DLG Test Report 6223 F

www.DLG-Test.deTest Center

Technology and Farm Inputs

Bridgestone Europe NV/SA

Agricultural Tyres for TractorsTraction/slip and fuel consumption in the premium category

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The Product

The Focus Test is a utility value test conducted by the DLG for product differentiation and special highlighting of innovations in machinery and technical products used predominantly in agriculture and forestry, in vegetable, fruit and wine growing, and in landscape care and municipal applications. In this test, the focus is on testing individual quality criteria of a product, such as durability, perfor­mance or quality of work.

The scope of the test can include criteria from the testing framework of a Signum Test, the DLG’s com­prehensive utility value test for technical products, and concludes with the publication of a test report and the awarding of the test mark.

The DLG Focus Test “Agricultural Tyres for Tractors” includes examina­tions of fuel effi­

ciency during fieldwork under cons­tant speed conditions, as well as determining the maximum traction under defined slip conditions. The measurements were carried out on the following sizes of Bridge­stone VT­Tractor tyres in the VF category: VF600/70 R30 on the front axle and VF710/70 R42 on the rear axle.

For the purpose of classifying the measurement results, figures were also recorded for the wheel combi­nations of the same sizes from two other well­known European manu­facturers of premium tyres opera­

ting under the same conditions. On account of the increased load capacity of a VF tyre compared to an IF tyre, the test pressure of the Bridgestone tyre could have been further lowered to 1.0 bar on the front axle (FA) and 0.8 bar on the rear axle (RA). For the pur­pose of a neutral comparison, how­ever, all of the tyres were tested with the same pressures: 1.2 bar (FA) and 1.0 bar (RA).

Since the competition does not offer VF tyres in the selected dimensions, the test was carried out with IF tyres as a comparison. Here, the pressures of all test candidates were set uniformly in accordance with the tyre pressure tables, and the Bridgestone tyres were adjusted accordingly.

Overview

Manufacturer and Applicant

Bridgestone Europe NV/SA Kleine Kloosterstraat 10 1932 Zaventem Belgium

Product: VT­Tractor VF

Contact: www.bridgestone.eu

Description and Technical Data

Technical information and data are available on the manufacturer’s homepage.

Figure 2:Towing tractor and braking tractor

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Table 1: Overview of results

* Evaluation range: + + / + / / – / – – ( = Standard, N.E. = No Evaluation)

Test characteristic Evaluation

Traction/slip behaviour + in slip ranges > 15 %

Specific fuel consumption +

Area treated per hour

Compared to their competitors, the Bridgestone tyres achieved the best results in the “Traction/Slip Behaviour” category, especially in the range above 15 % slip. In the range below 15 % slip, the VT­Tractor performed at an equal level to that of the other candidates.

The Bridgestone tyres dominate in the section of the test aimed at assessing specific fuel consumption, performing better than the other two candidates under the specified operating conditions. Here, they achieved an advantage of approxi­mately 3 % compared to the calcu­lated average consumption.

Assessment – Brief Summary

In terms of area worked per hour, all three tyres achieved similarly good results, due in part to the similar traction/slip results in the

lower slip range. In this case, the average value for all test subjects was 4.75 ha/h with a deviation of ± 1.2 %

The Method

The tyre sets to be tested were fitted to a towing test vehicle, in this case a John Deere 8335R with continuously variable transmission. The load was simulated with a braking vehicle which, in this case, was a John Deere 7280R that also had continuously variable trans­mission. The two tractors were connected with a steel cable with an integrated traction load cell. In addition, a Peiseler wheel was attached to the drawbar of the towing vehicle. This provided the actual driving speed during the tests. The wheel slip was deter­mined from the measurement of the towing vehicle’s wheel speed and the rolling circumference of the tested tyres. The fuel consump­tion was recorded using a volume­tric measurement system on the towing vehicle for the purpose of determining the efficiency.

The test procedure was identical for each tyre set. In the first sub­test, the fuel consumption was determined with a constant speed setting on the towing vehicle’s cruise control, as well as a con­stant traction load from the braking

Figure 3: Test field ground conditions (wheat stubble, trimmed; ground type: loess loam; average soil moisture in test field: 9.85 %, measured at a depth of approx. 10 cm at 21 measurement points)

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Table 2: Test details

Bridgestone Reference A Reference B

FA RA FA RA FA RA

Test combination VT-Tractor VT-Tractor

Size VF 600/70 R30 VF 710/70 R42 IF 600/70 R30 IF 710/70 R42 IF 600/70 R30 IF 710/70 R42

Average tread depth [mm] 54 63 53 58 47 60

Test pressure [bar] 1.2 1.0 1.2 1.0 1.2 1.0

Max. stat. load capacity according to manufacturer [kg]

4235 5630 3650 4850 3590 4805

Offset at test pressure [%] 4.2 2.0 1.3

Weight of test vehicle [kg] 7665 7400 7665 7400 7650 7415

vehicle. This was based on load data measured on a cultivator during standard stubble cultivation in the field.

