Repair of slewing ring of hydraulic excavator

2 work to achieve the confluence of the two pumps before and after.

Fault Analysis Since the bucket boom has no power and the symptoms are involved in large areas, it is first considered that the fault is caused by the common part. Assuming that the straight solenoid valve malfunctions when it is not traveling, the straight running valve operates, ie, the two pumps merge. As can be seen from the two, the valves that can cut off the unloading circuit or the actions that can be normally performed are boom raising and rotating arms stretching. And walking. The unloading and excavation of the boom's down-bucket can't cut off the access of the two-pump confluence circuit and the tank. For example, when the bucket is in motion, the right control valve can shut off the flow of the confluent oil directly to the tank, but due to the same position of the left control valve, the confluent oil can still be directly returned to the tank through the left control valve. The condition of the boom can be analyzed on its own. Note that the boom quick valve only has two positions, ascending and neutral, and is slower than the boom. At this time, the working pressure cannot be established. The flow rate of the main pump before and after is small, the median position is relatively low at the Ding valve, and the engine is in a light load state, which is the user's inability to excavate. After the test machine, all the actions are in accordance with the above analysis, which can be caused by the confluence of failures.

In the order from simple to complex, remove 8 = fuses, cut off the power supply of the confluent solenoid valve. After testing the machine, it was found that the machine was normal except when the operating device was operated while walking or rotating. So far it has been determined that the fault is caused by the circuit associated with the merging. It is easy to judge from 3 that it is caused by the fact that only the stroke switch cannot be reset. The limit switch is located at the bottom front of the cab and is often in contact with muddy water and sand to make it normally closed and cannot be reset. That is, whether it is walking or not, as long as the working device is rotated or the working device pressure or rotary switch is closed, it is satisfied. The condition of the solenoid valve operation always merges. After the removal switch is cleared, the machine is returned to normal.

According to experience, this type of excavator's boom bucket's inability to move or bias is mostly due to confluence. For example, the straight solenoid valve core is not flexible, and the travel switch is not in place or reset. PC20 excavator pump motor and other key parts are 1 Komatsu company production, the normal service life are more than 8 000, from the bottom of the plunger cylinder and the piston clearance of high precision, both require sealing and require relative movement, in If the factory is not confirmed to be damaged, avoid dismantling blindly. It is advisable to repair the PPM plant commissioned by Komatsu Public p.

Repair of hydraulic excavator slewing ring Tianjin Institute of Construction Machinery Ru Shijun 1 Failure phenomenon and reason analysis Sumitomo 52800 a hydraulic excavator has been working 8 6641 In a construction site construction, the bulldozer hits the excavator's counterweight on. Later, it was found that a lot of butter was thrown from the sealing device of the slewing bearing, and at the same time there was an abnormal sound inside the slewing bearing. When turning, each turn to the front and the left of the machine, the slewing ring squeaked into the slewing ring. With the bucket on the ground, the track was lifted off the ground and then lowered. The axial clearance of the slewing bearing was found to be large. Then, with the bucket bucket at the bottom, the arm is extended and it is found that there is also a large gap in the radial direction of the slewing ring. Rotary motors and rotary speed reducers are all normal. Therefore, the preliminary judgment is that the steel ball and the spacer sleeve inside the slewing bearing are damaged, so that the axial and radial clearances of the rotary support engineering machine, 20003 bearing, are increased, and the sealing device may be damaged.

