Locomotive Transfer Table

This project hails from the White River & Northern II, and as such constitutes one of the earliest animated devices I'd made (the only one older was the first water tower). It's a relatively simple-looking model with a somewhat complicated mechanism behind it.

It's based on the principle of the drafting table ruler, which is parallel no mater where it's positioned, thanks to a crisscrossed loop of thread. In the case of the transfer table, the monofilament thread (blue) that moves the bridge runs right against the rails in the pit, and are connected to the bridge between the wheels at each end. The rest of the thread runs under the pit, so nothing is visible.

Moving the table is a low-RPM motor with a capstan: the thread wraps around it once or twice, which is sufficient to grip the thread. Positioning is done by eye. Also, power to the bridge rails is supplied by the pit rails, and the wheels on the bridge transfer the power to the locomotive.

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