CA2074310A1

CA2074310A1 - Jaw type braking device for vehicles, in particular for heavy vehicles

Info

Publication number: CA2074310A1
Application number: CA002074310A
Authority: CA
Inventors: Rene Henri Jeanson
Original assignee: Individual
Current assignee: JIMECAL (SOCIETE A RESPONSABILITEE LIMITEE)
Priority date: 1991-07-22
Filing date: 1992-07-21
Publication date: 1993-01-23
Also published as: EP0524867A1; FR2679612A1; ATE130410T1; DE69206065D1; EP0524867B1

Abstract

TITLE: Jaw type braking device for vehicles, in particular heavy vehicles.
(Inventor: JEANSON René, Henri) FILED BY: JIMECAL (S.A.R.L.) and JEANSON René, Henri ABSTRACT OF THE DISCLOSURE

The invention relates to a braking device of the type including a disc (1), two jaws (3, 4) each having a first and a second end, these jaws being located on either side of the disc and mounted pivotally on two fixed pins (5, 6), two shoes (8, 9) articulated on the jaws about two axes (10, 11) parallel with the fixed pins, brake pads (12, 13) mounted on the shoes on either side of the disc, and control members (14) capable of causing the jaws to pivot in one direction or in the opposite direction, the pivot pins (5, 6) of the jaws (3, 4) being located between the first and second ends of the said jaws, while the shoes (8, 9) and the control members (14) are respectively adjacent to the said first and second ends.
According to the invention, the jaws comprise at their first end a cylindrical boss partially housed in a cylindrical recess of the same radius provided in the corresponding shoe, the bosses and the recesses providing the articulations of the shoes on the jaws.

Description

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Jaw tYPe brakin~ device for vehicles, in ~articular for heaw vehicles.
The present invention relates to a braking device including a disc rotatable with a member to be braked, in particular a vehicle wheel shaft, two jaws each having a first and a second end, these jaws being located on either side of the disc and mounted pivotally on two fixed pins integral with a frame, two shoes articulated on the jaws about two axes parallel with the fixed pins, brake pads mounted on the shoes on either side of the disc, and control members capable of causing the jaws to pivot in one direction ; in order to press the pads against the disc, or in the opposite direction in order to move them away from the said disc, the pivot pins of the jaws being located between the first and second ends of the jaws, while the shoes and the control members are respectively adjacent to the said first and second ends.
Braking devices of this type are bulky and difficult to install on vehicles, particularly on heavy vehicles, on which free space is limited. Furthermore, they are complex in structure, which makes them difficult and costly to assemble.
The present invention proposes to remedy this drawback and, in order to do so, it provides a braking device of the type indicated above which is characterized in that the jaws have at their first ends a cylindrical boss partially housed in a cylindrical recess of the same radius, with the exception of the mounting clearance, provided in the corresponding shoe, the bosses and the recesses ensuring the articulations of the shoes on the jaws.
These arrangements facilitate the mounting operations and contribute to reducing the cost price of the braking device.
Advantageously, the bosses comprise two axial extensions proiecting laterally from the jaws and advancing up to protuberances provided on the shoes, the shoes being retained "- ' ' ~ ' ~ ,. ~
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on the jaws solely by pins passing through the protuberances and extending along the extensions of the bosses.
Thanks to these further arrangements, the reaction of the braking force exerted by the pads on the disc is absorbed up by the protuberances of the shoes in such a way that the jaws are protected from any risk of accidental damage.
According to one particular feature of the invention, the control members include a rod carrying a first and a second annular piece on which the jaws are articulated, a lever fixed to the rod, between the annular pieces, and a pneumatic control device connected to the lever in such a way that the latter causes the rod to rotate about its longitudinal axis during a braking operation, at least one of the two annular pieces being capable of axial movement along the rod when the latter is rotated and of thus ensuring the actuation of the jaws.
It is desirable for the control members also to include a wear take-up mechanism comprising a first lug integral with the lever, a second lug integral with one of the annular pieces, the second lug being parallel with and adjacent to the first lug, and a pin fixed to the first lug but capable .~ of moving axially through an orifice in the second lug when a braking command is given, and of enabling the annular piece or pieces to be moved along the rod in the event of the pads becoming worn.
The wear take-up mechanism in fact enables the pads to . be used for a longer time, thus making for a reduction in the maintenance costs of the braking devices, as well as in the time for which the vehicles are off the road.
According to a first form of embodiment of the invention, and in order to achieve a substantial reduction in friction, and thus increase the overall performance of the braking device, the rod comprises a threaded lateral section !` having a thread engaging with a thread provided in the second . 35 annular piece, a smooth lateral section pivotally mounted in ` ' .

