Old Li, along with his two apprentices and Liu Li, carried the toolbox to the lathe and placed it on the ground with a clatter. Wrenches, sockets, copper bars, pullers, and oil pans were laid out in a row, along with chalk—it looked like they were performing surgery on the machine.
"Xiao Liu, tell me, where should we start?" Old Li wasn't treating her like an apprentice this time, but rather like a technical partner discussing something, pointing to the bedside box as he asked.
Liu Li didn't dawdle; time was of the essence: "Squad Leader Li, we have to do it in order. First, remove the front chuck and protective cover to unload the load; then disconnect the main shaft and gearbox connection key to cut off the power; only then can we pull the main shaft and bearing together out of the housing."
"That's the right approach!" Old Li immediately assigned tasks, "Da Niu, you're strong, so you're in charge of removing the chuck; Xiao Wang, remove the protective cover and find the location of the transmission key; Xiao Liu, you have good eyesight, so remember the order in which the parts were removed and mark them with chalk so you don't get them mixed up!"
"Understood!" the three replied in unison and immediately got to work.
The other workers in the workshop stepped back, watching from a distance and whispering among themselves. Master Wang moved a stool and sat not far away, holding an enamel mug in his hand, seemingly drinking water, but his eyes never left the lathe. Director Zhao was even more anxious, pacing back and forth beside him, glancing at the wall clock every now and then, his brows furrowed so deeply they could trap a fly.
"Heave-ho!" Da Niu strained and used an extended wrench to tighten the chuck screws. With a "clang," the heavy three-jaw chuck was removed and carefully placed on the ground, which was padded with a wooden board, so as not to bump it. Xiao Wang was also quick and efficient. In no time, he removed the protective cover, revealing the shiny conical surface at the front end of the spindle.
Next, disassembling the transmission part was where the trouble began. The space was narrow, and the screws were awkwardly positioned, making it difficult to even reach in. Liu Li's small hands, however, were an advantage. She took a small wrench and skillfully tightened it in the gaps, managing to get angles that even experienced craftsmen struggled with in just a few seconds.
"Squad leader, this set screw is rusted to death!" Xiao Wang was trying to tighten a crucial set screw, his face turned red, and he almost bent the wrench, but the set screw still wouldn't budge.
"Don't try to twist it! Put some kerosene on it, let it soak for a while, and then try again," Old Li said casually, full of experience.
"Squad Leader Li, after you've finished dripping the kerosene, could you tap the surrounding casing with a copper rod?" Liu Li added, "Shaking it will make the kerosene seep in faster. If that doesn't work, find a scrap nut, weld it to the set screw, and tighten it with a large wrench. It's safer than directly tightening the set screw head, so you don't strip the thread."
Old Li's eyes lit up: "That's a great idea! Da Niu, bring the welding machine over here!"
Sparks sizzled as the scrap nut was firmly welded to the set screw. Da Niu grabbed a large wrench and pulled hard; with a "squeak," the rusted set screw finally loosened!
"It's done!" Xiao Wang shouted excitedly. Old Li looked at Liu Li with a different gaze—this girl not only knew how to analyze things, but also knew clever repair techniques.
With most of the peripheral parts disassembled, we finally reached the most crucial step: removing the spindle bearing. First, we had to remove the spindle assembly from the headstock, which required removing the housing cover. The housing cover had numerous long screws, some even coated with sealant. Several people took turns tightening them, their arms aching, and their backs soaked with sweat.
"One, two, three, lift!" The men shouted in unison as they carefully lifted the heavy cast iron housing cover and placed it aside. The machine tool's "heart"—the spindle system—was finally revealed.
The gears, shafts, and oil lines were clearly visible, and a smell of engine oil mixed with metal wafted over. At the most crucial front bearing housing, the situation was immediately apparent: a ring of dark oil sludge surrounded the bearing housing, and shiny metal shavings were stuck in the gaps. The spindle was firmly stuck there, unable to move at all.
"Just like Xiao Liu said, that's the problem!" Old Li's tone turned serious.
Removable bearings are even more difficult to handle—the inner ring of the bearing is tightly fitted to the spindle, and normally a puller is needed. Now that the bearing is broken and stuck, it's even harder to fix.
"Mount the puller!" Old Li commanded. Da Niu hooked the three legs of the puller onto the inner ring of the bearing, aligned the middle set screw with the center hole of the spindle, and began to tighten it forcefully.
