Kadee website has #28 coupler for GE AC4400.
Can I use a #5.
Specs look awfully similar.
Thanks
pjjkgKadee website has #28 coupler for GE AC4400. Can I use a #5.
Running DC.
How do I tell if a frame is "hot"?
Use my VOM somehow?
doc steve
I'll bet you that I know someone who picked up a bundle of #5 couplers being marketed by someone sometime at 40% off retail; I will equally bet that said individual has his train room awash in #5 couplers!
If Mr Edwards says that the #28 coupler is the one that you want to use it is because Mr Edwards knows that a #28 coupler is the one that you want to use. Take his word for it; this is indicative of the fact that he has already put his VOM to good and purposeful use!
From the far, far reaches of the wild, wild west I am: rtpoteet
It appears from the locomotive exploded parts diagram,
http://www.hoseeker.org/assemblyexplosionAthearn/AssemblyExplosionAthearnac4400pg1.jpg
that the coupler on this model attaches to the engine frame. The frame is part of the current path, so therefore is "hot". When you screw the coupler to the frame, a current path is created through the screw (assuming a metal screw) and the coupler shank and knuckle. If coupled to a similar engine with a metal coupler the second engine gets electrically connected to the first. This is not a problem if both engines are coupled head to tail, since they will have their positive and negative motor leads on the same side. If the engines are coupled back to back, the positive and negative leads will be on the opposite sides and a short will occur. The insulated #28 coupler shank breaks the circuit connection between the engines.
Athearn 'BB' engines have a 'hot' frame. The lower motor brush is in contact with the chassis/frame. If you use a metal coupler like the Kadee #5, you WILL get a short circuit if you couple two 'BB' engines back to back. Trust me on this. I had a Athearn 'cow & calf' switcher set with metal couplers. The short was through the couplers(the knuckle springs 'glowed' cherry red).
Use the plastic couplers, or better yet; drill/tap for a 2-56 screw and bolt the entire Kadee coupler pocket to the frame(a much better solution).
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
pjjkgHow do I tell if a frame is "hot"? Use my VOM somehow?
1. Visually inspect the wiring of the locomotive. a. If the motor only has one wire coming from it - hot frame. b. If there is only one wire coming from each of the trucks, AND that wire is from the same side of the locomotive it means the other power has to be transfered through the hot frame. c. are there any wires connected anywhere to the frame = assume hot frame.
2. Put the loco on the track. Set the VOM to ohms and zero adjust it. Connect one lead of the VOM to the track and then touch the other lead to the loco frame where it isn't painted. If there is a reading then the frame is electrically connected to the track and therefore hot.
3. Put the loco on the tracks. Hold the loco so its wheels will slip and turn on the power supply. Set the VOM to about 20 volts DC. Connect one lead to the track. Touch the other lead to the frame (where it is not metal) and look for a reading. If there is a reading the frame is hot. If none switch the first lead to the other rail and try again. If there is a reading the frame is not. If neither rail gives a reading it is not hot.
4. etc.
If it's a BB model there won't be any wires going to the motor. There will be a contact strip on the top of the motor that connects with the contact arms on the trucks. This would definitely be a hot frame.
On the RTR version of the AC4400 there are wires going from both sides of the trucks to a circuit board on top of the motor. The frame is neutral.
Dr. Frankendiesel aka Scott Running BearSpace Mouse for president!15 year veteran fire fighterCollector of Apple //e'sRunning Bear EnterprisesHistory Channel Club life member.beatus homo qui invenit sapientiam
"Hot" chassis means the motor current flows thru the loco chassis. Probably more locomotives are hot chassis than not. Using the chassis as a conductor saves a wire or two, which lowers the cost of the locomotive.
To check for a hot chassis with a VOM, set the meter to ohms. Check the ohms function by momentarily touching the meter leads together. The meter shall read 0 ohms (a short circuit). Assuming the meter passes this simple check, proceed to measure the resistance between wheels and chassis. If you read 0 ohms from any wheel to the metal chassis, you have a hot chassis.
Just to check your technique, on a DC locomotive. Measure the resistance from wheels on one side to wheels on the other side. You should see the motor resistance, a few ohms. If the meter reads 0 ohms from side to side (and the engine runs properly) you have a metrology problem. Your meter isn't sensitive enough to distinguish between the low resistance of the motor and the even lower resistance of chassis to wheel. In this case I'd have my doubts about a resistance reading. Time to make a voltage measurement.
Put the locomotive on the tracks, block it from moving somehow, and apply enough track voltage to make the engine try to move. Measure said track voltage from one rail to the other. Remember this voltage and call it track voltage. Now measure voltage from the chassis to both rails. If you read track voltage to one rail and zero volts to the other rail, you have a hot chassis.
To get a good reading with either method you have to touch bright paint free metal, paint is an insulator. It may be necessary to file off a bit of paint to allow the meter lead to make good contact with the chassis.
Me, I assume locomotive chassis are hot, and use insulating couplers on locomotives. Either a plastic coupler or a metal coupler carefully installed in an insulating (plastic) coupler box with a plastic screw.
In the real world, it is possible to warp a #5 Kadee into anything. But using the Kadee recommended coupler can save a lot of filing, shimming, and hacking. Don't ask me how I know this :-)
David Starr www.newsnorthwoods.blogspot.com
If using the Kadee coupler box the coupler box on the Athearn frame will need to be filed down or the coupler will be "Low". The Kadee box will do away with the shorting and allow for use of number 5, 58, and if there is a pilot plow number 46 couplers.
The 28's are OK but from experience the plastic shank flexes and sometimes breaks.
The Athearn frame coupler box needs to be filed far enough to allow the Kadee box to hold the coupler at the proper hight. Kind of a file and fit, file and fit job. I did three AC4400's and have Kadee 46 couplers on the front and 5's on the rear. The coupler box holes in the pilots are at the correct hight when the body is attached to the frame.