Maintenance of truck crane hydraulic system

Truck crane Hydraulic oil is like the blood of people’s blood vessels. Hydraulic oil is the blood of construction machinery. The amount of hydraulic oil is more or less. Clean or unclean is directly related to whether the entire mechanical action is reliable or not. 

The truck crane oil tank is a container of hydraulic oil. The amount of oil can be checked for the hydraulic oil level of the oil tank.

Hydraulic oil specification picture for truck crane in summer and winter
Hydraulic oil specification picture for truck crane in summer and winter

 The recommended anti-wear hydraulic oil grades are: winter: L-HM32; summer: L-HM46. If it is missing, you can add it according to this grade, but you must remember the date when the crane was purchased at that time.

The winter or summer use oil. Ensure that the new oil is compatible with the oil in the hydraulic line. It is forbidden to use oil containing molybdenum and sulfide, because they will damage the supporting mechanism so as not to change the oil quality due to mixing, and cannot be used continuously.

 1. Daily observation of hydraulic oil

Picture of truck crane hydraulic oil tank
Picture of truck crane hydraulic oil tank

The reasons and hazards of hydraulic oil deterioration are as follows:

      1. The color becomes white and emulsified, and the hydraulic cylinder becomes weak. Reason: The hydraulic oil is mixed; water enters the hydraulic oil tank, which causes the oil to emulsify and deteriorate.

      2. If the color of the oil becomes darker and the oil becomes dark yellow or brown: it may be due to long-term high temperature operation and the oil is oxidized.

      3. If there is a problem with the oil quality, the abrasion resistance will be poor, leading to deterioration of the oil additives, and will corrode the moving components in the hydraulic system and increase wear.

      4. Observe whether there is precipitation in the hydraulic oil tank and whether the oil tank is tightly closed. If impurities enter during use, the oil will deteriorate.

      2. Replacement of truck crane hydraulic oil

      If the hydraulic oil has deteriorated, it must be replaced completely. The steps are as follows:

      1. After the crane is fully retracted, release the hydraulic oil in the tank from the screw plug at the bottom of the tank and install it in a large recycling container. At this time, attention should be paid to prevent environmental pollution;

      2. After draining the hydraulic oil in the oil tank, disassemble the oil return pipe, clean the oil tank and oil filter with a chemical cleaning agent with a solid particle pollution level not exceeding 21/17/13, and then dry it;

      3. After adding new oil of the same brand, start the engine and run it at low speed to make the oil pump work. Operate each mechanism separately. The new hydraulic oil is used to drain the old oil of each circuit of the system one by one. The discharged old oil shall not flow into the hydraulic oil tank until There is new oil flowing out of the oil return pipe, stop the rotation of the oil pump;

      4. Connect the oil return pipe to the oil tank, and finally put the components in the initial working state, and add hydraulic oil to the oil tank to the specified liquid level.

      Note: When changing the oil in each circuit, pay attention to continuously inject new oil to prevent the oil pump from sucking. Of course, we must pay attention to safety and prevent oil spills from polluting the environment. Waste oil should also be treated specially.

      3. Clean and check the truck crane hydraulic oil tank suction and return oil filter

Picture of truck crane hydraulic oil tank return oil filter
Picture of truck crane hydraulic oil tank return oil filter

 The suction and return filter of the fuel tank is a line of defense to ensure that the oil is clean. Some small iron filings and impurities in the system are intercepted and filtered by him. After a period of use, there will naturally be fine impurities adsorbed on it, and it often obstructs the passage of the oil circuit, so regular disassembly and inspection to remove impurities is also an important item.

      Fourth, the inspection of the truck crane hydraulic system pipeline

Picture of hydraulic system pipeline of truck crane
Picture of hydraulic system pipeline of truck crane

he hydraulic pipeline is the channel of the hydraulic oil, which is mainly connected with the hose and the hard pipe. It is also an easy-to-check item to ensure the normal use of the crane to check whether the connecting pipes are secure and that there will be no leakage. The hose is afraid of exposure to the sun, because it is easy to age, which will shorten the service life of the hose, and there will also be the possibility of cracking due to aging and reducing the pressure resistance to form a tube burst.

      Note: The service life of hydraulic hose: According to DIN20066: 2002-10, the service life of the hose assembly and the hose used shall not exceed 6 years.

      5. Inspection of truck crane hydraulic valves and locks

Truck crane hydraulic valve picture
Truck crane hydraulic valve picture

he role is to control the fluid pressure, direction and flow in the hydraulic system, thereby controlling all the functions of the entire hydraulic system, such as the working pressure of the system, the movement speed and direction of the working parts of the operating program of the actuator, as well as the conversion frequency, output force and torque Wait. 

Its reliable use plays a role of safety. In normal inspection and maintenance, pay attention to whether there is oil leakage, check whether the bolts are loose, whether the “O” sealing ring is damaged, and find the corresponding parts from the sealing package provided with the car. Replace, but in the process of disassembly and assembly, you must pay attention to release the residual pressure, and then cover it with a towel or the like to prevent the pressure oil generated when the pressure leaks from hurting yourself.

      Six, truck crane hydraulic cylinder part

Truck crane hydraulic cylinder picture
Truck crane hydraulic cylinder picture

 The hydraulic cylinder is an important part of the interconnected structural parts to produce a certain range of motion. Inspection items: Whether the surface of the piston rod of the main oil cylinder is oily or hard;

whether the valve lock installation surface of the oil cylinder and the connection of the hard pipe; whether there is oily oil at the position of the guide sleeve; whether the oil cylinder stops working when it moves halfway, whether automatic recovery occurs or The phenomenon of sticking out is used to judge whether the cylinder is working normally. 

In addition, the leaking part of the cylinder rod can be coated with butter for protection.

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