago-   deformation, the shaft (7) of the worm (5) moves towards the bottom of its blind hole (38), causing   the axial imprisonment and the rotational locking of the   (4) of the double ratchet, preventing it from making compensation that would not be due to wear, and during the locking of the sleeve (4), the integrity of the arm (35) is   ensured by its means of elastic extension.   4. Improvements to brake levers with dis-   Positive adjustment for the wear of the fittings, following one   any of the preceding claims, characterized by   the fact that, the bushing (4), the teeth (11), the spring (12), and the pulling rod (17) being independent and dismountable elements of the worm / crown mechanism (5, 6),   It is possible, simply by deleting them, to obtain a system   manual brake control system, by direct drive in rotation on the shaft of the screw without end (5).   5. Improvements to brake levers with dis-   positive setting adjustment for the wear of the linings, according to claim 4, characterized in that, when the compensation of the wear is by means of manual control only, the mounting of the shaft (7) of the worm (5) on the body of the lever (2) is made with the interposition of a sleeve (39) which has in its soul axial channels (40) semicircular forming diametrical walls, sleeve (39)   which encloses a longitudinal section of the shaft (7) in the-   which it has a diamond drilling (41) housing   the ends (42) joined by an intermediate spring (43) which forces them to unite two by two with respect to a   diametric pair of channels (40) so that by this accou-   In addition, it is possible to prevent the operating vibrations   -18- undesirably change the relative angular position   meshing the shaft (7) of the worm (5) with   port to the crown (6), this blocking being able, however, to be over-   mounted for deliberate manual re-adjustment.   6. Improvements to brake levers with dis-   positive adjustment for the wear of the fittings, according to one   any of the preceding claims, characterized by   the fact that the hoods (13) which laterally close the door   of the ring (6) in the body of the arm (2) and which each have a window (20) for the passage of the shaft (8) of the cam (3) each define a collar (21) which on its inner face receives seals (22) and   which can be riveted on their perimeter by means of   sectors (23) of internal deformation of the space with respect to which the hoods (13) are housed in the body of the arm (2).   7. Improvements to brake levers with dis-   positive adjustment for the wear of the fittings, following one   any of the preceding claims, characterized by   the fact that, in association with a peripheral flange on the cam (30) integral with the shaft (8) of the cam (30) is on the body of the lever (2) a limit stop (31) of the functional angular run of the shaft (8) which gradually approximates the linings (15) of the drum (14), so that, this stop being reached (31) there is no blockage of the linings (15) during exceeding the active profile of the cam (3).   8. Improvements to brake levers with dis-   positive adjustment for the wear of the linings, according to the   claim 1, characterized by the fact that the odd number   streaks (10) will be nineteen preferably.