The valve body on an automatic transmission fascinates me. It’s a maze of passages directing pressure changes in hydraulic fluid from electronically controlled solenoids. That orange ribbon (below) controls those solenoids based on the electric shift lever signal and physically coming through the orange plastic piece. This fluid movement through tiny passages changes gears powering a two-ton van down the road. Hydraulic fluid is something else. But what really blew my mind, coming from a world of manual transmissions with steel rods, couplers and u-joints, is that part of this control comes down to a paperclip sized wire. See that red arrow pointing to that wire? That’s it. The floor mounted shift lever action in this Eurovan is transferred to a small plunger rod the size of 1/3 of a pen by this wire. When moved in and out of gear, park to drive, the wire pulls this “plunger rod” to redirect fluid in the valve body along with the solenoids to change gears.
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