Benz was frightened for a different reason than the crowd.
The crowd was shocked by the locomotive's athletic ability, while Benz was shocked by the efficiency of the reversing mechanism.
The acceleration displayed by the model car during the forward and reverse driving processes is completely indistinguishable to the naked eye. This is not just a problem of the reverse switching method, but the entire power wheel transmission system is extremely mature, so that the reverse and forward driving are almost the same. mechanical energy conversion rate.
It’s hard to imagine that this thing doesn’t have a physical object. Is it really a human being who draws such a drawing purely based on ideas in his mind?
In order to further understand the role of various details of the locomotive, the team moved to a relatively gentle place on the hill behind the heavy industry. The factory helped coordinate and get cement from Xincheng Cement Factory to make cement rails.
Due to the requirements of convenient construction and reliable strength, the shapes of cement rails and railway rails are completely different. In fact, a 25 cm wide cement trough is opened on the flat ground. The steps on both sides function as rails. After integration, the relative strength It will be much higher.
Use this form to make a loop with a radius of fifty meters, which retains part of the slope, which is enough to complete various working conditions tests of the one-sixth model.
Of course, there are still many people who want to help. Anyway, I have to give birth to a baby when I go home from get off work at night. I can’t handle it every day, so why not come and watch the little train and help.
The work of one group went very smoothly, but the second group suffered a tragedy.
When the circular cement track on the back mountain was completed, the second team had not even finished the model... There were so many pipes, and there were some hydraulic devices inside, so the parts were very labor-intensive to make.
Fortunately, Benz, as the team leader, has been paying attention to the situation here. He made a decision halfway through to merge the two groups into one. Put aside the original braking system for the time being and borrow the components and concepts from it to design a simpler one. of.
In the beginning, there was no need to build a serious train braking system, just a model braking device. When necessary, a person could stand on the inside of the cement ring track and pull the rope to start it.
The reason for making this choice is that through the previous model experiments, Benz realized that not only himself, but also all manufacturers in the production process could not grasp the full-scale restoration of the locomotive on the drawings.
Therefore, after communicating with the railway bureau through the deputy factory director, it was decided to make a shortened and low-horsepower version.
The marked curb weight of the locomotive in the original picture is 120 tons. The two pairs of power wheels are removed to shorten the front of the locomotive. After the power is reduced, the coal box does not require so much coal. After the curb weight is directly reduced, the working environment corresponding to the workpiece is not so harsh, and the size will definitely increase Downsizing can also further reduce weight.
If the weight cannot be reduced by about one-third and the difficulty cannot be reduced to within the ability, then the weight can only be reduced further.
As for how far it has been reduced, the model in the experimental site will tell.
Regardless of aerodynamic force... they didn't learn this thing either. It was still the same 1:6 model as before. After adding a simple rope braking device, they started loading experiments.
The experimental site was not very rigorous. Only after work started here, Benz obtained a series of current standards from the Railway Bureau.
The maximum gradient of the laid railway is 7‰, and new railways are required to do everything possible to maintain the gradient within 10‰.
The maximum slope of the cement ring track test site was simply measured with a level and reached 15‰, far exceeding the existing railway standards.
However, from the perspective of the model, due to its light weight, the friction of the cement track will be greater, which is different from the dynamics of the real car. The slope should be slightly larger to see what trouble the real car will encounter in similar situations.
According to the existing fourteen-meter length standard of the Railway Bureau, a bunch of small flatbed car models were made for cargo loading experiments. The cargo was weighted with iron blocks, which is what many heavy factories have.
The weight of the 1:6 model should be 1/216 of the real car. Throwing away the fraction is equivalent to increasing the counterweight by a few percentage points to approximate the condition of the real car.
Each carriage is equipped with 100 kilograms of iron, and one is added to measure two wheels. Every time the locomotive starts, people shovel two shovels of coal into it, and then wait for it to stall or brake after completing a circle.
The model is really amazing. Twenty carriages were finally hung, and the counterweight iron alone weighed 2 tons. It can actually move!
!
But it finally reached its limit. When going up the steepest slope, the power wheels slipped and the pipe burst.
After inspection, it was found to be a model problem and had nothing to do with the real car.
In order to match the car model, the pipes of the model cannot be made very thick, and because there is no way to make particularly small seamless steel pipes, some of the pipes are heated and forged, and their strength is defective.
In a real car, even if there is a similar danger, the pipe burst can be avoided because the driver monitors the pressure gauge at all times.
It is even conceivable that the complete body of this thing can drag thousands of tons of things on the 7‰ slope section. Under such a total weight, all workpiece processing defects will be magnified without limit.
After this round of extreme testing, the team members were finally convinced and no longer dared to think about getting it right in one step.
After the squib model was repaired and given to the masses to play with, Benz and his team began to build a shortened version of the locomotive.
Instead of trying to reduce the size by a few percentage points, start with the simplest structure. There is barely enough room in the boiler for a secondary heating elbow pipe of only a little length. When the steam pressure is lowered, thinner pipes can be used, and the brakes are completely useless. To reach the air brake, just pull the brake directly, cut off the power and put down the brake to rub the power wheel.
Because it was too simple, after the final weighing conversion, the curb weight of the real car was only nine tons!
The power of this thing is so weak that it can only tow a fully loaded flatbed truck, and it is very laborious to climb hills.
However, compared with the human-operated hand-cranked trolley, it still has some advantages. The counterweight of 100 kilograms is equivalent to twenty tons of cargo on a real train. And the railway bureau now needs to transport twenty tons of cargo, which requires at least three hand-cranked locomotives.
The results of the comparative test between the weak and the strong are available, and then comes the office discussion and design session.
During this process, relevant personnel from the Railway Bureau, Iron Works, Fenggu Machinery Factory, and Shuangshi Machinery Factory were specially invited. The Railway Bureau discussed the needs, and everything else was related to the manufacturing process.
After a long discussion, we finally decided to make a locomotive with about 200 horsepower and a curb weight of less than 40 tons. The design difficulty is reasonable, the production difficulty is moderate, and it can also meet the current needs of the Railway Bureau.
However, even if there are so many manufacturers involved and the requirements are lowered to this level, it will not be easy to achieve.
First of all, the Benz team needs to do design work. The design must ensure the full working conditions of the 40-ton locomotive based on the existing model testing conditions. After that, model testing and adjustments must be made. Other manufacturers will start to explore the production process of parts during this period. Heavy factories themselves also have a lot of special-shaped parts to make. If the technicians cannot make them or the work is too slow, they may even need to build machine tools with new structures.
When each factory can produce the parts required on paper, produce, assemble, and test on the road, even if everything goes smoothly, it will take at least half a year to complete them all.
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