Before the 4 leg chock shield roof support was developed, all mechanized mining brackets had such a problem thathe top coal would be broken due to repeated support.This patented product successfully solves the dilemma of supportand cut by using smallsupporting force to retain the top and large supporting force to cut the top. Applying thistechnologyalso reduces the weight of the equipment. In addition, using large force tocut the top coal can apparently increase the re-covery rate of top coal.