KENYA STANDARD                                    DKS249: 2020  
ICS 43.040.40  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Automobile drum brake linings and disc 
brake pads – Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
No copying of this standard without KEBS permission except as permitt ed by copyright law   
 
 
 
 
 
 
TECHNICAL COMMITTEE REPRESENTATION    
  
The following organizations were represented on the Technical Committee:  
 
Toyota Kenya Ltd  
D.T Dobie  
Mitsumoto  
Isuzu E.A  
Kenya Association of Bus Manufacturers (KABM)  
Kenya Motor Repairers Asso ciation (KEMRA)  
Nissan  
Numerical Machining Complex (NMC)  
Gede Enterprises  
Mobius Motors  
KUMPIA  
Kenya Industrial Research and development Institute (KIRDI)  
Technical University of Kenya (TUK)  
Motorwise Valuers  
Kenya Auto Bazaar Association  
Honda (Nairobi)  
Egerton University  
Olive Technical Services Ltd  
Kenya Jua Kali Association  
MCI Ltd  
Kenya Bureau of Standards — Secretariat  
 
 
 
 
 
 
 
 
 
 
REVISION OF KENYA STANDARDS  
 
In order to keep abreast of progress in industry, Kenya Standards shall be regularly reviewed. Suggestions 
for improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards, 
are welcome.  
 
 
 
 
 
 
 
 
 
© Kenya Bureau of Standards, 2020  
 
 
Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, C ap. 12 of 2001  of the Laws of Kenya, copyright 
subsists in all Kenya Standards and except as provided under Section 26 of this Act, no Kenya Standard produced by Kenya Bure au of 
Standards may be reproduced, stored in a retrieval system in any form or tran smitted by any means  without prior permission in writing 
from the Managing Director . 
 
 
 
 
 
  
  KENYA STANDAR D      DKS 249:2020   
ICS 43.040.40  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Automobile drum brake linings and disc 
brake pads – Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
KENYA BUREAU OF  STANDARDS (KEBS)  
 
Head  Office:  P.O. Box 54974, Nairobi -00200, Tel.: (+254  020) 605490, 602350, Fax: (+254 020)  604031  
E-Mail: info@kebs.org,  Web:http://www.kebs.org   
 
Coast Region     Lake Region          Rift Valley Region  
P.O. Box 99376, Mombasa -8010 0  P.O. Box 2949, Kisumu -40100        P.O. Box 2138, Nakuru -20100  
Tel.: (+254  041) 229563, 230939/40  Tel.: (+254 057) 23549, 22396        Tel.: (+254 051) 210553, 210555  
Fax: (+254  041) 229448    Fax: (+254 057) 21814   
 
 
 
 
 
  DKS 249: 2020                                                                                                                      
©KEBS  
 2 Foreword  
 
This Kenya Standard wa s revised by the Brake  linings and Pads Sub -Committee of the Motor Vehicle 
Components and Accessories Technical Committee under the guidance of the Mechanical Engineering 
Industry Standards Committee and it is in accordance with the procedures of the Burea u. 
 
The revision was necessitated by the need to streamline certain aspects of requirements and tests in the 
standard which were found to be hindering proper implementation of the standard in Kenyan industry.  
 
The test procedures have been modified to incl ude some ISO recommendations.  
 
During the revision of this standard, the following documents were referred to.  
 
ISO 6311 -1980  Road vehicles – Brake linings – Internal shear strength of lining material – Test 
procedure.  
 
ISO 6312 -1981  Road vehicles – Brake  linings – Shear test procedure for disc brake pad and 
drum brake show assemblies.  
 
KS 06 -71: 1980       Method for Rockwell hardness test.  
 
Acknowledgement is hereby made for the assistance derived form the use of these documents.  
 ©KEBS    DKS 249: 2020 
3   
 
KENYA STANDARD  
 
Auto mobile drum brake linings and disc brake pads – Specification  
 
 
 
 
1. SCOPE  
 
This Kenya Standard specifies requirements for moulded automobile drum brake linings and disc 
brake pads.  It also gives tests for brake lining friction materials to determine mech anical 
characteristics.  
 
2. DEFINITIONS  
 
 For the purpose of this standard, the following definitions shall apply:  
 
2.1 rigid lining — Lining which is shaped to fit a specific brake drum diameter.  
 
2.2 flexible lining — Lining which can be shaped to fit brake drum s of different diameters.  
 
3. TYPES AND CLASSES OF LININGS AND PADS  
 
 The types and classes of linings and pads applicable to the automobiles shall be as follows:  
 
3.1 Type 1 shall be rigid linings or pads.  
 
3.2 Type 2 shall be flexible linings.  
 
3.3 Class  A shall be medium friction, with coefficient of friction between 0.25 to 0.35 inclusive.  
 
3.4 Class B shall be high friction, with coefficient of friction greater than 0.35.  
 
4. PERFORMANCE REQUIREMENTS  
 
4.1 Coefficient of friction at 50oC shall be as spe cified in  3.3 and 3.4 when tested in accordance with A1. 
 
4.2 When measured at a temperature of 200oC the lower values of the coefficient of friction shall not 
decrease by more than 25 per cent of the value calculated in 4.1, but also be within the criteri a laid 
down in 3.3 and 3.4. 
 
