... plunger drive, drive concise, compact structure. 20Y hydraulic clamp force in the oil field workover operations on dumping 23/8" ... driven back by clamp rack plunger drive, drive concise, compact structure. 2, Lord, forceps are used in the dorsal surface ... simultaneous release clamping or string. 5, friction braking institutions in the clamp heads of the adjustment, maintenance more convenient. 6, and ...