Rebirth of the Auto Giant

Chapter 59 Assessment

Claire visited Wang Shi's house again at noon on the third day after she left and brought news.

"Wang Shi, here's the news from Carter Company, two requests." Claire sat down and took out a few documents from her backpack and put them on the table.

"I don't know which two requirements are they?" Wang Shi wanted to know what the other party's requirements were.

"You take a look at this first." Claire took a few pieces of A3 paper and handed them to Wang Shi.

"Test paper?" Wang Shi took it over and took a look. These were two test papers, and they were both in Chinese. They were really good.

One is about excavators, and the other is some technical assessment of the Cummins engine equipped on the excavator.

"Yes, in order to better serve the product's three-guarantee service in the future, Carter and Cummins will conduct some assessments on your situation. This is the first one. Only if the technology passes the assessment will there be the second requirement.

After Claire finished speaking, she continued: "Hell, I'm now an employee of their Carter Company." Claire said complainingly.

Wang Shi also knew that the reason why Toclair handled the matter on his behalf was because the transportation was not convenient and the authentication procedures were a bit troublesome, so the other party simply asked Claire to handle it on his behalf.

"Come on, I don't believe they didn't pay you for your hard work." Wang Shi knows that Americans do things one by one and two by two. If you don't have money, no one will do it for you if you don't have money. They are not like us, who have

A good tradition of helping friends.

"Hehe." Claire was pointed out by Wang Shi, so she could only say "hehe" without saying anything else.

"Hell, hurry up and finish these two test papers so that I can go back and fax them to them." Claire urged when Wang Shi didn't write.

"Okay, it'll be quick." Wang Shi went to the bedside and took out the pen given by his previous client and started writing.

The first one is about excavator technology. Maybe the other party thinks that the Chinese people are not too advanced in excavator technology. The whole test paper is about some basic questions, including the function of each part of the excavator and the three-guarantee service.

Specific assessment of some work to be done.

For example, how many hours does the first maintenance take, what maintenance needs to be done and what specific precautions should be taken, etc.

1. Hydraulic excavators are mainly powered by engines, in which hydraulic power is provided by, and this component is lubricated by.

This is a fill-in-the-blank question, mainly to check the maintenance personnel’s examination of the working power source of the excavator.

The power of a hydraulic excavator mainly consists of two parts. One is the engine that provides the most primitive power, and the other is the main pump. The main pump is the heart of generating hydraulic power and the source of hydraulic power for each cylinder.

Mainly driven by the engine, it is connected to the engine crankshaft through a plastic joint, driving the six pistons inside to pump hydraulic oil outward to each working cylinder.

The hydraulic oil used by the main pump is also the lubricating oil of the main pump.

Thinking of this, Wang Shi wrote "main pump" and "lubricating oil" in the two spaces.

2. The work of the hydraulic excavator is controlled by components.

The bucket excavation of the hydraulic excavator also includes the lifting and lowering of the big and small arms, rotation and crawler walking. The main control valve installed behind the big arm and behind the cab distributes the hydraulic oil from the main pump to the entire cylinder and everyone.

Hydraulic components perform work.

If the main pump is like the heart of the excavator, then the main control valve is the brain of the excavator. The amount of flow output to each working cylinder is controlled by the size and duration of the valve opening and closing to perform work.

So the answer to this question is the main control valve.

3. The excavator can rotate 360 ​​degrees without twisting the pipeline, mainly due to the function of the components.

The reason why the excavator can rotate infinitely is because of the rotary joint. The oil circuit inside the rotary joint has a 360-degree ring groove design, so no matter how the excavator rotates, other pipes will not be twisted.

The answer is a swivel joint.

…

The basic knowledge of the entire test paper accounts for 70%, and about 30% of the knowledge is to examine the maintenance personnel's understanding of the three-guarantee work, such as the inspection of various parts and the replacement of gear oil. These will be provided with the operation manual in the future.

There are some above, but fortunately, Wang Shi has done three-guarantee service for excavators for six years before, so this knowledge does not trouble Wang Shi.

Wang Shi finished the entire test paper in less than ten minutes, followed by the Cummins engine test paper.

This is more difficult. It tests the maintenance personnel's basic knowledge of the engine and their technical ability. However, it depends on who the target is. For a senior auto mechanic like Wang Shi, it is even more handy.

At the end of the test paper is a fault diagnosis and troubleshooting question, in which the other party tells the result of the fault and requires the maintenance personnel to write down the entire diagnosis.

1. Now there is an increase in the engine oil of a Caterpillar D320 excavator. As an on-site maintenance personnel, please write down the diagnosis and maintenance process.

This question may seem simple, but it actually tests the maintenance personnel to have a comprehensive understanding of the engine structure and then improve it.

There are two main reasons for the increase in engine oil, one is water entering the oil, and the other is diesel entering the oil.

In addition to the body (which is less likely), the parts that come into contact with water and oil include the two sealing rings of the cylinder liner and the oil cooler. If the two sealing rings of the cylinder liner are aged and damaged, the cooling water between them will

It flows to the oil pan below; the same goes for the oil cooler. The oil cooler is designed to prevent the oil temperature from being too high. The cooler uses cooling water from the outside to cool the oil inside. If the oil cooler is damaged, then

The cooling water from the outside enters the engine oil inside, and then flows to the oil pan, causing an increase in engine oil.

It's more complicated when diesel oil is added to the engine oil.

Diesel and engine oil are one part of the fuel system and the other part of the lubrication system. They seem to be independent of each other. How could diesel get into the engine oil?

Among the previous intersections between the two, the sealing ring of the high-pressure oil pump plunger is one.

The high-pressure oil pump is lubricated by engine oil. If the sealing ring of the upper plunger is damaged, the diesel fuel in the plunger will flow into the engine oil below.

Poor atomization or damage to the fuel injector can also cause the engine oil to enter the diesel, causing the diesel to flow from the inner wall of the cylinder liner to the oil pan below; excessive wear of the piston ring causes poor sealing between the piston ring and the inner wall of the cylinder liner, causing the inside of the combustion chamber to

The incompletely burned diesel will flow to the oil pan below.

Thinking of this, Wang Shi wrote down the entire diagnosis process, and finally listed the replacement parts such as the fuel injector, the high-pressure oil pump plunger seal, the oil cooler... and several other parts.

"Huh!" It had been a long time since he had written with his own hands. Wang Shi rubbed his numb wrist and checked the two test papers again. If there were no problems, he handed them to Claire.

In the last ten years before time travel, with the popularization of computers and smart phones, people have already implemented paperless offices. Wang Shi sometimes did not even write twenty words in half a year. In addition, what he did after time travel was

As a repairman, I don’t deal with words much, so it’s really hard to get used to this sudden incident.