 
  
 ICS 65.060.10  
 
 
Reference number
DRS 450: 2019
© RSB 2019
  
 RWANDA 
STANDARD  DRS
450
1st edition
2019 -8-dd
 
Agricultural trailer — Specification  
 
   
DRS 450: 2020 
©RSB  2019 - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB2019  
All rights reserved. Unless  otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without  
prior written permission from R SB. 
Requests for permission to reproduce thi s document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw  DRS 450: 2019  
iii                ©RSB2019 - All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ...................... iv 
1 Scope  ................................ ................................ ................................ ................................ ................ 1 
2 Normative references  ................................ ................................ ................................ ....................... 1 
3 Terms and definitions  ................................ ................................ ................................ ...................... 2 
4 Types  ................................ ................................ ................................ ................................ ................ 5 
5 MATERIALS  ................................ ................................ ................................ ................................ ......6 
6 Capacity  ................................ ................................ ................................ ................................ ............ 7 
7 Dimensions  ................................ ................................ ................................ ................................ .......7 
8 Constructional Requireme nts ................................ ................................ ................................ .......... 8 
9 Lighting requirements  ................................ ................................ ................................ ...................... 9 
10 Other requirements  ................................ ................................ ................................ ........................  10 
11 Workmanship a nd finish  ................................ ................................ ................................ ................  11 
12 Marking  ................................ ................................ ................................ ................................ ...........  11 
Annex  A (normative)  material properties of mild steel to be used  ................................ ..........................  12 
Annex  B (normative)  Requirement of axle assembly  ................................ ................................ ...............  13 
Annex  C (informative)  cold brake performance test  ................................ ................................ ................  16 
Annex  D (normative)  Requirement of T -sign ................................ ................................ ............................  20 
 DRS 450: 2020 
©RSB  2019 - All rights reserved                  iv 
 Foreword  
Rwanda Standard sareprepared by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratifie d by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 450was prepared by Technical Committee RSB/TC 023, Road Vehicle . 
In the preparation of this standard, reference was made to the following standard:  
1) IS8213:2000A griculturaltractortrailer —Specification  
2) PNS/PAES 136 Agricultural Machinery — Agricultural Trailer —Specifications  
The assistance de rived from the above source is hereby acknowledged with thanks.  
Committee membership  
The following organizations were repres ented on the Technical Committee on Road Vehicle (RSB/TC 023) in 
the preparation of this standard.  
RP IPRC Kigali  
RP IPRC Ngoma  
Volks Wagen Rwanda  
University of Rwanda/ College of science and technology  
Mota Engil  
Ministry of Infrastructure (MININFRA)  
METROPOLE garage  
RWANTECH Boiler engineering  
Rwanda Garage Association  
Car Tech Solution Ltd  DRS 450: 2019  
v                ©RSB2019 - All rights reserved  
 Rwanda  Standards Board (RSB) – Secretariat  
 
 DRS 450: 2020  
1                ©RSB2019 - All rights reserved  
 Agricultural tractor trailer — Specification  
1 Scope  
This Draft S tandard specifies the construction and other requirements for agricultural trailer fitted with 
pneumatic tires and towed by an agricultural tractor at the traveling speed not exceeding 30 Kph.  
It is applicable to balanced trailers with up to 10 metric tons capacity andsemi -trailers  with upto5tonnescapacity  
2 Normative references  
The following document s are referred to in the text in such a way that some or all of  their content constitutes 
requirements of this document.  For dated references, only the editioncited applies. For undated references, 
the latest edition of the referenced document (including a ny amendments) applies.  
ISO 185Grey cast irons — Classification  
ISO 4251 -1 Code designated diagonal tyres (ply rating marked series) for agricultural tractors, trailers and 
machines — Part 1: Tyre designation and dimensions, and approved rim contours  
ISO 4 251-2 Code designated diagonal tyres (ply rating marked series) for agricultural tractors, trailers and 
machines — Part 2: Tyre load ratings  
ISO 18804:2017 Rims for agricultural, forestry and construction machines  
ISO 18137 Leaf springs — Technical specific ations  
ISO 4082:1981(en) Road vehicles  — Motor vehicles  — Flasher units  
ISO 5670 Agricultural trailers — Single -acting telescopic tipping cylinders — 25 MPa (250 bar) series — Types 
1, 2 and 3 — Interchangeability dimensions  
ISO 5692 -1 Agricultural vehicles  — Mechanical connections on towed vehicles — Part 1: Dimensions for hitch 
rings of 50/30 mm cross section  
ISO 5692 -2 Agricultural vehicles — Mechanical connections on towed vehicles — Part 2: Coupling ring 40 
with socket  
 
