Leaf spring for holding down the brake-lining carrier of a disc brake

Leaf spring (18) for holding down the brake-lining carrier (25, 26), of a disc brake wherein the brake-lining carrier (25, 26) has a friction-lining free section (39) onto which is fixed a central holding section (27) of the leaf spring. The leaf spring has two uneven shanks (32, 33) which are each transversely angled from the central neck section (27) towards the brake-lining carrier. The shank (33) faces in a preferred direction of travel (D) towards the entrance side of the brake disc (2) and is bent away (35, 36, 37) from the brake-lining carrier radially outward (37) and abuts with its end (38) against the edge (22, 24) of an opening (17) of the caliper unit, which opening (17) accommodates friction-lining-free-section (39) of the brake-lining carrier (25, 26).

BACKGROUND OF THE INVENTION 
The invention relates to a leaf spring for holding down the brake-lining 
carriers of a disc brake wherein the brake-lining carrier has a 
friction-lining free section extending radially towards the outside onto 
which is fixed a holding section of the leaf spring, whereby the leaf 
spring has two shanks which are transversely angled from the holding 
section towards the brake-lining carrier and supported on two support 
surfaces, arranged at the bottom on both sides of an opening of a caliper 
unit, which opening accommodates the friction-lining free section of the 
brake-lining carrier. 
In a leaf spring of this type, as described in German patent reference 
DE-OS 25 58 294, both shanks are identical in construction. When mounted, 
the leaf spring, supported against the caliper unit, exerts a centrally 
directed force on the brake-lining carrier. This means that the brake 
linings are only radially pretensioned against the respective guide 
surfaces which can be arranged either in the brake carrier or in the 
caliper unit. Disc brakes also have lateral guide surfaces against which 
the brake linings can support themselves during actuation of the brakes in 
dependence on the rotational direction of the brake disc. Thus, the 
occurring brake moment is transferred to and absorbed by a support member 
of the brake carrier. 
In order to guarantee easy running of the brake linings in the guide 
section, both during the braking and the return after the brake release, a 
certain play is provided between the lateral surfaces of the brake-lining 
carrier and the lateral guide surfaces in the support member of the brake 
carrier, which play also serves to compensate manufacturing tolerances. 
However, this present play results in the brake-lining carrier, which is 
only radially pretensioned by the leaf spring, being dragged along during 
braking from its inoperative position in the direction of rotation of the 
brake disc due to the adhesive friction developing between the brake 
lining and the brake disc, and after having overcome the present play, 
abruptly abutting against the lateral guide surfaces of the brake carrier. 
This causes a most undesirable knocking sound in the brake, which is 
particularly disturbing during frequent braking in town traffic, or 
frequent braking at short intervals. Furthermore, such abrupt loading can 
cause damage to the brake-lining carrier and the support member of the 
brake carrier, thus no longer guaranteeing easy running of the brakelining 
carrier in the guide section. 
A further disadvantage of the known leaf spring, which holds down the 
brake-lining carrier only in the radial direction, appears with a mounting 
position of the disc brake wherein the caliper unit is not above the brake 
disc but, as seen in the direction of travel, behind the vehicle axis. In 
this mounting position of the disc brake, the brake carriers will always 
be inclined, due to their own weight as well as vehicle vibrations, to 
abut against the lower lateral guide surface, so that not only the 
aforedescribed effect during braking is unavoidable, but additionally the 
knocking sounds when the brake is released. 
Further springs for holding down of brake-lining carriers are described in 
German patent references DE-OS 2 558 141, DE-OS 3 323 362, DE-OS 3 621 507 
and in European patent reference EP 0 248 385 A1. These already known 
holding-down springs exert only a pretensional force on the brake-lining 
carrier towards the center point of the brake disc. 
BRIEF SUMMARY OF THE INVENTION 
It is an object of the invention to create a leaf spring of the type 
referred to above and a suitable linkage between the latter and the 
brake-lining carrier, thus making it possible to force the brake-lining 
carriers of a disc brake radially and simultaneously in a preferred 
braking direction in the rotational direction of the brake disc against 
the guide surface of the supporting member of the brake carrier without 
effecting the easy running of the brake linings in the respective guide 
section. The invention thereby ensures that the holding-down spring cannot 
release itself from the brake-lining carrier, either in its mounting 
position or during necessary mounting or removal work. Furthermore, the 
respective parts are economical to produce and insertable on both sides of 
the brake disc and allow easy exchange of brake linings or the 
holding-down spring. 
