German to English Tech/Engineering Engineering: Industrial

I refer to our expert opinion on the rudder failure due to a hydraulic valve opening, and, following our meeting on 16/05/2013, would like to briefly summarise the main points, as it is difficult to understand the purely technical expert opinion at the level of its minute details.

>> Dem physikalischen Ansatz eines mechanischen Pendels, der Grundlage der Gutachten der Gegenseite ist, kann ich prinzipiell nicht folgen, da es sich ja um ein ***normalgängiges*** Ventil handelte und somit keine freie Bewegung des Hebels möglich war. > I can, essentially, not go along with the physical approach of a mechanical pendulum, which forms the basis for the opponent's expert opinion, as a valve ***opening and closing the regular way*** (???) was involved, and therefore no free movement of the lever was possible.

[Here's the story: two ships collide because of a rudder failure due to a hydraulic valve opening which it shouldn't. There is a lever involved and it gets pretty technical in the course of the dispute in Court, with the two parties' expert opinions being discussed by a third-party expert.]