第五教 · Dai Gokyo
Osoto Guruma 大外車
Major Outer Wheel
Mechanic
Tori drives uke's upper body backward while stepping in deep, laying one leg as a rigid bar across the back of BOTH of uke's legs. With both legs blocked at once, uke can't step back to save themselves and wheels over the bar onto their back.
Analogy
Someone strolls backward without looking and a knee-high garden fence catches them across the back of both legs at the same instant. Their feet stop dead, their shoulders keep going, and they rotate helplessly over the rail like a plank tipping over a ledge.
Why it maps
The fence is tori's extended leg: a fixed horizontal bar behind both knees that turns a backward push into a wheel, because neither foot can step back to rescue balance.