This object is achieved by the invention which includes a leaf spring for 
holding down the brake-lining carriers on opposite sides of a disc of a 
caliper disc brake, each brake-lining carrier having a friction-lining 
thereon and a friction-lining free section extending radially outwardly, 
two support surfaces arranged on radially inner surfaces on both sides of 
and defining an opening of a caliper unit, the friction-lining free 
section of the brake lining carrier being accommodated in the opening, a 
holding section, first and second uneven shanks extending substantially 
oppositely to each other and transversely at an angle from the holding 
section towards the brake-lining carrier, the first shank extending in a 
direction towards the entrance side of the disc brake relative to the 
direction of travel of the disc and having a portion bent away from the 
brake-lining carrier radially outwardly and an end portion engaging 
against a portion of one of the two support surfaces, and the second shank 
having a portion thereon engaging against at least a portion of the other 
of the two support surfaces.

DETAILED DESCRIPTION 
Although the invention as explained below is based on a sliding-caliper 
disc brake, it is accepted that the basic idea of the invention can be 
realized in an equally advantageous way with a fixed-caliper disc brake. 
As is particularly clear from FIGS. 1 to 3, the sliding-caliper disc brake 
consists of a brake carrier 1 including two lateral sections 3, 4 
extending over the brake disc 2, which sections serve as bolt seats of a 
caliper unit 5 (fist-type caliper) which also extends over the brake disc 
2. The caliper unit 5 includes a brake-operating device 6 through which a 
brake lining 7 can be brought into direct contact with brake disc 2, an 
area 8 extending over brake disc 2 and adjacent thereto radially inwardly 
extending area 9 which, upon actuation of the brake, indirectly causes the 
brake lining 10, opposite the brake-operating device 6, to abut against 
the brake disc 2. 
The two brake linings 7, 10 including their respective brake-lining 
carriers 25, 26 are held and guided in guide sections 11, 12 of the brake 
carrier 1 in radial inner guide surfaces 13, 13', 14, 14' and in the 
peripheral direction on lateral guide surfaces 15, 15', 16, 16'. 
The area 8 of caliper unit 5, which area extends over the brake disc 2, has 
an opening 17 which serves for visual inspection of the brake linings, the 
heat exchange of the brake and the accommodation of a holding-down spring 
18 in the form of a leaf spring. As is particularly clearly shown in FIG. 
4, the opening 17 of the caliper unit 5 forms a left and a right ledge 19, 
20. The cross-section of each ledge 19,20 proceeds transversely towards 
the inside over the periphery of the brake disc 2 in the direction of the 
sections 3 and 4 of the brake carrier 1 so that each one left and one 
right abutment surface 21, 22 for the holding-down spring 18 is formed at 
the caliper unit 5. Thereby, the transversely terminating abutment 
surfaces 21, 22 have a radius 23, 24 towards the top side of the caliper 
unit 5 to form an outer concave portion. 
The two brake-lining carriers 25, 26 and the holding-down spring 18, 
arranged on each of the carriers, are equal in construction, and the 
breadth of the holding-down spring corresponds with the thickness of the 
brake-lining carrier. 
As shown in FIG.S 4, 7 and 8, the holding-down spring 18, punched from 
steel sheet, has in its central section, serving as a holding section 27, 
two angled tongues 28, 29 with complementary openings 30, 31 extending 
radially downwards. The two tongues 28, 29 are positioned at an angle to 
each other, allowing safe fixing due to pretensioning of the tongues onto 
the brake-lining carriers 25, 26. 
From the holding section 27 of the holding-down spring 18, two shanks 32, 
33 extend on both sides in the tangential direction to the periphery of 
the brake disc 2, whereby the shank 32 is bent at its end 34 
semicircularly and radially inward. However, the other shank 33 has in the 
area 35 a radially outwardly extending bend radius 36 to form an outer 
concave portion, whereby a section 37 extending approximately parallel 
with the shank 33 is formed, which section 37 is at its end 38 angled 
approximately radially towards the outside with respect to the axis of the 
brake disc 2 to form an outer concave portion. 
The brake-lining carriers 25, 26 each has in its center a radially 
outwardly extending lining-free section 39 which includes a first shoulder 
40 in the form of a release. In this shoulder 40, another release in the 
form of a second shoulder 41 is centrally placed so that a step-like shape 
is formed in the section 39. The two shoulders 40, 41 can be manufactured 
when punching the brake-lining carriers 25, 26 so that a two-stage recess 
is created on its side positioned away from the brake lining, which recess 
is complementary to the first and second steps 40 and 41. 
