Linkage Driven Dobby with Dwell

Abstract

The dwell zones of a shedding cam allow lower strain on the warp sheet compared to linkage driven dobbies for the same warp interference factor. Cam driven dobbies can be designed with dwell zones but they give higher jerk compared to linkage driven dobbies. This work explores the use of six-bar linkages for driving dobbies which will allow the healds to be in near-dwell condition during picking. The healds must be level at the same position in each loom cycle. This requires a mechanism with two nearly equal and symmetrical dwell zones in a crank cycle. The challenges in designing such a mechanism have been outlined in this paper and two possible solutions have been suggested.