Disc brake with caliper having releasably lockable reinforcements

The caliper (52), in the form of a closed frame surrounding the fixed support (50), incorporates at least one axial reinforcing member (3) joining two axially separated zones (1, 2) of the caliper by passing through them and extending radially beyond the periphery of the disc (53). The reinforcing member incorporates a head (4), which is received within a complementary recess in the first zone of the caliper (1), and a threaded end cooperating with first and second locking and tightening elements, cooperating with each other (for example a locking nut 5 and a removable washer 10) of which the first elements is lockable on the threaded end so as to give, together with the second element, a predetermined tension to the reinforcing member, the second element being capable of being selectively disengaged to allow the reinforcing member to be separated (by tilting or longitudinal displacement) from the second zone (2) of the caliper.

The present invention concerns disc brakes, especially for motor vehicles, 
and more particularly a disc brake having a caliper slidingly mounted on a 
fixed support in which are housed, so as to be anchored and to slide, two 
friction components capable of coming into frictional engagement with the 
opposite surfaces of a disc during the operation of a brake actuator 
carried by the caliper, this caliper forming a frame positioned around the 
fixed support and incorporating at least one detachable axial tubular 
reinforcing member positioned radially beyond the periphery of the disc 
and joining first and second zones of the caliper, both sides of the disc 
in the axial sense. 
A brake of this type is described in the document EP-No.A-0,083,881 in the 
name of the Applicant Company. In the said document, the tubular 
reinforcing members particularly take the general form of bolts passing 
through aligned holes in line in the first and second portions of the 
caliper, and provided at one end with a support head, and, at the other 
end, with a thread cooperating with a nut for locking and for tightening 
the bolts. 
In such an arrangement, in order to replace the worn friction components or 
brake pads by friction components with new linings, it is necessary to 
dismantle the bolts by unscrewing the nuts, and after replacing the 
assembly, to retighten the bolts, which does not allow the correct factory 
tension adjustment to be guaranteed and results in substantial 
modification of the stresses in the caliper. Moreover, during these 
operations, the bolts and nuts may be damaged, or even lost. 
An object of the present invention is to overcome these disadvantages by 
proposing a brake arrangement of the type defined above, of simple 
construction, the setting up of which is easy and rapid, eliminating the 
need to provide for special operations, after changing the friction 
components, in order to re-establish the initial mounting tension of the 
reinforcing components, and also limiting the risk of loss of the 
reinforcing components and their locking and tightening means. 
To achieve this, according to a feature of the invention, the reinforcing 
member incorporates a headed end, cooperating in bearing engagement, with 
a corresponding surface of the first zone of the caliper, and an opposite 
threaded end cooperating with first and a second locking and tightening 
means, cooperating with each other, of which the first means is capable of 
being locked on the threaded end in a position giving, together with said 
second means, a known tension to the reinforcing component, 
said second means being capable of being selectively disengaged so as to 
allow the reinforcing member to be separated from the second zone of the 
caliper. 
According to a more particular feature of the invention, the first locking 
and tightening means is a nut screwed and locked on the threaded end of 
the reinforcing member, the second locking and tightening means 
incorporating a washer means interposed between the nut and the second zone 
of the caliper. 
According to another more particular feature of the invention, the first 
locking and tightening means 
consists of a tapped bush which is screwed and locked on the threaded end 
and which is received within the cylindrical opening of the second zone of 
the caliper, the second locking and tightening means consisting of a nut 
cooperating in abutment with a shoulder of the bush which is coplanar with 
an abutment surface of the second zone of the caliper.

FIG. 1 shows a disc brake incorporating a fixed support 50 intended to be 
joined to a fixed portion of a vehicle (not shown), and supporting so as 
to allow sliding, by means of two axial pins 51 in the example shown, a 
movable caliper 52 straddling the brake disc 53 and incorporating at least 
one hydraulic brake actuator 54, 54' pushing directly a first friction 
component or brake pad 55, one of a pair of friction components 55, 55' 
mounted, so as to be anchored and to slide, on the fixed support 50. 
