motor question

[pdlethbridge]

On an open frame motor like the bowser DC-71, which side gets the gray and orange wire? Could I use a multimeter to figure it out and how? Thanks in advance.

[Yampa Bob]

Scroll down to the fifth post on this page:
http://www.bachmanntrains.com/home-usa/board/index.php?topic=7439.15

In short, the orange wire connects to the motor terminal that produces forward motion when the controller direction switch is set to forward. Most, if not all our loco motors are "timed" at neutral, so the shaft turns at the same rpm regardless of rotation.

Also review "Principles of Motor Motion" on this page. (click 1. Place permanent magnet) to start the flash video.
http://www.mabuchi-motor.co.jp/en_US/technic/t_0102.html

(another good reason to have a spare DC pack to confirm direction of rotation).

[pdlethbridge]

if the leads on the power pack are reversed, will the motor run clockwise or counter clockwise?

[Yampa Bob]

Don't know, it depends on which way the motor was running before you reverse the leads. Whether the motor requires CW rotation or CCW rotation to make the loco go forward depends on whether the worm gear is toward the front of the loco or toward the rear. Which way is it?

First make sure the DC controller direction switch is set to FORWARD. Use your multimeter to determine which screw on your DC pack is positive, then mark it and the end of the test lead for that screw with a +.  Whichever motor terminal you touch the + wire to that produces correct rotation for the loco to move forward, is the terminal you connect the orange wire to.

[Guilford Guy]

Does it really matter, when you can alter the CVs to change the "forward" direction?

[Yampa Bob]

For the sake of uniformity and consistency, it very much matters. The decoder default is orange wire positive for forward motion. When I install a decoder, place the loco on the tracks and turn on my EZ Command, I first expect the loco to go forward (the default). I shouldn't have to cover up a mistake in wiring by prematurely changing the default direction. In short, I don't like surprises.

If it didn't matter, the decoder manufacturer would list the orange and gray wire as "It doesn't matter". 

[glennk28]

I'm not a DCC specialist--but I do know that both motor brushes MUST be isolated from the frame. Check with a multimeter.  The DC-71 normally has one brush grounded to the frame.  This could lead to a fried decoder.  gj

[Guilford Guy]

For the sake of uniformity and consistency, it very much matters. The decoder default is orange wire positive for forward motion. When I install a decoder, place the loco on the tracks and turn on my EZ Command, I first expect the loco to go forward. I shouldn't have to cover up a mistake in wiring by prematurely changing the default direction.

If it didn't matter, the decoder manufacturer would list the orange and gray wire as "It doesn't matter".  If running on DC power, all locos must be wired the same to comply with the right rail rule to run in consist.

Yes, but I usually choose operation of uniformity and consistency. While my decoder equipped locos are wired according to NMRA practice, in a case such as this I wouldn't. There's a 50% chance it will go forward, 50% chance it will go backwards, so taking that chance, and changing one CV if it doesn't work out is a risk I'd be willing to take.

[pdlethbridge]

My DC-71 is DCC friendly, it is 2 wires. I have the worm on the front of the motor.

[Yampa Bob]

From my other thread, if the worm gear is facing forward, and there are no idler gears (direct drive to the axle), then the shaft must rotate CCW for a right hand worm gear, or CW for a left hand worm gear.

[richG]

I wire my loco motors so the drivers are moving forward. No meter needed.

My Spectrum 4-4-0 and 4-6-0, the motor turns CCW for forward.

My Roundhouse locos, the motor is CW for forward.

Mantua tender drive and Bachmann tender drive, CCW for forward. Direct drive

Spectrum 0-6-0T, CW for forward.

Mantua 0-6-0T, CCW for forward. Direct drive

Look at the Spectrum diagrams for the rod engines and you will see gear reduction differences. Some the motor with turn CW, some CCW.

Rich

[Jim Banner]

From my other thread, if the worm gear is facing forward, and there are no idler gears (direct drive to the axle), then the shaft must rotate CCW.

This is for a right hand worm.  A left hand worm in the same circumstances would have to turn Clock-Wise.  Right hand worms tend to surge more going down hill, particularly in older locomotives with slanted open motors.  In newer designs with can motors mounted horizontally, there is little if any difference.

[Yampa Bob]

Yes, I edited my post.

Thanks