GB2114690A - Improvements relating to vehicle disc brakes - Google Patents
Improvements relating to vehicle disc brakes Download PDFInfo
- Publication number
- GB2114690A GB2114690A GB08200598A GB8200598A GB2114690A GB 2114690 A GB2114690 A GB 2114690A GB 08200598 A GB08200598 A GB 08200598A GB 8200598 A GB8200598 A GB 8200598A GB 2114690 A GB2114690 A GB 2114690A
- Authority
- GB
- United Kingdom
- Prior art keywords
- friction pad
- piston
- pistons
- pad assembly
- actuated friction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/14—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position
- F16D65/16—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake
- F16D65/18—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake adapted for drawing members together, e.g. for disc brakes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D55/00—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes
- F16D55/02—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes with axially-movable discs or pads pressed against axially-located rotating members
- F16D55/22—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes with axially-movable discs or pads pressed against axially-located rotating members by clamping an axially-located rotating disc between movable braking members, e.g. movable brake discs or brake pads
- F16D55/224—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes with axially-movable discs or pads pressed against axially-located rotating members by clamping an axially-located rotating disc between movable braking members, e.g. movable brake discs or brake pads with a common actuating member for the braking members
- F16D55/225—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes with axially-movable discs or pads pressed against axially-located rotating members by clamping an axially-located rotating disc between movable braking members, e.g. movable brake discs or brake pads with a common actuating member for the braking members the braking members being brake pads
- F16D55/226—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes with axially-movable discs or pads pressed against axially-located rotating members by clamping an axially-located rotating disc between movable braking members, e.g. movable brake discs or brake pads with a common actuating member for the braking members the braking members being brake pads in which the common actuating member is moved axially, e.g. floating caliper disc brakes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D55/00—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes
- F16D2055/0075—Constructional features of axially engaged brakes
- F16D2055/0091—Plural actuators arranged side by side on the same side of the rotor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2121/00—Type of actuator operation force
- F16D2121/02—Fluid pressure
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Braking Arrangements (AREA)
Abstract
The brake has at least two pistons 15, 17 on the same side of the brake disc 23, piston 15 abutting a directly actuated friction pad assembly 19 and piston 17 acting on an indirectly actuated friction pad assembly 21 through a caliper member 3 which is slidably mounted on a torque taking member 1. The drag on pad assembly 19 is taken directly on the torque taking member 1 and the drag on the pad assembly 21 is taken through the caliper member to the torque taking member via the sliding connection therebetween, but to counter caliper member rotation caused by drag on pad assembly 21 the pistons 15, 17 are arranged and/or have a valve system to produce a moment which counters any out of balance moments produced by the drag on the pad assembly 21 during a brake application. In Figure 1 the pistons 15, 17 which may have same or different diameters are axially offset. In other embodiments (e.g. Figure 5) four pistons are arranged in two opposed pairs, one piston 69 having larger effective area than piston 71. The specification includes a mathematical discussion regarding the moments. <IMAGE>
Description
SPECIFICATION
Improvements relating to vehicle disc brakes
The present invention relates to a vehicle disc brake.
In particular, the present invention relates to a reaction type brake e.g. pin slider or open slide configuration, with at least two opposed pistons on the same side of the disc, a first piston abutting a first or directly actuated friction pad assembly and a second piston acting on a second or indirectly actuated friction pad assembly through a clamp member or frame e.g. caliper member. The caliper member is guided slidably relative to a fixed or earth member e.g. torque taking member, the drag on the directly actuated friction pad assembly being taken directly to earth on the torque taking member and the drag on the indirectly actuated pad assembly being taken through the caliper member to the sliding connection and thence to the torque taking member.
Such a construction is disclosed in British
Patent Specification No. 1,567,602, in the form of a pin slider disc brake. However, a problem occurs with any such construction, the problem stemming from the fact that the indirectly operated friction pad is effectively keyed to the caliper member, causing the drag forces occurring between the friction pad lining and the disc during a brake application, to produce a couple or moment which tends to rotate the caliper member in a chordal plane, such that taper wear of the indirectly actuated friction pad assembly results.
