Actuator mounting assembly for a multi-disc brake

A disc brake for installation on heavy automotive vehicles, comprises at least two rotating discs fixed to each other and spaced apart axially and rigidly fixed on the brake rotor, and a stirrup fixed on the brake stator. The stirrup comprises two external portions between which the discs are disposed, and at least one intermediate portion between the discs. The stirrup portions have pairs of opposed coaxial cylinders to apply friction linings against the discs between them. The cylinders of the intermediate stirrup portion open in opposite axial directions and are staggered circumferentially and are blind and have a depth close to the thickness of the intermediate portion. The portions of the stirrup member are detachably interconnected and extend over an angular sector of about 180.degree. at the top of the brake.

The present invention relates to a disc brake, especially for automobile 
vehicles, and more particularly for heavy automobile vehicles. 
The overall dimensions of the disc inside the rim of the wheel is limited 
by the space which is available in that place. At the present time there 
is a tendency to reduce the diameter of the rims, whereas the performances 
of vehicles increase regularly. It thus becomes increasingly difficult to 
place a disc of satisfactory dimensions in position inside the wheel. This 
difficulty may be overcome if the performance of the disc is increased, by 
utilizing for example a disc provided with internal ventilation channels. 
This measure is however still insufficient in numerous applications, heavy 
lorry vehicles, machines, etc., and in any case it increases substantially 
the cost of construction. 
It is also possible to increase the number of discs, following the current 
technique in aeronautics. Several discs are provided so as to be axially 
mobile and gripped in a common stirrup member, but the cooling is slow, 
which is inacceptable for the application to automobile vehicles. 
Furthermore, this arrangement makes it necessary to provide splines on the 
moving discs and their hub, which in this case also increases the cost of 
construction. 
Certain vehicles are thus equipped with several discs mounted inside the 
same stirrup with friction linings interposed between the discs. The discs 
are axially free and the stirrup is mobile, which enables the provision of 
pistons between the discs to be dispensed with and thus reduces the axial 
dimensions of the brake. 
However, brakes of this kind have various disadvantages, in particular: 
expensive splines with a risk of jamming of the discs on these splines 
during the course of their movement; the residual friction due to the 
moving stirrup which increases the wear of the friction linings to a 
considerable extent, which constitutes a major drawback, especially with 
heavy lorry vehicles; and the floating of the discs during the running of 
the vehicle, which is liable to increase still further the wear of the 
linings and to affect the cooling adversely. 
In order to overcome these various disadvantages, it is possible to provide 
a multi-disc brake in which the discs and the stirrups are fixed axially. 
The present invention relates to a multi-disc brake of this kind comprising 
at least two rotating discs, fixed and spaced apart axially, rigidly fixed 
on the brake rotor, and stirrup means rigidly fixed on the stator of the 
brake. 
In brakes of this kind, and especially in two-disc brakes, the brake is 
generally produced by arranging two single-disc brakes one following the 
other, utilizing all the circumferential space available, that is to say: 
for one of the discs an individual stirrup is provided, while for the 
other disc another individual stirrup is used, staggered circumferentially 
with respect to the first. 
This method of procedure doubtless gives good results for the braking 
considered by itself, since the traditional technique of the single disc 
is employed, but it has the disadvantage of poor cooling. In fact, 
substantially all the circumference of the disc is occupied by the brake 
members, which leaves insufficient room for the ventilated zones. In 
addition, these known devices have the disadvantage of leaving at least 
part of the brake members and their actuating system exposed to bad 
weather and mud. 
In other known brakes, the stirrup is arranged in monobloc construction 
with an intermediate portion in which the pistons co-operating 
respectively with the discs are in line with each other, which gives a 
large axial dimension and this may be prohibitive in the application to 
atuomobile vehicles. In addition, this arrangement lends itself badly to 
the conditions of safety of a double circuit and to easy replacement of 
the friction linings, that is to say without dismantling the brake. 
The present invention has for its object a multidisc brake of the kind 
referred to above, with axially-fixed discs and fixed stirrup means, which 
is free from the various disadvantages previously referred to, the 
construction of which is simple and convenient, the operation is excellent 
and the cooling is adequate, with very good protection against bad 
weather, this brake having the further advantage of great ease of 
replacement of the friction linings. 
