How to improve the working efficiency of excavators?

How to improve the working efficiency of excavators?

Adjustment and maintenance methods

(1) Adjustment of engine throttle

For example, after long-term use, the diesel engine equipped on the truck crane sometimes grows slowly and cannot reach the maximum speed and power when operating the throttle on the bus. At this time, it is necessary to check and adjust the entire transmission chain of the pedal accelerator. This job requires two people, one is to get on the bus and control the accelerator pedal, and the other is to observe the action of the governor at the fuel injection pump. The crane used for many years, although the operator in the cab has stepped on the accelerator pedal to the limit position, in fact, the speed control lever of the diesel fuel injection pump sometimes fails to reach the limit position. Because the position of the speed control lever in the whole machine is not convenient for the operator to observe, its idle stroke is often ignored, so it is necessary to observe for a period of time and try several times more. The reasons for this situation are as follows: first, the dimension chain of diesel engine throttle transmission system has changed, and the accumulation of intermediate idle stroke is too large; Second, the fasteners on some transmission devices, such as set screws, are loose. At this time, it should be checked step by step according to the throttle drive dimension chain. When the accelerator pedal is pressed to the bottom, the speed control lever must also reach the limit. The idling distance on the throttle transmission chain should be taken as required, and it should be tightened 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 the inner surface, tooth top and tooth thickness of pump shell. The repair method is: brush a layer of metal coating on the worn part of the inner surface of the pump casing.

Liquid to restore its original size; The gear can be electroplated on its tooth top and tooth thickness to restore the tooth thickness and tooth top size; Generally, only the shaft sleeve is replaced without repair. When replacing the new shaft sleeve, we must pay attention to the axial length, leaving no room. Several used gear pumps of the same model can be accurately measured, and then the gears and pump bodies with light wear are selected for reassembly, and experiments are carried out on the test bench.

(3) Repair of plunger pump

The wear of plunger pump is mainly caused by the surface of plunger and the hole where the rotor fits with the plunger. Repair method: reassemble the plunger according to the measured size of the worn plunger hole, and the material, heat treatment process, outer diameter and surface roughness of the new plunger should meet the relevant technical requirements; Before assembly, the new plunger and the matching hole can be ground. In addition, the worn plunger and rotor plunger hole can be reassembled in several used plunger pumps of the same model. Generally speaking, the fit clearance between the old plunger and the hole should not exceed 35μm, and it should be scrapped when the wear reaches 45μ m..

(4) Repair of control valve

A new valve stem should be prepared according to the measured size of the worn valve stem hole, and the material, heat treatment process, size of each part and surface roughness of the new valve stem should meet the relevant technical requirements; Before assembly, it is best to grind the new valve stem and the valve stem hole on the valve plate (it is best to turn a process mandrel for grinding). If the conditions are not met, a new valve stem can also be ground. At the same time, whether the elasticity of the positioning spring and return spring of the control valve in the pressure regulating device meets the requirements should be tested. The repair method can also be determined according to the wear degree of the valve stem hole on each valve plate. If there are many old valves of the same model, it can be tested and deployed among several valves. The repaired valve should be tested on the test bench, or the valve can be leveled, filled with kerosene in the above two holes, and the oil leakage rate measured with a stopwatch to judge the sealing degree of the valve.

(5) Repair of hydraulic cylinder

The causes of internal leakage and external leakage of hydraulic cylinder are as follows: First, the surface of piston rod (or plunger) is seriously worn or pulled out, 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 low in price, it is usually replaced. Thirdly, the cylinder body of the hydraulic cylinder itself is seriously worn or pulled out of a deep ditch, or there is a cavitation zone on the inner wall of the cylinder body, which can also be repaired by brush plating. 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 automatically retract the hydraulic cylinder. There are three inspection methods for the hydraulic cylinder mounted on the vehicle: first, use a dial indicator to adsorb the magnetic gauge seat on the piston rod of the hydraulic cylinder, and the needle will be close to the end face of the cylinder, and observe the change value of the needle before and after the engine is turned off 15min (including the following two methods), which is the retraction amount of the hydraulic cylinder; Second, stick a piece of paper on the extended piston rod with butter, 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; The third is to lock the piston rod with a releasable locking rubber plate, and the measurement method is the same as paper. The above detection method is also a method to judge whether there is leakage in the hydraulic cylinder and its degree. According to the measured retraction of the hydraulic cylinder, the wear degree of the seal on the piston and the service time of the equipment can be accurately calculated. If the service time is short, it can be concluded that the seal is damaged due to improper assembly method. This is very useful for correcting the wrong assembly method and judging the degree of internal leakage of hydraulic cylinder.

(6) Clean the hydraulic system and filter the hydraulic oil.

Hydraulic oil pollution is the main factor of construction machinery failure, accounting for about 80% of the total. Therefore, check the hydraulic oil regularly, and filter it with 120 mesh filter when the conditions are simple; At the same time, the oil tank and the whole hydraulic system should be cleaned regularly, or the oil should be changed regularly.