Due to the particularity of small cranes, such as high center of gravity and strong mobility, in order to ensure the safety of lifting operations, outriggers must be set before lifting operations. below, Huai'an Crane Rental Company Analyze the common causes of crane outrigger failures in daily lifting operations!
1、 Automatic sinking phenomenon: The left front and left rear vertical outriggers of the small crane show an automatic sinking phenomenon during the support period. The left front outrigger is ignored before maintenance due to its relatively small subsidence; The hydraulic cylinder of the left rear outrigger has been disassembled, inspected and replaced with a sealing ring.
2、 Block and throttle valves: The outrigger and slewing mechanism (and accumulator) are connected in series with oil supplied by the gear pump. The small crane oil is limited to a higher working pressure by the pressure detector, and its setting value is 16Mpa. The expansion and contraction of the vertical outrigger and the horizontal outrigger are controlled by the solenoid valve. The block valve group is used to connect and cut off the oil circuit of the vertical outrigger and the horizontal outrigger. The block valve and throttle valve (its setting value is 3.5Mpa) form a low-pressure circuit (leading to the vertical outrigger cylinder) to prevent the crane from working under unsafe conditions when the three vertical outrigger cylinders are flat.
During the support period of the vertical outrigger cylinder, the hydraulic control check valve on the oil path of the rodless cavity stops in the reverse direction, and locks the oil path to avoid the "soft leg" retraction; In the driving state, it is locked reversely by a hydraulic control check valve on the main oil circuit of the rod chamber. To avoid self sinking. When the solenoid valve is in the neutral position, the oil from the triple gear pump supplies oil to the slewing and accumulator circuits, and the equalizing valve is used to avoid backflow.
3、 Hydraulic control check valve on outrigger: After analyzing the outrigger circuit, there are only two possible problems:
1. Internal leakage caused by internal damage of hydraulic control check valve on vertical outrigger;
2. The internal surface of the vertical cylinder of the outrigger is damaged, or the seal is damaged, causing internal leakage. Considering that there is no problem with the left rear vertical cylinder (the seal ring was replaced during the overhaul), the hydraulic control check valve on the oil circuit of the cylinder was first disassembled and inspected. It was found that the surface of the valve seat had damage marks and dust, which made the cone surface of the valve seat not tightly sealed. Clean and polish with sandpaper and oilstone.
After assembly, exchange the hydraulic control check valve on the oil circuit of the left front vertical cylinder, and the automatic sinking of the left front vertical outrigger is eliminated. It is clarified that the hydraulic control check valve is defective. The original problem of the hydraulic control check valve has been solved after maintenance. Then, the hydraulic control one-way valve was disassembled and inspected. The cause of the problem was the same as above. After treatment, it is installed on the oil circuit of the vertical cylinder of the left rear outrigger, and the problem of the automatic sinking of the left rear vertical outrigger is solved.
After Huai'an Crane Leasing Company Have you understood the introduction of? If you have any questions you must understand, you can directly contact our customer service, and we will provide you with a detailed explanation!