A multi-disc brake according to the invention has fixed stirrup means 
comprising on the one hand two outer portions arranged on the outside of 
the discs and each having cylinder means receiving piston means adapted to 
apply friction-lining means axially against the corresponding disc, and on 
the other hand at least one intermediate portion arranged between the 
discs and having piston means adapted to apply friction-lining means 
against the discs, and is especially characterized by the three following 
aspects which may be taken separately or preferably wholly or partly in 
combination: 1. According to a first aspect, the cylinder means of the 
intermediate portion which co-operate with a disc are circumferentially 
staggered with respect to the cylinder means of the intermediate portion 
which co-operate with another disc, the various cylinder means of the 
intermediate portion being blind and each extending axially over a depth 
in the vicinity of the thickness of the intermediate portion; 
2. According to a second aspect, the various portions of the stirrup means 
are constituted by separate parts assembled together by fixing means; 
3. According to a third aspect, the various portions of the stirrup means 
are assembled together in an angular sector of about 180.degree.. 
By virtue of such an assembly of the various parts of the stirrup in an 
angular sector of about 180.degree., the opposite sector of about 
180.degree., in which the discs are directly in contact with the air, if 
freed, permitting excellent cooling of the brake. 
In addition, the position of the semi-circumference comprising the stirrup 
means can be chosen at will so as to give the best possible protection of 
these stirrup means and of their actuation system. In general, in a brake 
fitted in an automobile vehicle, the position of the stirrup means will be 
chosen in the upper semi-circle which provides the best protection against 
bad weather and mud, while the free portions of the discs which extend 
into the lower semi-circle become cooled under the best possible 
conditions during the running of the vehicle. 
It will be appreciated that this advantageous assembly of the stirrup means 
in a sector of 180.degree. does not necessarily imply an increase in the 
overall axial dimension of the brake, since the intermediate potion of the 
stirrup has its thickness which is not doubled, contrary to known 
multi-disc brakes but which is single by virtue of the circumferential 
staggering of the cylinder means of the intermediate portion which 
co-operate respectively with the two discs. 
It should be noted that in the brake according to the invention, it is very 
easy to change the friction linings. 
The cylinder means of an external portion of the stirrup means associated 
with a disc are preferably arranged facing the cylinder means of the 
intermediate portion which are associated with this disc, while the 
cylinder means of the other external portion of the stirrup means 
associated with another disc are arranged facing the cylinder means of the 
intermediate portion which are associated with this other disc. By virtue 
of this arrangement, symmetrical conditions are obtained which are 
favourable to the gripping action on each of the discs. 
According to another characteristic feature, the fixing means are divided 
into three groups arranged substantially at the corners of a triangle: two 
end groups which are respectively arranged at the extremities of the outer 
portions of the stirrup and a central group which is arranged 
substantially in a central zone of the intermediate portion of the 
stirrup. This method of fixing in three zones which are arranged at the 
corners of a triangle provides extreme robustness of assembly and great 
rigidity, permitting uniform wear of the friction linings. 
The cylinder means of an external portion of the stirrup and the cylinder 
means of the intermediate portion of the stirrup which are associated with 
a disc, preferably co-operate with a hydraulic supply source which is 
independent of another hydraulic supply with which co-operate the cylinder 
means of the other external portion of the stirrup and the cylinder means 
of the intermediate portion of the stirrup which are associated with 
another disc. This arrangement makes it possible to satisfy the condition 
of a double circuit favourable to safety in braking, without any 
particular complications. 
According to the invention, packing pieces are advantageously interposed 
between the external parts and the intermediate portion of the stirrup, in 
order to permit the adaptation of the brake to various thicknesses of 
discs. 
It will be appreciated that the two external portions of the stirrup can be 
employed in their actual state so as to constitute a single disc, and the 
present invention has also for its object a single-disc brake, 
characterized in that its stirrup is constituted by the two external 
portions assembled directly together, of the stirrup of the multi-disc 
brake described above. This arrangement has a particular advantage of 
standardardization in the application to heavy lorry vehicles in which 
double-disc brakes can be utilized on the rear axle and single-disc brakes 
on the front axle.

