Car Maintenance Basics

Chapter 14 Item 1 Vehicle Maintenance Management ([-])
[-]. Basic knowledge of automobile maintenance management
learning purpose

Knowledge goal:

Understand the meaning, principle, classification and organization of automobile maintenance.

Master the signs of car classification faults sent for repair.

Familiar with the content of car incoming and final inspection.

task description
Under the guidance of teachers, understand the basic technical requirements of automobile maintenance, master the principles, significance, classification, etc. of automobile maintenance.Under the guidance of the work order task, complete the inspection operation of the car.Record and archive the completed work, consciously maintain safe operation and 5S work requirements.

related information
[-]. The meaning of car maintenance
During the use of the car, with the increase of the mileage, its technical condition is constantly changing, and the performance of the car gradually deteriorates until it cannot work.Therefore, it is of positive significance to prevent the deterioration of vehicle conditions and accidents caused by delayed repairs, improve the efficiency of vehicle use, and reduce transportation costs according to its changing rules.

Second, the principle of car maintenance
In the "Regulations on the Management of Vehicle Technology in the Automobile Transportation Industry", it is stipulated that "after the vehicle is repaired, the principle of condition-based repair shall be implemented." The so-called condition-based repair is to carry out repairs according to different operating scopes and depths according to the conditions according to the results of vehicle inspection, diagnosis and technical appraisal.Its purpose is to prevent the deterioration of vehicle conditions caused by delayed repairs and waste caused by early repairs.

Three, the classification of car maintenance
Automobile maintenance is divided into automobile overhaul, assembly overhaul, automobile minor repair and parts repair according to the scope of work.

1. Car overhaul
Automobile overhaul is to restore the intact technical condition of the vehicle by repairing or replacing any parts of the vehicle after the vehicle has been driven for a certain mileage (or time) through detection, diagnosis and technical appraisal, so that it can fully or nearly completely restore the technical performance and use of the vehicle. Restorative repair of performance.

2. Assembly overhaul
Assembly overhaul is a restorative repair that repairs or replaces any parts (including basic parts) of the main assembly of the vehicle after a certain mileage (or time) to restore its complete technical condition.

3. Minor car repair
Automobile minor repair is the method of repairing or replacing individual parts to ensure or restore the operational repair of the vehicle's working ability, mainly to eliminate the faults or hidden dangers that occur or are found during the operation or maintenance of the vehicle.

4. Parts Repair
Parts repair is the repair of parts that have been worn, deformed, damaged, etc. and cannot continue to be used.

Fourth, the organization of car maintenance
1. The process of car maintenance

Auto repair can be divided into many craft operations, and the process of completing these jobs in a prescribed order is called a craft process.Due to the different methods of repairing tissues, the process is also different.The technological process of automobile maintenance has two forms: the vehicle repair method and the assembly exchange repair method.

(1) On-the-car repair method

The car repair method is to remove the parts from the machine in turn during the repair process, after cleaning, testing, classification and repair or replacement, and finally reassemble to achieve the repair method of restoring performance.Due to the different repair cycles of each assembly in the on-vehicle repair method, the continuity of assembly is often affected, so the overhaul cycle is long.However, it is more appropriate to adopt this repair method for repair shops with small repair volume, many types of repair models and different repair units.The technical process of the vehicle repair method is shown in Figure 6-1.

(2) Assembly interchange repair method

The assembly exchange repair method is that in the repair process, in addition to refurbishing the original frame, it is only necessary to remove all the remaining damaged assemblies or accessories and replace them with pre-prepared (or repaired) assemblies or accessories. , and then assembled into a complete machine repair method.This method can greatly reduce the repair time of downtime, which is conducive to improving repair work efficiency, reducing costs and ensuring repair quality.This is also the most popular maintenance method in the maintenance system in the United States, which is of great significance for the user to improve the integrity rate, utilization rate and production efficiency of mechanical equipment.The technological process of the assembly interchange repair method is shown in Figure 6-2.

2. Auto repair operation method
The operation mode of automobile repair is divided into two ways: fixed station operation method and assembly line operation method.

(1) Fixed station operation method

The fixed-station operation method means that the disassembly and assembly of automobiles is fixed at a certain position to complete, and the repair operations after disassembly are still distributed to various professional groups.The advantages of this operation method are: small footprint, simple equipment required, disassembly and assembly operations are not restricted by continuity, and production debugging and adjustment are more convenient.Its disadvantages are: the assembly and bulky parts need to be transported back and forth, and the labor intensity of workers is high.It is generally suitable for small-scale or complex types of repair shops.