The disadvantage of taper wear is that it may result in residual drag of the friction pad assembly on the disc when the brakes are in a released condition. Residual drag causes excessively high disc temperatures which in turn accelerates the wear of the friction pads requiring premature pad replacement.
Considering the above problem, the degree to which the caliper member will rotate and thus the degree of taper wear, is dependent upon various factors:
1. The line of action and reaction when the braking forces are applied.
2. The coefficient of friction between the friction pad and the disc (itself variable and dependent upon environmental conditions for instance).
3. The position of the Centre of area and the centre of pressure on the friction pad.
4. The distance between the lines of action and reaction and the effective pivot point of the caliper member about the torque taking member.
5. The clearances existing between the parts of the sliding connection between the caliper member and the torque taking member; and
6. The amount of deflection etc. encountered during a brake application.
To counter the above problem it is known to provide an arrangement whereby the directly and indirectly actuated friction pad assemblies are offset from each other-see for example U.S.
Patent Specification No. 3,422,935. The centre of pressure of each friction pad assembly is positioned in predetermined relation to the line of action and reaction between the pistons and the caliper member, such that when the brake is applied, there is established a moment that counters the moment tending to rotate the caliper member in the brake applying mode. This tends to eliminate the taper wear feature. However, it results in uneven loading of the brake disc due to the fact that the centres of pressure and thus the lines of force on opposite sides of the disc are offset, and there must therefore be the disadvantageous tendency for the brake disc to twist or distort.Also, the offset pad arrangement can require the friction pad assemblies or the caliper member, to become "handed", and in such an instance there is the possibility that the friction pad assemblies could be installed incorrectly in the brake, resulting in an acceleration of taper wear.
The aim of the present invention is to provide a reaction type disc brake wherein the problem of taper wear is at least reduced without the above described resultant disadvantages.
According to the present invention there is provided a reaction type disc brake comprising at least two opposed pistons on the same side of the brake disc, a first piston abutting a directly actuated friction pad assembly and a second piston acting on an indirectly actuated friction pad assembly through a caliper member which is slidably mounted on a torque taking member, the drag on the directly actuated friction pad assembly being taken directly on the torque taking member and the drag on the indirectly actuated friction pad assembly being taken through the caliper member to the torque taking member via the sliding connection therebetween the pistons being constructed and arranged to produce a moment which counters any out of balance moments produced by the drag on the indirectly actuated friction pad assembly during a brake application.
To produce the required counterbalancing moment in the present invention there are two possible basic constructions. One construction can utilise offset first and second pistons, and the other construction can utilise two or more pistons which act upon the indirectly actuated friction pad assembly, these pistons being of selected size to produce the desired counterbalancing moment.
As an alternative to varying the piston sizes, different hydraulic pressures may be applied to the two or more pistons.
By virtue of the present invention a moment results on brake application, that opposes the out of balance moment which normally offsets the centre of pressure of the indirectly actuated friction pad assembly when the indirect and directly actuated friction pad assemblies are mounted symmetrically in relation to each other on opposite sides of the brake disc. The forces set up by the offset pistons, the different diameter pistons acting on the indirectly actuated friction pad assembly, or the different pressures acting upon the indirectly actuated friction pad assembly at spaced apart locations, effectively move the centre of pressure of the indirectly actuated friction pad assembly, back towards the centre of the pad, thus distributing the load more evenly over the pad area and eliminating taper wear.
In an embodiment of the present invention having offset first and second pistons of the same area, the following formula optimumly applies for the required design:- 12=l18+l3 where: y is the coefficient of frictions of the indirectly
actuated friction pad acting on the disc.
It is the distance of the indirectly actuated
friction pad drag from the pivot point.
12 is the distance between the central axis of
the said second piston and a parallel line
passing through the pivot point.
13 is the distance between the central axis of
the said first piston and a parallel line
passing through the pivot point.
In another embodiment of the present invention having two pairs of opposed pistons, the two pistons acting on the directly actuated friction pad assembly having like diameters, and the two pistons acting on the indirectly actuated friction pad assembly having different diameters (areas A2 and A3) from each other, the following formula optimumly applies for the required design:
where:
,u is the coefficient of friction of the indirectly
actuated friction pad acting on the disc.