The lining-free section 39 of each brake-lining carrier 25, 26 terminates 
on its side facing towards the shank 32 of the holding-down spring 18 at 
an incline 42 towards its periphery. The side of the lining-free section 
39 facing towards the other shank 33 of the holding-down spring 18 is 
arranged to be an abutment surface and includes an area 43 which is in 
parallel with the shank 33 to proceed into a concave curved area 44 which 
corresponds with the bend radius or convexity 36 of the shank or section 
35, and which then terminates in an incline against the outer periphery of 
the brake-lining carriers 25, 26. 
The mounting and removal of the holding-down spring 18 onto and from the 
brake-lining carriers 25, 26 and of the brake can be effected in an 
extremely simple manner. 
To mount the holding-down spring 18, it is applied onto the lining-free 
section 39 of the brake-lining carrier 25, 26 while slightly pressing the 
two tongues 28, 29 apart, and pushed over the second shoulder 41 so that 
the second shoulder 41 engages in the opening 30 of the tongue 29. The 
inside surface of tongue 29 will then abut against the outside surface of 
the first shoulder 40, whereas the other tongue 28 lies on the lining-free 
side of the brake-lining carrier 25, 26 in the recess which is 
complementary to the first shoulder 40 and abuts against the outside 
surface of the respective brake-lining carrier. The abutting arrangement 
is, as will be explained later, of great significance. Furthermore, the 
locally fixed holder arrangement between the holding-down spring 18 and 
the brake-lining carriers 25, 26 ensures that the holding-down spring 
cannot release itself from its mounting position or during necessary 
mounting or removal work. 
However, as regards the holding-down spring 18 coordinated with the 
opposite brake-lining carrier 26 the second shoulder 41 engages the 
opening 31 of the tongue 28. 
Thereafter, the two brake-lining carriers 25, 26 including the thereupon 
mounted holding-down spring 18 are inserted into the guide sections 11, 12 
of the brake carrier 1, whereby the shoulders 40, 41 of the brake-lining 
carrier 25, 26 are necessary so that, during mounting and removal, or 
during a required exchange of the holding-down spring or the brake lining, 
the caliper unit 5 can be swivelled in or out of the brake carrier around 
the rotational point of a bolt seat without the piston of the 
brake-operating device 6 making contact with the holding device. This 
consideration also applies to the inside surface of the area 9 of the 
caliper unit 5, which surface is facing towards the brake disc 2. 
When the caliper unit 5 is mounted on the brake carrier 1 via the sections 
3, 4, then the shank 32 of the holding-down spring 18 abuts with its shank 
end 34 against the left abutment surface 21 of the caliper unit 5, while 
the other shank 33 abuts with its bent area 35 against the complementarily 
formed areas 43, 44 of the lining-free sections 39 of the brake-lining 
carrier 25, 26, and with its concave curved shank end 38 against the 
radius or convex portion 24 of the right abutment surface 22. 
When such a disc brake is mounted, the shanks 32 of the two holding-down 
springs 18 always point in a preferred braking direction towards the exit 
side of the brake disc. 
The holding-down spring 18 operates as follows: 
Taking into consideration the preferred braking direction D (see FIG. 4) 
and the thus resulting mounting position of the holding-down spring 18 on 
each brake-lining carrier 25, 26, the shank 32 abuts with its end 34 
radially against the abutment surface 21 of the caliper unit 5. The 
outwardly bent section 37 and end 38 of the other shank 33 abut against 
the abutment surface 22 and the radius 24 both radially and tangentially. 
This pretensioning of the holding-down spring 18 results in the 
brake-lining carriers 25, 26 being forced both radially against the guide 
surfaces 13, 13', 14, 14' and in the braking direction tangentially 
against the lateral guide surfaces 15, 16 of the brake carrier 1. 
This results in the advantage that no knocking sounds occur in the 
inoperative state, and that due to the surface abutment the earlier 
mentioned knocking sounds do not develop during the braking either. 
If the brake is actuated in opposition to the preferred braking direction, 
then the brake-lining carrier 25, 26 is displaced against the 
pretensioning force of the sections 33 and 37 of the holding-down spring 
18 against the lateral guide surfaces 15', 16'. With release of the brake, 
the sections 33, 37 of the holding-down spring 18 push each brake-lining 
carrier 25, 26 back into its basic position.