66: Chapter 66 Unpowered Supported Exoskeleton

April 2nd, Saturday.

Six in the morning.

Before the alarm clock even had time to emit its first roar, Jiang Lin had already opened his eyes.

He washed up briefly, gently twisted open the security door, and walked out.

In Jiangcheng during early spring, the morning air was as chillingly cold as if it had been kept in a refrigerator.

A few minutes later, he stood in front of the garage door.

Unlocking, pulling the door open, turning on the lights.

Pulling the door down again, he walked over to the large workbench in the center of the garage, pulled over a plastic stool, and sat down.

On the workbench, a layer of clean oil-proof paper was spread flat.

On the paper, all the loose parts for the two rods were neatly laid out.

This was what he had made during his stolen moments of leisure over the past two weeks.

A prototype of a passive exoskeleton that relied entirely on mechanical principles and required no electrical power drive.

Four 7075-T6 aluminum alloy support rods, whose surfaces had undergone anodic oxidation treatment, presented a stern matte black, with each length being approximately 45 centimeters.

Four complexly shaped ratchet locks.

These were heavy-duty ratchet locators he had hunted down online, whose original purpose was not human weight-bearing.

Jiang Lin did not directly trust the merchant's load parameters, instead treating them as semi-finished blanks.

The truly load-bearing pawls, pins, and limit plates were all replaced by him with grade 45 steel parts, while the original factory parts only retained the housing and partial gear plate structure.

Eight high-strength stainless steel hinges gleamed with a cold light.

A four-meter-long black nylon strap, extremely tough in material, was of the specification used to make car seatbelts.

Next to it was also a transparent plastic parts box, filled neatly and categorized with a pile of internal hex screws, high-carbon steel washers, and retaining rings of various sizes.

Today was the final general assembly and verification.

Jiang Lin picked up the first aluminum alloy support rod.

The first step was to do an initial radial runout screening to determine whether this rod had obvious bending or surface abnormalities.

He moved a small cast iron inspection surface plate out of the moisture-proof box beneath the workbench and placed it on the desktop.

Then he took two ground V-blocks, placing them left and right on the surface plate.

The support rod was gently nested into the V-grooves.

The dial indicator's magnetic base attached to the edge of the cast iron surface plate, with its probe pressing against the middle section of the support rod.

Adjusting the dial and connecting rod, he let that extremely tiny ruby measuring probe of the dial indicator steadily press against the surface of the middle section of the support rod.

The pointer flickered slightly and stopped at a certain scale division.

Jiang Lin turned the outer ring of the dial to zero the scale.

Extending his left index finger to rest on one end of the support rod, he began to rotate this metal rod extremely slowly and steadily.

With the rotation of the round rod, the pointer on the dial indicator began to deflect extremely slightly.

The pointer deviated to the right by half a division, slowly fell back, and then deviated to the left.

A full circle was completed.

The maximum runout recorded by the dial indicator's pointer was also the maximum deviation value.

The maximum runout was 0.012 millimeters.

Jiang Lin calculated silently in his heart.

As a support rod meant to bear human weight and dynamic impact, at this length, a degree of bending of 0.012 millimeters was completely within the allowable tolerance range of elastic deformation.

He picked up a marker, wrote 1-0.012 on the end of the rod, and placed it in the qualified area on the right.

Switching to the second one.

Mounting, zeroing, rotating.

Maximum deviation: 0.008 millimeters.

The straightness of this rod was exceptionally good.

Switching to the third one.

When Jiang Lin slowly rotated this rod, the amplitude of the dial indicator's pointer's movement noticeably increased.

The pointer crossed the first division, crossed half a division, and finally stopped at a position that made one somewhat anxious.

Maximum deviation: 0.015 millimeters.

0.015 millimeters, which was one-fifth the diameter of a single strand of hair.

In the vast majority of civilian industries in the Real World, this was data that could be completely ignored.

But this rod was going to be taken to the Wasteland.

In that world, tiny tolerances would be infinitely magnified under extreme heavy pressure, ultimately evolving into fatal mechanical failures.

He looked at this rod with a 0.015-millimeter deviation, a hint of hesitation flashing in his eyes.

He really wanted to machine a new one.

However, the aluminum materials on hand had no allowance left, and time did not allow him to go procure new materials again.

Sighing, he took down this rod and placed it at the edge of the qualified area.