 
  
©RSB  2019 - All rights reserved                  2 
 3 Terms and definitions  
For the purposes of this standard, the follow ing terms and definitions apply  
3.1 
agricultural trailer  
Trailer  designed to carry load for agricultural purposes without power of its own  
3.2 
balanced trailer  
Agricultural trailer whose total load is supported by at leas t two axles with four or more wheels when detached 
from the towing tractor (see Figure  1) 
3.3 
semi -trailer  
Agricultural trailer with one axle and two wheels which, wh ile in use, part of its load is transferr ed to the towing 
tractor  and the rest of the load is carr ied on its axle (see Figure 2)  
3.4 
axle load  
total static load supported by the wheels on the respective axle  
3.5 
gross load  
gross weight sum of payload and unladen mas s of the trailer expressed in m etric tons  
3.6 
ground cl earance  
vertical distance between the ground and the lowest point of the trailer  
NOTE   In measuring ground clearance, the trailer shall be loaded to its payload and the tiresshal l be inflated at the 
recommende d pressure.  
 DRS 450: 2020  
3                ©RSB2019 - All rights reserved  
 3.7 
over-run brake  
brake actuated by a com pressive force in the hitch between a trailer and the towing tractor  used to decelerate 
a moving trailer  
3.8 
parking brake  
brake actuated by a pedal or lever to keep the trailer in stationary or parked position  
3.9 
payload  
net weight unifor mly distributed maximum safe load whic h can be transported by the trailer expressed intons  
3.10 
service brake  
brake actuated by a pedal or lever to decelerate and stop a moving trailer  
3.11 
tow eye  
hitch point of the trailer's pullbar to be attached to the towing tractor  
3.12 
unladen mass  
tare weightmass of a trailer with all its usual fittings but without any load  
3.11 
wheel base  
horizontal distance between forem ost and rearmost axles or w heels measured at the center of the ground 
contact  
  
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 3.13 
wheel tread  
distanc e between the outermost wheels at the Salne axle measured at the center of groundcontact  
3.14 
Reflex Reflectors  
Anassemblyreadyforuseandcomprisingoneormorereflectingopticalunits.Reflectorsshallbevisibleatnightfro malldi
stanceswithin31mto183mwhendirectlyinfr ontoflawfullowerbeamsofheadlamps.  
3.15 
Lamp Location  
Dimensionsinthisstandard,unlessspecifiedotherwise,arebasedonmeasurementstothelampfilament.  
3.16 
Head Light  
Illuminatinglightofavehicleintendedtoilluminatetheroadahead.  
3.17 
Stop Light  
Abrakeoperatedlight ingdevicewhichemitsredoramberlightattherearofthevehicleintendedtogivewarningoftheslow
ingdownorthestoppingofthevehicle.  
3.18 
Direction Indicator  
Alightingdevicetoshowinwhichdirection,thedriverintendstoturnbygivingaflashinglightonthesideofthevehi cletowar
dswhichtheturnwillbemade.  
3.19 
Tail Light  
Lightingdevicewhichemitsredlightindicatingthepresenceofthevehiclewhenseenfromtherearandintendedtosho wt
hewidth DRS 450: 2020  
5                ©RSB2019 - All rights reserved  3.10 
ReversingLight  
Deviceusedtoprovideawarningsignaltopedestriansandotherdrivers,whenthevehicleisreversingorisabouttorev ers
e.Thelightshallbewhiteincolour  
 
4 Types  
4.1Theagriculturaltrailersshallbeof the following  twotypes:  
a)Balancedtrailer(doubleaxle)(seeFig. 1) 
 
Semi -trailer(singleaxle)(seeFig.2).  
 
