Bsi bs au 268 2003

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BRITISH STANDARD

Passenger cars and
light vans —
Commercial towing
pole assemblies —
Specification

IC S 43 . 04 0. 70

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BS AU
268:2003


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BS AU 268:2003

Committees responsible for this
British Standard
The p rep aration of this Britis h S tandard was entrusted to Technical
C o mmittee AUE /9, Automob ile details and acces sories, up on which the
following b odies were re pres ented:

As s ociation of Vehicle Recovery O p erators
Automob ile Ass ociation
D ep artment of the E nvironment, Transp ort and the Regions

D ep artment of Trade and Indus try
Garage E quip ment Ass ociation
Ins titute of Trading S tandards Adminis tration
National Trailer and Towing Ass ociation
Recovery E quipment Manufacturers and S up p liers As sociation
Royal Auto mob ile C lub
S ociety of Motor Manufacturers and Traders

This Britis h S tandard was
p ub lis hed unde r the authority
of the S tandards Po lic y and
S trategy C om mittee
on 2 0 June 2 00 3

© BS I 2 0 June 2 0 0 3

Amendments issued since publication
Amd. No.

The fo llowing BS I references
relate to the work on this B ritis h
S tandard:
C o mmittee referenc e AUE /9
D raft fo r C omm ent 01 /70 785 1 D C

ISBN 0 580 41905 3

D ate

C omments

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BS AU 268:2003

Contents
Page
Committees responsible

© BSI 20 June 2 003

Inside front cover

Foreword

ii

1

1

Scope

2

Normative references

1

3

Terms and definitions

1

4

Dimensions

1

5

End fittings

1

6

Warning device

1

7

Strength

2

8

Marking

3

9

User instructions

3

Annex A (normative) Dynamic strength test method

4

Annex B (normative) Static strength test method

5

Annex C (normative) Inspection

6

i


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BS AU 2 6 8: 2 0 0 3

Fore wo rd

This Britis h S tandard has b een p rep are d b y Technical C omm ittee AUE /9 .

It has b e en ass umed in the drafting of this Britis h S tandard that the executio n of
its p rovis ions is entrus ted to ap p ropriately qualified and com petent p eople.

This p ub lication does no t p urp ort to include all the neces sary p rovisions of a
contract. Us ers are res pons ib le for its correct ap p lication.

C ompliance with a British S tand ard d o es no t of itself co nfer immunity
from legal ob ligations.

S ummary o f p age s
This document comprises a front cover, an inside front cover, page s i and ii, p ages
1 to 6, an ins ide b ack cover and a b ack cover.

The BS I cop yright notice dis p layed in this document indicates when the
document was last iss ue d.

ii

© BS I 2 0 June 2 0 03


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BS AU 268:2003

1 Scope
This British Standard specifies requirements for the dimensions, construction, and strength of towing pole
assemblies to be used commercially for towing passenger cars and light vans.
This standard is applicable to towing pole assemblies for use by towing vehicles of up to 3 500 kg gross mass
to tow vehicles of up to 3 500 kg gross mass.
NOTE

The towing pole assemblies specified in this British Standard are intended for towing broken- down vehicles.

2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
BS EN 571 - 1 , Non- destructive testing — Penetrant testing — Part 1 : General principles.

3 Terms and definitions
For the purposes of this British Standard, the following terms and definitions apply.
3.1
towing pole assembly

rigid strut device that acts in tension when towing and in compression when braking, to enable a
broken- down vehicle to be towed by another vehicle but does not impart a steering force to the vehicle being
towed
NOTE

A towing pole assembly comprises a towing pole and end fitting assembled in accordance with the manufacturer’s

instructions.