The caliper 50 forms a frame or structure in the form of a closed 
non-planar framework positioned around the fixed support 50 and 
incorporating two lateral arms 56 and 57, straddling the disc, joined by 
an outer portion 58 of the caliper and an inner portion 59 of the caliper 
incorporating the brake acutator. Each of the outer and inner portions of 
the caliper incorporates at least one zone projecting radially outwards 1, 
2, respectively, these two opposite zones being joined by one another by a 
tubular reinforcing member 3 extending axially, radially beyond the 
periphery of the disc 53 and above the friction components 55, 55'. 
The two opposite longitudinal zones 1 and 2 of the caliper are shown in 
FIGS. 2 and 3. In this embodiment, the reinforcing member consists of a 
bolt in the form of a column 3 provided, at its ends, with a head and a 
locking means, designated by the general references 4 and 5, respectively. 
The headed end 4 of the bolt 3 consists of a cylindrical head 6 whose 
surface facing the opposite end is provided with a conical chamfer 7, at 
45.degree. for example. The locking and tightening means at the end of the 
bolt here take the form of an assembly consisting of an end thread 8, 
machined on the corresponding end of the bolt, a nut 9 screwed in a proper 
manner on this thread, and a tightening device 10, described below, 
interposed between the opposite surfaces of the nut 9 and of the zone of 
the caliper 2. 
As may be seen in the figures, the bolt 3 passes through the two zones 1 
and 2 of the brake caliper via opposite aligned openings 11 and 12. The 
first of the latter, opposite the headed end 4, consists of a cylindrical 
hole of a diameter D, much greater than the diameter 7 of the bolt 3, and 
whose opening facing outwards relative to the brake, that is to say in a 
direction opposite to that of the caliper zone 2, is chamfered so as to 
form a conical seat 13, complementary to the conical chamfer 7 of the 
headed end 4. The opening 12 is provided, on the other hand, with a slot 
which opens radially outwards on the upper edge of the zone 2 of the 
caliper. 
In the particular case of FIGS. 2 and 3, the tightening component 10 
consists of a washer mounted on the thread 8 of the pillar 3 and whose 
central orifice 110 is extended radially by a lateral slot 14 which allows 
the thread to be disengaged laterally outwards. 
During the assembly of the brake provided with the device described, after 
having placed in position the pad carriers supported by conventional 
components of the support 50, not shown, the bolt forming the columns 3 is 
placed in the position shown and the nut 9 is screwed onto the thread 8. 
Before it comes into contact with the zone 2 of the caliper, the slotted 
washer 10 is introduced between the nut and the corresponding surface of 
the caliper zone 2. 
The nut 9 is then tightened with a torque wrench or any other similar tool, 
and the nut is finally locked on the thread 8, for example by means of a 
drop of hardening resin, not shown, or a blow from a center punch 15 
applied to the collar 16 of the nut (FIG. 4), so as to produce a 
corresponding deformation on the interface between the nut and the thread. 
From the time this is carried out, the pre-tension applied during assembly 
to the bolt forming the pillar is precisely determined and it is not 
possible to modify it without destroying the assembly of the bolt and nut. 
To change the brake pads, the washer 10 is extracted with the aid of a 
suitable percussion tool which is applied from below in FIG. 2, as a 
result of which the untightened configuration is obtained, indicated by 
the dotted lines in FIG. 3. The space thus created between the nut 9 and 
the caliper arm 2 allows the pillar 3 to swing upwards, as indicated by 
the arrow, until the end nut assembly 5 leaves the top of the caliper zone 
2; at this moment, the end nut assembly 5 may be displaced to the left 
until it comes into contact with the caliper zone 1, so that the upper 
opening of the caliper is clear to allow the worn pad carriers to pass 
upwards and to allow the new pad carriers to be placed in position. 
The assembly of the new pads is in fact carried out by repeating the 
operations described above in the reverse order. The last phase is the 
force-fitting of the washer 10, typically by percussion, with the 
provision, if necessary, of entry chamfers on the adjacent edges of the 
nut 9 and/or the edges of the washer 10. Thus it is understood that on 
remounting the washer 10 in its installation position, the tightening 
pre-stress established in the factory during the assembly of the brake is 
re-established. This justifies the name of tightening device or component 
used in the description and in the claims, given that the required 
tightening tension is re-established after each reassembly. 
This tightening component or washer 10 may have the half-moon configuration 
shown in the front view in FIG. 5. To prevent the accidental loss of this 
device due to operational vibrations, various devices may be provided. 
