As an auxiliary connecting device between components in the hydraulic system of construction machinery, the installation quality of tubing will directly affect the working effect of the hydraulic system besides its own quality. Improper installation will not only increase the pressure loss of the hydraulic system, but also cause problems such as noise and vibration when the hydraulic system works, and even cause some unknown mechanical failures, which will bring a lot of inconvenience to maintenance and operation. For example, in a P-300 hydraulic excavator, the operator found that the thread of a hydraulic cylinder pipe joint was worn during maintenance, so the elbow was replaced by a straight pipe joint. After that, the tubing burst several times in use, and the maintenance inspection failed to eliminate the fault, but the oil pressure of the system was within the normal range when the oil pressure gauge was connected for testing. After consulting the maintenance factory, an elbow joint was machined according to the original size and specification, and the fault was completely eliminated after replacement. It can be seen that whether the tubing of the hydraulic system is installed correctly plays a vital role in the use of construction machinery, especially when replacing some joints and tubing, don't change it rashly because of the appropriate size.

The following author talks about some views on the installation of hydraulic oil pipes in construction machinery for readers:

I. Installation of low-pressure pipeline

(1) Installation of oil suction pipe

1. The connection between the oil suction pipe and the pump should be sealed and reliable, and the oil pipe itself must have sufficient elastic strength; Otherwise, the pump will suck air when it is working, which will make the system produce noise and vibration, and even can't suck oil.

2. In order to increase the oil absorption area at the inlet of the oil absorption pipe, the nozzle can be obliquely cut into a 45-degree angle; The nozzle should be inserted below the lowest oil level, and generally the distance from the bottom of the oil tank is about twice the outer diameter of the oil pipe.

3. In order to reduce the oil absorption resistance, the tubing should be as short as possible, and elbows and elbows should be used as little as possible. If the tubing is suspended for too long, there should be a bracket in the middle; In general, the oil absorption height of the pump should not be greater than 500mm.

(2) Install the oil return pipe

1. The oil return pipe should be inserted below the oil level of the oil tank, but it cannot be stuck at the bottom of the oil tank.

2. The oil return pipe port and the oil suction pipe port should be separated by a certain distance.

3. After the end of the oil return pipe inserted into the oil tank is cut into an oblique angle of 45 degrees, the oblique mouth should face the side arm of the oil tank, so that the oil will not directly rush to the bottom of the oil, avoiding excessive impact of the hydraulic oil and prolonging the service life of the oil.

4. When the oil return pipe is placed horizontally, it should have a horizontal slope of (3~5)‰.

Second, the installation of high pressure tubing

(1) pipeline

1. Measuring pipe length: The pipe length shall be measured and selected according to the relative position of the mechanical parts installed in place, with a slight allowance.

2. Check the quality of the hose: according to the system pressure, first find out whether the hose diameter, the number of steel wires and the specifications and dimensions of the hose meet the design requirements; Secondly, check whether there are any defects such as degumming, aging and damage on the inner and outer diameter surfaces of the hose, and those with serious defects cannot be used.

3. Hose cleaning: Before installation, blow the inside and outside of each prepared hose with compressed air to prevent dust from entering.

(2) Installation

1. Because the hose will expand and contract by -4% ~ +2% when the working pressure changes, there should be no tension between the two parts after installing the oil pipe.

2. Pipes should be arranged as parallel as possible. When crossing is really necessary, a gap of at least 10mm should be left between the two pipelines to prevent vibration caused by mutual contact.

3. In order to avoid sharp bending at the joint, the bending radius during assembly should generally be more than 9 times the outer diameter of the hose, and the distance between the bending center of the hose and the joint should be at least 6 times the diameter (or look up the table according to the instruction), otherwise its pressure resistance will drop rapidly.

4. The installed hose is not allowed to be twisted (twisted).

5. In order to avoid contact and friction between the outer surface of the hose and the machine, guide protection devices, such as steel wire springs and protective steel plates, should be installed on the outer surface of the hose.