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4.2 Boththetypesoftrailers shalleither befittedwithfixedortippingplatform  
5 MATERIALS  
5.1Thematerialforimportantcomponentsandthatforaxleassemblyshallbeasgivenin  Column 3ofTable1  
Table1 — MaterialRequirementforComponentsofTrailer  
 
S/N Component  Material  Properties  
1. Drawbar  Mild steel  Annex A  
2. Tow eye or tow jaw  Carbon steel  (ISO 3755 Grade 
230-450) 
3. Platform  Mild steel  Annex A  
4. Side boards  Mild steel  Annex A  
5. Axle Structural steel Annex A  
6. Hub Cast iron  (ISO 185/JL/200)  
7. drum Brake  Cast iron  (ISO 185/JL/200)  
8. Cap Cast iron  (ISO 185/JL/200)  
9. Washer  Mild steel  Annex A  
 
 
DRS 450: 2020  
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 6 Capacity  
6.1 The gross load along with the pay load shall be declared by the manufacturer.  
6.2 The declared capacity shall not vary by ±5 % 
7 Dimensions  
7.1Thedimensionsgivenunder7.2to7.8shallnotinanywayinfringetherulesandregulationsof thelocaltransportautho
rity. 
7.2Theoverallwidthofthetrailer(seeAinFig.1andFig.2)measuredbetweentheextremepoints  shallno texceed2.5m.  
7.3Theoveralllengthoftheplatform(seeBinFig.1andFig.2)shallnotexceedthefollowing;  
a) 5mfortrailersupto5tonnescapacity,and  
b) 6.7mfortrailersabove5tonnescapacity.  
7.4 The height of the trailer, with tyres inflated at the recommended pressure, when mea sured from the level 
supporting surface to the top of the platform (see C in Fig.1 and Fig.2) shall be not more than 1.5 m. 
7.5 The height of the trailer, with tyres inflated at the recommended pressure, when measured from t he level 
supporting surface to the top of the sideboard (see D in Fig. 1 and Fig. 2) shall be not more than 3.5 m.  
7.6 In case of the balanced trailer, the  distance from the edge of the platform to the centre of front wheel (see 
E in Fig.1) and from rear edge of the platform to the centre of rear wheel (see F in Fig. 1) shall b e not more 
than 0.8 m.  (more research)  
7.7 In case of semi -trailer, the load trans fer from the trailer to the tow eye of the trailer shall not be more than 
20 %of the trailer capacity. Assuming that the trailer is loaded uniformly to the entire length of  platform and the 
centre of gravity lies in the lateral vertical plane at half the l engthof platform from rear edge, the value of G 
(see Fig. 2) can be derived from the following formula:  
 
G=୛×୆
ଶ− Rt(H+B)
(W−Rt) 
 
Where  
W = gross load of the trailer and  
  
©RSB  2019 - All rights reserved                  8 
 R = load transfer on tow eye, percent.  
 
7.7.1 On the basis of 20 %load transfer from th e trailer to the tow eye, the above formula can be written as 
follows:  
G=(3B−2H)
8 
 
