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How to Use Hobby Motors In Model Railroad Projects

Updated on January 23, 2013
MagicMan007 profile image

Bill Watson has authored 3 books and many articles online and for print publications such as Sports Afield, Income Opportunties and more.

Can You Use That Hobby Motor You Purchased For Your Model Train Layout?

If I'm correct, you want to make something move on your model railroad layout with that small hobby motor you purchased for a few dollars. And you're having trouble figuring it out because the motor turns way too fast for the project you have in mind. You've also found there is little help to be found online. What little you've discovered assumes you know more about motors, gears and pulleys than you do.

I know exactly where you're at and believe reading this will save you a ton of wasted search time as well as money lost buying "the wrong thing" on eBay or some other online retailer.

Having made every mistake known to man in this regard (and a few others) I can at least point you in the right direction.

It doesn't matter if you have a full blown model train layout or a simple diorama you wish to add some movement to, the project possibilities are many: a carousel; a ferris wheel; a skylift tram; a ski lift; an escalator; a crane... Why not add them all? I know, only after you figure out that pesky motor problem, right?

Okay, the cheap DC (direct current) hobby motor you have spins at a super high RPM (revolutions per minute). It's almost surely going over 1,000 turns per minute and whether you do N Scale, HO scale, O Scale or whatever it's way too fast. It might be a fine science project motor but for a model railroad project, 1,000 RPM is not even close to workable.

So how do you gear it down to just a few turns per minute to make that carousel turn at a realistic speed?

The answer is you probably can't. You're not that good with electronics, gears or pulleys to pull it off or you wouldn't be here reading this.

The first thing everyone in this predicament tries is to reduce the voltage by using a lower voltage battery. But that only reduces the speed slightly and at some point, well before the motor is close to the required 60-or-less-RPM, the voltage drops so low the motor stops completely. Next they try adding a resistor into the circuit. But all that does is reduce the voltage, same result.

So pulleys and gears must be the answer?

Well, partly true, but it's unlikely you can pull it off with the cheap pulley and gear kits sold at hobby stores. First there's the problem of mounting everything so the gears, pulleys and belts mesh perfectly and reliably. Even if you can pull off that minor miracle, using just a couple of pulleys and gears would require pulleys so large they'd stick up out of your model train layout like a giant UFO! Explain that to your layout viewers..."and that, uh...well that is where a 5,000 square (scale) foot UFO that looks suspiciously like a huge hobby pulley hovers permanently above Trainville!"

If you're really good with electronics (don't forget, you aren't) you can build a "pulse DC generator" that will basically maintain the correct voltage while turning the hobby motor on and off so rapidly that it will appear to be turn slowly and steadily at whatever RPM you set it to. But the parts are going to run you at least $10 with no guarantee it will work properly when completed. I'd avoid it unless you are familiar with ICs, transistors, soldering and such.

Dude, I'm going to blunt here: GIVE UP! The hobby motor can be used to power a toy car or something where high rpm's are useful; for your needs, you be needin' a new direction.

The Hobby Motor Gearbox - The hobby motor gearbox could work...maybe... if...

A commercially made gearbox reliably reduces the ratio between a high speed hobby motor and the output shaft of the hoby motor gearbox. The one shown here looks like a toy and was chosen so you can see the gears, but a smaller less toylike gearbox may actually work for you.

The problems encountered when purchasing a gearbox for your hobby motor are interfacing and mounting. Your hobby motor will need to hook up to the hobby motor gearbox, which may require an adapter. It would also need to be mounted in a very stable way to ensure there's no play at the interface point.

Too much hassle! Maybe another wild goose chase? Why bother?

May I Present: The Geared Motor...PROBLEM SOLVED! - The Geared Motor is the Real Deal!

A geared motor, also known as either a gearbox motor or a gearhead motor is what you need: A high RPM hobby motor with a commercially made, factory attached gearbox!

Apply the proper DC voltage with either a battery or with a DC adapter (a.k.a. "wall wart") and the shaft turns at a nice low RPM rate. The gearbox motor is inexpensive, reliable and gives you the speed you need.

It's EXACTLY what you've been looking for! Buy it!

