I’ve had that question on my mind that has been increasing in curiosity lately and this is just the place to ask I imagine. My understanding of a dual clutch transmission is there are two multi-plate clutch packs arranged concentrically. There is an output shaft going through each of them. One is hollow and that is connected to the larger clutch-pack and handles the odd gears while the smaller clutch pack is inside the hollow driveshaft and drives the even gears. From there, the engine and ECU are able to determine what the next gear is and serve up the next gear and clutch almost instantly (8ms is the VW shift time I’ve found on a Borg-Werner DSG system).

Based on some wikipedia and YouTube it looks like most DCTs are wet-packs meaning they are cooled using oil. That same oil is then used to create hydraulic pressure to sandwich the clutch pack together to actuate one of the clutch packs.

So here’s my question, how is that hydraulic pressure regulated? What is performing that hydraulic actuation in 8ms?

Here’s what I was able to find: