Spring Levers

How a rising shed system doesn't use jacks.

AVL employs a rising shed system like no other. Thanks to the original engineering genius of Jim Ahrens (the “A” in AVL), treadling on an AVL is unbelievable. Here’s why: due to the Spring Lever System, the more you press down on a treadle, the easier it gets. The AVL Rising Shed System is not a jack loom. Like many other parts on the AVL loom, Mr. Ahrens borrowed ideas from power looms, so that the AVL loom is truly an example of intermediate technology – a handloom that uses power loom technology.

The roots of the Spring Lever System form an interesting “back-story”. The earliest reference we can find dates back to an 1894 book by Thomas Fox “The Mechanism of Weaving”, so surely the Spring Lever idea predates the Spanish American War, The Columbian Exposition and Henry Ford’s first automobile. Fox called it Kenyon’s Reversing Motion and it confirmed what Jim brought back with his Spring Lever System; as the shed opens the weight is transferred. Here are Kenyon’s figures:

Thus showing the early Spring Lever System had displaced over 50% of the weight of the harnesses. Below is a drawing from Fox’ book: