Hydraulic cylinder structure forms are various, there are classification methods as following:
According to the mode of motion can be divided into linear reciprocating motion hydraulic cylinder and rotary swing hydraulic cylinder.
According to the liquid pressure can be divided into single acting and double acting hydraulic cylinder.
According to the structure, it can be divided into piston type, plunger type, multistage telescopic sleeve hydraulic cylinder, rack and pinion type, etc.
According to the installation form can be divided into tie rod, earrings, foot, hinge shaft, etc.
According to the pressure grade can be divided into 2000psi, 3000psi, 4000psi and so on.
Piston type
A single piston rod hydraulic cylinder has a piston rod on only one end. The piston can only move in one direction, its movement in the opposite direction needs to be completed by external force. But its stroke is generally larger than the piston type hydraulic cylinder.
Piston hydraulic cylinder can be divided into single rod type and double rod type two kinds of structure, the fixing way is fixed by the cylinder and the piston rod is fixed two kinds, according to the action of liquid pressure has single acting type and double acting type. In the single-acting hydraulic cylinder, the pressure oil is only supplied to one chamber of the hydraulic cylinder. The hydraulic pressure makes the cylinder move in a single direction, and the movement in the opposite direction is realized by external forces (such as spring force, self-weight or external load, etc.). The double acting hydraulic cylinder piston two directions of the movement is through the two cavities alternate oil intake, by the role of liquid pressure to complete.
Plunger type
(1) The plunger hydraulic cylinder is a single acting hydraulic cylinder, which can only move in one direction by hydraulic pressure. The return 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 the cylinder liner, so the cylinder liner is easy to process, so it is suitable for long stroke hydraulic cylinder.
(3) the total pressure of the plunger at work, so it must have sufficient stiffness.
(4) The weight of the plunger is often large, and it is easy to sag due to its weight when placed horizontally, resulting in the wear of the seal and guide side, so its vertical use is more favorable.
Form of contraction
The telescopic hydraulic cylinder has two or multiple pistons. The piston in the telescopic hydraulic cylinder extends sequentially from large to small, and the order of no-load retraction is generally from small to large. The telescopic cylinder can realize a longer stroke, and the length of the retraction is shorter, and the structure is more compact. This type of hydraulic cylinder is often used in construction machinery and agricultural machinery. There are more than one movement of the piston, each piston successive movement, the output speed and output force are changed.
Oscillating type
Swing type hydraulic cylinder is the actuator of output torque and reciprocating motion, with single blade, double blade, spiral swing and other forms. Vane type: The stator block is fixed to the cylinder block, while the blades are connected to the rotor. According to the direction of oil intake, the blade will drive the rotor for reciprocating swing. The spiral swing type is divided into single spiral swing and double helix. Now the double helix is more commonly used. The linear motion of the piston in the hydraulic cylinder is transformed into the composite motion of linear motion and rotation motion by two spiral pairs, so as to achieve the swing motion.
Cushioning device
In the hydraulic system, the hydraulic cylinder is used to drive the mechanism with a certain mass. When the hydraulic cylinder moves to the end of the stroke, it has a large kinetic energy. If there is no deceleration treatment, the hydraulic cylinder piston and the cylinder head will have a mechanical collision, resulting in impact, noise and destructive. In order to mitigate and prevent this harm, so can be set in the hydraulic circuit or in the cylinder block buffer device.
