Causes and solutions of no rotation failure of the

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Reasons and solutions for excavator no rotation fault

fault of excavator: it is found that there is no rotation action, while other actions are normal. When the operating handle is placed in the rotary position, the control oil reaches the control valve and pushes the rotary valve rod so that the high-pressure oil provided by the rear working oil pump enters the rotary motor; At the same time, the oil circuit of the control oil return tank is cut off to increase the pressure of the brake release valve, push its valve rod to make another circuit of auxiliary pressure oil enter the brake piston, and open the swing brake device to make the swing motor act; The slewing motor outputs power through the pinion of the transmission, and the pinion engages with the slewing ring gear to produce slewing action. 1. Failure cause analysis and inspection: from the working principle of the rotary mechanism, there are three reasons for the failure, namely, the main working oil circuit, mechanical transmission and control oil circuit. (1) Inspection of main working oil circuit if the pressure of main oil circuit of slewing is low, it will not produce slewing action. Measure the pressure of the main working oil circuit system. There is a hexagonal oil plug at the pressure outlet of the rear working oil pump due to the large capacitance of the tested cable. After removal, install the pressure gauge, operate the rotary handle, and accelerate the diesel engine. The measured pressure reaches 23.5mpa, which is the normal working pressure of the system, indicating that all hydraulic components of the main working oil circuit are extruder enterprise orders will be greatly recovered and normal. (2) Inspection of mechanical transmission part: the rotary motor outputs power through the pinion of the transmission, and the pinion rotates around the rotary ring gear. In the process of power output, if the meshing gears are blocked, no rotation action will also occur. Generally, abnormal gear meshing will produce abnormal sound. Now the driver has not heard abnormal sound during rotation, so the mechanical transmission fault can be temporarily excluded. (3) Check the control oil circuit. Since other actions of the excavator are normal, it indicates that the auxiliary oil pump providing control oil pressure works normally. There are three control oil circuits for the rotary action, namely, the oil circuit for controlling the rotary valve rod, the brake release valve and the parking brake piston. The specific analysis is as follows. When operating the rotary handle, there is a strong oil flu when touching the pressure oil pipe of the rotary motor, which indicates that the main working pressure oil has reached the rotary, which can directly produce the motors such as exterior trim, interior trim and functional parts for vehicles. The rotary valve rod of the control valve can be opened normally, and the control oil circuit works normally. Measure the oil pressure to the parking brake piston. Open the pipe joint from the oil circuit to the rotary motor, install the tee joint and pressure gauge, and the measured pressure reaches 4MPa, indicating that the oil circuit pressure is normal. Measure the oil pressure to the brake release valve. Open the pipe joint from the oil circuit to the rotary motor, install the tee joint and pressure gauge, and the measured pressure is 0 6Mpa. Obviously, this pressure is too low (the normal working pressure should be 4MPa), so the brake release valve cannot be opened, and the control oil in the other way cannot flow into the brake piston. Moreover, the pointer should have no blocking and jumping phenomenon, and the slewing brake device cannot be opened. Therefore, there is no action in slewing. There are two reasons for the low pressure of the oil circuit. One is the leakage of the control valve, which reduces the oil pressure entering the brake release valve (connect the pressure gauge to the pipe joint of the control oil pipe from the control valve to the brake release valve, and the measured oil pressure is only 0..6mpa, indicating that the judgment of the control valve leakage is correct); Second, the brake release valve has a larger fitting clearance due to wear, resulting in leakage (after disassembly and inspection, the valve rod fits well with the valve hole, and there is no jamming). 2. Troubleshooting: from the cause analysis and inspection of the fault, it is known that the main cause of the fault is the leakage of the control valve. Because it was difficult to repair, the control valve was replaced. After repair, the rotary action returned to normal

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