In the second sub­test, the aim was to determine the maximum trac­tion under real slip conditions with the prevailing ground conditions at the testing location. For this pur­pose, a constant speed was set on

the towing vehicle and the traction requirement was continuously increased via the braking vehicle up to a wheel slip of 40 %. With regard to moisture, the prevailing ground conditions at the time of the test were recorded by random sampling over the entire test field.

All tests were carried out with new tyres in the combinations listed

below and according to the cus­tomer’s specification. For the pur­pose of comparability of measure­ment data, the same air pressure was set for all tyre combinations, even though the Bridgestone tyres are VF tyres and not IF tyres like the other test subjects.

The Test Results in Detail

In the first sub­test, the specific fuel consumptions shown in Figure 4 were measured with an approxi­mately constant traction require­ment of approx. 50 kN. This shows that, according to the work done under the testing conditions, the best fuel consumption result was

Are

a tr

eate

d p

er h

ou

r [h

a/h

]

0,0

1,0

2,0

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4,0

5,0

6,0

4,81 4,76 4,69∅ During test: 4,76

Bridgestone

Reference A

Reference B

240

240

349359

370

∅ During test: 359

260

280

300

320

340

360

380

Sp

ecifi

c fu

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sum

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[g/k

Wh]

Bridgestone

Reference A

Reference B

Figure 5: Results for consequential area treated per hour

Figure 4: Results for specific fuel consumption

recorded by the Bridgestone tyre in comparison to the reference pro ducts.For the tractor settings, the boun­dary conditions of the reference attachment – in this case a cultiva­tor with a known working width and depth – were established and

the area worked per hour was cal­culated. The results are shown in Figure 5. Here, only minor diffe­rences were observed between candidates, in the region of ± 1.2 % from the calculated average. This corresponds to a difference in area per hour of approximately 0.06 ha

DLG Test Report 6223 F Page 5 of 6

10

0

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30

40

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5 10 15 25 30 35 40Tr

acti

on

[kN

]Wheel slip on rear axle [%]

20

BridgestoneReference AReference B

7 %32

3243

46

4249

75

7165

92

8281

98

9393

101

95 95

103

99 98

103

102100

10 % 15 % 25 % 30 % 35 % 40 %20 %Bridgestone

Reference A

Reference B

Slip

10

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Figure 6: Results for traction/slip, curve

Figure 7: Results for traction/slip, scaled

Conclusion

During the simulated towing acti­vities, the tested Bridgestone VT­Tractor tyre combination showed its advantages over the reference tyres, particularly in the region above 15 % slip. Here, it achieved the highest traction values at the same level of slip.

In the region below 15 % slip, the Bridgestone VT­Tractor tyre con­sistently performs at the same level as its well­known competitors; sometimes even better. This also

has an impact on the measure­ments of specific fuel consump­tion. The difference here is around 10 g/kWh, which corresponds to approx. 3 % of the average value under the given conditions and using the previously described test tractors.

No significant differences were observed with regard to area worked per hour. This is undoub­tedly due to the fact that the slip ratios used at constant speed dur­

ing the test were below the afore­mentioned 15 % limit.

All in all, this shows that, under the conditions used in the test, the new Bridgestone VT­Tractor VF tyre can indeed be classified in the premium tyre category.

on average. This result was influ­enced by the working speeds resul­ting from the different slip condi­tions and the different offset con­ditions.

During the second sub­test, the Zaim was to determine the maxi­mum achievable traction under increa sing slip conditions. Figure 6 shows a comparison of the slip levels achieved at the same level of traction. Due to the relationship between working speed and driving speed, there is a direct correlation here with the performance and with the fuel efficiency. To provide a better and more detailed over­view, the obtained results are shown again in scaled format in Figure 7.

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DLG e.V.Test Center Technology and Farm InputsMax­Eyth­Weg 1, 64283 Groß­UmstadtTelephone +49 69 24788­600, Fax +49 69 24788­690tech@DLG.org ∙ www.DLG.org

Further Information

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More information about the Net­work is available at www.entam.com or by writing to ENTAM at the email address: info@entam.com

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Around 180 full­time staff and more than 3,000 expert volunteers develop solutions to current pro­blems. More than 80 committees, working groups and commissions form the basis for expertise and continuity in technical work. Work at the DLG includes the preparation of technical information for the agricultural sector in the form of instruction leaflets and working documents, as well as contributions to specialist magazines and books.

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* Reporting engineer

2014­252

© 2014 DLG

Test execution

DLG e.V., Test Center Technology and Farm Inputs, Max­Eyth­Weg 1, 64823 Groß­Umstadt

Field

Vehicle technology

Project manager

Dipl.­Ing. (FH) Andreas Ai

Test engineer(s)

Dipl.­Ing. (FH) Niels Conradi *

Additional test reports on agricul­tural tyres are available to down­load at www.dlg.org/traktoren-zubehoer.html. The DLG Competence Center Agriculture and Food Business has published an instruction leaf­let entitled “Reifen richtig wählen und einsetzen” [Selecting and using the right tyres] (Instruction Leaflet 356). This is available free of charge in PDF format at www.dlg.org/merkblaetter.html