[TC10] Classic Locomotive

[1980-Something-Space-Guy]

It's looking really good! I really like the passive mechanism for the pneumatic piston. It seems to be struggling a bit, though. Maybe it needs another pump?

[Samer]

2 hours ago, BrickHat said:

It's looking really good! I really like the passive mechanism for the pneumatic piston. It seems to be struggling a bit, though. Maybe it needs another pump?

That did cross my mind. I don't have another big one.

[Samer]

I also have doubt would adding a pump increase power without additional motors?

[1980-Something-Space-Guy]

1 hour ago, Samer said:

I also have doubt would adding a pump increase power without additional motors?

Hehe, my bad, I meant a motorized pump.

[Appie]

*Googles 8462*

Oh yeah, that was one of the reasons that started my "dark ages"

 

So you're using a handpump in your compressor? With the spring still inserted? That would explain why you need 2 XL's to move that thing. I'd seriously suggest getting 1 or 2 actual compressors pumps from bricklink (or buy a set with them) or at least remove the spring from the handpump (though that would be modifying a part which is against the TC10 rules probably). Also 2 compressor pumps should provide pretty much the same speed of movement as 1 handpump. Also the reason why the L doesn't work in this configuration is because it obviously lacks torque to move this handpump with spring. The higher RPM of the L and M-motor should actually be better for Lego compressors (with compressor pumps) than the XL (M/L basically have double the RPM of the XL in any situation, source: Philo's Lego motor testing).

 

Other than that, it's coming along nicely, keep it up

Edited September 24, 2016 by Appie
Corrected some minor things

[Samer]

5 hours ago, Appie said:

*Googles 8462*

Oh yeah, that was one of the reasons that started my "dark ages"

 

So you're using a handpump in your compressor? With the spring still inserted? That would explain why you need 2 XL's to move that thing. I'd seriously suggest getting 1 or 2 actual compressors pumps from bricklink (or buy a set with them) or at least remove the spring from the handpump (though that would be modifying a part which is against the TC10 rules probably). Also 2 compressor pumps should provide pretty much the same speed of movement as 1 handpump. Also the reason why the L doesn't work in this configuration is because it obviously lacks torque to move this handpump with spring. The higher RPM of the L and M-motor should actually be better for Lego compressors (with compressor pumps) than the XL (M/L basically have double the RPM of the XL in any situation, source: Philo's Lego motor testing).

 

Other than that, it's coming along nicely, keep it up

Well... 

Realisticly through my experiments I found that my motors aren't struggling with the manual pump itself. They only struggle when the load is present. In other words, if I keep the pump's air connection open the pumping is fine, even with a single L motor. Connect the hose between the load and the pump and now the struggle begins. It maybe some power is wasted on the spring but I'm sure that would be a little fraction compared to the resistance the model presents to the air loop. 

Concerning the XL RPM I'm using 3:1 gearing so speed is fine. But that is open loop speed. Actual speed depends on the load so the objective was to get highest speed on the compressor with the minimum motor size/count. Experimenting yielded the 2XL configuration. 

I agree with  you that using the compressor (like the one in 42008) may be better but I don't think that 2 pumps are equal to the big manual one. We are talking here about much larger volume of air pushed by the large manual pump. The volume  ratio among the manual and auto pump is unknown to me but I think its several multiples. Any specific info about this?

And finally maybe I'll ask the admins to allow me to remove the spring.

Edit: and pardon me I loved 8462 

Edit 2: Another thing when I think of the spring, aren't we getting back the lost effort when the spring retreats? I guess the resulting spring loss if we take this into consideration may be negligible.

Edited September 24, 2016 by Samer

[1980-Something-Space-Guy]

You should get the work from the spring back, since spring forces are conservative. Maybe there are other losses in the system. The hoses might be to blame. Every turn in a pipe generates losses as well.

[Samer]

So far I cannot find any source of important loss and it seems to me this is what the available Pneumatic power driven by 2XLs can do with the given load and mechanism.  

