General transmission question.

[JayArr]

I've been watching 4l60E videos that show disassembly and assembly but they seem to assume I understand how it works.

I get the whole planetary gear thing and the band on the input drum and the intermediate shaft. What I don't get yet is how the maze in the bottom sends fluid to the pistons to compress the various clutches. I assume it's the pistons that push on the clutches.

Is the center shaft hollow with channels in it such that it picks up fluid from somewhere where it's supported at the body of the case and then releases it to the piston farther up the shaft?

Or does the pump apply pressure to a channel in the center of the shaft that feeds all the clutches and the valves in the bottom close off to energize a particular clutch or leave the flow open to leave the clutch uncompressed?

How is the fluid getting from the valve body to the piston?

 

[Mounce]

Fluid flows through small passages just like the oil passages in the engine as far as I know. Good question though as I'm not certain on it myself. Shafts are solid though as far as I know, minus the input staff having a couple layers for torque converter mating.

 

[mrrsm]

This ATSG THM-4L60E PDF Service Manual gets into the absolute "Nitty-Grtitty" of everything about the 4L60E... including the Valving and Shifting Pressure issues for controlling the Dexron ATF through the maze of fluid flow paths and may have the answers you seek: