Leclerc Back-Hinge Treadle Loom Evolution

Leclerc's Back-Hinge Treadle (BHT) loom design moves the pivot point of the treadles to the back of the loom which allows them to be lengthened giving the weaver greater leverage which makes the loom much easier to treadle.

Over the years, the Back-Hinge Treadle system used on Leclerc looms has evolved to the design currently available on looms like the Artisat, Colonial v2, Nilus and Nilus II. It has also been used on earlier models like the Nilart and Colonial I.

The Back-Hinge Treadle design went through quite a lot of iterations before the current approach was adopted back around 1999. A number of Nilart looms are still in use and are very different in design. This document shows some of these differences and expalins why changes were made to help owners make the looms operational. For these early designs, parts are not available and the documentation is very limited.

Pictures of any other variations which we may not have seen yet and assembly manuals for these looms are welcome and will help up expand the information we can provide on these looms. Our current collection of manuals can be found by clicking here


The Rocker

Unlike the regular Front Hinged treadles found on most older Leclerc looms, treadles attached at the back do not provide the same angle for the tie-ups needed to get a clean shed (ie. each shaft should rise slightly more than the one in front of it). When depressed they tilt in the opposite direction. To get the needed angle, Leclerc added an angled block of wood to the treadle with the eyescrews that the cords connect to. Initially this block was fixed, but, when not depressed, the angle caused the treadle weight to all be applied to one lam rather than be distributed across all the lams it was attached to. This caused the shafts attached to this lam to rise when they shouldn't.

Leclerc solved this by making the block of wood pivot so it automatically adjusted to distribute the weight across all the attached lams. They then needed a way to make sure this "rocker" piece was tilted to the correct angle when the treadle was depressed (lifted up at the front) and the first approaches were to put a "C" shaped bar on the side of the rocker or a screw sticking out from the bottom. Either of these would lift the front of the rocker when the treadle was depressed enough for the screw or bar to hit the frame below.

On a loom with floating treadles, the leverage changes on each treadle depending on how far it is from the center. As treadles move outward they get easier to push down but must be pushed down farther to get the same shed height as the center treadles. We believe by adjusting the screw on the base of the rocker the weaver could control how far the treadle could be depressed but on the versions with the "C" shaped bar, a sloped piece of wood was mounted on to the front floor beam under the treadles that allowed the treadle to go down further depending on how far they were from the center.

Eventually Leclerc realized that instead of having something underneath the treadle control the tilting of the rocker, a better approach is to tilt the rocker with a cord from above. This design not only simplified the design by running a cord from the jack box down to the rocker, it also made it easy to adjust how far the treadle could be depressed by shortening or lengthening the "Rocker Cord".

The picture attached shows the original fixed block on the right, the screw and the bar approach in the tweo center pictures and the current Rocker Cord design on the left. The fixed block model used special Treadle Hooks that locked in place with the small latch shown in the picture.



Treadle Attachment

Most of the Nilart looms have a castle depth that allows up to 12 shafts. In the 1980 Leclerc came up with a deeper version that supported 16 shafts. Rather than making two different treadle lengths, they made a longer treadle for the 16 shaft and then put two round holes in the end so it could be used on both models. The main picture is the incorrect configuration as it shows a 12 shaft frame with the hole for the 16 Shaft frame being used. Looms with the 12 shaft castle should be configured as shown in the smaller picture to ensure the treadles do not stick out too far.



Treadle Separators

The original Back-Hinge Treadle designs did not have a means to ensure the treadles did not swing side to side but in later versions Leclerc added a board with a row of metal "U" shaped rods that ensured the treadles could only move up and down. This was normally at the back close to the treadle attachment point as shown in the middle picture but in later years Leclerc moved it to the center of the loom inside the castle as shown on the left picture. At one point Leclerc added hooks to the top of each of the Treadles and a wood bar with springs which supported the weight of the treadles in a similar fashion as the current Treadle Springs used on later versions.




Documentation

The information we currently have on these early Back-Hinge Treadle models is limited to a simple drawing on the Nilart loom Parts List.




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Last Updated: Thursday January 9th, 2025

We often get asked about early Leclerc Back-Hinge Treadle looms. These are usually Nilart models and have an early version of the BHT mechanism that is very different from what Leclerc is currently using and has been since about 1999. To help those who are trying to configure and assemble these early versions we have put together a collection of pictures with explanations of how and why we feel the design evolved this way. Any information, photos or documentation that adds to this description would be welcome and will help expand what we currently know about them. https://www.camillavalleyfarm.com/loomhistory/early_Leclerc_Nilart_Back_Hinge_Treadle_Loom_Design.htm