Then he opened his notebook and picked up his pen.

"Third left lower support rod — runout 0.015 mm, may have slight bending or roundness errors, listed for priority re-inspection."

"During the sixth Wasteland mission, after using the exoskeleton for long-term low-position operations, this component must be disassembled and re-inspected to determine if permanent bending deformation has occurred."

After finishing writing this line, he felt a bit more at ease in his heart.

Surviving in the Wasteland, acknowledging flaws and establishing a monitoring mechanism, was far more reliable than blind self-confidence.

The fourth one.

Placed on, rotating.

Maximum deviation: 0.006 millimeters.

All four rods passed the initial inspection.

The second step was the heart test of the entire passive exoskeleton set.

The engagement precision of the ratchet lock.

This kind of exoskeleton had no motor, no hydraulic pump, and it purely relied on ingenious mechanical structures to work.

Its core principle was very simple.

When Jiang Lin needed to rest or squat down with a load, he bent his knees, and the support rods on his thighs and calves would slide relative to each other accordingly.

When reaching the specified angle, the locking teeth inside the ratchet lock would instantly drop, biting firmly into the tooth slots on the slide bar like a beast's fangs.

This locking process must be one-way.

Once locked, the two support rods would turn into a rigid pillar, replacing Jiang Lin's leg bones, and directly transmitting the weight of his upper body and backpack to the ground.

Unless Jiang Lin used his hand to flick the release paddle, this pillar would not slip, at least within the range of static load and low-speed impact he set.

Therefore, the precision of the engagement between the ratchet and the slide bar directly determined whether it was a life-saving straw or a fatal ghost gate on Jiang Lin's body.

Jiang Lin was all too clear about the stakes involved.

If there was even a half-millimeter sliding allowance between the engagement surfaces, then the moment Jiang Lin squatted down with a hundred-catty load, the lock would experience an extremely brief gear slip.

He would feel that the air chair he sat down on suddenly sank downward by half a centimeter.

On flat ground, this would at most make his heart panic for a moment.

But in the Wasteland environment, it was different.

He might fall over.

An accidental fall, a sprained ankle, or the back of his head hitting some protruding hard object.

In that world without surgeons, any of the above situations could be directly equated with death.

Therefore, this matter had to be done right, leaving no room for suspense.

Jiang Lin picked up the main body of the first ratchet lock and carefully secured it to the heavy-duty vise at the edge of the workbench.

Changing to a dial indicator with a sharp probe, he began to measure the tooth pitch of every locking tooth inside the ratchet.

A total of 24 teeth.

Holding his breath, he turned the handwheel, letting the probe slide past the bevel of the first tooth, fall into the root of the tooth, and recorded the reading.

Then continuing to slide, crossing the tooth tip, falling into the next tooth root, and recording again.

24 teeth, 24 dial indicator readings.

The reading resolution could reach the micron level, but Jiang Lin knew very well that this was not a tooth profile inspection in a metrology room.

It could only screen out obviously uneven tooth pitches and bad gear positions invisible to the naked eye.

He listed a dense row of data on his scratch paper.

Maximum deviation: 0.008 millimeters.

Minimum deviation: 0.003 millimeters.

Average deviation: 0.005 millimeters.

Even tooth pitches did not mean that twenty-four teeth would share the load together.

The ones truly bearing the strain were always the one or two teeth currently bitten by the pawl.

But the more stable the tooth pitch was, the more controllable the backlash was when the pawl fell into each gear, and the less likely it was for a certain gear to have excessively shallow engagement or sudden gear dropping.

The data was qualified.

Next was the tactile test.

He took the ratchet lock off the vise and picked up a fully-toothed slide bar serving as a benchmark.

This slide bar had been quenched with high-carbon steel, and its hardness was extremely high.

He inserted the slide bar into the slide way of the ratchet lock, then grasped both ends with both hands and began to push and pull repeatedly.

Accompanied by the movement of the slide bar, a succession of rhythmically distinct metallic impact sounds emitted from inside the ratchet.

"Click, click, click..."

Every time it sounded, it meant one tooth was firmly bitten to death.

Jiang Lin concentrated all his attention on the reaction force transmitted through his hands.

The tactile sensation of engagement was incomparably crisp, without a trace of lingering friction, let alone the kind of slipping phenomenon that made one's heart creeped out.