Ia is the distance of the indirectly actuated
friction pad drag from the pivot point.
12 is the distance between the central axis of
one of the pistons acting on the indirectly
operated friction pad assembly, and a
parallel line passing through the pivot point.
13 is the distance between the central axis of
the other of the pistons acting on the
indirectly actuated friction pad assembly,
and a parallel line passing through the pivot
point.
A2 is the area of said one piston acting on the
indirectly actuated friction pad assembly.
A3 is the area of said another piston acting on
the indirectly actuated friction pad assembly.
The present invention thus provides a reaction type disc brake with the following advantages: 1. As the friction pad assemblies are symmetrically arranged with respect to each other, there is no required "handing".
2. Evenly distributed load results from the present invention. Thus there is a tendency towards zero taper wear.
3. There is less of a tendency towards residual drag.
4. When four pistons are used the use of different diameter pistons acting on the indirectly actuated friction pad assembly, enables the mechanical/parking brake or automatic adjuster, to be accommodated in the larger piston where previously space may have precluded such an arrangement.
5. Because the centres of pressure of the friction pad assemblies are opposite to each other there is no tendency to distort the brake disc.
The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a schematic cross-sectional plan view of one embodiment of the present invention;
Fig. 2 is a schematic cross-sectional plan view of a further embodiment of the present invention;
Fig. 3 is a plan view of an actual brake constructed in accordance with the arrangement of the present invention, shown in Fig. 2;
Fig. 4 is a side view of the brake shown in Fig.
3; and
Fig. 5 is a cross-sectional view taken along line IV--IV in Fig. 4.
The disc brake constructed according to the present invention and schematically illustrated in
Fig. 1 of the accompanying drawings, comprises a fixed or torque taking member 1 and a clamp or caliper member 3. The caliper member 3 has a pin 5 which axially slidably engages in a bore 7 in the torque taking member 1 to provide the sliding connection therebetween.
Within the torque taking member 1 is a cylindrical bore 9 which has two axially offset portions 11 and 13, each portion being of like diameter. A piston 15, 17 engages in each bore portion 11, 13, and piston 1 5 directly engages a directly actuated friction pad assembly 19, whilst the other piston 1 7 engages the indirectly actuated friction pad assembly 21 via the caliper member 3.
When the brake is applied, hydraulic pressure fluid is forced into cylindrical bore 9 between pistons 1 5 and 17, causing friction pad assembly 19 to be applied to one side of disc 23 and friction pad assembly 21 to be applied to the other side of the disc 23. Friction between indirectly actuated friction pad assembly 21 and the surface of disc 23, causes pad drag (,uPA) which acts about point 'C' to try to rotate the caliper member 3. Such rotation can cause taper wear of the friction pad assemblies due to the centres of pressure of the two friction pad assemblies 19, 21 moving out of alignment, as is evident in prior art constructions. However, due to the central axes of pistons 1 5 and 1 7 being offset from each other a counterbalancing moment is produced which counters the caliper rotation and prevents taper wear.
Considering Fig. 1 of the accompanying drawings, the effective pivot point is at 'C' and to achieve the required result with nil taper wear, clockwise moments must equal anti-clockwise moments.
Therefore:- l1yPA+pAl3=pAl2 Thus: l2=l1+l3 (i) where: flz is the coefficient of friction of friction pad 21;
P is the pressure applied to the pistons;
A is the effective area of each piston;
I, is the distance between the friction drag on
pad 21, and point 'C'; 12 is the distance between the central axis of
piston 1 7 and a parallel line passing through
the pivot point 'C';
13 is the distance between the central axis of
piston 15 and a parallel line passing through
the pivot point 'C'.
By constructing the brake of Fig. 1 according to the above formula (i), a suitable counterbalancing moment will always be produced to counter any tendency for the caliper member 3 to rotate about 'C', irrespective of the brake pressure applied.
The disc brake constructed according to the present invention and schematically illustrated in
Fig. 2 of the accompanying drawings, comprises a torque taking member 25 i.e. fixed member, and a caliper member 27 i.e. clamp member. The caliper member 27 has a pin 29 which axially slidably engages in a bore 31 in the torque taking member 25 to provide the sliding connection therebetween.