(2) Assembly method

The assembly-line method is to carry out the disassembly and assembly of automobiles along the flow sequence, and gradually complete all the assembly and disassembly and repair operations in each professional group or station.The advantages of this operation method are: high degree of specialization, meticulous division of labor, high repair quality, short transportation distance of assembly and heavy parts, and high work efficiency.Its disadvantages are: large equipment investment and large floor space.It is suitable for repair enterprises with a single model and large production scale.

3. Organizational form of auto repair

Auto repair production can be divided into two organizational forms: comprehensive operation and professional division of work.

(1) Form of comprehensive operation organization
The form of comprehensive operation organization refers to the disassembly and repair of automobiles (except for the machining of individual parts and components), all of which are completed by a repair team.Therefore, the repair team has a wide range of operations and requires workers with comprehensive skills and high skills. However, it is difficult to achieve comprehensive proficiency in technology, so the work efficiency is low, the progress is slow, and the repair cycle is long.It is generally only suitable for repair shops with small production scale and complex models.

(2) Professional division of labor organization form

The organization form of professional division of work is that one or several professional groups are responsible for auto repair operations according to types of work, parts, assemblies, assemblies or processes.The degree of complexity of the division of labor depends on the size of the enterprise.This form of labor organization is applicable to both the fixed-station operation method and the assembly-line operation method.It facilitates the use of professional technology and equipment, ensures the quality of repairs, improves work efficiency, improves the operating skills of workers, shortens the repair cycle, and facilitates the organization of balanced cross-operation between units.It is generally applicable to repair enterprises with many vehicles and a single model.

task implementation
[-]. Tool preparation

Tip: Before implementing the homework, each group should prepare the materials and tools needed for this learning task according to the table below.

Data, number of names of tools Data, number of names of tools
A set of commonly used tools for a complete vehicle

One vehicle maintenance manual One vehicle maintenance management manual

[-]. Technical standards and requirements
① All operations meet the requirements for safe operation.

②All operations conform to the operation specification of automobile maintenance.

③ Safety accidents are not allowed during the operation.

[-]. The work to be done

Go to a company for an internship, understand the process of car maintenance, and record it.

learning assessment
[-]. Self-evaluation

1. Summarize the organization of car maintenance.

2. Please write down your experience of this learning task.

3. Self-evaluation of the learning environment (including dress, learning attitude, mastery of knowledge and skills, completion of work pages, etc.).

[-]. Group evaluation

Evaluation status of serial number evaluation items
Good to bad

1 team spirit
2 Whether learning is proactive
3 The situation of obeying the work arrangement

4 Use of tools and instruments
5. Tool finishing and site cleaning
[-]. Teacher Evaluation

Evaluation status of serial number evaluation items
Good to bad

1 Attendance
2 dressing situation

3 classroom order
4 Whether learning is proactive
5. Fill out the learning task book

6 Use of tools and instruments
7. Tool finishing and site cleaning
[-] Technical Standards for Automobile Maintenance

Learn
Knowledge goal:

Learn about the signs and classifications of various car repairs.

Master the basic knowledge of automobile fault inspection.

Familiar with the content of vehicle maintenance inspection.

Skill Goal:
Master the basic process of vehicle maintenance inspection.

task description
Under the guidance of teachers, learn about the technical standards of automobile maintenance, master the classification of automobile maintenance and the signs of repairing, etc.Under the guidance of the work order task, complete the inspection operation of the car.Record and archive the completed work, consciously maintain safe operation and 5S work requirements.

related information
[-]. Automobile and assembly overhaul signs
1. Car overhaul sign
①Passenger car overhaul sign.The sign of overhaul of passenger cars is mainly on the compartment, and if the combination of engine assembly or other sub-assemblies meets the overhaul conditions, it should be sent for overhaul.

② Truck overhaul sign.The overhaul sign of trucks is mainly the engine assembly, combined with the frame assembly or other sub-assemblies that meet the overhaul conditions, it should be sent for overhaul.

2. Assembly overhaul sign
① Engine assembly overhaul sign.Engine cylinder wear, cylindricity reaches 0.175-0.250mm or roundness has reached 0.050-0.063mm (based on the cylinder with the largest wear), the maximum power or cylinder pressure is reduced by more than 25% compared with the standard, fuel and lubricating oil consumption significant increase in volume.

②The overhaul sign of the frame assembly.The frame is broken, rusted, bent, twisted and deformed beyond the limit, most of the rivets are loose or the rivet holes are worn out, and other assemblies must be disassembled before correction, repair or heavy riveting.

③ Overhaul sign of transmission assembly.The shell is deformed and broken, the wear of the bearing hole exceeds the limit, the transmission gear and the shaft are viciously worn and damaged, and need to be completely repaired.

④ Overhaul sign of drive axle assembly.The axle housing is broken and deformed, the wear of the bearing hole of the half shaft sleeve exceeds the limit, and the gear of the reducer is worn, which needs to be corrected or completely repaired.

