Editing Jacquard machine (section)

==Principles of operation==
[[File:Jacquard 2.jpg|thumb| A schematic diagram of the Jacquard system]]
[[File:Telaio Jacquard 1849.jpg|thumb|19th century [[Engineering drawing]] of a Jacquard loom]]

As shown in the diagram, the cards are fastened into a continuous chain (1) which passes over a square box. At each quarter rotation, a new card is presented to the Jacquard head which represents one row (one "pick" of the [[shuttle (weaving)|shuttle]] carrying the [[weft]]). The box swings from the right to the position shown and presses against the control rods (2). For each hole in the card, a rod passes through and is unmoved; where there is no hole, a rod is pushed to the left. Each rod acts upon a hook (3). When the rod is pushed in, the hook moves out of position to the left; a rod that is not pushed in leaves its hook in place.  A beam (4) then rises under the hooks, and the hooks in the rest position are raised. The hooks that have been displaced are not moved by the beam. Each hook can have multiple cords (5). Each cord passes through a guide (6) and is attached to a corresponding [[heddle]] (7) and return weight (8). The heddles raise the [[Warp (weaving)|warp]] to create the [[shed (weaving)|shed]] through which the shuttle carrying the weft will pass.<ref>{{Citation |last=Victoria and Albert Museum |title=How was it Made? Jacquard weaving |url=https://www.youtube.com/watch?v=K6NgMNvK52A |publication-date=2015-10-08 |publisher=Youtube |language=en |access-date=2022-06-18}}</ref> A loom with a 400-hook head might have four threads connected to each hook, resulting in a fabric that is 1600 [[Warp (weaving)|warp]] ends wide with four repeats of the weave going across.

The term "Jacquard loom" is somewhat inaccurate.  It is the "Jacquard head" that adapts to a great many [[dobby loom]]s that allow the weaving machine to then create the intricate patterns often seen in Jacquard weaving.

Jacquard-driven looms, although relatively common in the textile industry, are not as ubiquitous as dobby looms which are usually faster and much cheaper to operate. However, dobby looms are not capable of producing many different weaves from one [[Warp (weaving)|warp]]. Modern jacquard machines are controlled by computers in place of the original punched cards and can have thousands of hooks.

The threading of a Jacquard machine is so labor-intensive that many looms are threaded only once. Subsequent [[Warp (weaving)|warp]]s are then tied into the existing warp with the help of a knotting robot which ties on each new thread individually. Even for a small loom with only a few thousand [[Warp (weaving)|warp ends]], the process of re-threading can take days.