KENYA STANDARD      DKS 463:2020  
ICS 43.040  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Telescopic shock absorbers for 
automobile suspension damping — 
Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
        
© KEBS 2020  Third  Edition 2020 
     
  DKS 463: 2020  
ii         © KEBS 2020 — All rights reserved   
 
TECHNICAL COMMITTEE REPRESENTATION  
 
The followi ng 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 Association (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  
 
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for improvements to published standards, addressed to the Mana ging Director, Kenya Bureau of Standards, 
are welcome.  
 
 
 
 
 
 
 
© Kenya Bureau of Standards, 2020  
 
 
 
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subsists in all Kenya Standa rds and except as provided under Section 26 of this Act, no Kenya Standard produced by Kenya Bureau of 
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from the Managing D irector . 
 
 
 
 
 
 
 
  
© KEBS 2020 — All rights reserved            iii 
   
 
 
 
 
 
 
 
 
KENYA STANDARD                 DKS 463: 
2020  
                ICS 43.040  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Telescopic shock absorbers for automobile 
suspension damping — Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   DKS 463: 2020  
iv         © KEBS 2020 — All rights reserved  KENYA BUREAU OF STANDARDS (KEBS)  
 
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© KEBS 2020 — All rights reserved            v 
  Foreword  
 
This Kenya Standard was prepared by the Road Vehicles Technical Committee under the supervision of the 
Transport, Packaging and Distribution Industry Standards Committee, and it is in accordance with the 
procedures of the Bureau.  
 
It is intended to assist local manufacturers to meet the minimum performance requirements expected of 
shock absorbers, and also to ensure that customers get reasonable service for their investments in motor 
vehicle spare parts.  
 
This Third Edition, which has been technically revised, cancels and replaces the First Edition, KS 463: 2005 . 
 
In developing this standard, the following documents were used:  
 
JASO C 602 -75: Telescopic shock absorbers.  
 
IS 5423 -1989:   Requirements for telescopic type hydraulic shoc k absorbers for automotive suspension 
(Second Revision).  
 
Acknowledgement is hereby made for the assistance derived from these sources. 
© KEBS 2020 — All rights reserved             1
             
             KENYA STANDARD                            DKS 463: 2020  
 
 
Telescopic shock absorbers for automobile suspension damping — 
Specification  
 
1 Scope  
 
This Kenya Standard specifies the general performance requirements for telescopic shock absorbers used in 
automobile suspension damping, not including struts and semi -struts.  
 
2 Definitions  
 
For the purposes of this standard, the following definitions shall apply:  
 
2.1  
sealed type shock absorbers   
those which are not permitted to be overhauled, as the shock absorber has to be cut or machined to take out 
the internal parts  
 
2.2   
serviceable type shock absorbers   
those which  can be ope ned by removing the top threaded cap  
 
2.3 
double acting    
shock absorbers which damp the oscillations of a vehicle suspension in both the directions, damping action 
being different or equal in either direction depending on the individual application requir ements  
 
2.4  
single acting   
shock absorbers which damp the oscillations of a vehicle suspension in one direction  
 
2.5  
compression stage  
a stage in which the mountings of shock absorbers approach each  other  
 
2.6   
extension stage   
a stage in which the moun tings of shock absorbers move away from each other  
 
2.7  
compressed length   
the length between the mountings eyes (centre to centre distance) or centre of the plain portion of shank (in 
case of studs) or mounting eye and plain portion of shank (in case of eye and stud) of a shock absorber 
when it is compressed to the maximum (see Figure 1) (and shall be within a tolerance of 3 mm or subject to 
the original drawing of the vehicle manufacturer, whichever is less)  
 
2.8  
stroke  
the difference between the exten ded length and the compressed length (effective maximum travel of the 
piston), see Figure 1  
 
 
 DKS 463: 2020  
 
2                                                                                            © KEBS 2020 — All rights reserved  2.9  
port  
the inside diameter of the cylinder of the shock absorber  
 
2.10   
fitment dimensions   
are required  for mounting the shock absorber on the vehicle (accordi ng to the vehicle manufacturer's 
specification similar to A, B, C, D, in Figure 1)  
 
 
Figure 1 — Fitment dimensions.  
2.11   
damping characteristics   
for any type of hydraulic shock, absorber, shall mean the damping forces at corresponding maximum piston 
velocity defined in 2.12  
 
 
 
                  DKS 463: 
2020  
© KEBS 2020 — All rights reserved           3 2.12  
maximum piston velocity   
subsequently referred to as “velocity”, shall be according to the vehicle manufacturer's specification or bear 
the relationship given by the expression:  
 
V max. = π.n.s.  
 
 where,  
 
 V max. = maximum piston velocity, metres/sec;  
       n = machine revolution, Cps; and  
       s = stroke, metres.  
 
 NOTE   n and s are derived from the endurance test of 4.2.  
 
3 General requirements  
 
3.1 Materials   
 
Telescopic shock abso rbers may be made from any suitable materials provided that the finished product 
shall pass the tests specified in Clause 4.  
 
3.2 Finish  
 
The piston shaft shall be uniformly hard chrome plated and be free from paint and other defects that may 
impair its as sembly of performance. The exterior surface of the shock absorber shall be protected against 
corrosion.  
 
3.3 Assembly   
 
The shock absorbers shall be assembled in such a manner that the movement shall be smooth throughout 
the stroke. For this purpose, the s hock absorbers shall be manually primed five times in a vertical position. 
This is only indicative of the uniformity of operation.  
 
3.4 End mountings   
 
Typical end mountings are shown in Figure 2.  
 
 
 
 DKS 463: 2020  
 
4                                                                                            © KEBS 2020 — All rights reserved   
 
 
 
Figure 2 — Typical mountings.  
 
