YYT28 Hydraulic Rock Drills | Hydraulic Drill Rigs Jinquan is China best manufacturers & suppliers of hydraulic drill rigs, with advanced technology, best working life with rational price. The YYT28 hydraulic rock drill is made for general excavations,quarrying and bolting with hexagonal shank rods with a shank size of 108mm(41/2")*22mm(7/8").The YYT28 can use water flushing or air flushing.YYT28 is a hydraulic rock drill to drill diameter 32mm(1 1/4") to 50mm(2") hole.