Bsi bs au 050 1 4 8 1998 (iso 11795 1997)

BRITISH STANDARD AUTOMOBILE SERIES BS AU 50 1 4 8 1998 ISO 11795 1997 Tyres and wheels — Part 1 Tyres — Section 4 Agricultural tractor and machine tyres — Subsection 4 8 Method of measuring tyre rolli[.]

ISO 11795:

ICS6 0 0.0 ; 8 1 0.3

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1 Mar h 1 9

© BSI 0 -1 9

ISBN 0 5 0 2 1 4 X

This British Stand ard reproduces v erb tim ISO 1 7 5:19 7 an implements it

as the UK national stand ard

The UK p rticip tion in its prep ration was entrusted to Tech ical Commit e

AUE/4, W he ls and ty res for motor v ehicles, which has the responsibi ty to:

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Foreword

ISO ( the International Org anization for Stand rdization) is a worldwide

federation of national stand ards bodies ( ISO member bodies) The work of

prep ring International Stand ards is normaly car ied out throug h ISO tech ical

commit e s Each member bod interested in a subject for which a tech ical

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commit e International org anizations, g ov ernmental and non-g ov ernmental,

in l aison with ISO,also take p rt in the work ISO col a orates closely with the

International Electrotechnical Commis ion ( IEC) on al mat er of

electrotech ical stand ardization

Draft International Stand rds a opted b the tech ical commit e s are

cir ulated to the member bod ies for v oting Publcation as an International

Stand rd req uires a prov al b at least 7 % of the member bod ies casting a v ote

International Stand rd ISO 1 7 5 was prep red b Tech ical Commit e

ISO/TC 31, Tyr es, r ims a nd va lve , S bcommit e SC 5, A gr iculur a l tyr es a nd

r ims

Annex A of this International Stand rd is for information only

Desc iptors: Ag ricultural machinery, ag ricultural tractor , driv -whe ls, tyres,pneumatc tyres,

tests, determinaton, cirumference, dimensional me surements

© BSI 0 -1 9

1

Introduction

Matching f ont an rear whe ls with diferent ty re

siz s on four-whe l driv e ag ricultural tractor

requires ac urate rol ing cir umference v alues The

test method to determine rol ng cir umference

outl ned below was dev eloped to fol ow this

req uirement The v alues th s obtained are not

intended for use as lev els of per ormance or q ualty

The test spe d has be n set at ty pical working spe d

when the four-whe l d riv e wi lkely be eng ag ed

and the most c itical match is req uired Generaly ,

the four-whe l d riv e is diseng ag ed at roa ing

spe ds Therefore, the d etermination of rol ng

cir umference is not related to the ty re’s ma imum

spe d , e.g 3 km/h or 4 km/h Nev ertheles , other

spe d s or cond itions ma be ru prov ided it is

clearly documented in the results

1 Scope

This International Stand rd specifies the method

for measuring rol ing cir umference for new ty res,

u der loa ed conditions, ma e for use on

ag ricultural tractor and machines, and a ples to

ag ricultural tractor driv e whe l ty res in diag onal

an ra ial construction

The fol owing stand ard s contain prov isions which,

throug h reference in this text, constitute prov isions

of this International Stand ard At the time of

publcation, the editions ind icated were v ald All

stand ards are subject to rev ision, and p rties to

ag re ments b sed on this International Stand rd

are encourag ed to inv estig ate the pos ibi ty of

a ply ing the most recent editions of the stand rds

indicated below Member of IEC and ISO maintain

reg ister of cur ently v ald International Stand ards

ISO 4251-1:—

1)

Tyr es (ply r a ting ma r ked s r ie )

a nd r ims fr a gr icul ur a l tr a ctor s a nd ma chine —

Pa r t 1: Tyr e d esigna tion a nd d imensions, a nd

a ppr oved r im contour s

ISO 4251-2:—

2)

Tyr es (ply r a ting ma r ked s r ie )

a nd r ims fr a gr icul ur a l tr a ctor s a nd ma chine —

Pa r t 2: Tyr e loa d r a tings

ISO 7 6 -1:19 6, Tyr es a nd r ims (metr ic s r ie ) fr

a gr iculur a l tr actor s a nd ma chine — Pa r t 1: Tyr e

d esigna tion, d imensions, ma r king a nd

tyr e/r im co r d ina tion

ISO 7 6 -2:19 6, Tyr es a nd r ims (metr ic s r ie ) fr

a gr iculur a l tr actor s a nd ma chine —

Pa r t2:Ser vic des r ipt on a nd loa d r a tings

ISO 8 6 :19 2, A gr iculur a l tr a cto d r ive-whe l

tyr es—Ser vic d es r ipt on (loa d ind ex — spe d

symbol ma r ked tyr es

3 Definition

For the purposes of this International Stand rd , the

folowing definition a ples

3.1

rol ing circum ferenc of tyre

d istance that the ( axle) centre of the ty re mov es in

one rev olution of the ty re u der the conditions

specified in clause5

4 Principle

The measurement consists of driv ing a ty pical

v ehicle eq uip ed with the test ty res on the driv e

a le, on a straig ht, lev el roa at a constant spe d,

and cou ting the number of ty re rev olutions ( or

portions there f) that oc ur whi e trav er ing a

measured d istance

5 Test conditions

5.1 Tyre instal ation

Ty re to be tested shal be instal ed as a sing le on the

d riv e whe ls of a v ehicle which shal be

representativ e of that used with the ty re siz being

tested An a prov ed rim in ac ord nce with

ISO4251-1, ISO 7 6 -1 or ISO 8 6 shal be used

Only the test a le shal be driv en

5.2 Test tyres

The ty res shal be a matched set of the same siz

d esig nation, ty pe, an brand, hav ing inflated ,

u loa ed ov eral d iameter within 0,5 % of each

other

5.3 Tyre lo d and inflation pres ure

The loa on each ty re shal be the ma imum rated

loa at 3 km/h, in ac ord ance with ISO 4251-2,

ISO7 6 -2 or ISO 8 6 Ty re inflation pres ure

shal be the reference inflation pres ure that

cor esponds to the 3 km/h loa The ty re shal be

inflated with air only

5.4 Tyre measurem ent

The ov eral d iameter of each ty re shal be measured

after being inflated for 24 h at ambient temperature

with no a pled loa and the inflation pres ure

specified in 5.3 Inflation pres ure shal be checked

and ad justed, if neces ary , immediately prior to

measurement

1)

To b published (Re ision of ISO 4 5 -1:1 9 )

2)

To b published (Re ision of ISO 4 5 -2:1 9 )

© BSI 0 -1 9

5.5 Test cour e

The test cour e for the distance specified in clause6

shal be a lev el, straig ht section offlat, dry roa

surace ( asphalt or conc ete)

5.6 Weather conditions

The ambient air temperature for measuring ,

warm-up, and test shal be betwe n 5°C and 3 °C;

howev er, an asphaltic sur ace shal be suficiently

co l that the sur ace is not tacky The win spe d

shal not exce d 15 km/h

5.7 Test m easurem ent

Distance shal be determined b direct

measurement or b ty re use of a calbrated fifth

whe l Each ty re on test shal be instrumented to

return a minimum of eig ht impulses per rev olution

5.8 Test spe d

Ty res shal be tested at 10 km/ h ± 2 km/h

6 Method oftest

6.1 Test preparation

Immediately prior to testing , the inflation pres ure

of the loa ed ty res shal be ad justed to the inflation

pres ure specified in 5.3 at the ambient

temperature Ty res shal be ru for 3 min

at 25 km/h±5 km/h or u ti inflation pres ure

sta i z s ( warm-up) The inflation pres ure shal

not be read justed afterwards

6.2 Test proc dure

Immediately after the test prep ration, ru the test

at the spe d specified in 5.8 to achiev e a minimum

of 1 0 0 impulses ov er a test cour e of 10 m

minimum whi e record ing the n mber of impulses

for the rig ht whe l and the left whe l sep rately

During the test ru , a diferential lock shal not be

eng ag ed, ac eleration and braking shal be av oided

and ste ring input should be kept to minimum.Two

ru s shal be ma e in each direction of trav el on the

test cour e Repeat this procedure if the n mber of

impulses recorded on any ru d ifer fom the other

b more than 0,2 %

In the ev ent of stop ag e or inter uption of the test,

repeat the whole test

7 Expr s ion ofr sults

The ty re rol ng cir umference is calculated b

av erag ing the impulses recorded for the eig ht

observ ations per test ( 4 ru s × 2 ty res) and then

using the folowing formula:

where:

8 Test report

The test report shal include the fol owing

information:

a) a reference to this International Stand rd ;

b) the id entification of the tested ty re;

c) the rim wid th ( code);

d ) the ty re ov eral diameter ( mm);

e) the ty re load ( kg );

f) the inflation pres ure ( kPa);

g ) the ambient air temperature ( °C);

h) the test spe d ( km/h);

i the test distance ( m);

j) the test result ( rol ing cir umference in mm);

k) the d te of the test ( y ear-month-d y )

9 Other test conditions

I d esired and ag re d upon among the interested

p rties, rol ng cir umference u der other

conditions ma be determined b folowing the

a ov e method of test The test report must clearly

ind icate that results were obtained u der

non-stand ard cond itions which shal be d efined

RC = rol ing cir umference, in mi imetres;

S = test cour e leng th, in metres;

ipr = n mber of impulses per ty re rev olution;

I = av erag e n mber of impulses recorded per

test

RC

10 0×S×ipr

I

=

© BSI 0 -1 9

Annex A (informative)

Bibl og ra phy

ISO 4251-3:19 4, Tyr es (ply r a ting ma r ked s r ie ) a nd r ims fr a gr icul ur a l tr a ctor s a nd

ma chine —Pa r t 3: R ims

ISO 11795:

1997

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