00:00Assume you're a squirrel and you're enjoying how the train switches tracks.
00:05Unfortunately, one part of the rail switch is loose.
00:09What's the impact of this?
00:13When these flexible tracks are positioned like this, the train wheels naturally follow this path.
00:19But once they reach the junction, can you spot the big issue?
00:24Do you have a design solution for this problem?
00:27To solve this intriguing challenge, we first need to remove the flange from one of the rail wheels.
00:33Also, let's use a single track.
00:36A single track which is getting divided into two.
00:39After reaching the junction, which direction will the wheel move?
00:43You're right, it's impossible to predict.
00:46Now, let's add a flange to the wheel.
00:50Can you tell which direction it will turn?
00:53Of course, to the right.
00:57If you want the wheel to follow the left track instead, simply make the right track a separate piece and bend it like this before the wheel reaches that point.
01:07This is the fundamental concept behind track switching.
01:11Now, let's see how this works in action.
01:14When both pairs of tracks are present, the flange is always on the inner side of the wheels.
01:20The portion of the track that bends is called the tongue track.
01:26Quite a fitting name, right?
01:28When the tongue tracks are bent as shown, the train will move on the yellow track.
01:33Remember, due to the presence of the flange, the left wheel cannot roll on the light blue track.
01:39Due to the same bending, the dark blue tongue is not at all touching the track.
01:45A large gap can be observed, so the right wheel will also be able to follow the yellow track on that side without any trouble.
01:52Now, let's bend the tongue tracks the opposite way.
01:56This time, a gap appears at the orange tongue region, and the train easily switches to the blue track and moves straight.
02:05What a simple and effective mechanism!
02:09The moving part of the tongue track doesn't need to be so long.
02:14You can shorten it by pivoting it like this.
02:18We'll explain the benefits of this shorter design toward the end of the video.
02:23Using this mechanism, switching works perfectly.
02:27However, if you try running your train on these tracks, it will inevitably derail.
02:33The problem lies in the crossing.
02:36The tongue tracks cross at one point.
02:38If the crossing design looks like this, the train will hit the orange tongue and derail.
02:44So, how can we fix this?
02:48To overcome this issue, just provide a gap near this crossing in both the rails.
02:55In this new crossing design, whether the train is going through the left or right track, the wheels cross the junction without hitting any track.
03:04So, in this new design, the train can switch the tracks and also cross the junction without any trouble.
03:11Now, here's a small design challenge for you.
03:15Watch the rail wheel movement in slow motion at the crossing.
03:20You'll notice the wheels drop into the gap.
03:24Can you think of a solution?
03:27We can overcome this issue just by increasing the length of the tongue rails as shown.
03:33They will provide good support to the wheels during the movement over the rail gaps.
03:38The design looks almost perfect now, but this design has a major flaw.
03:44To find out the important flaw, we metal 3D printed the entire track switching mechanism using the service of JLC3DP.
03:54Using the JLC3DP service was absolutely fun.
03:58What we did was just the CAD modeling.
04:01We went to their website and selected that we need metal 3D printing and also specified the material.
04:09To replicate the science behind the rail switches, metal 3D printing is the best.
04:15The experts from JLC3DP analyze your 3D models.
04:20In case of any issues, they will let you know.
04:23Our models got clearance in one go.
04:26In metal 3D printing, layers of metal powder are molten with the help of powerful lasers.
04:32Once one layer is complete, the machine adds another thin layer of metal powder above it, and the process is repeated.
04:40JLC3DP's metal printing starts at a price as low as $8.
04:46They even have to do post-processing of the 3D prints.
04:50After one week, we received this box from them.
04:54The 3D printed metal pieces were heavy.
04:58We truly enjoyed assembling them and achieved a perfect rail track switch.
05:04Now, let's roll the wheel along the track.
05:10Oh, did you notice that?
05:13The train is derailing again.
05:16Let's watch it in close-up.
05:19What's going on here?
