Measures to improve the efficiency of old construc

2022-07-24
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Measures to improve the efficiency of old construction machinery

bulldozers, loaders, excavators, truck cranes, etc. after being used for a period of time, there are often some phenomena such as poor sensitivity of the control mechanism and slow action of the working mechanism

1? Phenomenon

engine exhaust, operation and sound are all abnormal, starting is difficult and acceleration is slow; The oil in the hydraulic system is polluted, the external and internal oil drainage of hydraulic components, pipelines and joints are serious, and the hydraulic cylinder cannot be locked and retracts automatically; The transmission chain of each control handle of the whole machine is loose, and the operation is blocked and laborious

2? The reason

is mainly due to long-time overloaded work and working in an environment that does not meet the requirements; Daily maintenance is not timely, and major, medium and minor repairs fail to meet the standard requirements

3? Measures

(1) strictly manage and continuously improve the technical quality of operators to ensure the correct use of construction machinery

(2) strengthen the daily maintenance and inspection of equipment to improve the intact rate of equipment

(3) improve the technical level and heart of maintenance personnel to ensure the quality of major, medium and minor maintenance. Appropriate increase of special maintenance equipment, tools, instruments and technical data

(4) the annual output is nearly 2000 sets to adjust and repair the machinery

4. adjustment and repair methods

(1) adjustment of engine throttle

for example, after long-term use, the diesel engine installed on the truck crane sometimes has slow growth when operating its throttle on the truck, failing to reach the maximum speed and power. At this time, it is necessary to check and adjust the entire transmission chain of the pedal accelerator on the vehicle. After all, the worker needs two people to output the results of various curves or values, such as torque change angle. One person controls the accelerator pedal on the vehicle, and the other person observes the movement of the speed regulating lever at the fuel injection pump. Although the operators in the upper cab of the crane have stepped on the accelerator pedal to the limit position for many years, in fact, sometimes the speed regulating lever of the diesel engine fuel injection pump can not reach the limit position. Because the position of the speed regulating lever in the whole machine is not easy to be observed by the operator, its empty stroke is often ignored. Therefore, it is necessary to observe it for a while and try it for several times. The reasons for this situation are: firstly, the dimension chain of the diesel engine throttle transmission system changes, and the accumulation of idle travel between them is too large; Second, some fasteners on the transmission device, such as set screws, are loose. At this time, it should be checked step by step according to the throttle transmission dimension chain. When the upper throttle is pressed to the bottom, the speed control lever must also reach the limit. The idle distance on the throttle transmission chain shall be reserved as required, and shall be fastened and adjusted according to the specific conditions of each equipment

(2) repair of gear pump

the wear of gear pump is mainly the wear of inner surface of pump housing, tooth top and tooth thickness. The repair method is as follows: brush a layer of metal coating

solution on the worn part of the inner surface of the pump housing to restore its original size; For gears, the tooth top and tooth thickness can be electroplated to restore the tooth thickness and tooth top dimensions; Generally, the shaft sleeve is only replaced but not repaired. When replacing a new shaft sleeve, attention must be paid to its axial length and no space must be left. Several used gear pumps of the same model can be accurately measured, and then the gears with light wear and pump body can be re assembled and tested on the test bench

(3) repair of piston pump

the wear of piston pump is mainly caused by the piston surface and the hole where the rotor matches the piston. Repair method: re prepare the plunger according to the measured size of the worn plunger hole. The material, heat treatment process, outer diameter and surface roughness of the new plunger shall meet the relevant technical requirements; Before assembly, grind the new plunger and mating hole. In addition, the plunger and rotor plunger hole with light wear can also be used in several piston pumps of the same model for reassembly. Generally speaking, the clearance between the old plunger and the hole should not exceed 35 μ m. When the wear amount reaches 45 μ M shall be scrapped

(4) repair of control valve

new valve rod shall be prepared according to the measured size of worn valve rod hole, and the material, heat treatment process, dimension and surface roughness of the new valve rod shall meet the relevant technical requirements; Before assembly, it is better to grind the new valve rod and the valve rod hole on the valve plate (it is better to turn a process mandrel for grinding). If the conditions are not met, the new valve rod can also be used for grinding. At the same time, the elastic force of the positioning spring of the control valve and each return spring in the pressure adjustment device should be tested to see whether they meet the requirements. The repair method can also be determined according to the wear degree of the valve rod hole on each valve disc. If there are multiple old valves of the same model, they can be tested and deployed among several. The repaired valve shall be tested on the test bench, or the valve can be placed flat, the two holes above shall be filled with kerosene, and the oil leakage rate shall be measured with a stopwatch to judge the sealing degree of the PHA of the valve for the manufacture of decomposable fibers and textiles

(5) repair of hydraulic cylinder

causes of internal and external leakage of hydraulic cylinder: first, the surface of piston rod (or plunger) is seriously worn or pulled out of groove marks, which can be repaired by electroplating or metal brush plating. Second, the inner surface of the guide sleeve is worn. Because the guide sleeve is cheap, it is usually replaced. Third, the hydraulic cylinder body itself is seriously worn or pulled out of the deep groove, or there is a cavitation area on the inner wall of the cylinder body, which can also be repaired by brush plating process. Fourth, the sealing rubber ring on the piston is worn, and it can be replaced at this time. Both internal leakage and external leakage will cause the hydraulic cylinder to retract automatically. There are three inspection methods for the hydraulic cylinder installed on the vehicle: first, use a dial indicator to adsorb the magnetic gauge base on the piston rod of the hydraulic cylinder, with the gauge needle against the end face of the cylinder barrel, and observe the change value of the gauge needle before and after the engine shuts down for 15min (including the following two methods), that is, the retraction amount of the hydraulic cylinder; Second, stick a piece of paper on the extended piston rod with grease, and measure the change of the distance from the upper end of the paper to the end of the hydraulic cylinder, that is, the retraction of the hydraulic cylinder; Thirdly, a rubber plate that can be loosened and locked is used to lock the piston rod. The measurement method is the same as that of using paper. The above detection method is also a method to judge whether the hydraulic cylinder has internal leakage and its degree. According to the measured retraction amount of the hydraulic pressure cylinder, the wear degree of the seal on the piston and the service time of the equipment can be accurately calculated. If the marking on the buffer valve handle is aligned with the marking for a short time, it can be concluded that the seal is damaged due to improper assembly methods; This is very useful for correcting the wrong assembly method and judging the internal leakage degree of the hydraulic cylinder

(6) cleaning the hydraulic system and filtering the hydraulic oil

hydraulic oil pollution is the main factor for the failure of construction machinery, accounting for about 80%. Therefore, the hydraulic oil must be checked regularly. In case of poor conditions, 120 mesh filtration can be used for filtration; At the same time, the oil tank and the whole hydraulic system shall be cleaned regularly, or the oil shall be changed regularly

(7) adjustment and repair of various operation and control devices

operation and control devices include various handles, buttons, accelerator pedals, etc. the handles that are easy to loosen should be checked frequently to see their harmful size, and their locking devices should be readjusted or tightened; Severely worn parts can be repaired by welding or replaced; For electrical switches or buttons, the contact state of the contact can be adjusted or replaced

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