In the case of FIGS. 4 and 5, the washer 10 is surrounded on its periphery 
by a leaf-spring 18 whose ends are fitted around the ends of the slotted 
washer, as may be seen in the figures. In addition, one of the ends of the 
spring, or both ends, is curved inwards so as to serve as an abutment 19 
against the thread 8. This safety spring may be placed in position or 
removed by displacing it axially relative to the bolt 3. 
In the variant of this device shown in FIGS. 6 and 7, the washer 20, 
similar to the washer 10 above, is made of spring steel and its lateral 
entry opening 21 incorporates opposite flanks 22, complementary to the 
diametrically opposed surfaces of the threaded portion 8 of the bolt 3, so 
that the washer is joined to the bolt by snap fitting when sufficient 
radial pressure is applied. 
In the variant shown in FIGS. 8 and 9, the tightening device 10 consists of 
two washers, 23 and 24, freely mounted coaxially on the thread 8, between 
the nut 9 and the caliper zone 2 in the same way as for the washer 10 
previously described. The first washer 23 incorporates two laterally 
opposed flats 25, and the second washer 24 incorporates, on its surface 
facing towards the first washer, two pairs of axially extending lugs 26 
and 27. As may be seen in the figures, this position is such that the lugs 
can come to bear axially on the outward face of the flatted washer 23, so 
that the assembly of the two washers 23, 24 occupies a known axial length 
corresponding to the value necessary to apply the tightening pressure, or 
can be disengaged from this washer in the flats 25, by relative rotation 
about the axis of the washers, in order to create the necessary play for 
dismantling. Indeed, any other axial cam device producing the desired 
effect may be used in accordance with the invention. The actuation of the 
washer 24 can be achieved, for example, by means of a suitable pin wrench 
which is entered into holes 28 formed in the surface of the washer 24 
opposite the lugs 26, 27. Although the nut 9 shown here is not provided 
with a collar, obviously it may also be locked to the bolt 3 by any one of 
the methods described above. 
FIG. 10 describes another embodiment of a tightening device, here 
consisting of a sleeve 29 incorporating an internal thread, joined in the 
manner shown to the thread 8 of the bolt 3, and an external cylindrical 
surface 30 which is fitted in a closed cylindrical hole 31 in the caliper 
zone 2, which, in this case, replaces the open slotted opening 12 of the 
preceding embodiments. In this case, mounting is carried out by fully 
tightening the nut 9, until the required preliminary adjustment tension is 
obtained, driving the sleeve 29 along the thread. When the required 
tension is reached, the sleeve 29 is locked in the position thus reached, 
for example by means of a drop of hardening resin 32 or by a blow with a 
center punch similar to that previously described. As this operation must 
be carried out on the inside surface of the arm 2 of the caliper, the 
latter advantageously incorporates a widened part 33 so that the sleeve 
need not intrude into the space occupied by the pad carriers. Dismantling 
is carried out by unscrewing the nut 9 and displacing axially the bolt 3 
until the sleeve 29 comes into abutment against the opposite zone 1 of the 
caliper. During reassembly, the bolt is replaced and the nut 9 is again 
fully tightened against the sleeve 29, so as to re-establish the correct 
preliminary tension established in the factory. In this case, the nut 9 
can be of any current construction, preferably with a collar 34 forming a 
proper bearing surface, well centered, against the end of the sleeve 29 
and the outer surface of the caliper arm 2. 
In the variant shown in FIG. 11, the sleeve 29 differs from that described 
above in that it projects outwards, relative to the caliper 2, as a peg 
35, which is threaded externally at its end 36 to accept the nut 9 and 
which defines an intermediate step 37 corresponding functionally to the 
abutment at the right hand end of the sleeve shown in FIG. 10. Its 
function is the same as that already described. Instead of the collar 34 
of the nut, a ground washer 38 may be used, and instead of locking with a 
drop of resin 32, a center punch blow 39 may be applied on a small 
protuberance 40 projecting axially relative to the inner end of the 
sleeve, as may be seen in the half-section view of the upper portion in 
FIG. 11. 
Although the invention has been described in relation to a single axial 
reinforcing member, it should be understood applying equally to a brake 
whose caliper is provided with two or more axial reinforcements, as 
described in the document EP-NO-A-0,083,881 mentioned above.