A hydraulic pressure intermediary includes: a platform, which has a bowl-shaped surface having an annular, platform-surface edge region, a platform-surface central region depressed relative to the platform-surface edge region and surrounded by the platform-surface edge region, and an annular platform-surface transition region, which borders, on its inner side, the platform-surface central region and, on its outer side, the platform-surface edge region; a bowl-shaped, separating membrane having a flat, annular, separating-membrane edge region, a separating-membrane central region depressed relative to the separating-membrane edge region and an annular separating-membrane transition region, which borders, on its inner side, the separating-membrane central region and, on its outer side, the separating-membrane edge region. The separating membrane is connected with the platform-surface edge region within the separating-membrane edge region along a surrounding joint. Further, the separating-membrane transition region includes an annular moat having a moat outer side, a moat inner side, and a moat transition zone, wherein the moat outer side has a first annular inclined surface, which borders on the separating-membrane edge region, the moat inner side includes a second annular inclined surface, which borders on the separating-membrane central region, and the moat transition zone extends between the first and the second inclined surfaces.