Two. A brief history of excavators It has been 130 years since the first manual excavator came out. During this period, it has experienced a gradual development process from steam-driven bucket rotary excavator to electric-driven and internal-combustion engine-driven rotary excavator and fully automatic hydraulic excavator with electromechanical and hydraulic integration technology.
Due to the application of hydraulic technology, a suspended excavator equipped with a hydraulic backhoe appeared in the 1940s, and a traction full-rotary hydraulic excavator and a crawler-type full-hydraulic excavator were successively developed in the middle and early 1950s. The original trial-produced hydraulic excavator used the hydraulic technology of aircraft and machine tools, and lacked hydraulic components suitable for various working conditions of the excavator, so the manufacturing quality was not stable enough and the supporting parts were not complete. Since the 1960s, hydraulic excavators have entered the stage of popularization and vigorous development, and the manufacturers and varieties of excavators in various countries have increased rapidly, and the output has soared. During 1968- 1970, the output of hydraulic excavators has accounted for 83% of the total output of excavators, and now it is close to 100%.
Third, the composition of the excavator Common excavator structures include power device, working device, slewing mechanism, control mechanism, transmission mechanism, walking mechanism and auxiliary facilities.
From the appearance, the excavator consists of three parts: working device, upper turntable and walking mechanism.
Fourth, the development history of excavators Initially, excavators were all manual. They have been invented for 130 years, and have experienced various driving modes such as steam drive, electric drive and internal combustion engine drive.
After 1940s, hydraulic technology was applied to excavators, and in 1950s, crawler-type full hydraulic excavators were developed.
The three most important parameters of excavator are vehicle weight (mass), engine power and bucket capacity.
195 1 year, the first full-hydraulic backhoe excavator was launched by Poquelin factory, thus creating a new space in the field of excavator technology development.
Verb (abbreviation of verb) Classification of excavators The following are the classification of common excavators:
Classification of excavators: There are two common excavators: internal combustion engine-driven excavators and electric excavators. Among them, electric excavators are mainly used in flammable and explosive places such as plateau hypoxia and underground mines.
Classification of excavators 2: According to different walking modes, excavators can be divided into crawler excavators and wheeled excavators.
Classification 3 of excavators: According to different transmission modes, excavators can be divided into hydraulic excavators and mechanical excavators. Mechanical excavators are mainly used in some large mines.
Classification of excavators: According to the purpose, excavators can be divided into general excavators, mining excavators, marine excavators, special excavators and other different categories.
Classification of excavators: According to the bucket, excavators can be divided into front shovel excavators and backhoe excavators. The front shovel excavator is mainly used to dig materials above the surface, while the back shovel excavator is mainly used to dig materials below the surface.
Backhoe excavator backhoe is the most common one we have ever seen. It cuts the soil backwards and downwards. It can be used for excavation below the shutdown working face, and the basic operation methods are: ditch end excavation, ditch side excavation, straight line excavation, curve excavation, keeping a certain angle excavation, ultra-deep ditch excavation and ditch slope excavation.
Front shovel action form of front shovel excavator. Its characteristic is "advance, forcibly cut the soil". The front shovel has great digging force, which can dig out the soil above the parking surface. It is suitable for digging dry foundation pits with a height greater than 2m, but it must be equipped with an up-and-down ramp. The bucket of the front shovel is larger than that of the equivalent backhoe excavator, which can dig one or three kinds of soil with water content less than 27%, cooperate with the dump truck to complete the whole excavation and transportation operation, and can also dig large dry foundation pits and mounds. According to the different relative positions between the excavation route and the transport vehicle, there are two ways to excavate and unload the soil: front excavation and side unloading; Forward excavation and reverse unloading.
Eight, full hydraulic full rotary excavators Today's excavators account for the vast majority of all full hydraulic full rotary excavators. Hydraulic excavator is mainly composed of engine, hydraulic system, working device, walking device and electrical control. The hydraulic system consists of hydraulic pump, control valve, hydraulic cylinder, hydraulic motor, pipeline and oil tank. The electrical control system includes monitoring panel, engine control system, pump control system, various sensors, solenoid valves, etc.
