Let -off systems fall into one of three major categories. The simplest let- off system is known as negative let- off. This system merely consists of a brake continually applied to the warp beam to retard the motion of the beam.

• 送经系统有三种,最简单的是消极式送经机构,该机构仅仅是靠一个制动机构连续地给织轴施加制动作用以阻止织轴的转动。