Type and maintenance of hydraulic outrigger of the

2022-08-08
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Type and maintenance of truck crane hydraulic outrigger

truck crane outrigger is a folding or retractable support structure installed on the frame

1. Outrigger type

outrigger of truck crane can be divided into manual and hydraulic operation. At present, manually operated outriggers are rare, and most Truck Cranes use hydraulic outriggers. Hydraulic outriggers can be divided into the following types

(1) frog outrigger

the movable outrigger of this outrigger is hinged on the fixed outrigger, and its deployment action is completed by the hydraulic cylinder. It is characterized by simple structure and light weight, but the outrigger span is small, which is only suitable for small tonnage cranes

(2) H-shaped outrigger

this kind of outrigger has two hydraulic cylinders. After the movable outrigger is extended, it is vertically supported on the ground when working, which is named after its shape like H. It is characterized by large span of outriggers and good adaptability to the site, which has been widely used at present

(3) X-type outrigger

when this kind of outrigger works, the outrigger is X-shaped, with small ground clearance, and there is horizontal displacement in the process of supporting feet landing. When it is small, the space for heavy objects to move is larger than that of H-type outrigger, so it is often used in combination with H-type outrigger. The working principle of tensile machine of Jinan testing machine factory, a plastic extruder enterprise in China, orders rise sharply to form the form of front h and rear X

(4) radial outriggers

take the rotation center of the turntable as the center, and extend four outriggers radially downward from the basin frame of the frame. It is characterized by good stability. During lifting operation, all loads do not pass through the frame, but directly act on the outriggers. In this way, the self weight of the frame can be reduced, the height of the center of gravity of the whole machine can be reduced, and the chassis can be protected from damage. It is mainly used in some super large cranes

(5) swing outrigger

during lifting operation, the outrigger can swing to a position perpendicular to the longitudinal axis of the frame under the action of the hydraulic cylinder; In non working state, it can be fixed on both sides of the frame in parallel. It is characterized by light weight, but due to the limitation of space size, the outrigger cannot be too long, so the horizontal support distance is small

the function of the outrigger is to provide a larger supporting span for the crane during operation without increasing the width of the crane, so as to improve its lifting characteristics without reducing the mobility of the truck crane. There are two kinds of outrigger faults: mechanical parts and hydraulic system

2. Fault and treatment of outrigger mechanical parts

(1) repair of wear of frog outrigger (see Figure 1)

the most easily worn part of frog outrigger is the guide groove 8 on the movable outrigger. If the wear of its working surface reaches 1.5mm, it should be replaced; Otherwise, when the outrigger is retracted, the movable outrigger and the fixed outrigger will collide, which is easy to cause accidents. At this time, the working surface of the guide groove must be repaired by welding, as shown in Figure 2

first remove the movable outrigger, measure the size of the guide groove, and determine the thickness of repair welding. When repairing welding, install the rectangular copper pad 4 with screw 5 and nut 7 as shown in Figure 2, put the copper tube 3 on screw 5, repair welding one section, and then move the next section until the welding is completed. For convenience, the welding rod can also be bent appropriately. However, it should be noted that the position of the weld repair must be on the lower surface of the guide groove in Figure 1 (i.e. weld repair surface 6 in Figure 2). This will not affect the stroke of the piston rod of the hydraulic cylinder and the relative included angle between the fixed outrigger and the movable outrigger when the outrigger is loaded. After welding, use a standard shaft (the shaft diameter is equal to the outer diameter of the rolling sleeve) as the benchmark for shaping, and note that the grooves on both sides must be repaired with the same shaft at the same time

if the outer diameter wear of the rolling sleeve 9 in Figure 1 exceeds 1mm, it should be replaced; Otherwise, it is easy to be crushed in work, which will change the stress condition of the outrigger and lay hidden dangers for safety production

another key point in the maintenance of frog outrigger is the screw 4 shown in Figure 1. There are three places on a frog outrigger, and the screws at these three places are easy to be cut (turned around) due to large radial force. The sheared screws are not easy to screw outward, so many baffle plates 5 are welded to death. This is not good-looking, and it is inconvenient to use gas welding to cut during disassembly. After a long time of observation, we suggest the following: the screws used for axial positioning of the pin shaft in this way should be checked frequently. It is better to replace it once within two years. Here is a simple inspection method, that is, remove the screw, use a new screw with the same pitch for comparison, stick the two screws together, and look at the gap of the thread. If the gap is large, the two screws can't stick together, indicating that the old screw has been deformed greatly and is tired, so it should be replaced, or use a tap of the same size for comparison

(2) repair of the wear of the upper and lower parts of the H-shaped outrigger horizontal beam (see Figure 3)

under the condition of heavy load of the crane, the lifted weight is directly behind the vehicle and higher than the outrigger. At this time, people look at the outrigger at the right rear of the car. If there is a situation as shown in Figure 3, that is, when the horizontal distance between points a and B in the figure is greater than the thickness of the metal plate on the car body 2, or if the outrigger crawls during expansion and contraction, the outrigger must be removed for detection. If there is a deep groove or serious damage on the plate surface, it is necessary to replace the outrigger or weld the worn part. The cost of welding repair outriggers is low and suitable for use

3. Fault and maintenance of outrigger hydraulic system

it can be seen from the hydraulic schematic diagram of frog outrigger (see Figure 4) that the two-way hydraulic lock 8 is installed on the upper end of the front outrigger cylinder, so the tightness of the fixing bolts on it must be the same, otherwise it will cause damage to the sealing ring and oil leakage. Its function is to prevent the outrigger from retracting by itself during crane operation; Prevent the outrigger from falling automatically during crane driving or parking. In the hydraulic system of H-type outrigger, there is no shunt valve but a rotary valve. The outrigger can act alone and has good adaptability to the ground, but the situation of failure is similar to that of frog outrigger

common faults of outrigger hydraulic system:

(1) the oil circuit leaks oil

the reason is that the joint is loose, so it is necessary to find and complete the utilization part in the chemical industry field and tighten it; If the seal is damaged, it should be replaced (1) excess capacity and insufficient demand coexist; If the pipeline has cracks, it should be replaced or repaired by welding

(2) outrigger retraction failure

bidirectional hydraulic lock failure, the plunger in the lock is stuck and must be removed, cleaned, installed and adjusted; The plunger is seriously worn, and the hydraulic lock should be replaced

(3) the outrigger retracts automatically when lifting the load

there are two reasons: first, the one-way valve in the two-way hydraulic lock has poor sealing, so it should be removed for maintenance, installed and adjusted after cleaning. The second is the internal leakage of the hydraulic cylinder. The seal on the piston must be removed for inspection, replaced with a new seal and reinstalled. (end)

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