Hydraulic excavators generally consist of three parts: working device, rotating device and walking device. According to its structure and use, it can be divided into crawler type, tire type, walking type, full hydraulic type, semi-hydraulic type, full rotary type, non-full rotary type, universal type, special type, articulated type and telescopic arm type.
The working device is a device that directly completes the excavation task. It consists of boom, bucket and bucket. The lifting and lowering of the boom, the extension of the boom and the rotation of the bucket are all controlled by reciprocating double-acting hydraulic cylinders. In order to meet the needs of different construction operations, hydraulic excavators can be equipped with a variety of working devices, such as digging, lifting, loading, leveling, clamping, bulldozing, impact hammer and other working tools.
The rotary walking device is the body of the hydraulic excavator, and the upper part of the turntable is provided with a power device and a transmission system. The engine is the power source of the hydraulic excavator, so diesel oil can be used in convenient places, and motors can also be used instead.
The hydraulic transmission system transmits the power of the engine to the executive elements such as hydraulic motor and hydraulic cylinder through the hydraulic pump, and pushes the working device to move, thus completing various operations.
Nine. Problems needing attention in driving excavators 1. Excavators are fixed assets with large economic investment. In order to improve the service life of equipment and obtain greater economic benefits, equipment must be assigned personnel, machines and posts, and responsibilities must be clearly defined. When the post must be transferred, the equipment shall be disclosed.
2. After the excavator enters the construction site, the driver should first observe the geological conditions and surrounding environment of the working face, and there should be no obstacles within the rotating radius of the excavator to avoid scratching or damaging the vehicle.
3. After the machine is started, no one is allowed to stand on the bucket, shovel arm and crawler to ensure safe production.
4. When the excavator is working, it is forbidden for anyone to stay or walk within the radius of gyration or under the bucket. Non-drivers are not allowed to touch and touch the cab, and they are not allowed to bring training drivers to avoid damaging electrical equipment.
5. When the excavator moves, the driver should observe and whistle first, and then move, so as to avoid safety accidents caused by someone near the machine. The moved position shall ensure that the space of the rotating radius of the excavator is not hindered, and illegal operation is strictly prohibited.
6. After the work, the excavator should be moved away from the low-lying place or the edge of the geosyncline (ditch) and parked on the flat ground, and the doors and windows should be closed and locked.
7, the driver must do a good job of daily maintenance, repair, maintenance of equipment, do a good job of daily records in the use of equipment, found that the vehicle has a problem, can't work with illness, and timely report the repair.
8. The cab must be clean, and the surface of the car body must be clean, free of dust and oil; Get into the habit of cleaning the car after work.
9, the driver should make a record of the day shift, the day's work content statistics, the odd jobs or zero items outside the project recorded in time, and make a record of checkout.
10. Drivers are forbidden to drink and drive at noon during work. If it is found, it will be given economic punishment and the economic losses caused will be borne by itself.
1 1. In case of man-made vehicle damage, it is necessary to analyze the causes, find out the problems, distinguish the responsibilities, and impose economic penalties according to the severity of the responsibilities.
12, we should establish a high sense of responsibility, ensure safety in production, do a good job in communication and service with employers, do a good job in bilateral relations, establish a good work style, and work hard for the development and efficiency of enterprises.
X. Maintenance of excavators The purpose of regular maintenance of excavators is to reduce machine failures and prolong the service life of machines; Shorten the downtime of the machine; Improve work efficiency and reduce operating costs.
As long as the fuel, lubricating oil, water and air are well managed, 70% of failures can be reduced. In fact, about 70% of failures are caused by poor management.
1, different brands of diesel should be selected according to different ambient temperatures for fuel management (see table1); Diesel oil cannot be mixed with impurities, lime soil and water, otherwise it will make the fuel pump wear prematurely; The high content of paraffin and sulfur in inferior fuel will damage the engine; After daily operation, the oil tank should be filled with oil to prevent water droplets from forming on the inner wall of the oil tank; Open the drain valve at the bottom of the oil tank to drain water before daily operation; After the engine runs out of fuel or the filter element is replaced, the air in the road must be exhausted.