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the first annular piece, as well as an intermediate section forming a shoulder with the smooth lateral section and to which is connected the lever, a roller thrust bearing integral with the first annular piece being mounted on the smooth lateral section and bearing against the shoulder.
Adjustment tests have shown that, in order to improve the performances of the braking device, it was as preferable for the diameter of the smooth lateral section to be smaller than that of the threaded lateral section, and for the thread of the latter to have a pitch of at least 50 mm, and preferably 60 to 70 mm.
According to a second form of embodiment of the invention also permitting a substantial increase in the performance of the breaking device, the rod includes an intermediate section to which is fixed the lever, and two lateral sections having opposite threads delimiting, with complementary threads provided in the annular pieces, raceways containing bearing balls allowing the said annular pieces to move in opposite directions along the lateral sections during a braking operation.
In this form of embodiment, the annular pieces carry rings to prevent the bearing balls from escaping from the raceways, springs being provided between one of the rings and the end bearing balls adjacent to said one ring to bias all of the bearing balls back to their initial position after a ^braking operation.
,~'The presence of the springs between the end bearing ;-balls and the rings is an advantage as it makes it unnecessary to add a costly ball recirculating system while, at the same time, enabling the annular pieces to move in small increments along the entire length of the lateral sections of the rod to compensate for the wearing of the pads.
In order to facilitate the assembly and/or disassembly operations, the rod is made up of two half rods joined '' . ::

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together end to end at the intermediate section by a threaded element extending coaxially with the said half rods.
Furthermore, to enable the jaws to be articulated reliably on the first and second annular pieces, each of them preferably comprises two diametrically opposed studs projecting on their lateral surface, the jaws being articulated on the annular pieces via the studs.
Two forms of embodiment of the present invention will now be described by way of non-limitative examples with reference to the annexed drawings, wherein:
- figure 1 is a schematic side view of a braking device according t~ the invention;
- figure 2 is a schematic top view of the braking device shown in figure l;
- figure 3 is a cross-sectional view along line III-III
of figure 2, the positions of the annular pieces on the rod being those that they occupy when the pads are new;
- figure 4 is a view analogous to that of figure 3, but one in which the positions of the annular pieces on the rod ~ 20 are those that they occupy when the pads are worn;
;; - figure 5 is a top view, partially in cross-section, of another braking device according to the invention, the pads ` of this device being new, the one on the right being pressed against the disc;
- figure 6 is a partial top view of the braking device shown in figure 5, the pad shown being worn and pressed against the disc; and - figure 7 is an larger scale view showing the springs imprisoned between the bearing balls and the ring located to the left of the lever.
The braking device shown in figures 1 to 4 is designed to be fitted to a road vehicle, and more particularly to a lorry. It includes, in a manner known 'per se' a disc l rotatable with a wheel shaft 2 to be braked, two jaws 3, 4 each having a first and a second end, these jaws being :

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pivotally mounted on two fixed pins 5, 6 integral with a frame 7 carried by the chassis (not shown) of the vehicle, two shoes 8, 9 articulated on the jaws about two axes 10, 11 parallel with the fixed pins, brake pads 12, 13 mounted on the shoes, on either side of disc 1, and control members 14 capable of causing the jaws to pivot in one direction to : press the pads against the disc (and to brake the wheel shaft) or in the opposite direction to withdraw the pads from the disc.
Pivot pins 5, 6 of jaws 3, 4 are located between the first and second ends of the latter, while shoes 8, 9 and control members 14 are respectively adjacent to the said first and second ends.
According to the invention, jaw 3 comprises at its first end a cylindrical boss 15 partially housed in a cylindrical recess 16 provided in shoe 8 and having a radius equal, with the exception of the mounting clearance, to that of boss 15.
Similarly, jaw 4 comprises at its first end a cylindrical boss 17 partially housed in a cylindrical recess 18 provided in shoe 9 and having a radius equal, with the exception of . the mounting clearance, to that of boss 17.
~; Boss 15, the longitudinal axis of which forms the the ' axis 10 about which shoe 8 pivots on jaw 3, comprises two axial extensions 15' projecting laterally from the said jaw 3 and advancing up to protuberances 19 provided on shoe 8.
In an analogous way, stud 17, the longitudinal axis of which forms the axis 11 about which shoe 9 pivots on jaw 4, comprises two axial extensions 17' projecting laterally from ~ the said jaw 4 and advancing up to protuberances 20 provided ; 30 on shoe 9.
Pins 21 passing through protuberances 19, 20 and extending along the extensions of bosses 15, 17 are further . provided to prevent the shoes from becoming accidentally detached from the jaws.
;. 35 Returning now to control members 14, it will be noted . .

