​It has been more than 130 years since the first manual excavator came out. During this period, it has experienced the gradual transition from steam-driven semi-rotary excavators to electric-driven and internal-combustion-engine-driven full-rotation excavators, and fully automatic hydraulic excavators using electromechanical-hydraulic integration technology. development process. The production of excavators in industrially developed countries was earlier. France, Germany, the United States, Russia, and Japan are the main producers of single-bucket hydraulic excavators with a bucket capacity of 3.5-40m³. They have been producing extra-large excavators since the 1980s. For example, the stripping excavator with a bucket capacity of 50-150m³ produced by the American Marion Company, a walking dragline excavator with a bucket capacity of 132m³; Dragline excavators and excavators with a bucket capacity of 107m³ are currently the largest excavators in the world. Since the late 20th century, the international production of excavators has developed in the direction of large-scale, miniaturized, multi-functional, specialization and automation.

Longitudinal joints should use thermal joints as much as possible. Since the temperature of the mixture of two adjacent sheets during echelon operation is not much different, the material at the joints of the layers can still be extruded and has good adhesion, as long as a suitable lap joint is selected (Generally, the smaller the better, the maximum is 3 cm), and good lap quality can be obtained. If cold seams are used, they should be cut flush with the flat end plate of the screed or with a cutter after cooling to form a flat seam for easy control of subsequent laps.

reason The damage to the bucket hydraulic cylinder is mainly due to the fracture of the steel ring on the piston due to factors such as fatigue. The piston is in direct contact with the metal of the hydraulic cylinder barrel. In the frequent expansion and contraction of the piston rod of the hydraulic cylinder, the fractured stubble constantly scrapes the inner wall of the hydraulic cylinder, which will strain the cylinder wall and cause internal leakage. The speed of the hydraulic cylinder is reduced, and finally the operation valve cannot control the action of the hydraulic cylinder.

The damage of the working device under typical working cycle conditions: For the boom, the earliest damage occurs at the boom ear plate. After analysis, this part is the direct bearer of the force of the stick cylinder, with local stress concentration and the thickness of the ear plate. It is thinner, so it is damaged at the earliest; for the stick, the earliest damage occurs around the pin that is hinged with the boom and inside the pin. After analysis, this part is the connection position between the edge of the stick box and the pin, which is prone to stress concentration. , and is also the position where the stick is subjected to alternating loads, so it is damaged at the earliest.

What is an actuator? The basic hydraulic system includes oil tank, pump, control valve, oil cylinder, connecting line and relief valve. The cylinder is the actuator. Actuators are hydraulic system components that output power. Actuators convert hydraulic energy into mechanical energy. There are two types of actuators: linear and rotary. Hydraulic cylinders are linear actuators. It outputs force and linear motion. The hydraulic motor is the rotary actuator, which outputs torque and rotary motion.

At present, R-rings have basically become standard on Rexroth industrial valves, and have achieved good results in the food, pharmaceutical processing and plastic machinery industries that have strict requirements on leakage. So, why choose R-rings instead of the commonly used O-rings? The R-ring has a large contact area, and the heat generated during the movement is difficult to dissipate, so it is generally only used for static sealing;