Reference will first be made to FIGS. 1 to 8 which relate by way of example 
to an application of a double-disc brake according to the invention, to a 
wheel of a heavy lorry automobile vehicle. 
In FIG. 3, the stator 10 of the wheel and the brake has the form of a small 
trumpet 11 on which the rotor 13 of the wheel and the brake is rotatably 
mounted by means of bearings 12. On the rotor is mounted the web 14 of the 
wheel, the rim of which is seen at 15 and the pneumatic tyre at 16. 
The double-disc brake according to the invention comprises two rotating 
discs 17 and 18 fixed and spaced apart axially, rigidly fixed by screws 19 
on the rotor 13. The brake also comprises a fixed stirrup member 20 fixed 
on the stator 10 by screws 21. 
The stirrup 20 is in three parts 22, 23, 24 formed by separate pieces 
assembled together by the screws 21. 
The portion 22 or external portion, is arranged outside the disc 17 and 
co-operates with this latter. The so-called intermediate portion 23 is 
arranged between the discs 17 and 18 and co-operates with both these 
discs. The portion 24 also known as an external portion, is arranged 
outside the disc 18 and co-operates with this latter. 
As shown in FIG. 2, the portion 22 comprises two blind cylinders 25 
arranged side by side. Each cylinder 25 recieves a piston 26 in such a 
manner as to define a hydraulic chamber 27. The pistons 26 are adapted to 
thrust axially against a friction lining 28, forcing the latter against 
the outer face 29 of the disc 17. 
The intermediate portion 23 comprises two blind cylinders 30 and also two 
other blind cylinders 31, all placed circumferentially side by side, one 
after the other, but the cylinders 31 have their opening which is opposite 
to that of the cylinders 30 in the axial direction. The portion 23 is 
provided with cooling fins 23a (see FIGS. 4 to 8). 
Each cylinder 30 of the intermediate portion 23 (see FIG. 2) receives a 
piston 32 in such manner as to define a hydraulic chamber 33. The pistons 
32 are adapted to push a friction lining 34 axially against the internal 
face 35 of the disc 17. 
Each cylinder 31 of the intermediate portion 23 receives a piston 36 in 
such manner as to define a hydraulic chamber 37. The pistons 36 are 
adapted to push a friction lining 38 axially against the internal face 39 
of the disc 18. 
The external portion 24 comprises two blind cylinders 40 arranged side by 
side. Each cylinder 40 receives a piston 41 in such manner as to define a 
hydraulic chamber 42. The pistons 41 are adapted to push a friction lining 
43 axially against the outer face 44 of the disc 18. 
The hydraulic chambers 27 and 33 corresponding to the disc 17 receive an 
independent hydraulic supply through a control circuit 45 while the 
hydraulic chambers 37 and 42 corresponding to the disc 18 receive an 
independant supply through a separate circuit 46, which enables the safety 
in braking to be ensured. In the event of rupture of a circuit preventing 
the gripping of one of the discs, the other circuit permits the clamping 
action on the other disc. 
It will be noted that the cylinders 25 and 30 are placed exactly opposite 
each other while the cylinders 31 and 40 are also placed exactly facing 
each other, which provides perfectly symmetrical conditions of clamping 
for each disc, favorable for braking. 
Between the external portion 22 and the intermediate portion 23 of the 
stirrup 20 is arranged a packing shim 47, while between the portion 23 and 
the portion 24 of the stirrup 20 is similarly arranged a packing shim 48. 
This arrangement enables the brake to be readily adjusted for discs 17 and 
18 of various thicknesses. 
It will be appreciated that the external portions 22 and 24 and the 
intermediate portion 23 of the stirrup 20 are assembled together (see FIG. 
1) in an angular sector slightly less than 180.degree. (upper portion of 
FIG. 1) thus leaving free an opposite sector of more than 180.degree. 
(lower portion of FIG. 1) in which the discs 17 and 18 are perfectly free 
from parts of the brake and control system. 
It will also be observed that in the brake according to the invention, the 
friction linings 28, 34, 38 and 43 are very easy to change. 
