🔰 The first practical, fully operational spiral escalator in the world by Mitsubishi Electric was installed in 1985 at the International Exhibition Center in Osaka, Japan.
It was a monumental achievement in vertical transportation engineering because it overcame a mathematical problem that had baffled engineers for nearly a century: how to keep the step chains moving at different speeds along the inner and outer radiuses of a curve without binding, snapping, or wearing out.
📌The Breakthrough: The "Centralized Motion Method":
To make the 1985 installation possible, Mitsubishi Electric invented the Centralized Motion Method (often referred to as the Center Shift Method).
🔗 The Problem :
On a standard straight escalator, the mechanical chain moves at a fixed speed in a single vertical plane. If you bend that track into a circle, the outer edge of the curve is physically longer than the inner edge. A rigid, traditional escalator chain cannot handle this; the outer side would need to move faster than the inner side, causing the steps to tilt, twist, and jam.
🔐 The Solution :
Mitsubishi’s engineers designed a complex system where the center point of the escalator's circular trajectory dynamically shifts as the steps move.
•As the escalator transitions from the flat landing into a steep 30° incline, the radius of the curve changes.
•The system recalculates the arc by moving the theoretical rotation center across three distinct coordinate zones.
•Specialized spherical joints and custom-engineered guide rollers allow the chains to twist and flex in a true three-dimensional path, maintaining perfectly uniform tension.
🔰Manufacturing Precision:
Because of the immense complexity of these machines, they cannot be mass-produced.
•Handmade Craftsmanship (Takumi): The structural box beams and track rails must be meticulously bent and twisted by hand at Mitsubishi’s Inazawa Works in Japan.
•0.1 mm Tolerances: To prevent the curved steps from rubbing against the side panels (skirt guards), the entire structure must maintain a manufacturing tolerance of less than 0.1 millimeters.
✨️Since that first 1985 installation in Osaka, Mitsubishi Electric has remained the only commercial manufacturer of spiral escalators in the world, holding a 100% market share for this specific technology. Because they are highly complex and expensive, only slightly over 100 units exist globally.
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