Black Gold 1983

Chapter 31 MLS3-170

"The people from the third team?" Han Changhe shook his head: "I know your Uncle Mancang's men very well. They're good at drilling and blasting, but most of them didn't even finish junior high school. You want them to study hydraulic systems? That's like asking a farmer to sew a needle—they're simply not cut out for it!"

Han Changhe turned around and faced Renye: "Nephew, let me be frank with you. The selection of personnel for the comprehensive mining team is not up to me or the mine manager, but up to the machines. This equipment costs over a million yuan; it's no joke. Who gets promoted and who gets demoted depends on their actual abilities. If someone can't do it, they can't do it. If I force them in and something goes wrong, and the equipment breaks down, your Uncle Han can't take that responsibility."

Han Changhe slowly paced around the coal mining machine a couple of times, then reached out and patted its cold body as if he were petting a stubborn, unruly donkey: "Besides, I don't even understand it myself yet. I'll have to go to the coal machinery factory in a few days to learn more."

Renye didn't respond.

He knew that Han Changhe wasn't making excuses; this was no small matter that could be decided in a few words.

So he changed the subject, asking, "Are you going to the coal machinery factory? Didn't they send anyone over?"

"They sent three guys, they just loitered around the mine for two days and then left. Now the machine's broken, and they want us to fix it ourselves following the blueprints? Fix it like hell! If I knew how to fix it, why would I have hired them?!"

Several workers from the electromechanical department chimed in, each adding their own insults, giving the coal machinery factory's after-sales service a thorough dressing-down.

Renye didn't rush to speak. He circled the coal mining machine, looking it over and tapping on it. "What's wrong? Is there something wrong with this machine?"

Han Changhe raised an eyebrow at his gesture: "What, you can understand this?"

Renye casually replied, "I had nothing to do before, so I read 'Use and Maintenance of Coal Mining Machinery' published by the Coal Industry Press in the library."

"That's no use at all. Don't mess around with it, kid. This thing is more precious than our lives, it's very delicate! Right now, there's a strange noise in the moving parts, and the hydraulic system pressure is unstable. It's broken down before we even started working."

Renye smiled knowingly and asked, "After this machine arrived at the mine, did you test-run it?"

"We tried it." Han Changhe pointed to a motor next to him: "We tried it twice under no-load. It was okay at first, but on the third run, the traveling mechanism started making a rattling noise, and the pressure of the hydraulic system was unstable, fluctuating up and down."

"How much pressure?"

"The blueprints indicate a rated pressure of 16 MPa, but it can drop to 12 during operation, and in severe cases, it can drop directly to 10."

Renye frowned, not rushing to a conclusion.

During the no-load test run, the load on the hydraulic system was actually much lighter than the actual working conditions downhole.

If the pressure cannot be stabilized under these conditions, it indicates that the problem is not with the external load, but with the system itself.

"Was the hydraulic oil newly added?" Renye asked.

"Of course it's new. It came with the equipment and was already installed at the factory."

Han Changhe patted the fuel tank: "The first thing I checked was the fuel system. I suspected the fuel pump, but after taking it apart, the plunger was fine."

The two walked and talked.

"We also tested the valve assemblies one by one, but couldn't find the problem. We disassembled the running gear twice and checked the gears and bearings, and they were all fine."

"The hydraulic oil pressure isn't going up. Logically, it should be a problem with the oil pump, an internal leak in the valve assembly, or oil leakage in the cylinder. I've checked all three, but I still can't find the problem. Isn't that strange?"

After Han Changhe finished speaking, he chuckled and shook his head.

He didn't actually expect Renye to understand; he was just seething with anger and wanted to vent to anyone he could find.

Renye listened, and he already understood what was going on.

Han Changhe's investigation approach was flawless: he checked all three major components of the hydraulic system that could cause pressure problems: oil pumps, valve groups, and oil cylinders.

But he forgot one thing.

The most inconspicuous one was overlooked.

Renye walked to the fuel tank, squatted down, unscrewed the sampling port on the side, and put a little oil on his finger.

The oil is the wrong color.

Normal hydraulic oil should be amber in color and clear and transparent.

But the oil was dark and murky, and contained some tiny black particles that were clearly visible in the sunlight.

"Uncle Han, come and see."

