Equipment ON/OFF transducer for coal mining
Frictional metal prop
Conveyor belts -- Formula for transition distance on three equal length idler rollers -- For coal mining
Pneumatic support
Flameproof signal switch for coal mine
Flameproof control push button for coal mine
Sampling for checking samples of production in coalmine
Test method and judge rules of safety of permissible electric detonator for coal mining in firedamp
Guide for evaluation of coal laboratories