For some used construction machinery and equipment that have been idle for a long time, old construction machinery and equipment. Before use, the equipment must be tested. Today, Xiaobian will tell you about the test process before use.
engine
Phenomenon: The engine exhaust, operation, and sound are all abnormal, difficult to start, and slow to accelerate; the hydraulic system oil is contaminated, the external and internal leakage of hydraulic components and pipes, joints are serious, the hydraulic cylinder cannot be locked and automatically retracts ; The transmission chain of each control handle of the whole machine is loose, which is blocked and laborious during operation.
Reasons: Mainly long-term overload work and operation in an environment that does not meet the requirements; daily maintenance is not timely, and large, medium and small repairs cannot meet the standard requirements.
Measures
(1) Strict management and continuous improvement of the technical qualities of operators to ensure that construction machinery can be used correctly. (2) Strengthen the daily maintenance and inspection of equipment to improve the equipment's intact rate. (3) Improve the technical level and responsibility of maintenance personnel to ensure the quality of major, medium and minor repairs. Appropriate increase in special maintenance equipment, tools, instruments and technical information.
Adjust and repair machinery
Adjustment and repair methods
(1) Repair of gear pump
Gear pump wear is mainly due to the wear of the inner surface of the pump casing, the tooth tip and the tooth thickness. The repair method is: brushing a layer of metal coating liquid on the worn surface of the pump casing to restore the original size; the gear can be plated on the tooth tip and tooth thickness to restore the tooth thickness and tooth tip size; The sleeve is generally only replaced without repair, and when replacing a new sleeve, you must pay attention to its axial length and do not leave space. Accurate measurements can be made on several used gear pumps of the same model, and then select gears and pump bodies with lighter wear for re-assembly and test on the test stand.
(2) Repair of hydraulic cylinder
Reasons for internal leakage and external leakage of hydraulic cylinder:
First, the surface of the piston rod (or plunger) is badly worn or grooved, which can be repaired by electroplating or metal brush plating.
Second, the inner surface of the guide sleeve is worn out. Because the price of the guide sleeve is low, it is generally replaced.
Third, the hydraulic cylinder block itself is badly worn or deep grooves are pulled out, or cavitation areas appear on the inner wall of the cylinder block, 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:
One is to use a dial gauge to attract the magnetic dial base to the piston rod of the hydraulic cylinder, and the needle against the end surface of the cylinder barrel. Observe that the change value of the needle before and after the engine is turned off for 15 minutes (including the following two methods) is the hydraulic cylinder's value. Amount of retraction
The second is to stick a piece of paper on the extended piston rod with butter, and measure the change of the distance between the upper end of the paper and the end of the hydraulic cylinder, that is, the amount of retraction of the hydraulic cylinder;
The third is to lock the piston rod with a releasable and lockable rubber plate. The measurement method is the same as the measurement method with paper.
The above detection method is also a method to determine whether the hydraulic cylinder is leaking and its degree. According to the measured amount of retraction of the hydraulic cylinder, the degree of wear of the seals on the piston and the service time of the equipment can be calculated more accurately. If the use time is very short, it can be concluded that the seal is damaged due to improper assembly method; this It is very useful for correcting the wrong assembly method and judging the degree of leakage in the hydraulic cylinder.