Within the torque taking member 25 are two stepped bores 33 and 35, equispaced for ease of manufacture, about the line 26 passing through the centres of pressure of the friction pad assemblies 28, 30, two pistons being located in each bore. Pistons 37 and 39 (areas A,) axially slidably engage in like diameter ends 41 and 43 of bores 33 and 35 respectively, and are of like diameter. However, pistons 45 and 47 which engage in the other different diameter ends 49, 51 of bores 33 and 35 respectively, are of different diameter, pistons 47 being nearer to the effective pivot point 'C' between the caliper and the torque taking member, and having the smaller area A3.
When the brake of Fig. 2 is applied, the same hydraulic pressure is applied in each bore 33, 35 between pistons 37 and 45, and 39 and 47. Thus friction pad assembly 28 is applied squarely on the disc 53 by virtue of the equal area (A,) pistons 37 and 39. However, by virtue of the different diameter pistons 45 and 47 (areas A2 and A3) acting on indirectly actuated friction pad assembly 30, a moment is applied to the caliper member 27 when the brake is operated, this moment countering any opposed moment produced by the friction pad drag between friction pad assembly 30 and disc 53. By designing the brake so that these moments are equal and opposite, the caliper member 27 will not rotate about 'C' and no taper wear of the friction pad assemblies occurs.
To achieve counterbalanced moments let us consider Fig. 2 of-the accompanying drawings, with moments calculated about effect pivot point 'C'. For nil taper wear, clockwise moments must equal anti-clockwise moments.
Thus:
where: C4 is the coefficient of friction between the
indirectly actuated friction pad and the disc;
P is the pressure applied to the pistons;
A, is the effective area of each of the pistons
acting on the directly actuated friction pad
assembly;
A2 is the effective area of the larger piston
acting on the caliper member;
A3 is the effective area of the smaller piston
acting on the caliper member;
I, is the distance of the indirectly actuated
friction pad drag force from the pivot point 'C' 12 is the distance between the central axis of
the larger piston (A2) and a parallel line
passing through the pivot point 'C';
13 is the distance between the central axis of
the smaller piston (A3) and a parallel line
passing through the pivot point 'C'.
By constructing the brake of Fig. 2 according to the above equation (ii), a suitable counterbalancing moment will always be produced to counter any tendency of the caliper member 27 to rotate about point 'C', irrespective of the brake pressure applied.
Figs. 3, 4 and 5 of the accompanying drawings illustrate an actual brake constructed in accordance with the embodiment of the present invention schematically illustrated in Fig. 2. This brake comprises a caliper member 55 and torque taking member 57, caliper member 55 having a frame 59 which acts in the indirectly actuated friction pad assembly 61, pistons 63 and 65 in the torque taking member (see Fig. 5) acting directly on the directly actuated friction pad assembly 67. As seen in Fig. 5, four pistons in two opposed pairs 63 and 69, and 65 and 71 , act between directly actuated friction pad assembly 67 and caliper member 55. Pistons 63 and 65 are of the same size and effective area, piston 65 being axially slidable in bore 73 provided in torque taking member 57.However, piston 63 is axially slidable in a bore 75 provided in one end of piston 69, piston 69 being itself axially slidable in bore 77 provided in torque taking member 57, bores 73 and 77 being equi-spaced on either side of a line passing through the centres of pressure of the aligned friction pad assemblies 61 and 67.
Piston 65 is also slidable, with clearance, within a recess 79 in one end of piston 71 and hydraulic pressure is, during a brake application, applied in recess 79, annular area 81 in piston 71 increasing the effective area of piston 61. Hydraulic pressure is also applied, during a brake application, in bore 75 between pistons 63 and 69, annular shoulder 83 on piston 69 reducing the effective area of bore 75. Thus, whilst pistons 63 and 65 press against the directly actuated friction pad assembly 67 with equal force, the different effective areas of piston 69 and 71 cause a moment to be applied to the caliper member 55 such as to counterbalance, assuming smaller effective area piston 71 is the leading piston, the moment produced by the drag force between
indirectly actuated friction pad assembly 61 and the disc.Provided the brake is constructed according to equation (ii) given hereabove the pistons 69 and 71 will produce a moment which will exactly counterbalance the friction pad drag force, preventing any taper wear.
Considering the embodiments of Fig. 2 and
Figs. 3 to 5, instead of different area pistons, like pistons can be used, each piston acting on the caliper member being housed in its own individual cylinder in the torque taking member, and different pressures being applied to these pistons via, for example, a suitable valve system, to produce the required counterbalancing moment.
Such a split system design can also be applied to different area piston embodiments such as shown in Figs. 2 and 3.
The present invention thus provides a reaction type disc brake wherein the friction pad assemblies can be symmetrically arranged with their respective centres of pressure in alignment with each other, without taper wear to the friction pads occurring. Thus evenly distributed load results there is less tendency to distort the brake disc, and there is less of a tendency towards residual drag than in prior art arrangements. Also, with a four piston arrangement as in Figs. 2 and 5, the use of the larger pistons enables mechanical/parking brake/or automatic adjusters to be accommodated therewith in, where previously space may have precluded such an arrangement.
Claims (Filed on 7 Jan 83)
1. A reaction type disc brake comprising at least two opposed pistons on the same side of the brake disc, a first piston abutting a directly actuated friction pad assembly and a second piston acting on an indirectly actuated friction pad assembly through a caliper member which is slidably mounted on a torque taking member, the drag on the directly actuated friction pad assembly being taken directly on the torque taking member and the drag on the indirectly actuated friction pad assembly being taken through the caliper member to the torque taking member via the sliding connection therebetween, the pistons being constructed and arranged to produce a moment which counters any out of balance moments produced by the drag on the indirectly actuated friction pad assembly during a brake application.
2. A disc brake as claimed in claim 1, in which said first and second pistons are offset with respect to each other.
3. A disc brake as claimed in claim 2, in which said. first piston is coaxially arranged with respect to the central axis of the caliper and friction pad assemblies.
4. A disc brake as claimed in claim 2 or 3, in which said pistons are of like diameter.
5. A disc brake as claimed in claim 2 or 3, in which said pistons have different diameters.
6. A disc brake as claimed in claim 4 when dependent upon claim 3, in which the brake is designed according to the following formula: 12=l18+l3 where: is isthe coefficient of friction of the indirectly
actuated friction pad assembly acting on the
disc; I, is the distance of the indirectly actuated
friction pad drag from the pivot point; 12 is the distance between the central axis of
said second piston and a parallel line passing
through the pivot point; and 13 is the distance between the central axis of
the said first piston and a parallel line
passing through the pivot point.
7. A disc brake as claimed in claim 1, in which two pistons act on the directly actuated friction pad assembly and two further pistons act on the indirectly actuated friction pad assembly.
8. A disc brake as claimed in claim 7, in which the two pistons acting on the directly actuated friction pad assembly have like diameter, and the two pistons acting on the indirectly actuated friction pad assembly, have different diameters.
9. A disc brake as claimed in claim 7 or 8, in which the pistons are arranged in two opposed pairs, the pistons on each pair being coaxially arranged with respect to each other.
10. A disc brake as claimed in claim 9, in which the central axes of the respective pairs of opposed pistons are equidistantly spaced from the central
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (14)
1. A reaction type disc brake comprising at least two opposed pistons on the same side of the brake disc, a first piston abutting a directly actuated friction pad assembly and a second piston acting on an indirectly actuated friction pad assembly through a caliper member which is slidably mounted on a torque taking member, the drag on the directly actuated friction pad assembly being taken directly on the torque taking member and the drag on the indirectly actuated friction pad assembly being taken through the caliper member to the torque taking member via the sliding connection therebetween, the pistons being constructed and arranged to produce a moment which counters any out of balance moments produced by the drag on the indirectly actuated friction pad assembly during a brake application.
2. A disc brake as claimed in claim 1, in which said first and second pistons are offset with respect to each other.
3. A disc brake as claimed in claim 2, in which said. first piston is coaxially arranged with respect to the central axis of the caliper and friction pad assemblies.