7.8 Ground clearance shall not be less than 300 mm  
 
8 ConstructionalRequirements  
8.1 The loading platform maybe plain or provided with hinged or fixed sideboards. If trailer is provided with 
sideboards, some kind of locking provision shall be provi ded to keep it vertical. This  can be met by giving a 
latchingsystematthetopofthe  vertical 
postsfittedtotheplatform.Thehingesbywhichsideboardsarefixedshallbeprovidedwithsplitpinstores trictitslateralmo
tion. 
8.2Thetrailersshallbeprovidedwithlashinghooksfortyingdowntheload.  
8.3Forsingle -
axletrailer,toweyeofthedrawbarorhitchofthetrailer,whenfullyloadedmaybeparalleltothelevelsurfaceafter hitchingw
ithtowingtractor,forbalancedtrailerdrawbarorh itchof 
Thetrailershallbeofhingedtype sothatloadfromtrailerisnottransferredtothetowingtractor.Inthetowinghitch,shockab
sorbingdeviceshallbeprovided.Thehitchheightoftrailershouldalwaysbebelowrearaxleheightofthetractor  
8.4 Tow eye ofthetrailershall  be capable ofrotating  at 360° angle totake  on even rigid trailer hookof  the towing  
tractor. Ringtype  hitches sh allconform  to ISO 5692 -1 orISO 5692 -2  
8.5 For bal anced  trailers, the front axleshallhave  the capability toswivelto  a maximum of120°  (60° oneither  
side) abo ut theverticalaxis.  
8.6 The trailershall  be fitted withpneumatic  tyres andrimsco nforming toISO 4251 Parts 1 to 3  
8.7 The axle(s) shallconform  to requirements  specified inAnnex B. 
8.8 The trailer shall beprovided  with suspension for recommended loadcarryingcapacity  as per ISO 18137 . 
8.9 Trailers shall have  service (overrun) andparking  brake. It shall beensured  that during operation ofservice  
or parking brake,the  brakes atboth  the wheels of trailerare activated simultaneously.  (MORE Research)  DRS 450: 2020  
9                ©RSB2019 - All rights reserved  
 8.9.1The service brakesshall  be capable ofadeceleration  of 2.5 m/s2 measured inaccordance  with t estmethod 
described inAnnex Cwith operating brakes  pedal force  not exceeding 600Nand  400 Nin case 
offootoperatedand  hand operated brakesrespective ly. 
8.9.2  The parking brakeshall  hold full yladen  trailer ona12-%slopeuphill  or downhill.The  maximum forceto  
operate ahandlevershall  not exceed 400N.Theparking  brake shall operateon  the same drum andshoe  or disc 
andpad  as the service brake.  
8.10Hydraulic ram (cylind er)ofsuitable  capacity compatible withtractorhydraulic  shall beprovided  in case 
oftipping  type. Theram  may beused  in single ortandem  as per need andthe  operating pressureshall  not 
exceed 13.8MPa.  
8.11 Tipping angleofthebody,in  case oftipping  type, shall be 42° to50°.  
9 Lightingrequirements  
9.1 The trailer shall be freed with two red colored  reflectors at rear sides and two white colored  reflectors on 
front sides at a distance not more than 150 mm from extreme ends to the center  of reflectors. The reflectors 
shall be round with reflecting area not less than 3000 mm2. Rear reflectors may be incorporated as part of 
lensing in tail lamps described in9.2 . 
9.2 Every trailer shallbe  provided withtwo  tail lights ofred color atthe  rear. Thepoint  on the illuminating 
surfacefarthest  from themedian  longitudinal planeof  trailer shall benot  more than 400mm  from theextreme  
outer edgeof  the vehicle. Thedistance  between theinneredge  of the two illuminating surfaceshall  be not less 
than 600mm.  This distance maybereduced  to 400mm,where  the overallwidth  of the trail eris less than 1300 
mm.The  height oftail  lights abovethe  ground shall benot  less than 350mm  and not morethan  1600 mm. 
9.3 At least twoamber  flashing reversing lamps(warninglamps)  conforming toISO 4082 assymmetrically  
mounted andaswidely  spaced laterallyas  practicable, visiblefrom  both front andrear,  mounted atleast  1000 
mmheightbut  not more than 1500 mm.Lamps  shall flash inunison  at arate  of 60 to 120 flashes perminute.  
9.4 Every trailershall  be fittedwith  two turn indicators (Direction indicators) lamp sonthe  rear side. 
Thedirectional indicatorshall  be of amber color andshall  flash inunison  at arate  of 60 to 120 flashes 
perminute.The  light emitted bylamps  when inoperationshallbe  clearly visible fromboth  front andrearof  the 
vehicle. Thedirection  indicator shallbeso  designed andfitted  that thetractor  operator isaware  that itis operating 
correctly. Illuminated areaofeach  direction indicator shallnot  be less than 2250 mm2. 
9.4.1  The rear amber flashing warninglamps  (see 9.3)may  be used astheturnindicators.  
9.5Two  brake operated stoplight  shall beprovided  at the rear ofthe  trailer whichemit  red light intended 
togivewarning  of the slowing downor  stopping ofthevehicle .The stop lights may be provided asapart  of tail 
lamps (see9.2).  
9.6One SMV (Slow Moving Vehicle) identification emblem as shown in Fig. 9 consisting of a fluorescent 
orange equilateral triangle with a red retro -reflector border positioned with a point of triangle up shall be 
provided on the rea r side of the vehicle. The red retro -reflector border defines the shape of the fluorescent 
colour in daylight and appears as a hollow red triangle with path of motor vehicle headlight in the night. The 
emblem shall be mounted in a plane perpendicular to th e direction of travel and shall be visible from the rear 
of SMV. It shall be located 0.6 m to 1.8 m above the ground   
©RSB  2019 - All rights reserved                  10  
 