I've noticed that specific models of gearbox motors are not as ubiquitous as might be assumed. The best reason I can deduce is that toy manufacturers commission a limited production run of a specific RPM, voltage, shape, etc. and once the toy is out of production the surplus of a finite amount is sold to retailers. So if you run across one that works well for your needs it's smart to buy several. They may be gone for good next time you need one.

uxcell 6RPM 6V 0.45A High Torque Mini Electric DC Geared Motor
uxcell 6RPM 6V 0.45A High Torque Mini Electric DC Geared Motor

This motor is reliable, powerful and turns nice & slow (6 RPM which is one full turn every 10 seconds). Use as-is mounting the shaft direct to what you need to turn or use just two relatively small pulleys and/or gears to transfer power to where you need it, or even to gear it up or down a few RPM.

 
6VDC 45 RPM Pinky Finger Sized Gear Motor 1” Long x 15/32” x 3/8”
6VDC 45 RPM Pinky Finger Sized Gear Motor 1” Long x 15/32” x 3/8”

Need a motor that's closer to one revolution per second? This gearbox motor is a tad faster than the one featured. Just feed 6 volts from a little flashlight battery (or from 4 AA batteries wired in series) and you'll get 45 RPM out of this.

 

Hobby Motor Pulleys, Pulley Kits & Gear Sets

If your project permits attaching the motor shaft directly to the turn point, you're good. Otherwise, you'll need pulleys, gears or both.

These hobby motor pulley kits includes a variety of small plastic spacers that attach to the motor shaft to stop play between the pulley (or gear) and the shaft.

Would A Hobby Servo Motor Work?

Could it? Yes. But hobby servos are designed for robotics so in addition to the + and - feed for voltage, there is a third input for a computer signal that controls the servo. If you understand how to inject pulse width modulated code (PWM) signal or wish to invest serious time in learning how to do so, the hobby motor servo is a great choice. Otherwise, stick with the gearbox motor.

Other Items You WILL Need

1. The DPDT (double pole, double throw) switch is necessary to turn your motor on and off.

2. The hookup wire (buy both red and black) will create the circuit from the battery, through the switch, to the gearbox motor and back to the battery.

3. The 6 volt adapter is a good option for powering the motor if you intend to use it a lot. Simply cut the DC end of the adapter off (the little DC plug you'd normally plug into a device is what gets removed) strip the wires and there's your + and - power supply.

4. Another option for occasional use is the 6 volt battery. You'll need to replace it from time to time.

Wiring the DPDT switch:

The DPDT switch will have 6 connection points. The two in the middle are where you attach the power from either the battery or from the wall wart. Be sure the power is off before messing with the wall wart. The polarity of the connection does not matter.

Next run one red wire from one of the two the motor connections to one of the end connections on the switch. Run a black wire from the remaining motor connection to the switch end connection directly beside where you attached the red wire.

Now we'll run the "reversing" wires which will go to the two unused connections at the other end of the switch:

Connect a second red wire to the same motor terminal as the first red wire. If you ran the first red wire to the left side of one end of the switch then run the second red wire to the right side of the other end of the switch.

Finally, run a second black wire from the same connection the first black wire is connected to. Take it to the final unused connection.

Using a battery for power (connected to the wires coming from the two middle contacts of the DPT switch) flipping the switch "up" will cause the motor to run. Flipping it "down" should reverse the motor. Setting the switch in the middle position will result in the motor receiving no power.

If you're using an adapter (wall wart) for power you'll need to plug in the AC cord to an electric socket first. Be sure the adapter indicates the output is DC! The switch movements should yield the same result as described above.

DPDT Mini T/Switch 5AMP 120VMOM (2)
DPDT Mini T/Switch 5AMP 120VMOM (2)

This will give you "on" "off" and "reverse"

 
RED 22AWG Solid 300V Hook Up Wire - 25' Roll
RED 22AWG Solid 300V Hook Up Wire - 25' Roll

Your hookup wire. Order both red and black.

 
6V Battery
6V Battery

A second option. It will last longer than you think.

 

The Author's Gearbox Motor, Pulley Attached, Ready To Power An N Scale Tram Skylift Up A Mini-Mountain

The Author's Gearbox Motor, Pulley Attached, Ready To Power An N Scale Tram Skylift Up A Mini-Mountain
The Author's Gearbox Motor, Pulley Attached, Ready To Power An N Scale Tram Skylift Up A Mini-Mountain

Any Comments on Low RPM Motors, Belts or Pulleys? - Post Here!

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    • profile image

      anonymous 4 years ago

      GREAT IDEAS AND VERY HELPFUL.

    • Writingmystory1 profile image

      Writingmystory1 5 years ago

      Good info!