Rubber connection hoses in automobiles can be roughly divided into three categories: low pressure hoses, high pressure resistant hoses and oil resistant hoses. Although the structures of the hoses are different, they are generally composed of three basic parts: an inner rubber layer, a reinforcing layer and an outer rubber layer. The inner rubber layer is the working layer of the hose in contact with the medium. It plays the role of sealing the medium and protecting the reinforcing layer. It has long been subjected to the immersion, corrosion and friction of the transport medium. Temperature, corrosion resistance, friction resistance, a certain degree of air tightness, flexibility and strength. The reinforcement layer is the pressure-bearing part of the hose, while also giving the entire hose the necessary stiffness and strength. The outer rubber layer is the protective layer of the hose. Because it is in contact with the external environment, it is not only required to be abrasion-resistant, it must have a certain thickness, and it must also have certain resistance to corrosion and aging.
1. Low-pressure hose (radiator connection hose, brake bleed hose)
The mechanical properties of low-pressure hoses are not high. The appearance and size are mainly checked when matching. The appearance should be free of delamination, plastic holes, blistering, wrinkles, cracks, dents, distortion, uneven wall thickness, If necessary, heat aging test of radiator connecting hose can be done.
2. High-pressure hose (brake system, hydraulic system connection hose)
The reinforcement layer of the high-pressure hose uses woven hoses and wound hoses. It is required that the high-pressure hoses have good pressure resistance, oil resistance, and flex resistance, no cracks at low temperatures, vibration resistance, and low expansion. The inner rubber layer must be uniform, the surface is flat, and there must be no air holes; the reinforcing layer should tightly bind the inner rubber layer; the outer rubber layer should also be close to the reinforcing layer to prevent it from being damaged. The metal joint threads at both ends should be firmly embedded in the rubber surface. In addition to checking the appearance and size of the high-pressure resistant hose, a pressure test should be performed one by one before use.
3. Oil resistant hoses (gasoline, diesel, lube oil hoses)
Oil-resistant hoses have good oil resistance and can be used permanently under working pressure. The appearance and size of the hose shall meet the requirements.