Wheel bearing noise failure phenomenon and treatment method

There is noise in the wheel bearings of the car. This seemingly impossible fault does exist in reality. Let's discuss it together.

Trouble phenomenon: When one of the four wheel bearings of the vehicle is damaged, you will hear a continuous squeaking noise in the car while driving. This sound can't tell where it came from. I feel that the whole car is full of such buzzing sounds, and the faster the speed, the louder the sound. Generally, when the speed is from 60km/h, a slight hum can be heard, and the speed is 70, 80km/h. At 100km/h, the conversation in the car should be improved, and the sole of the foot has a fine vibration feeling. These are just superficial phenomena of failure. If it is the first time you encounter it, you really can't understand what is going on. Let's talk about the way to judge this fault.

Judgment method: When you hear this kind of squeaking sound during driving, don't panic, keep calm and continue driving, use these methods to judge the sound source roughly.

1. Open the window and hear if the sound comes from outside the car;

2. After increasing the speed (when the noise is loud), the gear position is in the neutral position to let the vehicle slide, and observe whether the noise comes from the engine. If the noise does not change when the neutral gear slides, most of the wheel bearings have problems;

3. Temporary parking, get off and check if the temperature of the axle is normal. The method is: touch the four wheels by hand and feel the temperature is consistent. (When the brake shoes and the gap are normal, the temperature of the front and rear wheels is The gap, the front wheel should be high), if you feel the difference is not big, you can continue to drive slowly to the repair station;

4. Raise the car with the lift (previously release the handbrake and hang the neutral). When there is no lift, the jack can be used to raise the wheel one by one. The manpower will rotate the four wheels quickly. When the problematic axle is encountered, it will make a sound. It is completely different from other axles. It is easy to tell which axle has a problem with this method. If there are accessories, you can directly replace the parts to eliminate the fault. If there is no accessory, what should I do? Then you have to take the sick car, and let's talk about the precautions when driving.

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Maintenance method of grinding machine static pressure bearing in imported bearing

The static pressure imported bearing has high rotation precision, good steel property, high bearing capacity, no wear and high durability. 1. Small hole throttle:

(1). Change the internal throttling to external throttling, and add a pressure gauge to instantly display the upper and lower chamber pressure. It is easy to maintain, especially it can be cleaned regularly, which is unmatched by the internal throttle.

(2). Throttling ratio. The theoretical value of the throttle ratio β is between 1.2 and 1.5, and 1.25 is preferred based on years of experience. In this way, the geometric accuracy of the main shaft, the geometrical accuracy of the front and rear bearing pads, the concentricity, the roundness and the taper need to be strictly controlled in order to ensure the β value. The e value (the eccentricity of the main axis and the geometric center of the bearing bush) is determined according to the load carrying capacity of the machine tool to optimize the β value.

(3). When the oil chamber is not equipped with the main shaft, the oil column of each oil outlet must be consistent (observation method). If it is inconsistent, the flow rate should be changed by changing the orifice diameter of the throttle. Taking 4 chambers as an example, the oil column of the lower, left and right chambers is generally between 20 and 25 mm, and the diameter of the small holes is 0.25 to 0.4 mm.

2. Thin film feedback throttle:

The film feedback throttling inlet bearing stiffness is very large, but the machine tool often appears to hold the tile, pull the hair, reduce the pressure and so on. The most critical of the film feedback is the film. In practice, the main reasons for the bearing lock and pulling are: 1 plastic deformation of the film; 2 slow feedback. When the external load is abrupt, the shaft and the tile have already rubbed when the film has not reacted; 3 the film is fatigued. The film is used for a long time and fatigue deformation, which is equivalent to changing the feedback parameters.

Increased film thickness and the use of some fatigue-resistant materials can achieve good results. Generally, a rigid film, a preload, and a gap are reserved. The specific method is: change the 1.4mm thick film to a 4mm thick rigid film, and place a 0.05mm thick tin foil in the lower cavity to adjust the spindle to a position 0.05mm higher than the ideal position. The purpose is to return to the ideal center just after the spindle is stressed (grinding weight, cutting force).

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