 
 
3.4.1  When eye or  stud mounting is used the maximum permissible deflection along the joint axis allowed 
during use shall be  = 5° maximum, or according to the manufacturer's specification.  
 
3.4.2  For the garden angle which is perpendicular to the joint axis the deflection  shall be  = 3° maximum, 
or according to the vehicle manufacturer's specification, whichever is the less.  
 
3.5 Fitment  
 
The fitment of the shock absorber shall be governed by the top and bottom mountings of the vehicle or bars.  
 
3.6 Inclination   
 
Telesco pic shock absorbers shall not be mounted at an inclination angle of more than 45° to the vertical 
plane of the chassis, unless otherwise specified by the vehicle manufacturer.  
 
3.7 Supplementary welding   
  
All eyes shall be supplementary welded to the caps  to a maximum length of 10 mm.  
 
4 Tests  
 
4.1 Damping force  
 
 
 
 
                 DKS 463: 
2020  
© KEBS 2020 — All rights reserved           5  
4.1.1  Each shock absorber shall be tested along its own axis, that is, the damper axis parallel to the stroke 
of the torque tester.  
 
4.1.2  Damping forces shall be recorded between the sixth an d tenth stroke.  
 
4.1.3  Test specification shall be only at one maximum piston velocity (or according to the vehicle 
manufacturer's specification).  
 
4.1.4  Tolerances on test damping force shall be ± 10 %.  
 
4.1.5  The arm of the application of damping force s hall be selected at the discretion of the shock absorber 
manufacturer, provided that the specifications of the vehicle manufacturer shall be satisfied. In the case of 
preloaded shock absorbers, preloading shall be taken into account when performing this te st. 
 
4.1.6  The effect of temperature as given in Clause 5 shall be applicable wherever necessary.  
 
4.2 Endurance test  
 
4.2.1  The test shock absorber selected shall be mounted on the torque tester and the initial damping 
resistances in tension and compress ion shall be recorded.  
 
4.2.2  Shock absorbers whose initial damping resistances have been measured shall be mounted on the 
endurance testing machine.  
 
Testing speed shall be 104 ± 9 Cpm or according to the vehicle manufacturer's specification, whichever is  
the less.  
 
4.2.3  During the test, temperature shall not exceed 85 °C, which shall be measured on the outer tube 
(reservoir) of shock absorbers. Where the temperature exceeds 85 °C, external cooling shall be applied to 
maintain the temperature at 80 ± 5 °C . 
 
In the case of shock absorbers where temperature does not rise above 85 °C, the test shall be carried at the 
temperature attained.  
 
4.2.4    The method of cooling during the endurance test is optional, but shall be such that any leakage of 
shock absorber fluid  can be easily seen during the endurance test.  
 
4.2.5  Shock absorbers shall be mounted on a torque tester with flexible end mountings, only in the vertical 
plane.  
 
4.2.6  The test shall be conducted for one million cycles, but where vehicle manufacturer's s pecifications 
exist, they shall prevail. At the end of the test, no leakage or damage shall be noticeable; and the shock 
absorber when subjected to the damping force test as indicated in 4.1, variation in resistance shall not 
exceed the values indicated in  Tables 1 and 2 (see also Figures 3 and 4) from the initial damping resistance 
recorded as in 4.2.1.  
 
Table 1 — Decrease in damping resistance after one million -cycle endurance test  
 
Damping resistance, 
newtons (N)  500 600 700 800 900 1 000  1 100  1 200  1 300 1 400  
Decrease 
in 
resistance  Tension  75 80 85 90 100 105 110 120 130 140 
Compression  100 110 120 130 145 165 185 190 195 210 
 
NOTE    For damping resistances 1 200 N and above a decrease of 10 % is allowable in tension and compression, respectively.  
 
 DKS 463: 2020  
 
6                                                                                            © KEBS 2020 — All rights reserved  
 
 
Initial damping resistance, newtons (N)  
 
 
Figure 3 — Decrease in damping resistance after one million cycle endurance test.  
 KS 463: 2020  
 © KEBS 2020 — All rights reserved                                                                                                                                                                                                        7
                    
                                          
 
Figure 4 — Increase in damping resistance after one million cycle endurance test.  DKS 463: 2020  
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4.3 Weld pull test   
 
Telescopic shock absorbers, when subjected to weld pull tests, shall withstand the following forces:  
 
–  small shock absorbers (up to 40 mm O.D.) 2.7 kN;  
 
–  medium -duty shock absorbers (over 40 mm up to 50 mm O.D.) 3.6 kN;  
 
–  heavy -duty shock absorb ers (over 50 mm up to 65 mm O.D.) 4.5 kN;  
 
–  extra heavy -duty shock absorbers (over 65 mm O.D.) 5.4 kN;  
 
5  Effect of temperature on damping characteristics  
 
No temperature correction shall be applied if the test room tempera ture is within the range of 1 5 °C to 35 °C.  
 
6 Marking  
 
The shock absorbers shall be  legibly and  indelibly marked with the following:  
 
i)  manufacturer's name and/or trade mark;  
 
ii)  country of origin;  
 
iii) month and year of manufacture;  
 
iv) Part number (on body).  
 
7 Packaging  
 
Shock absorbers shall be packed in suitable cartons marked with the part number, or polythene packaging to 
allow the part number to be read on the product.  
 
8 Additional information  
 
The following information shall be supplied upon request:  
 
8.1 Dimensions a s indicated in Figure 1.  
 
8.2 A graph showing the load characteristics, in newtons, for compression and extension at various 
piston velocities; or alternatively load values for compression and extension at specified maximum piston 
velocity.  
 
8.3 Any other  information relevant to the design of shock absorbers.