⑤ Sign of overhaul of front axle assembly.The cracks and deformation of the front axle, the wear of the kingpin bearing hole exceeds the limit, and those who need to be corrected or completely repaired.

⑥ Overhaul sign of passenger car body assembly.The skeleton of the carriage is broken, corroded, and deformed seriously, and the skin is damaged in a large area, which needs to be completely repaired.

[-]. Inspection of vehicles entering the factory and repairing

The inspection of automobiles entering the factory and repairing is a very important link in the process of automobile maintenance.

1. Car incoming inspection

Cars sent for repair must go through the factory inspection to determine the integrity and technical condition of the car, and provide the necessary basis for approving repair man-hours, material costs, arranging repair plans, and formulating repair processes.

① Check and accept the condition of the vehicle repair equipment.When the vehicle sent for repair enters the factory for inspection and acceptance, it is first necessary to check the equipment of the vehicle and master the relevant technical files.

② Understand the usage of the car.Ask the driver about the use, maintenance and repair of the car sent for repair, the mileage, and the symptoms of the fault, as the preliminary basis for determining the fault of the car.

③ Exterior inspection of the car.The steps are as follows:

a. Check the capacity of the car, check whether there is any bump on the outside of the car, whether all kinds of parts are complete, and whether there is any corrosion damage.

b. Check the frame and suspension mechanism to see if there are obvious fractures, deformations and loose rivets.

c. Check whether the tire nuts are fully tightened and the wear of the tires.

d. Check the car for oil leaks, water leaks, air leaks, etc.

e. Check the instruments and accessories in the cab.

f. Check the condition of the engine and accessories.

g. Check the connections of the transmission system, steering system, brake system and other parts.

h. Check the status of lighting, signaling devices, etc.

④Vehicle driving inspection.The steps are as follows:

a. Check the power performance and economic performance of the engine.

b. Check whether the clutch is rattling, trembling, slipping, incomplete separation, etc.

c. Check whether the transmission is rattling, jumping, chaotic and trembling.

d. Check whether the drive shaft is noisy or vibrating.

e. Check whether the rear axle sounds.

f Check the front axle and steering for instability, deviation, heaviness and front wheel swing. g. Check whether the brake is deviated, dragged, invalid and ineffective, etc.

⑤ record.After the vehicle is inspected at the factory, the results of the installation inspection shall be recorded, and several copies shall be handed over to the relevant departments for reference during vehicle repair and completion inspection, and shall be archived as original data.

2. Car repair inspection

After the car is repaired, a repair inspection should be carried out.Its purpose is to check the quality of the car repair through the external inspection of the car, road test and inspection.

According to the national standard GB3798.2-2005, the repair and inspection standards for trucks are as follows.

3. Basic requirements
① The appearance of the vehicle should be clean and intact, and the auxiliary facilities and equipment should be complete and effective.

②The main structural parameters should comply with the original design regulations, and the curb quality changed by repairs should not exceed 3% of the factory rated value of the new car.

③The difference between left and right wheelbase shall not be greater than 1/1000 of the original design wheelbase.

④ The operating temperature of each part is normal, and there is no oil leakage, water leakage, electricity leakage or air leakage everywhere.

⑤The instruments are operating normally and the indications are correct.

⑥Engine, chassis and other assemblies should be sprayed (painted) according to the original design regulations.

⑦The requirements for lubrication and other working media are as follows:
a. Each grease (oil) nozzle should be fully assembled and function effectively, and each assembly should be filled with sufficient lubricant according to the original design regulations.

b. Power steering device, transmission, transfer case, final reducer, hydraulic transmission device, engine cooling system, air brake antifreeze device, hydraulic brake device, air-conditioning refrigerant, windshield cleaning device, etc. shall be in accordance with the original design requirements , filling the specified quality and quantity of medium.

⑧ The supporting seats and pads at the connecting parts of each assembly and the frame should be complete and fixed reliably.

⑨All the bolts and nuts of the whole vehicle should be fully assembled and locked reliably.The tightening sequence and torque of bolts and nuts at key parts shall comply with the maintenance technical requirements of the original manufacturer.Generally, the fasteners should be firm and reliable, and there should be no looseness or defects.Disposable locking bolts must not be reused.

⑩The joint surface of each riveted part should fit tightly, the rivet should be full of nail holes without looseness, the rivet head should not have cracks, defects or incomplete phenomena, and bolt connection should not be used instead of riveting.

All welding parts should be welded according to the regulations, and the weld seam should be flat and smooth, and there should be no welding defects such as slag inclusions and cracks.

The key parts of the steering system, braking system and driving system that affect the driving safety of the car shall not be repaired.