When he tried to pull in the opposite direction with force, the lock had no jamming or vibration from metal deformation.

He pushed and pulled once, pulled it out, and inserted it again.

Repeated a full twenty times.

Every sense of damping, every crisp locking sound, was as if carved from the same mold.

Jiang Lin let out a long breath of foul air, looked at the lump of metal in his hands, and nodded.

Then, the second one.

The third one.

The fourth one.

All the tests were as rigorous as mechanical replication, and the results went without any surprises.

All passed.

Third step, final assembly.

Jiang Lin took the main belt bracket that had been made in advance.

The main body of the bracket was a thick aluminum alloy plate.

The back of this plate, which was the side that would press against Jiang Lin's waist stress pad, presented a matte texture covered with intersecting fishscale-like patterns.

However, the belt was not the main load-bearing part and was only responsible for positioning.

The parts that truly bore the weight were the load-bearing pads under the hips on both sides and the cushion on the back of the thighs.

After locking in a half-squat, the body weight first fell onto these two load-bearing pads, and then was transmitted to the footrests and the ground through the support rods.

If the belt had to take the full load directly, bruises would form on both sides of the hip bones in less than half a day.

In fact, what he was truly checking was not the side against the waist.

The places against the body had rubber pads and canvas pads, so excessively pursuing flatness was meaningless.

What he needed to check with a dial indicator was the metal mating surfaces of the hinge base and the ends of the support rods.

Once those places had any warping, after the screws were tightened, eccentric loads would form, and under long-term impact, fatigue cracks would appear first.

In the Real World, if it cracked, it cracked; at worst, he could just buy another one online.

But in the Wasteland, for such core components, once made, he had to ensure that it could be used for many years, or even under certain extreme conditions, it could be patched up to last until it sent him back to the Real World.

Over-machining was the most expensive insurance he bought in the Wasteland.

He carefully inserted the connection end of the first support rod into the precision hole reserved in the belt bracket.

The tolerance fit was just right, producing a muffled airflow sound similar to pulling out a syringe.

He picked up a few high-strength hexagon socket screws, applied a little blue thread-locking adhesive, and gently screwed them into the threaded holes with his fingers until his fingers could no longer turn them.

Four support rods, eight hinge points, all secured with screws.

Next was the locking phase.

He took a torque wrench with a scale dial out of the toolbox.

Following the diagonal order, he aimed the socket at the first screw.

In the first round, he only applied thirty percent of the design torque's force.

After going around once, he ensured that all mating surfaces bore force evenly, without any tilt or warping, not even at the micrometer level.

In the second round, the torque was increased to seventy percent.

In the third round, the value of the torque wrench was adjusted directly to one hundred percent of the design value.

"Click."

The torque wrench emitted a crisp idling sound, indicating that the force had reached the preset critical point.

Finally, he went through the diagonal order again, performing a final confirmation on each screw with the wrench.

Final assembly completed.

On the workbench lay two mechanically intricate devices.

In the folded state, they looked like two thick metal rods about 60 centimeters long with complex hinges, compact and sturdy.

But when they were fully deployed and combined with that wide belt, the length was just right to cover Jiang Lin's entire lower body.

Once the ratchet locked, they could bypass Jiang Lin's fragile knee joints and transmit all the heavy compressive force from above along the straight aluminum alloy rods to the ground under his feet.

Fourth step, bench static load test.

Jiang Lin first tested the single-side module.

The single-side module was the most dangerous, because the left and right forces could never be evenly divided forever.

If even a single side couldn't hold up, the entire structure would have no meaning.

First was thirty kilograms for ten minutes.

No slippage.

Sixty kilograms for ten minutes.

The red lead impression on the contact surface of the pawl was normal.

Ninety kilograms for three minutes.

The pin shaft had no visible bending, the ratchet teeth didn't shed chips, and the locking sound remained crisp.

He didn't continue adding more weight upwards.

This was not a destructive test.

What he wanted was to confirm that this set of things wouldn't kill someone immediately within the design load range.

Fifth step, live-wearing test.

Jiang Lin stood up and took those two heavy mechanical structures down from the workbench.

First, he tightly fastened the nylon belt with thick and wide cushioning pads above his hip bones, locking the quick-release buckle.