05:23Let's watch it from the opposite angle.
05:26The right wheel is supposed to travel along this track.
05:31But unfortunately, the wheel is traveling along the wing rail and derailing.
05:36The majority of the tracks use a larger radius for the turn.
05:41If the track has a low radius or high deviation, the chance of traveling along the wing rail is minimum.
05:48It's clear from this visual.
05:51These two pieces, the check rails, are the saviors of the train wheels.
05:56The check rails are placed with a fixed gap with the main rails on either side.
06:01Even if the wheels try to travel on the wing rail, the check rail will prevent this.
06:06This will channel the wheels onto the track properly, and the wheels will easily pass through the intended trajectory.
06:13So even during high speeds, the train can change its journey smoothly.
06:18In this 3D printed model, the tongue tracks are flexible.
06:24Let's enjoy the design of a perfect rail switch mechanism using this model.
06:29Now let's understand the importance of a shorter tongue track.
06:49This is, in fact, considered a design optimization.
06:53Where do you think the maximum stress occurs in switching rails?
06:57It's at the toe of the switch and the nose of the crossing.
07:02These parts wear out faster and are replaced more frequently than the main rails.
07:07That's why the tongue rail is split into two parts.
07:14When the switch rail wears out, you only need to replace that section, reducing steel waste and cost.
07:23The tongue tracks are operated together using a switching rod.
07:29Long ago, this switching rod was controlled manually by an operator called the point man.
07:35You might have seen this cute machine in movies.
07:38Nowadays, a smart device called a point machine, which is an electromechanical device, does this task.
07:45It's quite a powerful machine.
07:47You can see a lot of rods connected to this machine.
07:50And it has a lot of electrical contacts and gears.
07:54Out of these five rods, one rod is a throw rod.
07:58Suppose this is the current position of the tongue rails.
08:01If the station master wants to flex it towards the opposite direction, that signal will be received by the electric motor, and it starts to spin.
08:10The torque of the motor gets multiplied by these gears, and eventually the throw rod moves.
08:16When the tongues touch the opposite track, with the help of the indicator rods, the station master gets a signal that the tongue tracks are in the required position.
08:25Along with this, did you notice these electric contacts getting closed?
08:30When this happens, the last two rods, the locking rods, automatically get locked.
08:36The purpose is that when the train travels through the junction, we don't want any movement to the tongue tracks.
08:42With the help of these two rods, they automatically get locked as soon as the tongue reaches the other end.
08:48We can easily ensure this.
08:50Now it's time to add more complexity and fun to the railway switches.
08:56How can you design a three-way switch?
08:59A rail switch which can guide the train to any of these three tracks.
09:03Here, of course, you have to introduce one more point machine.
09:07But since you already understand the core concept of switching, these animations will make it easy to grasp how the train switches between all three tracks.
09:16One of the most fascinating innovations in rail switching is double slip switch rail.
09:36Here, the design challenge is that train A should have the option to travel along two tracks.
09:41Similarly, train B should also have the option to travel along two tracks.
09:46Two point machines are needed for the double slip switch design.
09:50With the help of simplified point machine connection, the way the DSS achieves all these four scenarios are illustrated here.
09:58Routine lubrication of switch points, rods, and moving parts are crucial in smooth operation of a railroad switch.
10:17They should also ensure that there's a tight contact between the switch point and the stock rail.
10:23So far, when we learned about track switching, we focused only on a few pairs of wheels.
10:29But it's truly fascinating to watch how a full train with multiple coaches behaves while switching tracks.
10:36Starting from a simple rail switch, we have understood working of even DSS in this video.
10:45However, if you activate the logic of rail engineering new further, you can even design a switching network as complex as this.
10:55I hope you truly enjoyed the experiment using the metal 3D prints.
11:04I was truly amazed by the precision of these metal components produced by JLC3DP.
11:10If you would like to transform your engineering dreams into reality, please check out their website.
İlk yorumu siz yapın