4. Requirements for each assembly mechanism
(1) Engine requirements

The engine shall comply with the provisions of GB/T3799.1 and GB/D 3799.2.

Steering mechanism requirements

①The steering wheel should be flexible in rotation, light in operation, free from abnormal noise, heavy or stuck.The components of the steering mechanism must not interfere with other components during the steering process of the vehicle.

②The steering wheel should be able to return to the center automatically and have a stable straight-line driving ability.There should be no shimmy or other abnormal phenomena when driving on a flat road, and there should be no oversteer when driving on a curve.

③The maximum free rotation of the steering wheel shall meet the requirements of the relevant provisions in GB7258.

④ The lateral slip of the steering wheel of the automobile shall meet the requirements of the relevant provisions in GB7258.

⑤Wheel alignment and maximum steering angle should comply with the original design requirements.

⑥Steering knuckles and arms, steering tie rods and tie rods and ball pins should be free from cracks and damages, and ball pins should not be loose, and tie rods and tie rods should not be tailor-welded.

(3) Requirements for transmission mechanism

① The clutch should be engaged smoothly, disengaged completely, easy to operate, reliable in operation, without abnormal noise, slipping or trembling, and the pedal force should not exceed 300N.

②The free travel and effective travel of the clutch pedal should comply with the original design regulations.There should be no interference with other non-related parts during the action, and the pedal can quickly return to its position when the pedal is released.The fit between the bushing and the shaft should meet the maintenance technical requirements of the original manufacturer.

③Manual transmission and transfer case should be easy to shift, accurate and reliable, with effective interlocking and self-locking devices, and there must be no disordered gears and self-jumping phenomena; there is no abnormal sound during operation, and it is not overheated under normal working conditions.

④ The engine cannot be started when the operating device of the automatic transmission is in any gear position other than P and N.When it is in the P gear, it should have a parking lock function.When the vehicle is running, it can upshift and downshift according to the specified shift points, and the shifting is smooth, without slipping, without impact, and without abnormal noise.Under normal operating conditions it does not overheat.

⑤The transmission shaft and intermediate bearing should work normally without looseness, vibration, abnormal noise and overheating.For vehicles equipped with a retarder, the retarder should function normally and effectively, and the retarding rate should meet the original design requirements.

⑥ The main reducer, differential and wheel reducer should work normally without any abnormal noise, and they should not overheat under normal working conditions.

(4) Requirements for walking mechanism
① The lateral swing and radial runout of the wheel assembly should meet the requirements of the relevant provisions in GB7258.

② For vehicles with a maximum design speed greater than or equal to 100km/h, the wheels shall undergo a dynamic balance test, and the dynamic unbalanced mass shall not exceed 10g.

③ The tires used in automobiles should be compatible with their maximum design speed.

④The tire crown and sidewall shall not have cracks or cuts sufficient to expose the tire ply.

⑤ The depth of the pattern on the tire crown should meet the requirements of the relevant provisions in GB7258; the type, variety and pattern of the tires used on the coaxial top should be consistent; After the rim made by the craft is damaged, it must be replaced with the same rim.

⑥The cooperation between the steering knuckle and the bushing and the pretightness of the hub bearing should meet the maintenance technical requirements of the original manufacturer.

⑦ For vehicles with non-independent suspension, the cooperation between the steering knuckle and the bushing, the cooperation between the journal and the bearing, and the adjustment of the bearing preload meet the technical requirements of the original manufacturer's maintenance, no abnormal noise, and no heat under normal working conditions; shock absorbers , The leaf spring works well and effectively without abnormal noise, and the connecting rods of each part are not loose.

⑧Independent suspension vehicles, the upper and lower ball pins of the steering knuckle are not loose; the coordination of the bearing and the journal, and the adjustment of the bearing preload meet the technical requirements of the original manufacturer's maintenance, no abnormal noise, and no heat under normal working conditions; shock-absorbing springs , torsion bar spring, airbag spring, and shock absorber are functioning normally and effectively without abnormal noise. The connecting rod bushes, ball pins, and gaskets of each part are complete and not loose.

(5) Requirements for braking mechanism

① There is no self-braking phenomenon when the car is running.

② For vehicles using pneumatic brakes, the equipment and performance of the brake system should comply with the relevant provisions of GB7258.

③Proportional valves, pressure limiting valves, load sensing valves, inertia valves or brake anti-lock braking devices equipped in the brake system should work normally and effectively.

④ For diesel vehicles equipped with exhaust brakes, when the exhaust brake device is closed for 3/4 of the stroke, the linkage mechanism should completely stop the fuel supply from the fuel injection pump; and when the exhaust brake device is turned on, it can supply fuel normally .

(End of this chapter)