Chapter 405

Chapter 405

Seeing the traction engine and road passenger car before him, King Sejong’s eyes sparkled as he examined various parts of the traction engine.

“Binding the wheels with a large band made of iron, how truly unique?”

“It’s called a caterpillar track, Your Majesty.”

“Caterpillar track?”

“If I explain the principle...”

As Hyang tried to explain the principle, King Sejong raised his hand to stop him.

“Enough, let me see it move once. I’ll try to figure it out myself. It looks quite interesting somehow.”

“Yes, Your Majesty.”

‘I forgot! Father was also a man with little left but curiosity!’

At King Sejong’s order, Hyang immediately stepped back and relayed the command to the traction engine operator.

Hiss!

As the operator who received the order drove the traction engine, it slowly moved forward. After observing it move about 1 jang (about 3 meters), King Sejong nodded.

“I see, simply put, it’s moving on a path made of iron. This way, even if the ground is soft or muddy, it can ignore it to some extent and move, right?”

“Yes, that’s correct.”

‘As expected, he’s extraordinary!’

“Hmm...”

While examining the caterpillar track after hearing Hyang’s answer, King Sejong asked Hyang a question.

“Is the steering of this traction engine done by those two separate wheels in front?”

“That’s correct, Your Majesty.”

While answering, Hyang explained the idler wheel mechanism installed on the traction engine. As he explained to King Sejong, Hyang added inwardly.

‘It can be called a steam-powered half-track.’

King Sejong, who was examining the steering mechanism using an axle, gears, spiral shaft, and chain protruding from the left side of the vehicle body (Note 1), turned to Hyang.

“I roughly understand how it steers, but looking at it now, is the largest wheel attached at the back among those wheels on the caterpillar track the one that exerts power?”

“Yes, that’s right.”

“When I read the technology-related booklets produced by the research institute and Area 51 before, I remember reading that every time a cart turns, the number of rotations of the inner and outer wheels differs. For ordinary carts, it doesn’t matter because the wheels rotate separately, but for iron horses, it becomes a problem because power is transmitted. I heard that to solve this, you need to either differentiate the power transmitted to the two wheels or make the turning radius very large.”

“That’s correct.”

Hyang nodded at King Sejong’s point and continued.

“The iron horses currently moving in Hanseong solved this problem by transmitting power to only one wheel. And for larger iron horses that need to move with greater power and speed, we plan to follow the latter method.”

“Then does this traction engine also follow the method of the iron horses moving in Hanseong?”

To King Sejong’s question, Hyang immediately replied.

“No, it’s a new method.”

“A new method?”

Hyang led King Sejong to the back of the traction engine and pointed to the underside of the vehicle body.

“You can see it here.”

“Oh?”

At the rear bottom of the traction engine, there was a large iron box attached, with the power shaft and wheel axle connected to that box.

“We’ve named it the Differential Power Transmission Device[1].”

The device Hyang pointed out was a gearbox containing differential gears.

***

The point King Sejong made was also raised during the development of the traction engine.

“We already came up with a solution for this part during the iron horse development process, didn’t we? Couldn’t we just transmit power to only one wheel like that?”

When most of the development team submitted such opinions, Hyang shook his head.

“The iron horses in Hanseong move on well-maintained roads in Hanseong, along dedicated rails, and lastly, at slow speeds, so there’s no particular problem. But the issue is that traction engines need to go where there are no roads.”

“Ah...”

The development team members who were nodding at Hyang’s explanation realized what the problem was and showed expressions of despair.

The statement ‘need to go where there are no roads’ meant that power had to be transmitted to both wheels.

Seeing the despairing looks of the development team, Hyang inwardly muttered.

‘There was a famous advertising copy in the 20th century that went something like this, right? It goes on roads. It goes where there are no roads.’

To solve this problem, the first thing the development team came up with was to attach independent braking devices to both wheels.

“Simply put, it’s the same method as the tanks operated during World War I and World War II, but...”

“At maximum capacity, it can tow 5 Byeongshik cannons and all the carts loaded with shells and gunpowder for those cannons. However, for safety reasons, it’s set to tow only the cannons. Gunpowder and shells are transported using horse-drawn carts as before. However, even moving just the cannons is expected to bring a significant increase in combat power.”

“Hmm... I see... That’s a good plan.”

As King Sejong nodded and approved, Kim Jeom and Jo Mal-saeng showed contrasting expressions of joy and sorrow.

However, King Sejong’s imagination knew no bounds.

“Crown Prince, even if we can’t load cannons and gunpowder due to the risk of explosion, what about carrying soldiers instead?”

“Soldiers, you say?”

“Yes, if it has the power to tow 5 Byeongshik cannons and the shells and gunpowder for them, couldn’t it carry soldiers?”

“For that, we’d need to redesign again...”

“No, not creating space in the traction engine, but armoring this passenger car and connecting it. What do you think?”

At King Sejong’s words, one image came to Hyang’s mind.

‘An armored train? No... Something more similar would be the BV206? It’s similar, but... That one needs power transmitted to the rear as well... Could we use a joint shaft for that part?’

After doing various calculations, Hyang answered King Sejong.

“I’ll consider it.”

“Alright, I look forward to good results.”

“But the budget...”

“Make it a long-term project.”

At King Sejong’s firm answer, Hyang replied in a gloomy voice.

“...Yes, Your Majesty.”

***

While such conversations continued inside the passenger car, the traction engine steadily moved towards Onsu County.

“The speed is quite good. From what I can see, it’s about the same speed as a horse’s trot. Is this the fastest speed?”

“The fastest speed is slightly slower than a horse’s full gallop, but we prohibit running at that speed. It’s because of the cargo issue.”

Nodding at Hyang’s answer, King Sejong looked around the interior of the passenger car he was riding in and asked Hyang.

“I see. By the way, this is a very well-made passenger car, isn’t it? There’s very little shaking.”

“Yes, we will improve this further and use it for the passenger cars of post horses and railways. Both will have the same structure, with only differences in size.”

At Hyang’s answer, King Sejong turned to Kim Jeom and said.

“We’ll be able to save a lot on the budget.”

“That’s right.”

“Kim Jeom will have fewer occasions to take health tonics.”

At King Sejong’s joke, Kim Jeom replied with a bitter smile.

“It’s all thanks to Your Majesty’s grace. Your grace is boundless.”

***

Thanks to traveling by traction engine, King Sejong’s party was able to arrive at Onsu County in just two days.

The officials and people who had rushed to the entrance of the county upon hearing the news of King Sejong’s visit waited for him with expectant faces.

Chug chug puff puff! Chug chug puff puff!

“What’s that sound?”

“I’m not sure...”

The people and officials who were tilting their heads at the sound they had never heard before widened their eyes and dropped their jaws when the traction engine appeared at the county entrance along with the cavalry.

“What is that?”

“A lump of iron is moving?”

Toot!

When a loud whistle sounded from the approaching traction engine, the gathered people scattered with screams.

“Oh my goodness!”

“Save us!”

“It’s a monster!”

***

Note 1) It would be good to refer to this.

https://youtu.be/N3yFa32meQM

Note 2) Again, it would be good to refer to this.

https://youtu.be/We-oNHoGf5Q