Then, he bent down, carefully adjusting the angles of the support rods on both sides and the damping of the slide rails, making them fit along the outer contours of his thighs and calves like two metal skeletons.

He picked up four thick nylon straps, and tied his flesh and blood tightly to the cold metal at the base of his thighs, above his knees, at his calves, and at his ankles respectively.

The straps were tied very tightly, and the edges of the nylon slightly sank into the fabric of his clothes.

Now, he was a half-human, half-mechanical hybrid.

His feet were apart, shoulder-width apart, and then he slowly bent his knees and made a deep squatting motion.

As his center of gravity descended, the aluminum alloy slide bars on the sides of his legs began to slide down in the guide rails.

When his thighs approached the preset angle, Jiang Lin pushed down the locking paddle on the outer side of his thigh with his thumb.

"Click."

The pawl engaged the teeth.

The steel teeth inside the four ratchet locks bit into the card slots on the slide bar sequentially.

The four ratchets were not for showing off skills, but for upper and lower two-stage locking. The upper stage was responsible for the sitting posture angle, and the lower stage was responsible for preventing the slide bar from continuing to sink under impact.

Complexity increased, but the risk of single-point failure decreased.

He didn't relax his strength immediately, but instead gently shook his body first to confirm that both the left and right sides were locked, before gradually releasing the continuous exertion of his quadriceps.

He didn't fall.

He sat steadily there, as if there were an invisible chair beneath him.

The continuous burning-like load on his quadriceps visibly disappeared; he still needed to use his waist, abdomen, and ankles to maintain balance, but the most agonizing part of the muscle burden during a half-squat was undertaken by this exoskeleton, and stably transmitted to the cement slab on the ground through the aluminum alloy footrests and rubber anti-slip pads at his ankles.

This was the ultimate working state of this passive exoskeleton.

Maintaining this suspended sitting posture, he closed his eyes and felt the feedback of every stress point on his body.

There was no snapping sound of loosening coming from any of the screws.

Not a single lock experienced even a millimeter of slipping.

The marble-cold metal structure was temporarily stable, without emitting any unnecessary frictional abnormal noise.

One minute later, he flipped up the release paddle while his leg muscles took over the effort again.

The pawl lifted, the lock disengaged, and he smoothly stood straight.

He began to walk back and forth in the narrow space of the garage.

The various hinge joints of the support rods smoothly operated following the bending angles of his knees.

The metal rods closely clung to his leg shape, producing no swaying during walking, let alone any awkward interference and friction with his skin or muscles.

No jamming.

He stopped his footsteps and squatted down again.

Locked.

Sat on the air chair and maintained it for a few seconds.

Released.

Stood up and continued walking.

Like an untiring testing robot, he repeated this extremely tedious set of actions twenty times.

Every squatting height was the same, every locking sound was equally crisp, and every exertion to stand up was equally smooth.

He walked back to the front of the workbench, sat down on the stool, untied the straps, took the exoskeleton off his legs, and placed it neatly on the tabletop.

Eleven o'clock in the morning.

The light filtering in from outside the garage became somewhat dazzling.

Jiang Lin folded up the wiped-clean exoskeleton, and together with the spare screws and washers scattered on the tabletop, packed them into a thick canvas storage bag.

[ Crafted Item: Passive Support Exoskeleton. ]

[ Time Consumed: Intermittent machining for about 20 days. ]

[ Initial Inspection Passed ]

[ One, wearing while climbing is prohibited. ]

[ Two, locking on scree slopes is prohibited. ]

[ Three, running with loads is prohibited. ]

[ Four, locking is not allowed in strong wind environments. ]

[ Five, disassemble and inspect the pawl, pin shaft, footrest, and hinge every seven days of continuous use. ]

[ Six, immediately discontinue use if any instance of gear slipping, abnormal noise, or unilateral locking delay occurs. ]

One o'clock in the afternoon.

When Jiang Lin pushed open the door home, his nasal cavity was instantly flooded with a wave of meaty fragrance mixed with the burnt aroma of soy sauce and the sweetness of white sugar.

The range hood in the kitchen was humming, and his mother was busy inside.

Meals, bowls, and chopsticks had already been set on the dining table.

A plate of braised pork belly with a bright red color and a balance of fat and lean meat, a dish of stir-fried emerald green vegetables, and a pot of white rice.

His father had just woken up, holding a thermos cup in his hand, yawning while watching TV.