This mechanism is a compact rotary fluid joint that allows fluid to pass through a spinning shaft without leaking into the surrounding housing. The yellow shaft contains an internal flow path, and the green elbow fitting delivers the incoming fluid. Several O-rings sit in grooves along the shaft, creating radial seals against the transparent outer sleeve. These seals tolerate continuous rotation while maintaining pressure retention, letting the connector move without interrupting the flow.

Components — Yellow rotating shaft with internal port, green fluid elbow, transparent stationary sleeve, O-rings in machined grooves, threaded nut, and end cap.

How it works — When fluid enters through the green elbow, it flows into a port on the yellow shaft and continues down its center. The shaft can rotate freely because the O-rings form sliding radial seals between the shaft and the transparent housing. As the shaft turns, the rings ride smoothly on its surface, preventing fluid from escaping while allowing rotation with minimal friction. The threaded nut and end cap secure the assembly, keeping the sealed interface properly compressed.

Applications — Coolant supply to rotating tools, small rotary unions, laboratory equipment, packaging machines, and any device requiring fluid transfer through a rotating element.

Why it matters — The design enables fluid routing through a shaft that cannot remain stationary, eliminating the need for external hoses that twist or tangle. Using simple elastomeric seals, it delivers reliable leak prevention in a compact and inexpensive assembly.