Newsham Engine circa 1730
Fig #5: Chain Mechanism at Maximum Extension.
When the treadle to the right of this illustration is all the way down, as shown here, the chain on the same side is fully extended. The chain on the left side lies deep in its groove.
As seen in photos, the treadle system of Newsham engines in museums is often missing. The bow-tie gear is also gone. It could be that some users found them cumbersome, especially if they did not have a trained department.