Hydraulic cylinders, also known as hydraulic cylinders, can be mainly divided into five categories: double acting double piston rod hydraulic cylinders, single acting plunger hydraulic cylinders, telescopic hydraulic cylinders, plunger hydraulic cylinders, and rack piston hydraulic cylinders. The first four types of hydraulic cylinders all achieve linear reciprocating motion, outputting thrust and speed; The rack piston hydraulic cylinder achieves swing motion, outputting torque and angular velocity.
The oil cylinder can be divided into two types according to its mode of action: single acting and double acting. The pressure in a single acting hydraulic cylinder can only be achieved by the piston (or plunger) moving in one direction, and the reverse movement must be achieved by external force (spring or self weight); A double acting hydraulic cylinder can have hydraulic pressure to achieve movement in two directions.
The characteristics of a single piston rod hydraulic cylinder are: different reciprocating motion speeds - commonly used to achieve rapid return and slow working feed of machine tools. The areas at both ends are different, resulting in unequal output thrust. When there is no rod cavity for oil suction - working feed motion (overcoming large external loads). When the rod cavity is filled with oil, the driving working component quickly retracts and moves (only overcoming the effect of friction). The range of motion of the workbench is equal to twice the effective stroke of the piston rod. The structure diagram of a single piston rod hydraulic cylinder is shown in the figure. The cylinder body 1 and the bottom cover are welded together. Piston 2 is guided by the support ring 4 and sealed with a Y-shaped sealing ring 5, and piston 2 is connected to piston rod 3 with threads. The piston rod 3 is guided by the guide sleeves 6 and 8 and sealed with a V-shaped sealing ring 7. The end cover 9 and cylinder body 1 are connected by threads, and the nut 10 is used to adjust the tightness of the V-shaped sealing ring. The cylinder bottom cover and piston rod head both have earrings for easy articulation. Therefore, when this hydraulic cylinder reciprocates, its axis can freely swing according to work needs, and is commonly used in construction machinery such as hydraulic excavators.
The telescopic hydraulic cylinder mainly consists of cylinder body 5, piston 4, sleeve piston 3, etc. There are oil inlet and outlet ports A and B at both ends of the cylinder block. When oil enters Port A and returns to Port B, first push the first stage piston 3 to move to the right. Due to the large effective area of the first stage piston, the movement speed is low and the thrust is high. When the first stage piston moves right to the end point, the second stage piston 4 continues to move to the right under the action of pressure oil. Due to its small effective area, the movement speed is fast, but the thrust is small. The sleeve piston 3 is both a primary piston and a cylinder block of a secondary piston, serving a dual purpose. If oil enters port B and returns port A, the second stage piston will first return to the end point, and then the first stage piston 3 will return.
The characteristics of telescopic hydraulic cylinders are: the piston rod has a long extended stroke, and the structural size after contraction is small, suitable for the telescopic arm of tipping trucks, cranes, etc.
A double acting double piston rod hydraulic cylinder mainly consists of parts such as cylinder body 4, piston 5, and two piston rods 1. The piston 5 and piston rod 1 are connected by a cotter pin 9. The piston rod 1 is guided by guide sleeves 7 and 9 respectively, and is sealed with a V-shaped sealing ring 6. The screw 2 is used for the tightness of the V-shaped sealing ring. Two end caps 3 are equipped with inlet and outlet ports. When the right chamber of the hydraulic cylinder receives oil and the left chamber returns oil, the piston shifts to the left; On the contrary, the piston shifts to the right. Due to the same diameter of the piston rods on both sides, the effective area of action on both ends of the piston is the same. If oil with the same pressure and flow rate is input into the left and right ends respectively, the thrust and round-trip speed generated on the piston are also equal. This liquid