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What are the reasons for the failure of the automobile brake hose assembly?

Update:04-11-2020
Summary:

Analysis of the reasons for the failure of the brake ho […]

Analysis of the reasons for the failure of the brake hose assembly.

1. Performance: The inner tube of the hose is very hard and is now cracked.
Reason analysis: High temperature simply separates the plasticizer of the inner tube, which is a substance that can make the hose soft and plastic. The oil with trapped gas can oxidize the inner tube. The oxidation reaction on rubber products can harden it. Oxygen and high temperature will greatly accelerate the hardening of the inner tube of the hose. The appearance of cavitation inside the inner tube has the same effect.

2. Performance: The hose is cracked inside and outside, but the elastic material is still soft and flexible at room temperature.
Reason analysis: The reason is that the ambient temperature when the hose is flexed is extremely low. The extra temperature of most standard hoses is -40 degrees, some AQP hoses have an extra temperature of -49 degrees, usually military hoses have an extra temperature of -54 degrees, and some thermoplastic hoses have an extra temperature of -54 degrees. The extra temperature of the fluoroethylene hose is -73 degrees.

3. Performance: The hose breaks, peel off the outer rubber to check the steel wire reinforcement layer and find that there are irregular steel wire cracks over the entire length of the hose.
Reason analysis: This shows that the hose is in high and frequent pressure fluctuations. The SAE American Automobile Industry Association's impact test on the two-layer steel wire woven hose requires 200 000 cycles at 133% of the recommended working pressure. SAE's impact test on four-layer surrounding hose requires 500,000 cycles. If the number of extrapolation pulses in the system exceeds 1 million in a short period of time, it is best to choose a hose around the reinforcement layer.

4. Performance: The hose breaks, but there are not many steel wires cracking in the entire hose length. The hose can break in more than one place.
Reason analysis: This shows that the pressure has exceeded the minimum explosive strength of the hose. It is recommended to use higher strength hoses, or the hydraulic lines present faults that can cause abnormal high pressure conditions.