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that they include a rod 22 carrying a first and a second annular piece 23, 24 on which jaws 3, 4 are articulated, a lever 25 fixed to rod 22, between the annular pieces, and a pneumatic control device 26 (shown only in figure 1) connected to lever 25 in such a way that the latter causes rod 22 to rotate about its longitudinal axis during a : breaking operation.
Annular pieces 23, 24 each comprise two diametrically opposed studs 23', 24' projecting on their lateral surfaces and on which jaws 3, 4 are articulated.
As to pneumatic control device 26, this includes a pneumatic cylinder 27 fixed to frame 7 and comprising a control rod 28 on which is articulated the free end of lever 25, control rod 28 being designed to cause rod 22 to pivot about its longitudinal axis by causing lever 25 to pivot when the pneumatic cylinder is actuated.
Control members 14 also include a wear take-up mechanism 29 comprising a first lug 30 integral with lever 25, a second ;; lug 31 integral with annular piece 23, lug 31 being parallel with and adjacent to lug 30, and a pin 32 fixed by two nuts 33 to lug 30 but able to move longitudinally through an ; orifice 34 provided in lug 31.
With more particular reference to figures 3 and 4, it will be noted that rod 22 includes a threaded lateral section ~ 25 35 having a thread engaging with a thread provided in second annular piece 24, a smooth lateral section 36 pivotally mounted in first annular piece 23, and an intermediate section 37 forming a shoulder 38 with smooth lateral section 36 and to which is connected lever 25.
A roller thrust bearing 39 integral with first annular piece 23 is mounted on smooth lateral section 36 and bears against shoulder 38.
In the form of embodiment represented, smooth lateral section 36 has a diameter less than that of threaded lateral section 35, while the thread of the latter has a very large 2 ~ 3~

pitch, of at least 50 mm, preferably from 60 to 70 mm.
When it is wished to brake wheel shaft 2, a pedal (not shown) is actuated, placing pneumatic cylinder 27 under pressure. Rod 28 of cylinder 27 then causes lever 25 to pivot in the direction of arrow F in figure 1. As lever 25 is rotatable with rod 22, the latter also rotates in the direction of arrow F, while second annular piece 24 moves longitudinally along it in the direction wherein it moves away from first annular piece 23.
As a result of the movement of second annular piece 24 along rod 22, jaws 3, 4 pivot about pins 5, 6 to press pads 12, 13 of the shoes against disc 1.
It will be noted here that, thanks to the very large pitch of the thread of threaded lateral section 35, the braking device offers excellent performance.
To put an end to the braking command, it suffices to cease actuating the pedal, so that lever 25 can be returned to its initial position by an elastic member (not shown).
As prolonged use of the braking device leads to the wearing of pads 12, 13, the wear take-up mechanism 29 is used to compensate for this wear by acting in such a way that the second annular piece 24 can move from its initial position, represented in figure 3, which corresponds to the case in which the pads are new, to the position represented in figure 4, which corresponds to the case in which the pads are completely worn.
The braking device represented in figures 5 and 6 comprises components having the same structure and the same function as those of the corresponding components of the braking device described with reference to figures 1 to 4.
These components will thus be identified herebelow by the same reference numbers as those used in figures 1 to 4, but suffixed with the letter "a".
The device shown in figures 5 and 6 differs from the device already described, in fact, only in respect of rod 22a ~ ~i ;",~

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and annular pieces 23a, 24a of its control members 14a.
Rod 22a has an intermediate section 40 to which is connected lever 25a and two lateral sections 41, 42 having opposite threads delimiting, with complementary threads provided in annular pieces 23a, 24a, raceways 43, 44 containing bearing balls 45, which enable the said annular pieces to move in opposite directions along lateral sections 41, 42 during a braking operation.
Bearing balls 45 are retained in raceways 93, 44 by two rings 46, 47, fixed to the ends of annular pieces 23a, 24a, springs 48 housed in the raceways 43, 44 being compressed between rings 47 which are adjacent to lever 25 and the end ~ bearing balls closest to these rings.
"~ During a braking operation, annular pieces 23a, 24a move; 15 along rod 22a away from one another and cause jaws 3a, 4a to pivot so as to press pads 12a, 13a against disc la.
Then, when the braking operation has been completed, annular pieces 23a, 24a return substantially to their initial positions, bearing balls 45 being biased back to their ` 20 initial positions by springs 48.
It will be noted here that the wear of pads 12a, 13a of the braking device according to figures 5 and 6 can also be compensated for, as the positions of the annular pieces on lateral sections 41, ~2 of rod 22a can vary, thanks to the wear take-up mechanism and to springs 48 designed to return bearing balls 45, from the position shown in figure 5, which corresponds to the case in which the pads are new, to the position shown in figure 6, which corresponds to the case in which the pads are worn.
For the sake of completeness, it is pointed out that rod 22a is made up of two half rods, 49, 50, joined together end to end at its intermediate section 40 by a threaded element 51 extending coaxially with the said half rods, and that it can thus be very easily mounted on the braking device, or removed therefrom.
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Claims