NOTE  Emblem must be mounted with the point upward  
Figure 9 — Slow moving vehicle identification emblem  
10 Otherrequirements  
10.1 The semi -trailer shall be provided with  the parking jack in the front for keeping the trailer in a leveled 
position when detached from the towing tractor.  
10.2 All the parts requiring lubrication shall be provided with  greasing nozzles  which 
shallbeeasilyaccess ibleandindicatedwithsymbols  
10.3Aunobstructedlocationshallbemadeavailableonthetrailerchassisforfixingaliftjackforcarryingoutnece ssaryrep
airstothetrailers.  
10.4Incaseoftippingtypetrailer,provisionsshallbemadefortiltingtheplatformwithoutdisturbingthetrailer .10.5Whent
hetrailerisloadeduniformlywith25 %additionalpayloadandoperatedatanaveragespeedof25  km/hto30  
km/hfor3h.Itshallnotshowanysignofbreakageofdeformationinany  part.Thistestshallbeconductedonmetalledroad.  
 
 
 
DRS 450: 2020  
11                ©RSB2019 - All rights reserved  
 11 Workmanshipandfinish  
11.1 The sharpness of the edges and corners shall be removed.  
11.2 Castings and forgings shall be free from blow holes, cracks and other visual defects.  
11.3 Welding shall not be porous.  
11.4 All wooden and metal surfaces shall be covered with a coat of suitable preservative. The metal parts 
should be de -rusted, treated with anti -corrosive material and an appropriate primer painting.  
 
12 Marking  
12.1 The trailer shall be marked with the following information on identification plate which shall be welded or 
riveted to the body:  
a) Manufac turer’s name and registered trade - mark, if any;  
b) Unladen mass;  
c) Gross load; and  
d) T-sign at the rear ( annex D). 
 
 
 
  
©RSB  2019 - All rights reserved                  12 
 Annex  A 
(normative)  
 
material properties of mild steelto be used  
 
 
Grade  
Designation  TensileStrength  
Rm,  
Min MPa 1)(See 
Note 1)  Yield Stress  
ReH, MinMPa 1 Percentage  
ElongationA, Min 
at Gauge  
Length,L o=5.65  Internal bend 
diameter (Min)  Charpy -V notch Impact 
energy (Min J)  
<20 20-40 >40 ≤ 25 >25 Room 
temperature  -20 
E 410   540 410 390 380 20 2t  3t 25 25 
 
 DRS 450: 2020  
13                ©RSB2019 - All rights reserved  
 Annex  B 
(normative)  
 
Requirement of axle assembly  
NOMENCLATURE  
FortheaxleassemblythenomenclaturegiveninFig.3shallappl y 
A-2CLASSIFICATION  
A-2.1 For the purpose of this standard, the axle assembly shall be of the following two classes:  
Class A — The axle assembly of load carrying capacity up to 3 t onnes.  
Class B — The axle assembly of load carrying capacity up to 5 tonnes.  
 
A-3 DIMENSIONAL REQUIREMENTS  
A-3.1 The dimensions of various components of the axle assembly shall be as given in Co1 3 and 4 of Ta ble 
2. The applicable standards for the components are given in Co1 5 of Table 2 for guidance.  
A-3.2 The axle assembly shall have wheel track of 1500 mm or 1700 mm.  
A-4 OTHER REQUIREMENTS  
A-4.1 the dust cover shall be fitted with the help of three round head screws and spring washers.  
A-4.2 Oil seals or grease retainers shall be provided to make the axle assembly leak and dust proof.  
 
