Advantages and disadvantages advantages Jic hydraulic fittings bracket covering hydraulic bracket: roof beams short force on the roof of a uniform, controlled from the top frame shift hydraulic fittings suppliers is small, the number of small to support the roof again, help protect the integrity of the roof. Pillar tilt arrangement, a large increase in scope, because the pillars not withstand lateral loads, the stress state is good, not easy to damage. Multiseal metric hose fitting Dagan perfect block device allowing work space and roof, completely separated from the old pond, Jic hydraulic fittings effectively prevent leakage partings, and Chung channeling gangue gangue. Shield hydraulic support for the stable motion mechanism, the horizontal force frame shift caused by the four-bar linkage bear, thus requiring the horizontal thrust of good performance can be achieved with a pressure shift rub the top shelf. Mechanical and hydraulic systems than simple, easy operation and maintenance, work space, large ventilation resistance is inappropriate to have a strong period of pressure and gas emission from large coal.