4.3 The finished linings shall have no deformities on the surfaces or any other defects likely to impair 
their performance.  
 
4.4 Finished linings shall be of uniform composition throughout their thickness, width and length to 
ensure uniform wear during service.  The rate of abrasion, tested in accordance with A3 shall not 
exceed 0.14 mm.  
 
4.5 Flexibility of Type 2 Linings — When the brake lining is wound around the cylinder of the diameter 
specified in Table 1, there shall not o ccur any cracks which would impair the normal performance of 
the lining.  
4.6 When tested in accordance with A2, the recovery after the wet friction test shall not be less than 90 
per cent of the value obtained at 200oC as per 4.2. 
 
4.7 When subjected to bo nding shear strength test in accordance with A4 the shear strength of linings 
and pads shall not be less than 2.8 MPa.  
 
 
 DKS 249: 2020                                                                                                                    
©KEBS  
 4  
         TABLE 1. FLEXIBILITY TEST  
 
THICKNESS OF LINING  
mm DIAMETER OF TEST  
CYLINDER  
mm 
Below 6.5  200 
6.5 to 10.0  250 
Above 10.0  25 times thickness  
 
 
4.8 When subjected to an internal shear strength test in accordance with A5, the internal shear strength 
of friction materials shall not be less than 2.8 MPa.  
 
4.9 When tested in accordance with A6, Rockwell Hardness (scale R) shall be  in the range 40 to 80.  
 
5. TOLERANCE ON SIZE OF LININGS AND PADS  
 
The tolerance on width and thickness of brake linings and pads shall be in accordance with Table 2.  
TABLE 2. TOLERANCES ON SIZE  
 
  TOLERANCE  
mm 
Drum Brake 
Lining  Width  
 + 0 
- 1.5 
Thickn ess + 0 
- 0.3 
Disc Brake 
Pad Thickness  + 0 
- 0.3 
 
6. TESTS  
 
Brake linings and pads shall be subjected to tests in A1 to A6 specified in Appendix A.  
 
7. MARKING  
 
7.1 Lining or Pad Sets — Each lining or pad shall be clearly and indelibly marked  at the rear  of the 
pad/lining  with the following:  
 
 (i) manufacturer’s name and/or trade mark;  
 
 (ii) manufacture’s part number  
                
             (iii) Country of origin  
 
7.2 Packaging — Packages of linings or pads or rolls of linings shall be legibly and inde libly marked 
with the following : 
 
(i) manufacturer’s name  and/ or trade mark;  
 
 (ii) Part number  
 
             (iii)        Country of origin  
 
 
 
 
 
 
 
 ©KEBS                                                                                                                                         DKS 249: 2020 
 5  
 
 
 
 
Annex A  
 
Tests 
 
A1. FRICTION TEST  
 
A1.1  The friction coefficient shall be tested on a test specimen not less than 25 mm x 25 mm in size cut 
from the centre of lining or pad.  The thickness of the specimen shall be between 5 mm and 6 mm.  
 
 The specimen shall be conditioned (bedded) to the surface of the drum at a surface speed of 300 
metres per minute at a pressure of 0.6 to 0.7 MPa and a maximum temperature of 100oC for a 
minimum of 20 minutes to obtain at least 95 per cent contact (for a drum diameter of 300 mm).  
 
A1.2  The sample is held against a revolving drum made of automotive cast iron under a press ure of 0.6 
MPa.  With the drum revolving at a surface speed of 400 metres per minute, continually drag the 
specimen against the drum at a pressure of 0.6 to 0.7 MPa from room temperature to 200oC.  Note 
the coefficient of friction at 50oC and 200oC. 
 
A2. WET FRICTION TEST  
 
 The test piece after the test in A1.2  shall be placed in water for 2 hours and then removed, and the 
normal friction test shall be carried out as in A1.2 . 
 
A3. ABRASION TEST  
 
A3.1  Prepare a specimen as in A1.1 . 
 
A3.2  Measure specimen  
 
A3.3 With the drum rotating at a surface speed of 375 metres per minute continually drag the specimen 
against the drum at a pressure of 0.6 to 0.7 MPa for 2 hours.  
 
 The temperature shall not exceed 130 oC. 
 
A3.4  Measure the Specimen — The decrease in thickn ess shall be as specified in 4.4. 
 
A4. SHEAR STRENGTH (BONDING) TEST  
 
A4.1  The test shall be conducted on a compression, tension or universal testing machine or any other 
 suitable equipment.  
 