The lowest ambient temperature is 0℃-10℃ -20℃ -30℃
Diesel brand 0#-10# -20# -35#
2. Management of other oils Other oils include engine oil, hydraulic oil and gear oil. Different brands and grades of oils cannot be mixed; Different kinds of excavator oil have different chemical or physical additives in the production process; Make sure the oil is clean and prevent impurities (water, dust, particles, etc.). ) from mixing; Select the oil label according to the ambient temperature and use. When the ambient temperature is high, the engine oil with high viscosity should be selected; when the ambient temperature is low, the engine oil with low viscosity should be selected; The viscosity of gear oil is relatively large to adapt to large transmission load, and the viscosity of hydraulic oil is relatively small to reduce the flow resistance of liquid.
Table 2 Selection of Oil for Excavators
External temperature of container℃ Oil replacement cycle h Replacement quantity l
Engine oil pan -35-20 CD SAE 5W-30 250 24
-20- 10 CD SAE 10W
-20-40 CD SAE 10W-30
- 15-50 CD SAE 15W-40
0-40 CD SAE 30
Rotating mechanism box -20-40 CD SAE 30 1000 5.5
Shock absorber housing CD SAE 30 6.8
Hydraulic oil tank CD SAE 10W 5000 PC200 Model: 239
Type PC220: 246
CD SAE 10W-30
CD SAE 15W-40
Final drive CD SAE90 1000 5.4
3. Grease management using lubricating oil (butter) can reduce the wear of moving surfaces and prevent noise. When storing grease, dust, sand, water and other impurities should not be mixed; It is recommended to choose lithium-based grease G2-L 1, which has good wear resistance and is suitable for heavy load conditions. When filling, try to squeeze out all the old oil and wipe it clean to prevent sand sticking.
4. Maintenance of the filter element The function of the filter element is to filter impurities in the oil or gas path to prevent impurities from invading the system and causing failures; Various filter elements should be replaced regularly according to the requirements of the operation and maintenance manual; When replacing the filter element, check whether the old filter element is attached with metal, and diagnose and take improvement measures in time if metal particles are found; Use pure filter elements that meet the requirements of the machine. The poor filtration ability of fake and inferior filter elements, and the quality and material of filter layer do not meet the requirements, which will seriously affect the normal use of the machine.
5. Contents of regular maintenance ① After the new machine works for 250 hours, the fuel filter and additional fuel filter should be replaced; Check the clearance of the engine valve.
② Daily maintenance; Check, clean or replace the air filter element; Clean the inside of the cooling system; Check and tighten the track shoe bolts; Check and adjust the back tension of the track; Check the air inlet heater; Replace the bucket teeth; Adjust the bucket clearance; Check the liquid level of the front window cleaning solution; Check and adjust the air conditioner; Clean the floor of the cab; Replace the crusher filter element (optional). When cleaning the inside of the cooling system, after the engine is fully cooled, slowly loosen the filler cap, release the internal pressure of the water tank, and then drain the water; Don't clean the engine when it is working, the high-speed rotating fan will cause danger; When cleaning or replacing coolant, the machine should be parked on a level ground; Replace the coolant and corrosion inhibitor according to Table 3. The ratio of antifreeze to water is as required in Table 4.
Coolant internal cleaning and replacement cycle types of corrosion inhibitor replacement cycle of cooling system
AF-ACL antifreeze (super antifreeze) every 2 years or every 4000 hours, every 1000 hours or when changing coolant.
AF-PTL antifreeze (long-acting antifreeze) every year or 2000 hours.
Add AF-PT antifreeze (winter type) every 6 months (only in autumn).
Table 4 Mixing ratio of antifreeze and water
Ambient temperature℃/capacity l-5-10-15-20-25-30
Antifreeze PC 200 5.16.7 8.09.110.211.
