DRAFT UGANDA STANDARD  
  DUS 484 
First  Edition  
2019 
 
 
 Reference numb er 
US nnnn -n: yyyy  
© UNBS yyyy   
  
Light vehicle towed trailer  — Specification  
 US 484: 2019  
ii © UNBS yyyy  – All rights reserved  
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible for its corr ect application  
© UNBS 2019   
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, including photocopying and microfilm, without prior written 
permi ssion from UNBS.  
Requests for permission to reproduce this document should be addressed to  
The Executive Director  
Uganda National Bureau of Standards  
P.O. Box 6329  
Kampala  
Uganda  
Tel: +256 41 4 333 2 50/1/2/3  
Fax: +256 41 4 286 123  
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  US nnnn -n:yyyy  
© UNBS 2019  – All rights reserved  iii 
 Table of Contents  
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 TYPES  ................................ ................................ ................................ ................................ .....................  2 
5 MATERIALS YIELD STRENGTH  ................................ ................................ ................................ ...........  2 
6 CAPACITY  ................................ ................................ ................................ ................................ ..............  3 
7 DIMENSIONS  ................................ ................................ ................................ ................................ ..........  3 
8 CONSTRUCTIONAL REQUIREMENTS  ................................ ................................ ................................ . 3 
9 LIGHTING REQUIREMENTS  ................................ ................................ ................................ .................  4 
10 OTHER REQUIREMENTS  ................................ ................................ ................................ ......................  4 
11 WORKMANSHIP AND FINISH  ................................ ................................ ................................ ...............  5 
12 MARKING  ................................ ................................ ................................ ................................ ...............  5 
A-1 NOMENCLATURE  ................................ ................................ ................................ ................................ ........  6 
A-2 CLASSIFICATION  ................................ ................................ ................................ ................................ .........  6 
A-3 DIMENSIONAL REQUIREMENTS  ................................ ................................ ................................ .........  6 
A-4 DESIGNATION  ................................ ................................ ................................ ................................ ........  7 
A-5 LIGHTING REQUIREMENTS  ................................ ................................ ................................ .................  8 
B-1 GENERAL  ................................ ................................ ................................ ................................ ...............  9 
B-2 TEST CONDITIONS  ................................ ................................ ................................ ................................  9 
B-3 PROCEDURE  ................................ ................................ ................................ ................................ ..........  9 
B-4 REPORT  ................................ ................................ ................................ ................................ ................  11 
B-5 TOLERANCE  ................................ ................................ ................................ ................................ ........  11 
 US 484: 2019  
iv © UNBS yyyy  – All rights reserved  
 Foreword  
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Trade , Industry and 
Cooperatives establish ed under Cap 327 , of the Laws of Uganda , as amended .  UNBS is mandated to co -
ordinate the elaboration of standards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission o n Food Standards, and  
(c) the National Enquiry Point on TBT  Agreement  of the World Trade Organisation (WTO).  
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in  a given field or area and consists of key stakeholders 
including government, academia, consumer groups, private sector and other interested parties.  
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Standards by the National Standards Council.  
The committee responsible for this document is Technical Committee UNBS/TC 08, transport and 
communication  
 UGANDA STANDARD  US nnnn -n: 2019  
 