[Appie]

 

The volume  ratio among the manual and auto pump is unknown to me but I think its several multiples. Any specific info about this?

 

The comparison is based on using the hand pump manually instead of using it for something it wasn't really intended for. Double compressor pump combined with the 300-400rpm of a M/L motor (or in your gear ratio 900-1200) should be about equal to a manual pump used manually. This is based on seeing models on youtube with double compressor pump. And also based on observing sets and seeing how much time their movement takes compared to a manual pump.

 

Once the loop is closed that adds extra pressure on the parts (cylinders and switches) so it makes sense it struggles more than when the hoses aren't connected to anything.  

 

It also doesn't matter that you regain the energy on the way back of the motion unless you add a second hand pump that alternates its motion with the first pump like a Lego piston engine. With only 1 hand pump with spring your PF motor(s) have to use alot of torque to make half of the motion and are then forced to a faster rotation speed for the second half where the hand pump with spring extends. 

 

It's your choice obviously, but I'd still suggest getting 2 compressor pumps or use an extension cord behind the model to which you have attached a hand pump to use manually instead of using this mechanism.

 

 

 

[1980-Something-Space-Guy]

Some interesting suggestions here! They sound good to me as well, but again, it's your choice.

[Samer]

You seem very confident about the double small compressor. I have one 42043 unopened so I would take its compressor pump to try with the one I have from 42008. Anybody can confirm if v1 and v2 6L pumps work together? 

[Appie]

Yup, the only difference is the nozzle to which you attach the hose. The nozzle of the 42043 pump makes it easier to attach hoses. 

[Samer]

Hi again everybody. Sorry for being so slow in progress, its life...

 My main source of problems turned out to be one of the cylinders is rusted a little and hence, less efficient and not balanced with its brother. Luckily I had a third good one. I tried the small pump as per some suggestions and found it yielding very low pressure to rely on it solely. However, its good enough to enhance the performance (see video). I'm waiting to get some other small pumps from Bricklink. So now I have one large pump driven by 2 XLs and one small pump driven by one M. Once I get the extra pumps, I will try some other pumping options.

Going on with the body design, I redesigned the model back from the beginning to hide these 2 big XLs. I also managed to remove shaking from the boiler. Finally, I found a better shape for the boiler's front. Next I have to build the cabin.

Here is the video (Sorry its not running on the ground yet this time as I still didn't arrange the pipes after the redesign) :

 

Edited October 13, 2016 by Samer

[Rikus]

I really like your project!

I only suggest you to take in consideration the option of using a multiple small pump compressor, instead of a single big one...

 

Sariel showed some good building options, using up to 4 pumps, easily operated by an M motor.

Take a look HERE

Or a reciprocating, 8 pumps, version, HERE

Using a single L or XL motor should allow you to use up to 8 small pumps, that will give you a really big and smooth air stream.

Should you have te opportunity, it could be great to add an Air Tank, too, for an ever smoother movement.

Edited October 13, 2016 by Rikus
Added links

[Samer]

7 minutes ago, Rikus said:

I really like your project!

I only suggest you to take in consideration the option of using a multiple (small) pump compressor.

Sariel showed some good building options, using up to 4 pumps, easily operated by an M motor.

Using a single L or XL motor should allow you to use up to 8 small pumps, that will give you a really big and smooth air stream.

Should you have te opportunity, it could be great to add an Air Tank, too, for an ever smoother movement

Thanks :-)

I am considering several pump options, just waiting for the Bricklink order to arrive. Once I get it I plan to try these options, up to 4, I hope I don't regret not buying more to make it 8 :-/ . I also tried the air tank; it does not enhance the movememt, just delays the start. I will try it again later anyway and will make a video of that..

