page_title: Jacquard machine
section_title: Principles of operation
hierarchical_section_title: Jacquard machine / Principles of operation
caption_attribution_description: Italiano: Telaio Jacquard tratto da Nuova enciclopedia popolare. 13
context_page_description: The Jacquard machine is a device fitted to a loom that simplifies the process of manufacturing textiles with such complex patterns as brocade, damask and matelassé. The resulting ensemble of the loom and Jacquard machine is then called a Jacquard loom. The machine was invented by Joseph Marie Jacquard in 1804, based on earlier inventions by the Frenchmen Basile Bouchon, Jean Baptiste Falcon, and Jacques Vaucanson. The machine was controlled by a "chain of cards"; a number of punched cards laced together into a continuous sequence. Multiple rows of holes were punched on each card, with one complete card corresponding to one row of the design. Several such paper cards, generally white in color, can be seen in the images below. Chains, like Bouchon's earlier use of paper tape, allowed sequences of any length to be constructed, not limited by the size of a card.
  Both the Jacquard process and the necessary loom attachment are named after their inventor. This mechanism is probably one of the most important weaving inventions as Jacquard shedding made possible the automatic production of unlimited varieties of pattern weaving.
context_section_description: On 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.  The box swings from the right to the position shown and presses against the control rods (2).  Where there is a hole the rod passes through the card and is unmoved whereas if the hole is not punched the 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 those hooks in the rest location are raised; the hooks that have been displaced are not moved by the beam.  Each hook can have multiple cords (5).  The cords pass through a guide(6) and are attached to their heddle (7) and a return weight (8).  The heddles raise the warp to create the shed through which the shuttle carrying the weft will pass.  A loom with a 400 hook head might have four threads connected to each hook, resulting in a fabric that is 1600 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 looms 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 so many different weaves from one 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 warps are then tied into the existing warp with the help of a knotting robot which ties each new thread on individually.  Even for a small loom with only a few thousand warp ends the process of re-threading can take days.
caption: 19th century Jacquard loom
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