Model (scale 1:2) in iron of steam power loom, with tappet motion with spool of yarn and material in process, patentee Bennet Woodcroft, England, c. 1838.

This is a model of a nineteenth century iron steam power loom. In the power loom, rotation of the main shaft causes separation of the warp threads to form the 'shed', the passage of the shuttle through it, and the other necessary motions for the automatic weaving of cloth. Typically, as here, each turn of the shaft corresponds to one 'pick', or passage of the shuttle. As in the handloom, the warp threads are raised and lowered by 'heddles'. Here there are four, which would allow the weaving of a twill or similar pattern. However, unlike in the handloom where the heddles are moved by treadles, in this loom they are worked by 'tappets' or cams at one end, rotated through gearing from the shaft. The model illustrates the use of 'Woodcroft's positive tappets' which were made and fitted in segments and could be altered to change the pattern of weaving. Iron framing, introduced around this time in place of wood, became essential as looms were run faster.