Han Changhe leaned closer, squinted at the oil on Ren Ye's fingers, and let out a soft "hmm".

"What's going on?"

"The hose is delaminated," Hitono replied.

"Isn't this new equipment? How could it be peeling off?" A repairman nearby chimed in.

Renye stood up, wiped the oil off his gloves, and explained, "Currently, the overall level of the domestic rubber industry is not high. The inner rubber layer of hydraulic hoses has problems such as unstable formula and substandard vulcanization process."

"Another issue is that there is often a gap of several months between the equipment leaving the factory and being installed on site. If the temperature and humidity are not properly controlled during storage, problems can easily occur with the hoses."

"In places like Jixi, the temperature drops to minus 30 degrees Celsius in winter. When it gets warmer and damp here, rubber hoses are most vulnerable to this. Once the inner rubber layer ages prematurely, it may look fine on the surface, but it's easy to cause problems when pressure is applied."

Han Changhe listened intently, his eyes fixed on the screen.

He'd worked in electromechanical engineering for so long, and he always just fixed what was broken. If the gears were making noise, he'd check the gears; if the pressure dropped, he'd check the oil pump. Who would connect a malfunction to transportation or storage from months ago?

It's not that I can't think of it, it's that I simply wouldn't even consider that direction.

The repairmen nearby exchanged bewildered glances. This kid had even thought of temperature differences?

Renye continued, "The rubber layer on the inner wall of the hydraulic hose has gotten mixed into the oil. These impurities are clogging the damping holes in the valve assembly, so the pressure naturally can't go up."

He walked to the hydraulic valve assembly and pointed to the densely packed row of valve bodies: "The MLS3-170 hydraulic system uses a pilot-operated relief valve, and the damping orifice of the main valve core is less than one millimeter. Such a fine orifice can be blocked by even a small impurity."

"If the pressure is not high enough, the traction of the traveling mechanism will be insufficient, and the meshing force between the gear and the pin will be uneven, which will cause abnormal noise."

These are all problems caused by very small details, but they are often the easiest to overlook.

Han Changhe and several repairmen listened intently and nodded subconsciously.

"And another thing." Renye squatted down and pointed to the cover of the running gear: "When the new machine leaves the factory, the gearbox of the running gear only has assembly oil added, not real lubricating oil."

"The assembly oil has a low viscosity and is mainly used to clean the anti-rust coating on the gear surface during test runs. It cannot be used as a lubricant. This equipment has been sitting for a long time, and you've run it three times without load. The anti-rust coating on the gear surface should be almost worn off, but the actual lubricant hasn't been added yet. The gear surfaces are dry-grinding, so it's no wonder it's making noise."

Han Changhe stared at Ren Ye for several seconds, his expression unreadable, whether it was surprise or something else.

He didn't rush to reply, but squatted down, unscrewed the observation hole of the walking mechanism, put his finger in and rubbed it, smelled it under his nose, and then rubbed it. It really was assembly oil.

"You bunch of good-for-nothings!" Han Changhe whirled around, pointing at the workers beside him, his tone stern. "You can forget such basic things? You didn't even change the assembly oil, and you dare say there's no problem?"

The workers who were being scolded scratched their heads, none of them daring to step forward and risk offending the boss.

However, this problem is particularly easy to overlook. Some workers even think that the oil that comes with the machine can be used directly to save the trouble of changing the oil, so they start working right away.

Renye stood aside without saying a word. When the leader is reprimanding his subordinates, it is most taboo for others to interrupt and try to smooth things over.

Firstly, it would be a loss of face for the leader, making it seem like Han Changhe couldn't control people or establish rules.

Secondly, subordinates will develop a sense of complacency, thinking that someone will bail them out when they are scolded, and they will take it even less seriously in the future.

Han Changhe took a deep breath, suppressing his anger, and waved his hand at the worker: "Go change the oil right now, and check the pipes again. If you make this kind of basic mistake again, get the hell out of here!"

The worker nodded in agreement and turned to prepare to change the oil.

Renye chuckled, "Uncle Han is really impressive!"

"Stop flattering me." He paused, then looked at Renye suspiciously. "Did you learn all this from books?"

Renye shrugged: "Didn't you always tell me that reading a book a hundred times will make its meaning clear?"

"Bullshit! When did I ever say that? I said, 'Do it a hundred times, and the flaws will become apparent!'"