"Gah... Gah..." A piercing sound came out. The pointer on the puller showed that the force was already very strong, but the bearing still did not move. Instead, fine metal fragments were squeezed out from the gap.
"No! If we pull any further, we'll either damage the main shaft or break the pulley first!" Old Li quickly called for a stop, his brows furrowing even more.
Everyone around held their breath, even Director Zhao came over, forgetting to smoke.
"How about using a gas welding torch to heat up the inner ring of the bearing?" a mechanic suggested. "It expands and contracts with heat, so it'll be easier to disassemble once it expands."
"No way! It's too dangerous!" Old Li immediately objected. "The spindle is too close to the bearing housing. If the temperature isn't controlled properly, the spindle will anneal or deform, and the whole spindle will be ruined!"
Liu Li stared at the stuck bearing, her mind racing, and suddenly spoke up: "Squad Leader Li, Master Wang, I have an idea."
All eyes were on her. Master Wang put down his enamel mug, looked at her, and for the first time asked, "What do you mean?"
Liu Li composed herself and spoke a little faster: "The bearing is stuck because the ball bearing is broken, and the debris is stuck in the raceway. Pulling it forcefully won't work, and heating it won't work either. How about trying a combination of 'knocking loose + oiling + pulling'? Use a copper rod to rhythmically tap the inner ring of the bearing to loosen the debris; at the same time, drip kerosene mixed with machine oil into the gap to lubricate and penetrate; keep the puller pulling gently, maybe we can get it off."
This method was neither forceful nor risky, and everyone present thought it was feasible. Master Wang nodded: "Let's try it as she says."
"Okay!" Old Li immediately gave instructions, "Da Niu, you keep the horse steady and speak up if you feel any movement; Xiao Wang, you're in charge of dripping the oil; Xiao Liu, you keep your hand steady, you knock, but watch your strength, don't use too much force!"
Liu Li took a deep breath and picked up the copper rod. She didn't rush to strike; she first calmed herself down, recalling the tip Master Wang had taught her: "Keep your hands steady." Then she began to strike—"Dong...dong...dong..." The rhythm was even, each strike landing on a different spot on the inner ring of the bearing, neither too light nor too heavy, like keeping a beat.
Xiao Wang held the oil can and dripped the mixed oil into the crack, drop by drop. Da Niu gripped the wrench, concentrating intently on feeling the pressure.
Time ticked by, and sweat dripped down Liu Li's face, soaking her work clothes. Director Zhao smoked one cigarette after another, leaving cigarette butts scattered on the ground.
"Something's moving!" Da Niu suddenly growled. "The wrench seems a little loose!"
Liu Li's eyes sharpened. She maintained the same rhythm of tapping, but slightly adjusted the force, making it more targeted. Xiao Wang also increased the speed at which he dripped oil.
"Crack...squeak..." A different sound came from the bearing, much softer than before.
"It moved! It really moved!" Da Niu shouted excitedly, slowly turning the wrench in his hand, and the pull screw of the horse moved forward little by little—although slow, it was indeed moving!
"Don't stop! Keep going!" Old Li's voice trembled slightly.
Liu Li continued tapping, her eyes fixed on the bearing. Suddenly, a soft "plop" sounded, as if something had fallen, and the puller felt much lighter—the damaged bearing had finally been pulled out intact!
"It's done!" The people around couldn't help but cheer, and some even applauded. Liu Li put down the copper rod, wiped her sweat, and finally smiled.
Old Li carefully placed the bearing on a clean cloth, and everyone gathered around to look—the cage was broken into several pieces, the balls were either cracked or pitted, the raceway was full of grooves and embedded with metal shavings. There was also a scoring mark on the spindle journal, but fortunately it wasn't deep and could still be salvaged.
"My God, with it ground like this, how can it not get stuck?" an old worker sighed.
"Xiao Liu, you're amazing!" Old Li gave him a thumbs up. "From diagnosis to disassembly, your skill level is almost on par with a veteran mechanic!"
Master Wang also came over, picked up the bearing and looked at it, then touched the scratches on the spindle journal, and finally looked at Liu Li, saying only two words: "Not bad."
Those two words were more effective than anything else. Liu Li knew that she had truly won the approval of the mechanics this time—not only could she diagnose faults, but she could also solve difficult problems. Next was finding a spare bearing, repairing the spindle, and putting it back together. Looking at the disassembled lathe, she felt more confident, her eyes shining—she had overcome this hurdle again.
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