HO Scale Operational Hi-Rail

Discussion in 'HO Scale Model Trains' started by Freelancer, Sep 1, 2008.

  1. Freelancer

    Freelancer Member

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    I am on my second attempt at an operational hi-rail. The first one will probably become a nice static modelwall1, but this one I am hoping to try something new. I know that there are some rtr ones available, but I am pretty set on making my own. As for now I could use some help...

    I am going to be using a motor from Radio Shacks Zip Zaps to power the beast, but I am having a hard time figuring out how to get the voltage down. I plan on making this DCC compatible and since the motor runs on a 1.2v 100mah battery, I need to get the 12 volts down to 1.2 or 1. Will a simple resistor do the trick, or will there need to be some complicated electronics involved? I have read that using a single resistor to down-step that much will push it to its limits and it will have a melt down. If that is the case, will a series of resistors do the trick, or is there a safer approach?

    I have asked before about using a capacitor to help provide power over rough track, but have been advised to steer away from that approach. However, I have since found some threads discussing the use of bi-polar capacitors accross the motor function wires. Has anyone here had any experience using these? If so, how do you determine what size will work?

    Any and all help would be greatly appreciated!
  2. Kevinkrey

    Kevinkrey Member

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    Sorry, can give you any help, but it sounds like an awesome project. Any more detail as to what you modeled the first one after? Any pics?
  3. e-paw

    e-paw Member

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    There are some old slot cars that have really small 12v motors in them that might be a better starting point for a motor. You can use a resistor to knock dawn the voltage to 1.2 v, but that resistor will get very HOT. If you have any kids you may be able to salvage a small 6 to 12 v motor from there old toys, they seam to be pretty common.
  4. Freelancer

    Freelancer Member

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    I did not specifically model the first one after anything. I obtained a box of misc. stuff that had a couple IHC accessory motors (used to power their amusement park rides) and I decided that I could put that in a truck and throw some hi-rail gear on it. I went to the LHS and grabbed the first truck that looked like I could conceal the motor in and went from there.

    The plan was to send the motor through the base of the bed, and then use a slot car axle and gearset to transfer the power. All in all it went pretty well and I was able to get the truck to pull itself along. However I had to provide an extension cord for it as I could not get sufficient power pickup from the rails, also the wheels did not keep the truck on the rails very well either.

    I cannot seem to find the pictures with the gear on it, but here are some towards the beginning of the project.

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  5. Kevinkrey

    Kevinkrey Member

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    Are you going to give the new one a set of Hi-Rail wheels?
  6. Freelancer

    Freelancer Member

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    Yes, but that is where I am going to take a different approach. I am going to do like Bachmann's hi-railers and use regular wheelsets to pickup the power and provide for the tracking, and then use the hi-rail wheels for comsmetic purposes only. Then after I have it running well I plan on gluing the hubs and rubber tires onto the outside of the metal wheels to hide them. Obviously they will not be completely hidden, but hopefully enough so that you will only see them if you study the model for a while.
  7. Kevinkrey

    Kevinkrey Member

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    You want to hide the Hi-rail wheels?

    Why not give the model a set of N scale wheels behind the rear axle, and ahead of the front axle? You could give the N scale wheels longer axles and let them pick up the power and drive the model.
  8. Freelancer

    Freelancer Member

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    I wasn't able to get another Boley International (which would have been my choice) and since I am pretty eager to get this project under way I got this Mini Metals International box truck. I kind of doubt that there were many hi-rail box trucks so I will take off the box and make a bed for it. I was thinking of puting a small crane, some misc. stuff, and a tarp on it to cover up the decoder.

    I would like to continue using the Zip Zap motor (or something similar in size) as it is small and fits perfectly between the frame and is barely visable from the sides.
    Does anyone know if there are 6V to 12V pager motors?

    Depending on how well this approach works, I might go back to the Boley truck, but it has been torn up and cut up so many times I want to make sure that this will work before I go at that truck again.

