QDS Bolter Valve Home / Products / QDS Bolter Valves Products Proportional Directional Valve Hydraulic Pilot Control Device Compact Hydraulic Valve Pneumatic valves QDS Bolter Valves Directional Spool Valve NG4 Electronic Control Components Cement Plant Hydraulics Search for:Search Button Proportional Valve Solenoid 7709050G24 More content is on its way. QDS Bolter (Boar) hydraulic valve The QDS Bolter (BOAR) is designed for secondary support capable of bolting the roof, ribs and faces when connected to an LHD. QDS Bolter (Boar) hydraulic valve