OECD AGR/CA/T (2000)25 Comparison between hydraulic power tests carried out according to OECD Code 1 and ISO 789-10

The ISO 789-10 standard "Hydraulic power at tractor/implement interface" was updated in 1996 and the revised version was distributed to delegates for discussion at the 1997 Annual Meeting of Designated Authorities [AGR/CA/T(96)20]. Delegates agreed that the amendments of OECD Code 1 with ISO 789-10 would be substantial and did not appear desirable. The Turin testing station proposed carrying out comparative tests on different tractors in accordance to both methods, to verify the differences in measurements [Summary Record AGR/CA/T/M(97)1, item 17]. 2. At the 9th Biennial Test Engineers' Conference in Omiya, Japan, the Turin station presented document AGR/CA/T(97)33 regarding instruments and components used to set up test equipment verifying the hydraulic system performance in accordance with OECD Codes and ISO 789-10. Procedural differences were described in order to give a clear view of each of the two methodologies. Increase in cost and time necessary to carry out hydraulic power tests following the ISO 789-10 was highlighted. Moreover, equipment needed seemed to be very expensive if outlying and uncertain values were to be avoided. After discussion, Delegates found it was premature to agree on the relevance of ISO 789-10 for OECD testing. A Working Group led by the Turin Station and including Japan, USA, Germany and UK was established to conduct more experiments on the subject [Summary Record AGR/CA/T/M(97)2, item 7]. 3. Interest in adoption of the ISO standard as an acceptable test method in OECD Codes wherever possible encouraged the US delegation to present an amendment to the OECD hydraulic power test [AGR/CA/T(99)19]; this amendment would make mandatory those portions of ISO 789-10 that are similar to the current Codes 1 and 2 requirements, and additional tests specified in the ISO standard would be considered optional on manufacturer's request. The proposal was discussed during the 10th Biennial Test Engineers' Conference in Prague and once again the difficulties for adopting ISO 789-10 in the OECD Codes were pointed out. The Turin Testing Station was invited to pursue the inquiry on hydraulic power behaviour under both tests [AGR/CA/T/M(99)2, item 7]. 4. In the present paper, the Turin testing station submits recent results of comparative tests on agricultural tractors hydraulic system performed according to OECD Code 1 and ISO 789-10.