Three, hydraulic jack type and structure Hydraulic jack a wide range of different sizes, different functions, so the structure is not the same. 1, double acting hydraulic cylinder, piston, cylinder head by Jack, pad (cap or seat), seal and joint. 2, single acting hydraulic jack by gravity reset cylinder, piston, cylinder head, pad (cap or seat), seal and joint. 3, spring return single acting hydraulic jack by oil cylinder, piston, cylinder head, pad (cap or seat), spring (spring), seal and joint. 4, the gravity reduction of single thin hydraulic jack sealing by the oil cylinder, a piston, Components and joints. 5, spring return single thin hydraulic jack by the oil cylinder, piston, cylinder head, spring (spring), seal and joint. 6, gravity reset single action nut self-locking hydraulic jack from the oil cylinder, screw plunger, locking nut, seal and fittings. 7, double acting hydraulic jack by hollow plunger cylinder, hollow piston, a hollow guide column, cylinder head, pad (cap ...