A4.1.1  The test machine shall be provided with equipment to reg ister the exact applied load at the moment 
of shear.  
 
A4.1.2  The rate of load application shall be controlled in such a way that the load increases at an average 
rate of 4 500 ± 500 N/s.  
 
A4.2  Fixtures ( see Figures 1 and 2)  
 
A4.2.1  For drum brake linings, the fixture shall be so designed that the stamp contacts the edge of the lining 
for the full length and thickness within 1 ± 0.2 mm of the shoe table or rim.  
 
A4.2.2  Load application on the stamp shall be in a parallel direction to the plane of the shoe ri m.  The shoe 
shall be supported to maintain uniform loading along the length of the lining sample.  
 
A4.2.3  For disc brake pads, the fixture shall be so designed that:  
 DKS 249: 2020                                                                                                                    
©KEBS  
 6 (a)   The location of the plane of the back plate is parallel to the plane of the stamp.  
 
 
 
 
(b) The stamp contacts the edge of the pad within 1 ± 0.2 mm of the back plate and conforms 
adequately to the contours of the pad.  
 
(c) The stamp contacts the full sample length of the pad edge parallel to the disc periphery.  
 
(d) The load bearing edg e of the back plate rests against a rigid support with a thickness equal 
to that of the back plate.  
 
(e) A pressure fixture applies a pressure of 0.5 MPa at right angle to the shear load, in such a 
way as not to influence the shear load measurement.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ©KEBS                                                                                                                                         DKS 249: 2020 
 7  
 
 
 
 
 
 
 
 
FIG. 1 — PRINCIPLES OF TEST FIXTURE – DRUM BRAKE SHOES  
 
 
 
 
 
 
 
 
 
 
 
 
 
DKS 249: 2020                                                                                                                    
©KEBS  
 8  
 
 
 
 
 
 
 
FIG. 2 — PRINCIPLES OF TEST FIXTURE – DISC BRAKE PAD  
 
 
©KEBS                                                                                                                                         DKS 249: 2020 
 9  
 
 
 
 
 
 
A4.3  Test Procedures  
 
A4.3.1  Place the brake shoe or disc pad in th e appropriate shear test fixture.  Ensure that the fixture 
conforms to the requirements of A4.2.1  to A4.2.3 . 
 
A4.3.2  Apply load as specified in A4.1.2  and continue until failure occurs.  The load shall be applied without 
shocks.  Record the load at which f ailure or destruction occurs.  
 
A4.4  Calculation of Shear Strength — The shear strength is calculated from the formula:  
 
 S  =  
AF  N/mm2 (MPa)  
  
where,  
 
 A is the area (mm2) and F the shear force (N).  
 
A5. INTERNAL SHEAR STRENGTH TEST  
 
A5.1  Test specimens shall be chosen so that they will shear in a plane parallel to the plane or surface of 
stress at normal service conditions.  
 
A5.2  Dimensions of test specimens shall be:  
 
 Length   20 ± 0.1 mm  
 
 Width   20 ± 0.1 mm  
 
 Thickness  5 ± 0.1 mm  
 
 Or  10 ± 0.1 mm  
 
A5.3  Apparatus shall consist of tensile or compression test machine which is equipped with a fixture that 
can apply the required load in the prescribed manner (Figure 3).  The machine shall be equipped so 
as to be able to register the lo ad at shear.  
 
A5.4  The rate of application of load shall be controlled within the range 4 500 ± 500 N/s.  
 
A5.5  The fixture (Figure 3) shall consist of 2 blocks which slide with as little friction as possible against 
one another, with a maximum movement of 0.1 mm.  The friction between the block and the guide 
shall be minimal or capable of being recorded so that an allowance can be made in calculating the 
applied load.  The specimen shall fill the grooves completely to prevent tilt under load.  
 
A5.6  It is es sential that the shear force is applied through the centre of fixture and specimen and parallel 
to the guide within 0.1 mm at a length of 100 mm.  
 
A5.7  Test Procedure — Place the specimen in the fixture and apply the continuously increasing load in a 
direc tion parallel to the direction of stress at normal service conditions.  
 
 The load must not be applied in shocks and the rate of increase shall be as specified in A5.4 . 
 
A5.8  Calculations —The internal shear stress is calculated as:  
 DKS 249: 2020                                                                                                                    
©KEBS  
 10  IS = 
AF  N/mm2 (MPa)  
    
where F is the load and A the area of shear.  
 
 
 
 
 
 
FIG. 3 — INTERNAL SHEAR TEST  
 
 
©KEBS                                                                                                                                         DKS 249: 2020 
 11 A6. ROCKWELL HARDNESS  
 
The test shall be done in accordance with KS 06 -71: Part 2.  Method for Rockwell Hardness test, 
using scale R.