© UNBS 2019  – All rights reserved  1 
 Light vehicle towed trailer — Specification  
1 Scope   
This standard specifies material, constructional and other requirements of trailer operated by a light vehicle  
This standard covers requirements of balanced  and un balanced  trailers up to 3.5 tonnes  
2 Normative references   
The following referenced documents 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 edition cited ap plies. For undated 
references, the latest edition of the referenced document (including any amendments) applies.  
US 479:2003, Code of practice —Inspection of road vehicles for roadworthiness  
US EAS 358:2004 , Pneumatic tyres for passenger cars — Specificatio n  
US 845:2017 , Road vehicles — Requirements for inspection and testing of used motor vehicles for road 
worthiness  
3 Terms and definitions  
For the purposes of this document, the following terms and definitions apply  
ISO and IEC maintain terminological data bases for use in standardization at the following addresses:  
— ISO Online browsing platform: available at http://www.iso.org/obp  
3.1  
Reflex Reflector s 
An assembly ready for use and comprising one or  more reflecting optical units  
3.2  
Stop Light  
A brake o perated lighting device, which emits red,  or amber light at the rear of the vehicle intended to give 
warning of the slowing down  or the stopping of the vehicle  
3.3  
Direction Indicator  
A lighting device to show in which direction, the driver intends to tur n by giving a flashing light on the side of 
the vehicle towa rds which the turn will be made  
3.4  
Tail Light  
A lighting device, which  emits red light indicating the presence of the vehicle when seen from the rear  and 
intended to show the width. A tail light  has direction light, reverse light and licensed plate light   
2 © UNBS 2019  – All rights reserved  
 4 TYPES  
4.1 The light vehicle towed trailers shall be of following tw o types:  
a) Balanc ed trailer (two  axel and three axle trailer ), and  
b) Single axle  trailer . 
4.2 Both the types of trailers ma ybe fitted with fixed or tipping platform  
 
Fig. 1  Single axle  trailer  
5 MATERIALS  YIELD STRENGTH  
5.1 The material for important components and that for axle assembly shall be as given in column 3 of Table 
1.The material shall conform to ISO 3573  and grade  given in col umn 4 of Table 1  
Table 1 Material Requirem ents for Components of Trailer  
S/No Components  Material  Grade  
1 Chassis  Mild steel  Fe 410 -S 
2 Drawbar  Mild steel  Fe 410 -S 
3 Tow eye or tow 
jaw  alloy steel  20C 
Grade 23 to 45  
4 Platform  Mild steel / timber  Fe 410 -S 
5 Side boards  Mild steel / aluminium  
Timber  Fe 410 -S 
 
5.2 The material  of the brake drum, hub and cap  shall be cast iron of grade FG 200  
5.3 The axle material  shall be structural steel of grade Fe 410 -S US 484: 2019  
© UNBS 2019  – All rights reserved  3 
 6 CAPACITY  
The capacity of a trail er shall be its  gross load and shall be  up to 3.5  tonnes. The manufacturer shall declare 
the gross load along with the payload  
7 DIMENSI ONS  
7.1 The d imensions given under 7.3  to 7.6  shall not in any way infringe the rules and regulations of  the 
Uganda  traffic and road safety act 1998  
7.2 The overall width of the  trailer  shall not exceed 2.5 m   
7.3 The overall length of the trailer shall conform to provisions specified in US 845:2017  
7.4 The height of the trailer, with tyres inflated at the recommended pres sure, when measured from the 
level supporting surface to the top of the platform shall not be  more than 1.5 m.  
7.5 The height of the trailer, with tyres inflated at the recommended pressure, when measured from the level 
supporting surfa ce to the top of the  sideboard  shall not be  more than 2.2 m  
7.6 In case of semi -trailer, the load transfer from the trailer to the tow eye of the trailer shall not be more 
than 20 percent of the trailer capacity. Assuming that the trailer is loaded uniformly to the entire le ngth of  
platform and the centre of gravity lies in the lateral vertical plane at half the length of platform from rear edge, 
the value of G (see Fig. 2) can be derived from the following formula ; 
 
where  
W = gross load  of the trailer, and 
R, = load transfe r on tow eye, percent.  
On the basis of 20 percent load transfer from the trailer to the tow eye, the above formula can be written as 
follows:  
 