 
  
©RSB  2019 - All rights reserved                  14  
 
S/N Component  Dimension  
Class A  Class B  
1. Axle shaft size, mm 63 square or 80 
round  75 square or 80  
round  
2. Outer bearing, bore size diameter, mm  45 45 
3. Inner bearing, bore size diameter, mm  
 55 55 
4. Castle nut, nominal size  M42 x1.5  M42 x1.5  
5. Split pin for nut, nominaldiameter, mm  8 8 
6. Washer for nut, nominal size,mm  
 43/45  43/45  
7. Roundheadscrew:  
  
Nominal size  
 
 M6×1  
 
 M6×1  
 
 
Length, mm  
 
 12 12 
Number  3 
 3 
 
 
8. Wheelstud:  
 
  
Nominal size  
 M16×1.5  
 
 M16×1.5  
 
 
DRS 450: 2020  
15                ©RSB2019 - All rights reserved  
 Pitch circle diameter, 
mm  
 
 165 
 185 
 
Number  5 
 6 
9. Hub flange:  
  
Thickness, mm  
 
  
20  
25 
Diameter, mm  
 210 
 230 
 
10. Brake drum:  
  
Diameter, mm  
 
  
254  
254 
Nominal width, mm  50 50 
 
 
A-4.3 The hub shall be fully packed with multi -purpose grease between the bearings.  
A-5 DESIGNATION  
A-5.1 An axle assembly shall be designated by its class and wheel track.  
A-5.1.1 Example1  
An axle assembly of Class A having wheel track of 1500 mm shall be designated as: Axle A 150 0 
A-5.1.2 Example2  
An axle assembly of Class B having wheel of 1700 mm shall be designated as:Axle B 1700  
WORKMANSHIP AND FINISH  
A-6.1 The castings shall be free from blowholes, pits, burrs And other visual defects.  
A-6.2 The sharp edges shall be removed.  
A-6.3 A protective coating shall be provided  
 
  
©RSB  2019 - All rights reserved                  16 
 Annex  C 
(informative)  
 
cold brake performance test  
B-1 GENERAL  
B-1.1 During all the tests of service brake the trailed vehicle shall be coupled to a towing vehicle w ith which it 
is recommended for use by the manufacturer.  
B-2 TEST CONDITION  
B-2.1 The test surface shall not exceed one percent longitudinal slope and 3 %side slope.  
B-2.2 The trailer should be loaded to the maximum specified gross capacity.  
B-2.3 In case of a multiple -axle trailer having any unbraked axles, the unbraked axles shall be loaded to its 
maximum axle load. For trailed vehicles having more than one axle and brakes on all wheels, the fron t axle 
shall be loaded to its maximum axle load.  
B-2.4 The test track shall have a dry, clean, concrete, bituminous or an equivalent surface having good 
adhesion,  
B-2.5 The test shall be performed when the wind velocity is below 10 m/s  
B-2.6 The braked axle(s) shall be equipped with the largest diameter tyres specified by the vehi cle 
manufacturer. The tyres shall be inflated to pressure(s) specified by the vehicle manufacturer.  
B-2.7 At the start of each test, the brakes shall be cold. A brake is deemed to be cold if one of the following 
condition is met:  
The temperature measured over the disc or on the outside of the drum is below 100”C;  
In the case of totally enclosed brakes, including oil immersed brakes, the temperature  
Measured on the outside of the housing is below 50°C, or within manufacturer’s specifications;  
The brakes have not been actuated for one hour  
 
 
 DRS 450: 2020  
17                ©RSB2019 - All rights reserved  
 B-3 PROCEDURE  
B-3.1 Prior to the start of the test, the brakes shall have been fully bedded -in (burnished) and adjusted in 
accordance with the manufacturer’s instructions. Thereafter, the brakes shall not be further m anually adjusted 
during the complete test.  
B-3.2 With the towing vehicle and trailed vehicle traveling at the maximum design speed of the trailed  vehicle 
but not exceeding 30 km/h, measure deceleration for a series of different forces applied to the cont rol of the 
braking device. Calculate the corresponding values of mean deceleration from the following formula  
 
