AbleChristopher

MOC UP #844 Power System Opinions

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Hello all,

I am hoping to start a discussion on the types of geared power systems that folks in this forum use to power their steam locomotive MOC's, specifically larger builds with 3 or 4 driving wheels. I am partway through a build of a Union Pacific FEF-3: #844. I want to power this locomotive with two large power function motors (Item No: 99499c01) and I am struggling with choosing the appropriate gear assemblage to transfer the power to the drivers.

The pictures below are the two methods I have been experimenting with. Assemblage #1 is the power system used on Brickmania's S160 Locomotive recreated here for demonstration only. Assemblage #2 is just a basic motor to driver setup. Rumor has it that the NYC Mohawk from Brickmania is powered by two sets of the S160 gear/motor assemblies, can anyone verify this? My goal is to make the #844 model true to her real life counterpart - very fast and very powerful. The renders were made quick and dirty, please excuse the clipping of parts, they are just to show the two systems. Any good ideas? Thank you all!

Overall locomotive:

52393946891_f51fc51c61_o.png

Gear assemblage #1:

52394456508_43ed542e62_o.png

Gear assemblage #2

52394401370_08cdc92945_o.png

Edited by AbleChristopher

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Option 1 is good because it's stronger and less fiddly. However you'll need to make sure you have the clearance for the wider gears. I also don't know what gears are in there going to the axles themselves but Option 1 gives you more options for choosing gear ratios to get either more torque or more speed. (Use http://gears.sariel.pl/ if you don't want to do the math yourself.) Option 2, unless there's more I'm not seeing, won't change the ratios and you'll have the standard speed and torque of the L motors. I also like option 1 better because if the drive trains aren't connected one set of drive wheels can slip slightly if one motor runs better than the other. In Option 2 if one motor is slightly faster/ stronger it will stress the gears and the axles unless you have a differential in there.

Of course either way if you have the motors facing each other they'll have to be running in opposite directions to make the train go the same way. In option 1 the wheels will fight each other while in option 2 it will simply eat your gears or just rip itself apart.

Personally I'd try to have the motors facing the same way with the gearing from 1 and set to drive both flanged wheels. (It looks like you should have room for that but I obviously don't have the whole picture.

 

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That is great feedback @engineermax, thank you for commenting.

Option 1

Option 1 should be a 1:1 gear ratio, it goes up in size to transfer the power vertically but then back down in size where the gear attaches to the driver axle. I think I do have room to fit both motors in line with each other (instead of facing each other) and have one motor power one flanged driver and the other motor power the other flanged driver. Do you think that if one motor is running slightly faster than the other, since the drivers are all connected, that it would stress the motors or the coupling rod too much?

Option 2

You're seeing the whole picture, I believe (based on gear size) that it should be 1:1 also and give me the same speed and torque as option 1. In your experience, do you think a 1:1 gear ratio is adequate (i.e. the standard speed and torque of the L motors is enough)? One of the elements here that I have been scratching my head over is exactly what you point out: one motor being stronger/faster than the other. Since I will likely buy used motors I presume this will be the case and I don't want to burn one out. I don't think that I have enough room to put in a differential assembly.

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I’d agree with @engineermax here - Option 1 certainly looks to be stronger than the other, though my education in this field is honestly very poor.  You’re building a beautiful MOC though - I’ve actually been quietly building the same model in the same paint scheme, only numbered locomotive 836.  Maybe one day I’ll be able to build my dream greyhound paint scheme Overland Limited consist - but good to see others appreciate the beauty of the paint scheme!  I’ve actually decided to use DBG and black though rather than LBG and DBG, but I’m interested to see what yours will look like in real life!

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Thank you very much! Gotta love that two-tone gray paint scheme with Armor Yellow lettering and striping. I plan to issue two versions of this locomotive, one in two-tone gray with yellow accents and one in freight black with white accents as she is seen today. A mid 1940's version and a 1950's to present day version, if you will.

