Bergdala Spinnhus

Reflections on counterbalance looms

This article will describe the most common Swedish 4-shaft counterbalance loom, with one pulley and two "horses" each side.

There is also a part 2, which describes "dräll" pulleys - or many-level pulleys.

The most common Scandinavian counterbalance (CB) loom has one pulley which holds two horses in each side. This setup can handle two, three or four shafts, depending on how you tie the horses to the shafts.
The shafts are assumed to be the usual Swedish style: one shaft consists of two sticks held together by the heddles. Heddles can be Texsolv or string, never metal.

Swedish looms have looked like this for centuries, with only small variations.
Usually, they can be broken down into two side pieces and a pile of sticks. Usually they are held together by wedges. (This was because the looms were used only during "weaving season", winter, - the rest of the time they were put away to make place for other activities.)

This article will, hopefully, describe the mechanics of such a loom.

old 4-shaft counterbalance loom

Starting with only two shafts (and no horses), looking at one of the pulleys from the side:
The shafts are connected by a cord over a pulley: if one shaft goes down, the other shaft comes up.
For some reason, in the American weaving literature, this is often called a "sinking shaft" loom. In reality, both shafts are affected and travels the same distance – one comes down, the other comes up. This happens because of the mechanics.

two shafts joined over the pulley

At some point in history, weavers saw that they could easily add more shafts by adding "horses".
A horse is, in essence, a stick with a hole in the middle. The ends may have a slit or a notch to hold the cords that attach the top shaft bar(s). The hole in the middle holds a cord that goes over the pulley and connecta to the other horse of the pair.

a pair of horses
Now it is the horses that are connected over the pulley, and the horses are connected to the shafts.
A schematic view from the top, and a photo:
a folding 4-shaft loom
Let the horses hang level, and lower the two foremost shafts – the two back shafts go up, and the horses are still level (but not at the same height).
The function is the same as above, with the difference that there are two shafts on each side of the pulley.
shafts 1 and 2 down, make shafts 3 and 4 go up
Next logical step: the horses can tilt.
If a tabby is treadled (assuming a straight threading), the horses pivoting point stays at the same level, but the horses themselves tilt. This means that shaft 1 and 3 go down, and because of the mechanics, shafts 2 and 4 go up.
Now, if we combine the movements: say that we want shafts 1,2 and 3 to go down, the following happens:
The front horse goes down (and stays level) - therefore the back one comes up, and tilts.
With correctly tied treadles, this will give an "unbalanced" shed.
The same happens if we want only one shaft to go down: the horse of that shaft tilts, and goes down – the other horse comes up, like the shaft connected to the top of the tilted horse.

Note: this works the same whether using a "direct" tie-up (and thus using both feet) or using a regular tie-up (and thus tie more than one shaft to each treadle).

tree down, one up
And... just to prove that the resulting sheds are adequate and even, some pictures from the side:

This loom is a small folding one, with the brand name Göta. Let me call it a "compromize" loom, meant to be easily moved, folds with warp in place.
A real floor loom is typically deeper and has a taller castle. The taller castle allows for longer cords and longer horses, which both allow for taller sheds.

Left to right: two up-two down; tabby (1 up, 1 down, 1 up, 1 down); three up, one down
left: 2/2; middle: 1/1/1/1; right: 3/1
And that is all there is to it!

For part 2, about conterbalance with "dräll" pulleys, click here!

  © Kerstin Fröberg 2016