PC 220 5.4 7.0 8.4 9.6 10.7 1 1.65
Water pc20017.115.514.213.12.01.
PC 220 17.9 16.3 14.9 13.7 12.6 1 1.65
③ Check items before starting the engine. Check the coolant level (add water); Check the oil level and add oil; Check the fuel level (add fuel); Check the hydraulic oil level (add hydraulic oil); Check whether the air filter element is blocked; Check the wires; Check whether the horn is normal; Check the lubrication of the bucket; Check the water and sediment in the oil-water separator.
④ Every 100 maintenance items. Boom cylinder head pin shaft; Boom pin; Rod end of boom cylinder; Pin shaft of bucket cylinder head; Connecting pin of boom and bucket arm; The cylinder rod end of the stick cylinder; Bucket cylinder head pin shaft; Half-bar connecting rod connecting pin; Bucket rod and rod end of bucket cylinder; Bucket cylinder head pin shaft; Connecting pin of connecting rod; Check the oil level in the slewing mechanism box (refueling); Drain water and sediment from the fuel tank.
⑤ Check the oil level in the main reducer box every 250H for maintenance items (add gear oil); Check the battery electrolyte; Change the oil in the engine oil pan and engine filter; Lubricate the slewing bearing (2 places); Check the tension of fan belt, check the tension of air conditioner compressor belt and adjust it.
⑥ Maintenance items every 500 hours. At the same time every 100 and 250H maintenance projects; Replace the fuel filter element; Check the height of the grease for the slewing pinion (add grease); Check and clean radiator fins, oil cooler fins and cold sensor fins; Replace the hydraulic oil filter element; Change the oil in the final drive box (only at the first 500 hours, and then at 1000 hours); Clean the air filter inside and outside the air conditioning system; Replace the hydraulic oil drain element.
⑦ Maintenance items every 1000h. At the same time, carry out maintenance projects every 100, 250 and 500h; Replace the oil in the slewing mechanism box; Check the oil level (oil return) of the shock absorber housing; Check all fasteners of turbocharger; Check the clearance of turbocharger rotor; Inspection and replacement of generator belt tension; Replace the anti-corrosion filter element; Change the oil in the final drive box.
⑧ Maintenance items every 2000 hours. 1. Complete the maintenance project every 100, 250, 500 and 1000h; Clean the filter screen of the hydraulic oil tank; Clean and check the turbocharger; Check the generator and start the motor; Check the engine valve clearance (and adjust); Check shock absorber.
Pet-name ruby above 4000 h maintenance. Increase the inspection of the water pump every 4000 hours; Add the item of changing hydraulic oil every 5000 hours.
Attending long-term storage. When the machine is stored for a long time, the working device should be placed on the ground to prevent the piston rod of the hydraulic cylinder from rusting; The whole machine is cleaned, dried and stored in an indoor dry environment; If it can only be stored outdoors due to conditions, the machine should be parked on a well-drained cement floor; Before storage, fill the oil tank, lubricate all parts, replace hydraulic oil and engine oil, coat a thin layer of butter on the exposed metal surface of the piston rod of the hydraulic cylinder, and remove the negative terminal of the battery, or remove the battery for separate storage; According to the lowest ambient temperature, an appropriate proportion of antifreeze is added to the cooling water; Start the engine once a month, operate the machine to lubricate the moving parts and charge the battery at the same time; Turn on the air conditioner for refrigeration for 5- 10min.
6. Selection of hydraulic oil and maintenance of hydraulic system 1). Reasonable selection of hydraulic oil.
(1) hydraulic oil viscosity
The principle of determining the viscosity of hydraulic oil is to make the viscosity of hydraulic oil (used for pumps, motors and other parts) in the best range (16-36x 10-6mm 2/s) on the premise of considering the working temperature and efficiency of hydraulic circuit. The short-time cold start viscosity corresponding to the lowest ambient temperature is ≤1000x10-6mm 2/s; The viscosity at 90℃ corresponding to the maximum allowable oil leakage temperature in a short time is ≥10x10-6mm 2/s.