3.2

D value

theoretical reference value for the horizontal forces imposed on the towing vehicle and the towed vehicle
3.3
broken-down

incapable of self- propulsion

4 Dimensions
The assembled length of the towing pole assembly shall be not less than 1 . 5 m nor more than 4. 5 m.

5 End fittings
The forward end of the towing pole assembly shall be fitted with an end fitting. The end fitting shall be
compatible with a vehicle coupling device specified by the towing pole manufacturer.
The rear end of the towing pole assembly shall be supplied with a fitting that is intended to engage with
the vehicle manufacturer’s recovery eye provided on the towed vehicle.

6 Warning device
The towing pole assembly shall be clearly visible to other road users. The method of ensuring this visibility
shall be permanent and comprise at least one of the following:
a) a coloured and conspicuous flag or other similar warning device securely attached to the middle of the
length of the towing pole assembly. The device shall have a minimum area of 300 cm

2

when viewed from

the side;
b) a brightly coloured finish covering the towing pole assembly;
c) fixed brightly coloured and conspicuous markers along the length of the towing pole assembly, having

a minimum total proj ected area of 300 cm

© BSI 20 June 2 003

2

when viewed from the side.

1


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BS AU 2 6 8: 2 0 0 3

7 S tre ngth

D
For towing pole assemblies, the D value in kilonewtons (kN) shall be as given by the following equation:
D = {(RtRv )/(Rt + Rv)}9.81
where
Rt is the mass of the towing vehicle (in tonnes);
Rv is the mass of the towed vehicle (in tonnes).
Since the towing pole assembly is intended for use by a towing vehicle of up to 3 500 kg gross mass to tow
vehicles of up to 3 500 kg gross mass, when the towing vehicle has the same mass as the towed vehicle the
equation can be simplified as follows:
D = (R/2)9.81
where
R is the mass of the vehicles (in tonnes).
7.1

value

7 . 2 Dynamic stre ngth

7.2.1

Solid towing poles

The towing pole assembly shall be tested for dynamic strength in accordance with Annex A. The dynamic
test load Dd in kilonewtons (kN) applied to the towing pole assembly shall be as given by the following
equation:
Dd 0.6[{(RtRv)/(Rt + Rv)}9.81]
where
Rt is the mass of the towing vehicle (in tonnes);
Rv is the mass of the towed vehicle (in tonnes).
Which can be simplified to the following equation:
Dd = 0.6D
If after 500 000 cycles the post-test inspection reveals no permanent deformation greater than 0.4 % of the
original dimension, cracking or the enlargement of any defect noted before the test, the towing pole
assembly shall be deemed to have passed the test.
=

7.2.2

Towing poles fitted with a shock absorbing device

A towing pole fitted with a shock absorbing device shall conform to
.The towing pole assembly may
undergo dynamic strength testing with the shock absorbing device made inoperative by removing,

clamping or otherwise making it rigid for the duration of the test. This could be achieved by replacement
of the shock absorbing device with a solid link.
If a towing pole assembly is tested in accordance with Annex A with the shock absorbing device so modified,
the towing pole assembly shall be inspected to determine whether any failure of the inoperative shock
absorbing device could compromise the integrity of the towing pole assembly in service. If the inspection
reveals that failure of the inoperative shock absorbing device does not compromise the integrity of the
towing pole assembly in service, the towing pole assembly shall be deemed to have passed the test.
7. 2 . 1

7 . 3 Static stre ngth

The towing pole assembly shall be tested for ultimate strength in accordance with Annex B. The ultimate
strength test load Ds in kilonewtons (kN) applied to the towing pole shall be as given by the following
equation:
Ds (0.6R)9.81
where
R is the mass of the vehicles (in tonnes).
=

2

© BSI 20 June 2003


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BS AU 2 68 :2 0 0 3

The towing pole assembly shall be deemed to have passed the test if the post-test inspection reveals no
permanent deformation greater than 0.4 % of the original dimension, cracking or the enlargement of any

defect noted before the test.
8 Marking

All towing pole assemblies shall be permanently and legibly marked with the following information:
a) the manufacturer’s name or trademark;
b) the number and date of this British Standard, i.e. BS AU 268:20031) ;
c) maximum gross mass of the towing vehicle and of the towed vehicle in kilograms (kg);
d) the D value in kN;
e) the vehicle coupling device the end fitting of the towing pole assembly is compatible with;
f) any limitations on use, e.g. “only compatible with a 50 mm towing ball”;
g) instructions or a pictorial symbol referring the user to the vehicle manufacturer’s handbook.
When the towing pole assembly is supplied packaged, the information specified in shall be clearly
visible on or through the packaging.