7.7 Ground clearance  shall not be less than 300 mm.  
8 CONSTRUCTIONAL REQUIREMENTS  
8.1 The loading platform may b e plain or provided with hinged or fixed sideboards. If trailer is provided with 
sideboards, some kind of locking provision shall be provided to keep it vertical. This can be met by giving a 
latching system at the top of the vertica l posts fitted to the pl atform. The hinges by which sideboards are fixed 
shall be provided with split pins to restrict its lateral motion.  
8.2 The trailers shall be provided with lashing hooks for tying down the load.  
8.3 Tow eye of the trailer shall be capable of rotating at  180 degrees angle to take on even rigid trailer hook 
of the towing vehicle  
8.4 For bal anced trailer s, the front axle shall have the capability to swivel to a maxi mum of 120° (60° on 
either side)  about the vertical axis.   
4 © UNBS 2019  – All rights reserved  
 8.5 The trai ler shall be fitte d with pn eumatic tyres conforming to US EAS 358:2004  
8.6 The axle(s) shall conform to requirements specified in Annex A  
8.7 The braking system shall apply to all trailers exceeding 750kg  
8.8 Trailer s shall have service (overrun) and parking brake. It shall be ensur ed that during operation of 
service or parking brake, the brakes at  both the wheels of trailer  are activated simultaneously.  
8.9 The service brakes shall be capable of a deceleration of 2.5 m/s2 measured in accordance with tile 
method described in Annex B  with operating brakes pedal  force not exceeding 600 N and 400 N in case of 
foot operated and hand operated brakes respective y.  
8.10 The parking brake shall hold ful ly laden trailer on a 12 percent sl ope uphill or downhill. The maximum 
force to operate a h and lever shall not exceed 400 N. The parking brake shall operate on the same drum and 
shoe or disc and pad as the service brake.  
8.11 Hydraulic ram of suitable capacity compatible with tractor hydraulic shall be provided in case of tipping 
type. The ram m ay be used in single or tandem as per need and the operating pressure shall not exceed 13.8 
MPa.  
8.12 Tipping angle of the body, in case of tipping type, shall be 42° to 50°  
9 LIGHTING REQUIREMENTS  
9.1 The trailer  shall be fitted with two red coloured refl ectors at rear sides and two white coloured reflectors 
on front sides at a distance not more than  150 mm from extreme ends to the centre of reflectors. Rear 
reflectors may be incorporated as part of lensing  in tail lamps described in A-5 
9.2 At least two a mber flashing reversing lamp s (warning lamps) as symmetrically mounted and as widely 
spaced laterally as practicable, mounted at least 1000 mm height but not more than 1500 mm. Lamps shall 
flash in unison at a rate of 60 to 120 flashes per minute.  
9.3 Every trailer shall be fitted with two turn indicators (Direction indicators) lam ps on the rear side. The 
direction  indicator shall be of amber colour and shall flash in unison at a rate of 60 to 120  flashes per minute . 
9.4 The re ar amber flashing warning lamp s may be used as the turn indicators  
9.5 Two brake operated stop light shall be provided at the rear of the trailer which emit red light intended to 
give warning of the slowing down or stopping of the vehicle, The stop lights may be provided as  a part of t ail 
lamps  
10 OTHER REQUIREMENTS  
10.1 The semi -trailer shall be provided with suitable arrangement in the front for keeping the trailer in a 
levelled position when detached from the towing vehicle  
10.2 In case of tipping type trailer, provisions shall be ma de for tilting the platform  without disturbing the 
trailer  
10.4 The dust cover shall be provided  
10.5 Oil seals or grease retainers shall be provided to make the axle assembly leak and dust proof  
10.6 The hub shall be fully packed with multi -purpose grease  between the bearings  US 484: 2019  
© UNBS 2019  – All rights reserved  5 
 10.7 Reflectors shall be visible at night from all distances within 31 m to 183 m when directly in front of lawful 
lower beams of headlamps  
11 WORKMANSHIP AND FINISH  
11.1 The sharpness of the edges and corners shall be removed  
11.2 Castings and forgings shall be free from blowholes , cracks and other visual defects  
11.3 All wooden and metal surfaces shall be covered with a coat of suitable preservative. The metal parts  
shall be de -rusted, treated with anti -corrosive material and  an appr opriate primer painting  
12 MARKING  
The trailer shall be marked with the following information on identification plate which shall be  welded or 
riveted  to the body  
a) Manufacturer’s name and registered trademark, if any  
b) Unladen mass , and 
c) Gross load; a nd  
6 © UNBS 2019  – All rights reserved  
 Annex  A 
(Normative )  
 
