Could you clear something up for me – the David Loom is a “sinking shed jack” – does that mean that it is a counterbalance loom?
The David Loom is a sinking shed loom but it is not a counterbalance loom. Counterbalance looms work with 2 sets of rollers. When you tie-up a treadle to any combination of shafts then you have an opposite movement of what has not been tied-up.
The David has shafts that are attached to cams and springs inside the castle. All the harnesses always live in the up position of the shed and then what you tie-up moves down through the midpoint to the bottom of the reed giving you a sinking shed action (which means only one part of the warp moves) but you have a counterbalance shed which gives you equal tension on both parts of the warp. Louet is the only loom manufacturer to use this system….they invented it. You have no sag in your warp ever and you get no rolling of the weft inside the shed which are both problems with traditional jack looms. I hope that makes sense to you.