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Slowing Down Nigel Lawton’s Bachman Remotoring Kits

From Matt Coleman, 13 Nov 2005

A few weeks ago there was a discussion about whether or not you could slow down the speed of the Bachman 0-4-0T with Nigel’s improved motor conversion kit. Nigel had suggested that someone try with various resistors to see what works.

This is not a definitive engineering study but I have tried the following resistors (all from Radio Shack) with the following results. All resistors 1/2 watt.

  • Resistor 220 ohms — way too slow, loco would move until I applied 10 volts.
  • Resistor 100 ohms — still very slow, loco started at about 7 volts, ran smoothly but never developed full power. Couldn’t haul more than one or two cars.
  • Resistor 82 ohms — started at 5 volts, ran smoothly, top speed very reasonable, limited in power — pulled 3 cars, got very slow with four cars and power at 12 volts.
  • Resistor 47 ohms — started at 4 volts, ran smoothly, top speed a bit high but developed full power (could pull six cars around loop — same as before adding resistor except that there was no driver slippage.)
  • Resistor 33 ohms — same as above but top speed too high.

My recommendation is for the 47 or 82 ohm resistors. Radio Shack product code 271-1105 and 271-1107 respectively. The resistors are $0.99 for a pack of five.

This really makes the locomotive with the upgraded motor a superb runner with a reasonable top speed and good control even with a cheap throttle. Again, Nigel has done a great job engineering the drive and I hope that others can upgrade those old Bachman chassis’ to modern standards.

Also, if you find that some of the gears have split, just ‘weld’ them back together with a very low wattage soldering iron and a quick, deft touch. I have done four gears like that and they are like new.

Cheers!

Matt

I always feel stupid responding to my own email messages but I did a bit more work with the motors and resistors yesterday and would have to say that the 82-ohm may be the better choice. I think the limitations on power I experienced were because I was using a very cheap, very small, very old powerpack. When I retested with my somewhat less ancient MRC pack, both the 47-ohm and 82-ohm resistors provided equal pulling power, with the 47-ohm resistor giving a slightly higher top speed.

Just a bit more info for those who care.

Cheers!

Matt

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