8. 1

8. 2

8. 1

9 Use r instru ctions

Each towing pole assembly shall be supplied with user instructions that contain at least the following
information.
a) Detailed instructions for assembly of the towing pole assembly and connection of the towing pole
assembly to vehicles.
b) Maximum gross mass of the towing vehicle and of the towed vehicle in kilograms (kg).
c) Recommended procedures for the safe towing of broken-down vehicles by use of the towing pole
assembly. Specific reference and guidance shall be given with regard to each of the following warnings:
1) the need for a lighting board together with a relevant registration (number) plate consistent with

that of the towing vehicle, at the rear of the towed vehicle;
2) the problems associated with towing automatic transmission vehicles;
3) the problems associated with towing four-wheel drive vehicles;
4) the problems associated with towing vehicles without the benefit of power steering;
5) the problems associated with towing vehicles without the benefit of servo braking;
6) the problems associated with towing vehicles whose gearboxes require an active engine for efficient
lubrication;
7) the problems associated with towing a vehicle with an active engine;
8) the differentiation of “lashing” and “recovery” eyes;
9) reducing allowable speeds when towing;
10) the need for the towed vehicle’s handbook or the vehicle manufacturer to be consulted prior to
towing a vehicle with a towing pole assembly;
11) limitations on the towing capacity and gross train mass of the towing vehicle;
12) the need for the towing pole assembly to be inspected before use, for signs of damage, wear or
defects.

Marking BS AU 268:2003 on or in relation to a product represents a manufacturer’s declaration of conformity, i.e. a claim by
or on behalf of the manufacturer that the product meets the requirements of the standard. The accuracy of the claim is solely the
claimant’s responsibility. Such a declaration is not to be confused with third-party certification of conformity.

1)

© BSI 20 June 2003

3


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BS AU 268:2003

Annex A (normative) Dynamic strength test method
A.1 Principle
This test assesses the dynamic strength of the towing pole assembly by subj ecting the assembly to a load
which varies between calculated limits for a specified number of cycles.

A.2 Apparatus

Towing pole assembly.
A.2.2 Test machine , capable of applying an axial alternating force at a frequency not exceeding 35 Hz to

A.2.1

the towing pole assembly.

The selected test frequency shall differ from resonance frequencies of the test set- up, including that of the
towing pole assembly being tested. The alternating force shall vary between values of ±
shall be considered to be the complete sine wave from zero to +

D

d

D

to –

d

D

d

and one cycle

and back to zero. The clearance,

or free movement, in end fittings designed for use with towing eyes fitted by the vehicle manufacturer may
be eliminated. The test shall be carried out in a manner which ensures that the end fitting is subj ected to
the alternating force applied to the towing pole.

A.3 Procedure
A.3.1 Assemble the towing pole in accordance with the manufacturer’s instructions. If the towing pole
assembly is fitted with a shock absorbing device render this inoperative if required (see 7.2.2 ) .
A.3.2 Inspect the towing pole assembly in accordance with Annex C.
A.3.3 Fit the towing pole assembly to a testing machine (A.2.2 ) .
A.3.4 Apply the test load

D

d

for 500 000 cycles. For straight towing poles ensure the direction of the test

load is within ±1 ° of the axial centre line of the towing pole assembly being tested. For towing pole
assemblies having an adj ustable j oint designed, for example, to provide clearance around vehicle bodywork,
test the towing pole assembly in the worst- case condition.

A.3.5 Remove the towing pole assembly from the testing machine.
A.3.6 Inspect the towing pole assembly in accordance with Annex C.

