Classification of hydraulic cylinders

Hydraulic cylinders have various structural forms, and their classification methods are also various: according to the motion mode, they can be divided into linear reciprocating motion type and rotary swing type; According to the action of hydraulic pressure, it can be divided into single action type and double action type; According to the structure, it can be divided into piston type, plunger type, gear rack type, etc;

1. Piston type

The single piston rod hydraulic cylinder only has a piston rod at one end. As shown in the figure, it is a single piston hydraulic cylinder. The inlet and outlet oil ports A and B at both ends can be connected with pressure oil or return oil to realize two-way movement, so they are called double acting cylinders.

The piston can move in one direction, and its reverse movement is completed by external force. However, its stroke is generally larger than that of the piston type hydraulic cylinder.

The piston type hydraulic cylinder can be divided into single rod type and double rod type structures. Its fixing methods are cylinder block fixation and piston rod fixation. According to the action of hydraulic pressure, there are single acting type and double acting type. In the single acting hydraulic cylinder, the pressure oil is only used for one chamber of the hydraulic cylinder. The hydraulic pressure enables the cylinder to move in one direction, while the reverse movement is achieved by external forces (such as spring force, dead weight or external load); The movement of the piston in both directions of the double acting hydraulic cylinder is completed by the action of hydraulic pressure by alternately feeding oil into the two chambers.

Only one side of the piston is provided with a piston rod, so the action areas of the two chambers are different. When the oil supply is the same, the piston moves at different speeds when the oil is fed into different chambers; When the load force to be overcome is the same, oil is fed into different chambers.

2. Plunger type

(1) The plunger type hydraulic cylinder is a single acting hydraulic cylinder, which can only achieve movement in one direction by hydraulic pressure, and the return stroke of the plunger depends on other external forces or the weight of the plunger;

(2) The plunger is only supported by the cylinder liner and does not contact with the cylinder liner, so it is suitable for long stroke hydraulic cylinder;

(3) The weight of plunger is often large, and it is easy to sag due to its own weight when it is placed horizontally, resulting in unilateral wear of seals and guides.

3. Swinging type

Swing type hydraulic cylinder is an actuating element that outputs torque and realizes reciprocating motion. It has several forms, such as single blade, double blade, spiral swing, etc. Blade type: the stator block is fixed on the cylinder block, while the blade is connected with the rotor. According to the oil inlet direction, the blade will drive the rotor to and fro swing. The spiral swing type is divided into single spiral swing and double spiral swing,