I am familiar with the general workings of a torque converter. The engine-side blade pushes the fluid, the fluid spins the transmission-side blade. What I am all fuzzy about is, for lock-up torque converters, the tranny-side blade gets physically bonded to the engine-side blade above certain RPMs.
HOW does this happen? Is it a clutch-like friction thing? I've read different things in different places, so are there different implementations from different manufacturers?
There is an internal clutch that locks the converter when engaged by the torque converter clutch solenoid. Fluid pressure it routed through the input shaft into the converter clutch, which engages the clutch.
If it is non electronic transmission it uses a pressure switch inside the transmission to engage the solenoid (gm calls it a tcc solenoid) at a given speed and current gear (gear is usually 3rd and overdrive, if electronic, the trans computer controls lockup using the solenoid. When it engages it depends on make/model of transmission and software programming.