4. A disc brake as claimed in claim 2 or 3, in which said pistons are of like diameter.
5. A disc brake as claimed in claim 2 or 3, in which said pistons have different diameters.
6. A disc brake as claimed in claim 4 when dependent upon claim 3, in which the brake is designed according to the following formula: 12=l18+l3 where: is isthe coefficient of friction of the indirectly
actuated friction pad assembly acting on the
disc; I, is the distance of the indirectly actuated
friction pad drag from the pivot point; 12 is the distance between the central axis of
said second piston and a parallel line passing
through the pivot point; and 13 is the distance between the central axis of
the said first piston and a parallel line
passing through the pivot point.
7. A disc brake as claimed in claim 1, in which two pistons act on the directly actuated friction pad assembly and two further pistons act on the indirectly actuated friction pad assembly.
8. A disc brake as claimed in claim 7, in which the two pistons acting on the directly actuated friction pad assembly have like diameter, and the two pistons acting on the indirectly actuated friction pad assembly, have different diameters.
9. A disc brake as claimed in claim 7 or 8, in which the pistons are arranged in two opposed pairs, the pistons on each pair being coaxially arranged with respect to each other.
10. A disc brake as claimed in claim 9, in which the central axes of the respective pairs of opposed pistons are equidistantly spaced from the central
axis of the caliper and friction pad assemblies, on opposite sides thereof and parallel thereto.
11. A disc brake as claimed in claim 9 when dependent upon claim 8, in which the smaller of the two pistons acting on the indirectly actuated friction pad assembly, is closest to a pivot point about which the brake will tend to turn when operated.
12. A disc brake as claimed in claim 10 or 11, in which one pair of opposed pistons comprises a piston which acts upon the indirectly actuated friction pad assembly, which piston is hollow and open at one end, which piston is axially slidably located in a bore in the torque taking member, and a piston which is axially slidably locatable within said hollow piston and which projects therefrom to engage the directly actuated friction pad assembly.
13. A disc brake as claimed in claim 12, in which said hollow piston has an annular shoulder which faces away from the directly actuated friction pad assembly.
14. A disc brake as claimed in claim 12, in which said hollow piston has an annular shoulder or rim which faces the directly actuated friction pad assembly.
1 5. A disc brake as claimed in claim 11,
in which the brake is designed according to the following formula
where: FL is the coefficient of friction of the indirectly
actuated friction pad assembly on the disc; Ia is the distance of the indirectly actuated
friction pad drag from the pivot point; 12 is the distance between the central axis of
one of the pistons acting on the indirectly
actuated friction pad assembly, and a
parallel line passing through the pivot point,
13 is the distance between the central axis of
the other of the pistons acting on the directly
actuated friction pad assembly, and a
parallel line passing through the pivot point;
A2 is the area of said one piston acting on the
indirectly actuated friction pad assembly; ;
and
A3 is the area of the said another piston acting
on the indirectly actuated friction pad
assembly.
1 6. A reaction type disc brake constructed substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08200598A GB2114690A (en) | 1982-01-09 | 1982-01-09 | Improvements relating to vehicle disc brakes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08200598A GB2114690A (en) | 1982-01-09 | 1982-01-09 | Improvements relating to vehicle disc brakes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2114690A true GB2114690A (en) | 1983-08-24 |
Family
ID=10527555
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08200598A Withdrawn GB2114690A (en) | 1982-01-09 | 1982-01-09 | Improvements relating to vehicle disc brakes |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2114690A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109027069A (en) * | 2018-09-10 | 2018-12-18 | 浙江零跑科技有限公司 | A kind of used in new energy vehicles brake drags torque and reduces device |
-
1982
- 1982-01-09 GB GB08200598A patent/GB2114690A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109027069A (en) * | 2018-09-10 | 2018-12-18 | 浙江零跑科技有限公司 | A kind of used in new energy vehicles brake drags torque and reduces device |
| CN109027069B (en) * | 2018-09-10 | 2023-08-08 | 浙江零跑科技股份有限公司 | Brake drag torque reducing device for new energy vehicle |
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