ܽ=ݒଶ
2ݏ 
Where  
a= average deceleration in m/s;  
v = initial speed in m/s; and  
s = stopping distance in m  
B-3.3 If the trailed vehicle service braki ng device control is independent of the towing vehicle braking device 
control, apply the trailed vehicle brakes only. When the brakes of trailed vehicle is operated, the engine in the 
towing vehicle shall be disengaged by the clutch so that the force to st op entire system shall come from 
brakes of trailed vehicle.  
B-3.4 If the braking device transmission is not mechanical, measure an appropriate transmission parame ter, 
such as fluid pressure, during each stop in such a way that the measurement does not interfere with the 
dynamic characteristics of the braking system.  
B-3.5 Repeat the procedure for a series of different forces applied to the control of the braking devi ce up to 
maximum force which can be applied without locking of the wheels, or up to a ma ximum input  
Force of 600 N for foot -operated controls or 400 N for hand -operated controls if the braked wheels are not 
locked.  
B-3.6 For each value of force applied to the braking device control, calculate the trailed vehicle bra king force 
from whichever o f the following formula is appropriate:  
B-3.6.1 If the trailed vehicle brakes only are applied,usethefollowingformula  
 
 
  
©RSB  2019 - All rights reserved                  18 F2 = (m1 + m2) a3  
F2 = the trailed vehicle braking force in N;  
M1= the towing vehicle mass in kg;  
M2 = the trailed vehicle mass in kg;  an 
a3 = the mean deceleration of the towing and trailed vehicle combination in m/s2  
B-3.6.2 If the towing and trailed vehicle brakes are applied, use the following formula:  
F1 = (m1 + m2)a3 –m1a1  
where  
a, = mean deceleration measured with the towing vehic le alone at the same value of force applied to the 
towing vehicle brakingdevice control which produced deceleration aj of the vehicle combination in m/ s. 
B-3.7 For each value of braking force Fz, calculate the equivalent mean deceleration (az) of the trail ed vehicle 
from the following formula:  
 
ܽ=ܨଶ
݉ଶ݉/ݏଶ 
B-3.8 for each value of the equivalent mean deceleration a 2, calculate the equivalent stopping distance S 2of 
the trailed vehicle from the following formula:  
where  
 
S2 = equivalent stopping distance of the trailed vehicle in m; and  
V2 = measured initial velocity of the trailed vehicle in m/s.  
B-3.9 Repeat the test with the trailed vehicle unladen.  
B-4 REPORT  
B-4.1 Report for both the laden and the unladen trailed vehicle, the relationship between input forces , stopping 
distance mean deceleration either in the form of a graph or table values.  
DRS 450: 2020  
19                ©RSB2019 - All rights reserved  
 B-4.1.1 If the braking device transmission is not mechanical, report the relationship between stopping  
distance, mean deceleration and an appropriate transmission parameter, such as fluid pressure, in th e form of 
a graph or table of corresponding values.  
B-5 TOLERANCE  
The following measuring tolerance shall be adhered to when conducting the test:  
Measurement Tolerance, % 
Travel speed ±3  
Vehicle mass ±3  
Deceleration ± 3  
Stopping distance ±1  
Brake control input force ± 5  
Tyre inflation pressure ±5  
Brake system fluid (gas) ± 5  
 
 
  
©RSB  2019 - All rights reserved                  20 Annex  D 
(normative)  
 
Requirement of T -sign 
2. DIMENSIONS  
 
2.1 The T -sign plate shall be at least 175 mm wide and 200 mm high.  
 
2.2 The dimensions of the ‘T’ mark shall be as shown in Fig. 1. These are the minimum dimensions.  
 
3. COLOURS  
 
3.1 The plate shall be painted in black.  
 
3.2 The letter ‘T’ shall he painted in white.  
 
 
 
The T -sign shall be painted with a luminous paint so as to make it visible at night.  
 
DRS 450: 2020  
 
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