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  9. Freelancer

    Freelancer Member

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    No, I want the hi-rail wheels to be visable. I will be using N scale wheels for the hi-rail, but since they are not big enough to get good pickup and keep the truck on the rails I will be using HO scale wheels as the main traction. So I need to hide the HO scale metal wheels.

    I originally wanted to use Z scale wheels for the hi-rail, but metal Z scale wheels seem to be virtually impossible to obtain. Does that make sense?
  10. 60103

    60103 Pooh Bah

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    Not being an electronic whiz, could I suggest something based on a transistor throttle? these are able to cut the power way down but I think might require a major heat sink.
    Would an SCR throttle work?
    I think that a plain resistor would have to dissipate 90% of the current to the motor's 10% and that would go into heat.
  11. Freelancer

    Freelancer Member

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    :eek: I have no clue what a SCR throttle is and after a quick search the schematics look way over my head. Do you think that it would be possible to fit this on an HO scale vehicle?
  12. diburning

    diburning Member

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    You might want to try one of Bachmann's Ready to Run HO scale Hi-rails. They are actually pretty nice!. They are all powered and will run!

    Here's a pic.

    [​IMG]

    MY LHS has them for around $30

    Bachmann also makes a Hi-Rail Utility truck

    [​IMG]

    And also this thing which I can't quite describe

    [​IMG]
  13. Freelancer

    Freelancer Member

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    Thanks diburning, I have looked at those a couple of times but I guess I am just making things difficult as I was kind of looking for something different, and unique. And as stupid as it is I want to be able to say "I made that!". However that van has always peeked my curiosity. Do you know how well they run?
  14. diburning

    diburning Member

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    Well, it's from Bachmann's normal line and you can get mixed results with their normal line. The hi-rails are smaller so they weigh less but their motors are also small. I've never actually seen one being run, but next time when I visit the LHS, I will ask if they can run one to show me.

    I'll let you know how it goes.
  15. Freelancer

    Freelancer Member

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    Made some more progress last night so hopefully this will clear up how I will be using the HO scale wheels. I was also able to get the drive gear installed.

    I did some more research on dropping the voltage down but unfortunately the only thing that I can find is using a voltage regulator or an SCR like David mentioned; but by the time I try and put all of the electronics on the truck I would need to leave the box on there anyway so I might as well save myself the hassle and just use a larger 12v motor.:cry: Oh well, maybe I will find something better for the next one.

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  16. Kevinkrey

    Kevinkrey Member

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    That looks funny!:p
  17. Freelancer

    Freelancer Member

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    :agree1: I would have to agree with you on that. I am hoping that gluing the original hubs and tires to the outside will cover it up and make it look more natural.

    So I was thinking (pretty scary I know)and was wondering if it would be possible to control the voltage going to the motor through the decoder. Does this sound like a possibility? Are there any CV values that can be changed that would regulate the voltage for the motor output?
  18. Colton_modeler

    Colton_modeler Member

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    I'd take a look thru a Walthers N & Z scale catalogue for some ideas on motors and assemblies.
  19. Russ Bellinis

    Russ Bellinis Active Member

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    Is your motor significantly smaller than one for an n-scale locomotive?
  20. Freelancer

    Freelancer Member

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    :genius2: Hey that is a great idea and they run on 12v right?

    I don't know how this compares to an n scale motor, this motor is about 1/2" x 1/4" (12.7mm x 6.35mm) and the accessory motor I might have to use is 3/4" x 3/4" (19mm x 19mm). Does anyone have dimensions for an affordable n scale motor?

    *edit*
    I did a search for z scale motors and I am guessing that they do not naturally run on 12v as it was suggested to use a Zener diode circuit to make it compatible with 12v operation. I am still trying to make heads and tails of this circuit but it seems promising. Does anyone have any knowledge of the Zener diode?

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