Disassemble the slewing bearing. The outer race of the slewing ring is connected with the upper car, and the inner race is connected with the lower car. Remove all the tubing on the swing motor and seal the head of the tubing with a clean plastic film. Use a crane to gently lift the upper car, and then loosen the bolts of the outer ring of the slewing bearing and take them all. The car and the car will be separated to pay attention to the balance of the car. The slewing bearing is still connected with the car. The taper pin 2 is ejected, and then the plug 3 is removed with a screw, and then the steel ball and the spacer are removed with a wire. After the steel ball and the isolation sleeve were all removed, only two of the isolation sleeves were found to have the original shape, and the rest were all crushed into pieces. Clean the steel ball with diesel oil. More than 30 steel balls have severe pitting and deformation, and the rest are repaired. Outer seat 2. Tapered pin 3. Plugging 4. Sealing device 5. Inner race 6. Steel balls have different degrees of pitting. After the outer race is removed, put the butter on the inner and outer races in the raceway, wash the net, the inside and outside raceway is on the front and the left side part of the machine is in front of the sun and can clearly understand when the excavator is hit, equivalent to The radial direction of the slewing bearing suddenly exerts a very large impact force, resulting in part of the isolation sleeve inside the slewing bearing damage the isolation sleeve 2, made of nylon, is soft, if you continue to work, the damage of the isolation sleeve will be more and more, make inside and outside The clearance between the seat ring is increased, butter is thrown from the gap between the inner and outer races, and the raceway spacer and steel ball are not lubricated, thereby aggravating the damage of the raceway spacer and the steel ball, causing the excavator to be abnormal during turning. Sound and jamming 2.1 Repair of slewing bearing If the replacement of the new slewing bearing needs to be imported, and the price is high, it is about 10,000 yuan and the lead time is longer. The excavator itself is an old machine and there is no need to replace the new slewing bearing, so it is decided to repair the original slewing bearing. Due to the timeliness of the discovery, the damage to the inner and outer raceways of the slewing bearing was not very serious. After observation and measurement, the inner and outer raceways of the slewing bearing are not deformed, but the raceway has pitting points and can still be used. Therefore, it was decided to adopt a method of replacing the steel ball and sealing device of the isolation cover for repair. The diameter of the original slewing bearing steel ball measured 28.48, while the domestic product can only buy the steel ball with a diameter of 28.60,1, which is larger than the diameter of the steel ball of the original machine 12 The original machine slewing bearing has a separate sleeve and ball 136 One. The length of the balls and spacers in the raceway is longer than the original 16.3213612 Claw 1 The size of each spacer should be reduced by 0.12 in order to ensure that the spacers and steel balls in the slewing ring just fill the raceways. When purchasing steel balls, the selection method must be used to ensure that the ball diameter error is less than 0.002mm. The isolation sleeve must also be used for assembly. If the final number of doors cannot be guaranteed to be the same as the original number of doors, the size of the portion of the isolation food should be reduced until it is the same as the original slewing ring and the number of balls, and the entire track is filled.

2.2 Safety of slewing bearings First, the slewing bearing inner and outer races include raceway steel balls. Isolating sleeve sealing device and bolt holes are cleaned and the outer seat ring is placed on the inner seat ring, basically ensuring that the raceways of the inner and outer races are on the same plane, and then the steel balls and the isolation sleeve are released through the radial holes. The raceway is placed in a separate ball sleeve until it is full, and the plug 3 is plugged and the taper pin 2 is tightened. When assembling the sealing device, contact the sealing device with the sealing groove to see if there is any seizure. If there is a clamping phenomenon, it should be repaired so that it can be flexibly rotated. Finally, butter is added to the butter mouth of the outer ring of the slewing bearing so that the raceway is filled with butter and filled with butter in the oil pool of the rotating pinion and the slewing ring gear ring.

Lift the excavator's car with a crane, align the rotary platform's factory, align the outer race of the support, align it, and use a round bar with a similar diameter as the bolt to get on and off the car through the bolt hole. Position positively, then assemble the bolts. The threads of the bolts should be coated with Loctite anti-loose glue. Bolts are installed symmetrically in an angle 3. Install the first group of 3 bolts first, and then install the second group of 3 bolts. At the beginning, the bolts cannot be tightened. After the bolts are installed, the claw torque wrenches tighten the bolts one by one, the tightening torque is 650, the installation is completed, the machine is started, and the machine is switched to other functions until it returns to normal. .

Since the machine is repaired, it has been made for one year did not find any support turn to ask.