1. A braking device including a disc (1; 1a) rotatable with a member to be braked (2), in particular a vehicle wheel shaft, two jaws (3, 4; 3a, 4a) each having a first and a second end, these jaws being located on either side of the disc and mounted pivotally on two fixed pins (5, 6; 5a, 6a) integral with a frame (7), two shoes (8, 9; 8a, 9a) articulated on the jaws about two axes (10, 11; 10a, 11a) parallel with the fixed pins, brake pads (12, 13; 12a, 13a) mounted on the shoes on either side of the disc, and control members (14; 14a) capable of causing the jaws to pivot in one direction in order to press the pads against the disc, or in the opposite direction in order to move them away from the said disc, the pivot pins (5, 6; 5a, 6a) of the jaws being located between the first and second ends of the jaws, while the shoes (8, 9; 8a, 9a) and the control members (14; 14a) are respectively adjacent to the said first and second ends, characterized in that the jaws (3, 4; 3a, 4a) comprise at their first end a cylindrical boss (15, 17; 15a, 17a) partially housed in a cylindrical recess (16, 18; 16a, 18a) of the same radius, with the exception of the mounting clearance, provided in the corresponding shoe, the bosses and the recesses providing the articulations of the shoes on the jaws.

2. Braking device according to claim 1, characterized in that the bosses (15, 17; 15a, 17a) comprise two axial extensions (15', 17'; 15'a, 17'a) projecting laterally from the jaws and advancing up to protuberances (19, 20, 19', 20') provided on the shoes (8, 9; 8a, 9a), the shoes being retained on the jaws (3, 4; 3a, 4a) solely by pins (21; 21a) passing through the protuberances and extending along the extensions of the bosses.

3. Braking device according to claim 2, characterized in that the control members (14; 14a) include a rod (22; 22a) carrying a first and a second annular piece (23, 24; 23a, 24a) on which the jaws (3, 4; 3a, 4a) are articulated, a lever (25; 25a) fixed to the rod, between the annular pieces, and a pneumatic control device (26) connected to the lever in such a way that the latter causes the rod to rotate about its longitudinal axis during a braking operation, at least one of the two annular pieces being capable of axial movement along the rod when the latter is rotated and of thus ensuring the actuation of the jaws (3, 4; 3a, 4a).

4. Braking device according to claim 3, characterized in that the control members (14) include a wear take-up mechanism (29, 29a) comprising a first lug (30, 30a) integral with the lever (25, 25a), a second lug (31, 31a) integral with one (23, 23a) of the annular pieces, the second lug being parallel with and adjacent to the first lug, and a pin (32, 32a) fixed to the first lug but capable of moving axially through an orifice (34, 34a) in the second lug when a braking command is given, and of allowing the annular piece or pieces to be moved along the rod (22, 22a) in the event of the pads (12, 13; 12a, 13a) becoming worn.

5. Braking device according to claim 3 or 4, characterized in that the rod (22) comprises a threaded lateral section (35) having a thread engaging with a thread provided in the second annular piece (24), a smooth lateral section (36) pivotally mounted in the first annular piece (23), as well as an intermediate section (37) forming a shoulder (38) with the smooth lateral section and to which is connected the lever (25), a roller thrust bearing (39) integral with the first annular piece (23) being mounted on the smooth lateral section (36) and bearing against the shoulder (38).

6. Braking device according to claim 5, characterized in that the smooth lateral section (36) has a diameter smaller than that of the threaded lateral section (35) the thread of which has a pitch of at least 50 mm.

7. Braking device according to claim 3 or 4, characterized in that the rod (22a) includes an intermediate section (40) to which is fixed the lever (25a), and two lateral sections (41, 42) having opposite threads (43, 44) delimiting, with complementary threads provided in the annular pieces (23a, 24a), raceways containing bearing balls (45) allowing the said annular pieces to move in opposite directions along the lateral sections during a braking operation.

8. Braking device according to claim 7, characterized in that the annular pieces (23a, 24a) carry rings (46, 47) to prevent the bearing balls from escaping from the raceways, springs (48) being provided between one of the rings and the end bearing balls adjacent to said one ring to bias all of the bearing balls back to their initial position after a braking operation.

9. Braking device according to any one of claims 3, 5 and 7, characterized in that the rod (22a) is made up of two half rods (49, 50) joined together end to end at the intermediate section (40) by a threaded element (51) extending coaxially with the said half rods.

10. Braking device according to any one of claims 3 to 9, characterized in that the first and second annular pieces (23, 24; 23a, 24a) each comprise two diametrically opposed studs (23'; 24') projecting on their lateral surface, the jaws (3, 4) being articulated on the annular pieces via the studs.