T 0055/86 15-03-1988

I. European patent No. 0 014 575 was granted with two claims on the basis of European patent application No. 80 300 309.4 on 2 March 1983.

II. The patent was opposed in due time and form on 22 August 1983. The Opponent requested revocation of the patent on grounds of lack of inventive step in the light of DE-C-2 152 996 and of DE-C-1 131 535.

III. On 26 April 1984 the Patentee contested the arguments of the Opponent, filed new Claims 1 and 2, suggesting also amendments to the description and requested that the patent be maintained in the amended form.

IV. In the Interlocutory Decision within the meaning of Article 106(3) EPC, dated 2 January 1986, the Opposition Division maintained the patent as amended on the basis of the documents specified in the communication pursuant to Rule 58(4) EPC, dated 6 November 1984, and incorporating the above-mentioned new Claim 1.

V. The Opponent appealed against this decision on 29 January 1986, at the same time paying the appropriate fee. In his Grounds for the Appeal, filed 3 February 1986, the Appellant (Opponent) argues for revocation of the patent in its entirety. He is of the opinion that the characterising feature of Claim 1 is known from DE-C-2 152 996, and that it would be obvious for the person skilled in the art, wishing to eliminate the check valve before the circuit protection valve, to replace the fluid pressure biased members in the relay valves by spring biased members.

VI. In his observations, filed 12 may 1986, on this statement of the Appellant, the Respondent (Patentee) requests that the appeal be dismissed. He argues that in fact GB-A-1 397 307, mentioned in his patent, represents the nearest prior art. Moreover, even if one considers the disclosures of both GB-A-1 397 307 and DE-C-2 152 996 together, it would not be obvious for the person skilled in the art to adopt the present invention in order to dispense with the non-return check valve.

VII. In a response filed 19 November 1987 to a communication from the Board setting out its provisional opinion that DE- C-2 152 996 represents the nearest prior art, and that the subject-matter of Claim 1 appears to lack an inventive step in the light of the disclosures of DE-C-2 152 996 and GB-A- 1 397 307, the Respondent made the following observations:

(a) The present invention arose as a result of an expectation of a higher level of residual braking on trailers and the simplicity of the system of EP 0 014 575 to achieve this as compared with that of DE-C-2 152 996 is self-evident.

(b) The subject of higher levels of residual braking with two-line control of trailers had been of continuing interest over the period covered by these patents. In spite of this, there appears to have been no substantial advances between October 1971 and Patentees' proposal of February 1979, which is now energetically argued against by Opponent's.

(c) The reduced complication of Patentees' system resides not only in the fact that the mentioned check valve is dispensed with but also in that the practical realisation of the valve assemblies 10 and 12 of DE-C-2 152 996.

The need inter alia for dividing walls 59, 60 and associated seals is clearly avoided by virtue of the invention.

(d) In DE-C-2 152 996 it is to be noted that it is necessary to provide at least one further check valve 18 for maintaining pressure in line 7 during an emergency brake application. Moreover, with only one such check valve as shown therein only the reservoir 15 is able to supplement the pressure in pipe 7 for the purposes of establishing emergency brake application. Accordingly, if there is a loss of pressure in reservoir 15 due to a failure, emergency operation of the remaining circuit using pressure from reservoir 16 is likely to be seriously impaired. Although braking regulations may not demand that the eventuality of two faults shall be catered for, this is clearly an advantage with the present invention without check valves.

(e) Whilst it is not denied as known that fluid pressure biasing can be replaced by spring biasing in appropriate applications, until filing of the opposed patent, skilled engineers had either failed to realise or had rejected such possibility in the present context. Only after the Patentees' disclosure has Opponent's now appreciated the practical and cost advantages to be achieved by apparatus as claimed in the patent.

VIII. At the oral proceedings held on 15 March 1988 at the request of the Respondent, both parties re-iterated their arguments, and the Respondent filed new Claims 1 and 2, (based on the disclosure of DE-C-2 152 996 as the closest prior art), amended during the oral proceedings to read as follows:

1. A trailer or semi-trailer vehicle fluid pressure braking apparatus for two-line operation including first and second relay valves (10, 11) responsive to the magnitude of fluid pressure in a first brake control line (2) to apply braking pressure respectively from first and second reservoirs (6, 7) to independent brake pressure circuits, said first and second reservoirs being chargeable via circuit protection valve means from a second emergency/supply line, which enables charging of one said reservoir from the second line even with excessive loss of air from the other reservoir, at least one said relay valve having a pressure responsive member with a discrete fluid pressure-responsive area (31) connected to be subject to pressure at a second emergency/supply line and being such that collapse of fluid pressure in the second line enables said member to cause an emergency brake application by the respective circuit regardless of the fluid pressure in the first line and characterised by said member being biased by a spring, which is normally counteracted by the presence of said fluid pressure in the second line and the, or each, reservoir, which is supplying a said at least one relay valve being connected directly to the second line for charging via the circuit protection valve means (4, 5).

2. A braking apparatus as claimed in Claim 1, characterised by both said relay valves having a spring biased pressure responsive member with a discrete fluid pressure-responsive area (31) connected to the second line, to cause an emergency application by the respective circuit regardless of the fluid pressure in the first line.

IX. The Appellant (Opponent) requests cancellation of the decision against which he is appealing and revocation of the European patent in its entirety. The Respondent (Patentee) requests that the appeal be dismissed and the patent maintained on the basis of Claims 1 and 2 as filed and amended during the oral proceedings on 15 March 1988.