SUPPORT ASSEMBLIES FOR MINERAL MINES

摘要

A support assembly with two frames each having telescopic props carried by base members pivotably interconnected to a rigid member disposed therebetween. The rigid members are connected through a shifting device usable to alternately advance the frames. Each frame has a leaf spring attached at its center to the rigid member and pivotably connected at its ends to the base members or props. Between the center and each end of the spring is a portion which follows a sinusoidal course. Upon pivotal movement of a base member and the rigid member in one direction the associated portion of the spring elongates and eventually limits the amount of pivotal movement. Pivotal movement in the opposite direction is limited when the portion of the spring engages an abutment surface of the rigid member.