REQUIREMENT OF AXLE ASSEMBLY  
A-1 NOMENCLATURE  
A-1.1 For the axle assembly the nomenclature given in Fig. 2 shall apply.  
A-2 CLASSIFICATION  
A-2.1 For the purpose of this standard, th e axle assembly shall be of the following two classes:  
a) Class A — The axle assembly of load carrying capacity up to 3 tonnes.  
 b) Class B — The axle assembly of load carrying capacity up to 5 tonnes.  
A-3 DIMENSIONAL REQUIREMENTS  
A-3.1 The dimensions of v arious components of the axle a ssembly shall be as given in Col 3 and 4 of 
Table 2. The applicable standards for  the components are given in COl  5 of Table 2 for guidance.  
A-3.2 The axle assembly shall have wheel track of 1500 mm or 1700 mm  
 
Fig 2. Nomenc lautreofaxle assemeily  
Table 2 Dimensions of Various Components of Axle Assembly  
S/N Component  Dimensions  
Class A  Class B  
i.  Axle shaft size,mm  63 square or   US 484: 2019  
© UNBS 2019  – All rights reserved  7 
 80 round  
ii.  Outer bearing, bore size diam eter, mm  45 45 
iii.  Inner bearing, bore size diameter, mm  55 55 
iv.  Castle nut, nominal size  M42 x1.5  M42 x1.5  
v.  Split pin for nut, nominal diameter, mm  8 8 
vi.  Washer for nut, nominal size,mm  43/45  43/45  
vii.  Roundheadscrew:    
 a) Nominal size  M6 x1  M6 x1  
 b) Length,mm  12 12 
 c) Number  3 3 
viii.  Wheel stkt:    
 a) Nomi nal size  M16 x1.5  M16 x1.5  
 b) Pitch circle dkneter, mm  165 185 
 c) Number  5 6 
ix.  Hub flange:    
 a) Thickness, mm  20 25 
 b) Diameter, mm  210 230 
x.   Brake drum:    
 a) Diameter, mm  254 254 
 b) Nominal width, mm  50 50 
 
A-4 DESIGNATION  
A-4.1 n axle assem bly shall be designated by its class and wheel track.  
A-4.1.1 Example 1  An axle assembly of Class A having wheel track of 1500 mm shaI l be designated as Axle 
A 1500  and 
A-4.L2 Example 2  An axle assembly of Class B having wheel of  1700 mm shall be designate d as Axle B 
1700.   
8 © UNBS 2019  – All rights reserved  
 A-5 LIGHTING REQUIREMENTS  
Every trailer shall be provided with two tail lights of red colour at the rear and conforming to provisions of US 
479:2003  
The point on the illuminating surface farthest from the median longitudinal plane of trai ler shall not be more 
than 400 mm from the extreme outer edge of the vehicle. The distance between the inner edge of the two 
illuminating surface shall not be less than 600 mm. This distance may be reduced to 400 mm, where the 
overall width of the trailer is less than 1300 mm. The height of taillights above the ground shall not be less 
than 350 mm and not more than 1600 mm  
A-6 OTHER REQUIREMENTS  
All the parts requiring lubrication shall be provided with suitable arrangement wh ich should be easily 
accessible  US 484: 2019  
© UNBS 2019  – All rights reserved  9 
 Annex  B 
(NORMATIVE )  
 