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I think in option 2 you DO want both motors turning the same way. In option 2 you can control for different motor directions in how you place the bevel gears on the axles. That said, option 1 is superior because it relies on double bevel gears which are a lot stronger than the single bevel gears. Also, it does not concentrate all of the power on just one gear.

Personally, I would build an axle connector between the two flanged drive axles, but I'm extra cautious. It does have the benefit that you can power the central axle wherever it is convenient rather than coming straight down on the drive axles themselves.

You probably have room to do a third option,

52072618975_f832302309_z.jpg

But you would also need to hide the bottom of the motors in this case

 

On 9/30/2022 at 7:16 PM, Vilhelm22 said:

I’d agree with @engineermax here

That doesn't surprise me one bit, just look at your avatars, you're practically twins. (grin)

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@zephyr1934 I agree, axle connectors are a must in my opinion, otherwise all the strain is being put on the main rod which is brittle and more for show anyway (on Lego models). I used that bevel gear system through the frame on the Mercury with a motor assembly like option 2 above, but option 1 is probably much stronger. I have come up with a third option...both motors will turn in the same direction relative to their orientation here (i.e. one of them will have the polarity reversed on the controller). Gears are in blue so they are easier to see.

 

52400731003_a61703e563_o.png

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On 9/30/2022 at 4:37 AM, engineermax said:

 I also like option 1 better because if the drive trains aren't connected one set of drive wheels can slip slightly if one motor runs better than the other. In Option 2 if one motor is slightly faster/ stronger it will stress the gears and the axles unless you have a differential in there

I see this claim made all the time with little proof. @Philo has tested this and there's not an appreciable difference with having a differential in there.

Normally I'd question the need for two L motors, but you are running them 1:1 to the driven axle with very large drivers. Are you trying to pull a train very fast?

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40 minutes ago, jtlan said:

I see this claim made all the time with little proof. @Philo has tested this and there's not an appreciable difference with having a differential in there.

Normally I'd question the need for two L motors, but you are running them 1:1 to the driven axle with very large drivers. Are you trying to pull a train very fast?

I am hoping for speed and strength. My worry with one L motor is that I won't have enough torque to pull a significant consist. The gear ratio should actually be 3:5 to the driven axle (20 tooth gear down to a 12 tooth gear) which is then connected to XXL diameter drivers. I think that one L motor wont provide enough torque to get a significant consist rolling. Ultimately I would like this to have a fast running speed, akin to the real life counterpart.

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Looking good.

 

On 10/2/2022 at 6:15 PM, AbleChristopher said:

52400731003_a61703e563_o.png

One thought, I would try to get a technic half beam on either side of that gear stack to ensure the gears do not force themselves apart. Right now it looks like it is technic axle clutch on the left and stud clutch on the right. In fact you could probably just use full technic beams in place of the axle connectors and bricks.

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Agree fully with Zephyr's comment on the gear train separating the stack of bricks/plates. I've had that problem and it's difficult to overcome. It does look like on the left side motor you do have a liftarm that's barely visible in there that solves that problem. So looks very robust.

Dave

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On 10/4/2022 at 7:38 AM, zephyr1934 said:

Looking good.

 

One thought, I would try to get a technic half beam on either side of that gear stack to ensure the gears do not force themselves apart. Right now it looks like it is technic axle clutch on the left and stud clutch on the right. In fact you could probably just use full technic beams in place of the axle connectors and bricks.

Yeah I plan to reinforce the whole assembly, with some thin liftarms and probably will double up the brick tower if not convert the whole thing to technic liftarms and connectors.

 

On 10/4/2022 at 8:01 AM, bogieman said:

Agree fully with Zephyr's comment on the gear train separating the stack of bricks/plates. I've had that problem and it's difficult to overcome. It does look like on the left side motor you do have a liftarm that's barely visible in there that solves that problem. So looks very robust.

Dave

Thats great feedback that you have had issues with the bricks/plate method, I will almost certainly convert the whole thing to be a technic assembly.

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