Good hydraulic oil for small ship cranes should have the following characteristics:
1. Good anti-foaming property and air release property
In the air-oil conversion tank, due to the air bubbles mixed in the oil circulating with the oil, not only will the system pressure drop and the lubrication conditions deteriorate, but also abnormal noise and vibration will be generated. In addition, the air bubbles increase the contact area between the oil and the air, accelerating the oxidation of the oil. Therefore, the hydraulic oil is required to have good anti-foaming and air release properties.
2. appropriate viscosity and good viscosity-temperature characteristics
Viscosity is the first factor to be considered when choosing hydraulic oil for small ship cranes. Under the same working pressure, if the viscosity is too high, the movement resistance of hydraulic components will increase, and the pressure drop and power loss in the pipeline will also increase. If the viscosity is too low, it will increase the volumetric loss of the oil drum. The internal leakage of the component increases, causing the oil film of the sliding parts to become thinner, the supporting capacity to decline, and there is atomization, which overflows from the exhaust port.
3. Good shear stability
When hydraulic oil passes through oil drums, valve throttling ports and gaps, it undergoes intense shearing action, causing some large-molecule polymers in the oil, such as tackifiers, to break down into smaller molecules and reduce viscosity. When the viscosity drops to a certain extent, the oil becomes unusable. Therefore, it is required to have good shear resistance.
4. Good resistance to chemical reactions
Hydraulic oil can also undergo oxidation during the operation of small ship cranes. The acidic substances produced after the oxidation of hydraulic oil will increase the corrosiveness to metals, and the oil sludge sediment generated will clog filters and tiny gaps, causing the gas-hydraulic booster cylinder to work abnormally. Therefore, it is required to have good chemical reaction resistance.
5. Good Lubricity (anti-wear property)
The hydraulic system has a large number of moving parts that need lubrication to prevent wear on the relative moving surfaces. Especially for hydraulic equipment with relatively high pressure, the anti-wear property of the hydraulic oil is required to be much higher.
6. Good rust prevention and corrosion resistance
During the operation of small ship cranes, hydraulic oil inevitably comes into contact with moisture, air and acidic substances produced by oxidation, which can cause rust and corrosion to metals and affect the normal operation of gas-liquid booster products. Generally, hydraulic oil should be replaced every six months.
What causes overloading of small ship cranes
1. Faults in the main moving parts (such as cylinder seizing, shaft seizing, etc.) cause high power consumption.
2. the fuel supply volume of the fuel injection pumps in each cylinder is not adjusted evenly, and even some cylinders do not work, resulting in overload of certain cylinders.
3. the power of the diesel engine was not corrected when operating in high-altitude and low-pressure environments. The black smoke emitted by a diesel engine due to overloading is mainly caused by excessive diesel injection into the cylinder, reducing the air coefficient. This results in insufficient fresh air for diesel combustion in the combustion chamber, leading to incomplete combustion of diesel. For the black smoke caused by overloading due to power regulation, controlling the overload operation can eliminate the black smoke. If overload is caused by excessive power consumption due to the failure of the main moving parts, the faulty components need to be repaired, the corresponding faults eliminated, and the normal operation of the diesel engine restored. Due to uneven adjustment of fuel supply from the fuel injection pumps of each cylinder, either too much or too little, some cylinders may be overloaded. You can start the diesel engine to increase its speed to around 900r/Min, touch the temperature of the exhaust pipes of each cylinder with your hand, identify the cylinder corresponding to the exhaust pipe with little or significant temperature change compared to before starting, and remove the fuel injector of that cylinder for technical inspection. If there are any faults such as abnormal fuel injection or no fuel injection, the fuel injector should be repaired or replaced, and the fuel injection pressure of the fuel injection pump should be corrected. After installation, the faults of uneven operation of each cylinder or even individual cylinders not working, causing some cylinders to be overloaded and emit black smoke, can generally be eliminated. For diesel engines operating in high-altitude and low-pressure environments, it is necessary to make power corrections in advance (reduce their output) to avoid black smoke emissions due to overloading.
4. The diesel engine speed is too high. Under normal circumstances, the speed bolts of diesel engines are sealed when they leave the factory. Generally, if they are not unsealed, it is impossible for the rated speed of the diesel engine to be high. However, some drivers privately increase the engine speed in order to achieve higher power at higher speeds. Such power adjustment can also cause black smoke to be emitted.
Before the ship crane test, all power supplies should be cut off, an appearance inspection should be carried out, and the installation condition of the crane should be inspected, which should meet the following requirements:
1. The ends of the steel wire rope should be fixed, and the winding in the drum and pulley block should be correct. Apply thick grease to the steel wire rope.
2. The insulation resistance and wiring of the ship crane's electrical circuit system and all electrical equipment should be correct. The grounding resistance of the entire machine should comply with the regulations.
3. Rotate the brake wheels of each mechanism to make the last shaft (such as the wheel shaft, drum shaft, etc.) rotate one full circle without any jamming.
4. Mechanical Inspection and Maintenance
(1) Check the oil level of the gear oil in the transmission and whether the oil has deteriorated.
(2) Pre-adjustment of the hoist brake;
5. The tracks and car stops are laid and installed correctly; All mechanisms, protective devices and instruments are in good condition. Good lighting and signal systems:
(1) The ballast of the ship crane track should be compacted to ensure the track surface is level and straight, with a height difference of ±5 centimeters on both sides of the track surface.
(2) Check and re-tighten the bolts for each component of the ship crane.
(3) The operation room should be hung with an operation procedure board, and the gantry crane should be hung with a load limit tonnage board.
(4) Inspection of the running wheel gearbox, lubrication of gear oil and shafts, and restoration of brakes;
(5) Check whether the electrical part meets the production requirements and whether short-circuit and leakage protection devices are installed in the main power supply of the operation room.
(6) The limit device is excellent and easy to use.
(7) Check whether there are any broken rubber sheaths or exposed wires on various cables, and deal with them in a timely manner.