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 with which it 
is recommended for use by th e manufacturer.  
B-2 TEST CONDITIONS  
B-2.1 The test surface shall not exceed one percent longitudinal slope and 3 percent 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.  
B-2.4 The test track shall have a dry, clean, concrete, and bituminous  or an equivale nt surface having good 
adhesion.  
B-2.5 The test shall be performed when the wind velocity  is below  10m/s . 
B-2.6 The braked axle(s) shall be equipped with the largest diameter tyres specified by the vehicle 
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 cold if one of the following 
condition is met:  
a) The temperature measured over the disc or on the outside of the drum is below 100”C;  
b) In the case of totally enclosed brakes, including oil immersed brakes, the temperature mea sured on 
the outside of the housing is below 50°C, or within manufacturer’s specifications; and  
c) The brakes have not been actuated for one hour.  
B-3 PROCEDURE  
B-3.1 Prior to the start of the test, the brakes shall have been fully bedded -in (burnished) and a djusted in 
accordance with the manufacturer’s instructions. Thereafter, the brakes shall not be further manually adjusted 
during the complete test.  
B-3.2 With the towing vehicle and trailed vehicle traveling at the maximum design speed of the trailed  vehic le 
but not exceeding 30 km/h, measure deceleration for a series of different forces applied to the control of the 
braking device. Calculate the corresponding values of mean deceleration from the following formula:  
 
where   
10 © UNBS 2019  – All rights reserved  
 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 braking device control is independent of the towing vehicle braking device 
control, apply the trailed vehicle brakes only. When the brakes of trailed vehic le is operated, the engine in the 
towing vehicle shall be disengaged by the clutch so that the force to stop entire system shall come from 
brakes of trailed vehicle.  
B-3.4 If the braking device transmission is not mechanical, measure an appropriate transmi ssion parameter, 
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 th e braking device up to 
maximum force which can be applied without locking of the wheels, or up to a maximum 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 for ce applied to the braking device control, calculate the trailed vehicle braking force 
from whichever of the following formula is appropriate:  
B-3.6.1  If the trailed vehicle brakes only are applied, use the following formula  
 
where  
F2 the trail ed vehicle braking force in N;  
m1 the towing vehicle mass in kg;  
M2 the trailed vehicle mass in kg; and  
a3 the mea n deceleration of the towing and traile d vehicle combination in m/s2. 
B-3.6.2  If the towing and trailed vehicle brakes are applied, use the fo llowing formula:  
 
where  
a, mean deceleration measured with the towing vehicle alone at the same value of force applied to the 
towing vehicle braking device control which produced deceleration a 1 of the vehicle combination in m/s.  
B-3.7 For ea ch value of braking force F 2, calculate the  equivalent mean deceleration (a 2) of the trailed vehicle 
from the following formula:  
 
B-3.8 For each value of the equivalent mean deceleration a 2, calculate the equivalent stopping distance s2 of 
the trailed vehicle from the following formula:  
 
Where  
s2 equivalent stopping distance of the trailed vehicle in m, and  US 484: 2019  
© UNBS 2019  – All rights reserved  11 
 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 force, 
stopping distance mean deceleration either in the form of a graph or table values.  
B-4.1.1  If the braking device transmission is not mechanical, report t he relationship between stopping 
distance, mean deceleration and an appropriate transmission parameter, such as fluid pressure, in the form of 
a graph or table of corresponding values.  
B-5 TOLERANCE  
The following measuring tolerance shall be adhered to whe n conducting the test:  
S/NO  Measurement  Tolerance, percent  
I.  Travel speed  ±3 
II.  Vehicle mass  ±3 
III.  Deceleration  ±3 
IV.  Stopping distance  ±1 
V.  Brake control input force  ±5 
VI.  Tyre inflation pressure  ±5 
VII.  Brake system fluid (gas)  ±5 
  
12 © UNBS 2019  – All rights reserved  
 Bibliography  
[1] IS 8213:200 0 Agricultural tractor trailer — Specification  
[2] Technical Requirements https://www.infrastructure.gov.au/vehicles/vehicle_regulation/bulletin/vs . 
[3] The traffic a nd road safety act, 1998  
[4] NSW Government Vehicle standards information , rev 5  
[5] Design, Analysis and Optimization of Automobile wheel hubUS nnnn -n: 2019  
© UNBS 2019  – All rights reserved  13 
  US nnnn -n: 2019    
 
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