Curious what diameter the hydraulic lines of the space shuttle thrust vector control system might have been. Even a ballpark figure would be OK. Is this info by chance public?
Here's an approximate answer.
This is the right Space Shuttle Main Engine (SSME) mounting "hole" on Orbiter OV-104 (Atlantis). The yellow cylinders sticking out are covers over the shafts of the Thrust Vector Control actuators.
Zooming in, we can see the hydraulic lines to/from the pitch actuator as well as the bolt circle for the gimbal bearing.
The SSME Orientation p.10 says the gimbal bearing is about a foot wide. So the hydraulic lines are around an inch in diameter, roughly speaking.