A.3.7 For towing pole assemblies with a shock absorbing device that was rendered inoperative, inspect the
towing pole assembly to determine whether any failure of the shock absorbing device could compromise the
integrity of the towing pole assembly in service.

A.4 Test report
The test report shall include the following information.
a) The results of the pre- test inspection in accordance with Annex C.
b) The loads applied to the towing pole assembly.
c) The test frequency.
d) The number of cycles after which the towing pole assembly failed in the test if breakage occurred.
e) The results of the post-test inspection in accordance with Annex C.
f) For towing poles with a shock absorbing device rendered inoperative, whether or not failure of any part
of the shock absorber device in service could compromise the integrity of the towing pole assembly.
g) Test location, date of testing, name of operator.

4

© BSI 20 June 2003


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BS AU 268:2003

Annex B (normative) Static strength test method
B.1 Principle
This test assesses the static strength of the towing pole assembly by subj ecting the assembly to a load for
a specified period of time.

B.2 Apparatus

B.2.1

Towing pole assembly. The towing pole assembly shall not be repaired or renovated between the

tensile and compressive stages of the test.

B.2.2

Testing machine, capable of applying a tensile and compressive load to the towing pole assembly.

B.3 Procedure
B.3.1 Assemble the towing pole in accordance with the manufacturer’s instructions.
B.3.2 Inspect the towing pole assembly in accordance with Annex C.
B.3.3 Fit the towing pole assembly to the testing machine (B.2.2 ) .
B.3.4 Apply a tensile load of

D

s

at a constant rate in a period between 5 s and 1 00 s.

B.3.5 Hold the tensile load for a period not less than 60 s.
B.3.6 Remove the tensile load.
B.3.7 Apply the compressive load

D

s

at a constant rate and in a period between 5 s and 1 00 s.

B.3.8 Hold the compressive load for a period not less than 60 s.
B.3.9 Remove the compressive load.
B.3.1 0 Remove the towing pole from the testing machine.
B.3.1 1 Inspect the towing pole assembly in accordance with Annex C.
B.4 Test report
The test report shall include the following information.
a) The results of the pre- test inspection in accordance with Annex C.
b) The loads applied to the towing pole assembly.
c) The results of the post- test inspection in accordance with Annex C.
d) Test location, date of testing, name of operator.

© BSI 20 June 2 003

5


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BS AU 268:2003

Annex C (normative) Inspection
C.1 Principle
This test assesses any defects in the towing pole assembly prior to strength testing and notes any increase
in defect that occurs due to the strength tests.

C.2 Procedure
C.2.1

Visually examine all welds and record any defects on the inspection report. Measure the length of

any defect in mm.

C.2.2

Inspect all welds using a dye- penetration method of crack testing in accordance with BS EN 571 - 1 or

an equivalent non- destructive method and record all indications on the inspection report. Measure the
length of any crack in mm.

C.2.3

Visually examine the towing pole assemb ly for any indications of b ending, b uckling or damage, and

record any observations on the inspection rep ort. Measure the length of the towing pole assemb ly in mm.

C.3 Results
In the post- test inspection determine the axial displacement in mm of the towing pole assemb ly due to the
strength test.
In the post- test inspection calculate the permanent deformation of the towing pole assemb ly as a
p ercentage from the elongation of the towing pole assembly due to the strength test.

C.4 Inspection report
The inspection report shall include the following information.
a) Information on the towing pole assemb ly inspected:
— designation;
— dimensions;
— material;
— surface condition.

b ) Any defects detected in welds and the length of any defect in mm.
c) Any indications from crack testing using a dye- penetration method and the length of any crack in mm.
d) Any observations of bending, b uckling or damage.
e) The axial displacement in mm if appropriate.
f) Permanent deformation of the towing pole assembly as a p ercentage if appropriate.
g) Test location, date of testing, name of operator.

6

© BS I 2 0 June 2 003


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BS AU
268:2003

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