(2) Viscosity index (VI)
This index directly reflects the property that the viscosity of oil changes with the change of temperature (that is, the viscosity-temperature characteristics of oil). The high viscosity index of oil means that the viscosity of this oil changes little with the change of temperature. On the contrary, it is bigger. The viscosity index of anti-wear hydraulic oil of well-known foreign manufacturers (such as Mobil and Shell) is all VI≥ 1 10, and the viscosity index of domestic advanced anti-wear hydraulic oil is about VI=95. However, the viscosity index of high viscosity index hydraulic oil (HV) and multi-grade engine oil produced abroad is VI >；; 140。 This point should pay special attention to users who use large imported hydraulic excavators and domestic hydraulic oil (or use engine oil as hydraulic oil). The decrease of viscosity index will reduce the environmental temperature range that oil can adapt to. If it is not necessary to use it, it is necessary to consult the oil manufacturer for relevant information, appropriately adjust the use range of oil products, and change the relevant set values of equipment (such as limit temperature, etc.). ) If necessary.
(3) Other comprehensive performance
Due to the high working pressure (≥32MPa) of the hydraulic system of modern large-scale hydraulic excavators, the allowable working oil temperature is high (about 90℃). In order to ensure that the hydraulic system can work normally during the normal oil change cycle, the oil selected by the system is required to have good quality in lubricity, oxidation stability, wear resistance, rust prevention and corrosion resistance, emulsification resistance, foam resistance, shear stability and extreme pressure load.
2) Good hydraulic oil cooling system
For the improvement of the hydraulic oil cooling system (more precisely, the hydraulic oil temperature control system) of large hydraulic excavators, although the specific methods adopted by various manufacturers are different, the basic idea is the same, which can not only balance the hydraulic oil temperature in the ideal range during continuous operation, but also make the hydraulic system quickly heat up (reach the normal working temperature range of oil) when it is put into operation in cold state. On the premise of using qualified hydraulic oil, when the hydraulic oil is overheated, the inspection steps of the hydraulic oil cooling temperature control system are as follows:
(1) Whether the hydraulic oil radiator is blocked by dirt, resulting in a decrease in heat dissipation efficiency, clean the radiator if necessary.
(2) Detect the actual working pressure of the fan speed control system under extreme conditions, so as to judge whether the hydraulic part of the loop is faulty and whether the oil temperature sensor or control circuit works normally. At this time, the fan speed and system working pressure should be the maximum; Otherwise, the corresponding parameters of the system should be adjusted or the damaged parts should be replaced.
3) Check related hydraulic parameters of the system
At present, there are two main control methods for the working pump of large hydraulic excavators: limit load regulation (GLR) with pressure cut-off function and load sensing regulation (LS). When the working pressure of the system reaches the set value, the deflection angle of the swash plate of the variable displacement pump is reduced, so that the pump can only be kept in the "residual" flow state needed to maintain the pressure and avoid overheating caused by overflow of the overflow valve. In order to achieve this goal, according to the process requirements, the system parameters are matched to make the set value of the cut-off valve in the loop lower than the set value of the primary pressure valve; Otherwise, the opening of the main pressure valve will cause the overflow to overheat.
At the same time, check whether the secondary valve works normally. This work must be carried out in strict accordance with the technical requirements, and the relevant parameters of the system should be restored if necessary.
4), eliminate abnormal internal leakage
Mainly refers to the abnormal internal leakage caused by the locking of reversing valve and pressure valve caused by the pollution of hydraulic oil in the system. Inspection method: measure the pressure, check the function, or listen for abnormal noise ("throttle flushing sound caused by lax valve opening") or touch to check whether the local temperature is too high.
5), prevent the component volume efficiency decline.
Pay attention to both abnormal wear and normal wear. The former may happen in a very short time, which can be judged by checking the oil quality and combining with the functions of the system (such as whether the actuator moves normally and whether the speed drops). ); The latter should follow certain laws, conduct a comprehensive investigation and take timely measures.