In addition, as can be seen from the various FIGS. 1 to 8, the cylinders 30 
of the intermediate portion 23 are circumferentially staggered with 
respect to the cylinders 31 of this same portion 23, and all these 
cylinders 30 and 31 each extend axially (see FIGS. 2, 5 and 6) over a 
depth which is close to the thickness of the intermediate portion 23, 
which enables the brake to have a reduced axial dimension. 
As can be more particularly seen from FIG. 2, the friction linings 34 and 
38 corresponding to the intermediate portion 23 are respectively received 
in housings 34a and 38a of the portion 23. The depth of the housing 34a is 
greater than the thickness of the bottom 31a of the blind cylinder 31, and 
similarly the depth of the housing 38a is greater than the thickness of 
the bottom 30a of the blind cylinder 30. 
This arrangement, which is permitted by the circumferential staggering of 
the cylinders 30 and 31 has the additional advantage of still further 
reducing the overall thickness of the intermediate portion 27 and in 
consequence the axial dimension of the brake. 
The screws 21 enable the stirrup 20 to be fixed on the stator 10 and serve 
at the same time for fixing the various parts 22, 23 and 24 to each other, 
including the packing shims 47 and 48. 
As can more particularly be seen from FIGS. 1 to 4, these screws 21 are 
divided into three groups 21a, 21b and 21c, arranged substantially at the 
corners of a triangle. The end groups 21a and 21c are arranged at the 
extremities of the external portions 22 and 24 of the stirrup, while the 
central group 21b is arranged substantially in a central zone of the 
intermediate portion 23 of the stirrup 20. A particularly robust fixing is 
thereby obtained. 
It will be appreciated that the brake which has just been described with 
reference to FIGS. 1 to 8 is of a particularly simple and convenient 
construction with a small overall size, both circumferential and axial. It 
has excellent cooling by virtue of the fins 23a of the portion 23, and 
also due to the fact that the lower portion of the brake comprises solely 
the discs 17 and 18, exposed to the ventilation air. Furthermore, the 
stirrup 20 and the hydraulic control circuits 45 and 46 are protected from 
mud and bad weather, since they are located only in the upper half of the 
brake. In addition, the fact that the circuits 45 and 46, respectively 
associated with the two discs 17 and 18 are independent, provides 
excellent safety in braking. 
The external portions 22 and 24 of the brake of FIGS. 1 to 8 may be 
utilized in their actual state so as to constitute a single-disc brake 
(see FIGS. 9 and 10). 
The cylinders 25 of the portion 22 are arranged exactly opposite the 
cylinders 40 of the portion 24. There will again be seen at 28 and 43 the 
friction linings associated with these cylinders, but in this case these 
linings are adapted to clamp the single disc of the brake, having here the 
reference number 50. 
The possibility of utilizing the portions 22 and 24 of the double-disc 
brake of FIGS. 1 to 8 so as to constitute the single-disc brake of FIGS. 9 
and 10 has an advantage of standardization, especially in the application 
to heavy lorry automobile vehicles, in which double-disc brakes may be 
used on the rear axle, while single-disc brakes can be utilized on the 
front axle. 
The invention which has been described with reference to FIGS. 1 to 8 in 
its application to a double-disc brake may also be applied to all 
multi-disc brakes, and for example to a three-disc brake such as shown in 
FIG. 11. 
In this FIG. 11, the same reference numbers have been employed as in FIGS. 
1 to 8 for indicating similar parts, followed however by an apostrophe. 
In FIG. 11 there are again seen at 22' and 24' the external portions of the 
stirrup 20', but two intermediate portions 23'.sub.1 and 23'.sub.2 are 
provided in this case instead of a single portion 23. 
The portions 22' and 23'.sub.1 co-operate with a first disc 17', while the 
portions 23'.sub.2 and 24' co-operate with the second disc 18'. As regards 
the two intermediate portions 23'.sub.1 and 23'.sub.2, these co-operate 
with the third disc having the reference 51. 
The arrangement and the operation of the three-disc brake of FIG. 11 are 
furthermore similar to those which have been described with reference to 
the double-disc brake of FIGS. 1 to 8. It will be observed that the 
circumferential dimension of this three-disc brake is not increased as 
compared with a corresponding double-disc brake.