Edited October 13, 2016 by Samer
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[Rockbrick]

the RC motor is very light and slim and perfect for making a compressor: (works better without airtank as you say the airtank causes a delay)

Edited October 13, 2016 by Rockbrick

[Samer]

Thanks for the links Rikus. It will be interesting for me to experiment with such options once I have the pumps. But please note, and as I already noted in my experiments, that in my specific model, the focus is on strong air pressure rather than smooth air continuity. Secondly, having a shaky compressor is not very useful in my case. Finally, once the train is on the ground, there would be load and it will trasfer to the pump which will present resistance to the motor. In my experiments so far there is no movement at all using one small pump. But anyway once I get more pumps I will try and experiment again and I hope to get good results like you and others are pointing.

1 minute ago, Rockbrick said:

the RC motor is very light and slim and perfect for making a compressor:

Exactly! it has  the power, the speed as well as the flat shape. The perfect combination for my model! But it has a slight problem, I don't have access to one and its expensive to get now :-/

[Rikus]

1 hour ago, Samer said:

Thanks :-)

I am considering several pump options, just waiting for the Bricklink order to arrive. Once I get it I plan to try these options, up to 4, I hope I don't regret not buying more to make it 8 :-/ . I also tried the air tank; it does not enhance the movememt, just delays the start. I will try it again later anyway and will make a video of that..

You're welcome ;-)

 

About the air tank delay... it's only a matter of how you make use of it!

The air tank is not supposed to be connected to an "open" system; you should put a pneumatic switch after the tank, to let the pressure rise.

Only when the tank will reach a good pressure, by turning the switch you'll start the train.

 

[wissamms]

Exciting model! Looking forward for the next posts :)

[Appie]

10 hours ago, Samer said:

I tried the small pump as per some suggestions and found it yielding very low pressure to rely on it solely. However, its good enough to enhance the performance (see video). I'm waiting to get some other small pumps from Bricklink.

 

Nice progress, though the suggestion was 2 small pumps. One small pump on official sets is slow too for big cylinders, so 2 pumps is like a bare minimum for speed. But you're waiting for more I see (thought you had 2 to test), so you can test it yourself in a little while.

 

 

Edited October 13, 2016 by Appie

[Samer]

This is an early version of the cabin

and this is an early look at the final model. I still wait for some extra parts to enhance the shape and function.

 

Edit: I feel I need to make the cabin shorter and close its front edges. I also feel I need to try to use only curved panels on the cabin's roof.

Edited October 14, 2016 by Samer

[mobi]

Use wheels from http://www.bigbenbricks.com/ and then it can be run on G scale (45 mm gauge) tracks like Garden Railways 

[Samer]

Just now, mobi said:

Use wheels from http://www.bigbenbricks.com/ and then it can be run on G scale (45 mm gauge) tracks like Garden Railways 

Thanks, this is very interesting for future consideration, but for now i don't think this is allowed in this contest.

22 hours ago, Appie said:

Nice progress, though the suggestion was 2 small pumps. One small pump on official sets is slow too for big cylinders, so 2 pumps is like a bare minimum for speed. But you're waiting for more I see (thought you had 2 to test), so you can test it yourself in a little while.

 

 

Yes I'm waiting for extra pumps to arrive and if that proves better we will replace the big pump. I didn't want to open the Arocs until I prove the concept. I bought 2 pumps on the way, if 2 pumps are good I'll open the Arocs and make them 4.

On 10/13/2016 at 11:13 AM, Rikus said:

You're welcome ;-)

 

About the air tank delay... it's only a matter of how you make use of it!

The air tank is not supposed to be connected to an "open" system; you should put a pneumatic switch after the tank, to let the pressure rise.

Only when the tank will reach a good pressure, by turning the switch you'll start the train.

 

True, we may use a switch but I think at the end the pressure is the same, or even a little less because of more connections. I promise to try that anyway and we will implement the better configuration

On 10/13/2016 at 1:09 PM, wissamms said:

Exciting model! Looking forward for the next posts :)

Thank you :-)

[JJ2]

Looks really god but the XL motors dont look great there

[Samer]

19 minutes ago, JJ2 said:

Looks really god but the XL motors dont look great there

True. I have a plan to replace them with M motors if that works. Otherwise they have to stay, no better place but they will be covered by the rest of the build.

Edited October 14, 2016 by Samer
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