The "DEAD" Spot

I have changed some of my single pickup rollers with double rollers, to help operation over the switches. they fit into the same space for my MTH locos. I have attached a pdf of how to change the rollers & prevent shorting when passing over switches. The PDF shows a double roller pickup.

I hope this helps clear things up: Joe K

Anyone know if the MTH double roller will fit my locomotive?  Posted the number product number earlier.

I think I am going to inspect my switches tomorrow and clean them well.  While poking around I noticed some glue.  Not a lot but a small amount in the area.  I cannot see how that can kill power as there is another roller and many other wheels to keep the ground in check.  But when I meter the glue spot it does go to zero.  Glue spot is about 1/8th of an inch.  Maybe less.

It always seems to be the hot center rail that needs the jumper. I needed jump the hot on either side of the frogs....

The double roller is an interesting idea.  I like it!  I just received a new RailKing switch engine (received yesterday!) and it has the double rollers on it.  I notice the spring pressure seems to be greater than the single rollers.  Perhaps this is a good solution for contact pressure.   [I deleted my comment about the engine "jumping" over switches.  I found a traction tire that was not fully seated -- from the factory!]

Joe K:  do you have a part number for the double roller assembly and perhaps price?  I might want to try this just for the "experience". Will this fit "older" MTH engines?  Thanks.

The double rollers have been around for sometime. This SW9 from Atlas dates to 2003.

By the way Joe K.....the roller assemblies that came with my new Rail King CSX SW-9 Switcher are slightly different than the ones you have in your pictures.....see below:

Yeah clean  the glue off. Don't forget the other roller may be going the dead section of the switch. It's dead on purpose  , the hot roller has to roll over an outside rail near the frog. If that outside  rail was hooked up there'd be a dead short. Having said that I don't believe the small glue is the problem. I would bet both rollers are on dead spots and we're almost back at the beginning.   Again in your pic, is there power on the center rail just below the left roller??  Last request,    Ball game on.....

Following up with Gregg's thought, The curved lead rail near the center hot needs to have no connection to common. The center rail rolls over it.

Moonman,

Are you saying if I put an AC meter between the red circle and the green dot in this picture that I should have no power?  With both switches in the straight through position?

Yes that is correct.   

The center  rail at the green dot is the  location  I would be concerned about.  If the switches are pre-wired there should be power at the green dot.  If they are not pre-wired there will be no power on that little section., It's very difficult to tell if the switches are pre-wired without turning them  upside down.   It's also very difficult to get an answer from you whether that  little center  section has power or not...

Put  one lead of your volt  meter on the green dot and the other lead on an outside rail.

is there voltage??   

I  am not trying to be difficult.  I am not good at electricity.  My switches were pre-wired by Ross and I can see the jumpers they put on.

I will test at the locations and let you know in a few.  Thanks.

There is no voltage at the red and green points.  If I go to the right and hit the part of the switch that moves there is voltage. It is this way on both switches.  Next step?

That's a good question.... we know the switches are pre-wired (at least the center rails).  I would jumper the outside rails   together on track before the switch with alligator clips  for testing   .     Clean the track .. Loosen any track screws so they're not pulling the track down or making it uneven.

Last step...  try the stall test again   and make note of where   each roller  is touching the track.

. . It does look like in your pic that the left   roller should be picking up center rail power.     Outside of replacing the rollers or adding a small section of straight track I 'm out of ideas. 

For what it's worth I always jumper the outside rails  together   just before the switch  with a few exceptions  Signals , crossing gates etc.  good luck

No,

the rail with the red circle around it should have no continuity with any rail. That's an outside rail that the roller has to roll over, which would short the hot to common.

Well I must say I appreciate all the help here.  This one had me stumped but I fixed it, here's how.

I simply noticed that when the locomotive stalled, a slight push to one side, and I mean slight, brought power back again.  Someone said to check for this a while back in the thread.  I shimmed the switches with two pieces of cardboard and it is fixed.

I will find some black shim material and replace the cardboard.

Obviously something is breaking ground when the locomotive moves through the two switches.  It stops at the same spot every time to with a millimeter.  The only thing I can think of is the trucks are pivoted just right within the rails to stop the contact.  As is only happens in reverse I am still stumped.  As it only happens at slow speed it makes sense because the dead spot is so small I can momentum through it.

Thanks for all the help...was a tough two days on the railroad.

Thanks Carl, My switches check out exactly as you describe.

Joe K:  Can you share the MTH part number for the dual roller assemblies?  This looks like a great idea!  Thanks.

Yes that was a tough one.. Last minute thought, I believe MTH engines have a black ground wire on each truck that goes to the circuit board. (it's usually right beside the the red hot wire from the roller. Perhaps one of then is malfunctioning  (broken wire)  Unfortunately you have to take the shell off to get a good look.  

The Roller in JoeK's picture is BD-0000090, but that is now filled with a BD-0000097 which has the black insulators on the side of the roller (The 3-2 roller) shown is some one else's picture.   G

Anyone know if these are universal or how to spec one out to determine if it will work on a particular engine?  Mounting holes etc.?  Thinking of doing this to a Lionel I had mentioned above.

Glad you solved your issue, many times sliding it will get the flange to complete the circuit. Jumping a wheel to common with a wire is also a quick check. Sadly even though this loco has 6 wheel trucks, those 4 blind "dummy" wheels in addition to the 4 rubber tired wheels leave you 1 axle on each truck to complete the circuit reliably. Have Lionel FM's which have this same pain in the ___ issue. Any rail on a switch which has a pick-up roller crossing it will be insulated. Even worse is a Geep 7 or 9 with 4 of its 8 wheels insulated by rubber tires. Having to modifying brand new expensive locos to get them to work is not looked upon very highly by the boss here!

How o you typically modify them as I see this in my future :-(

I will probably only fit on units that have the longer pickups.  Anything shorter and you will most likely short out to the chassis.  G

Was going to replace the trucks but Lionel has had 2 or 3 truck revisions since these were produced and not sure the trucks are at all interchangeable. Unlike MTH 3/2 where you can drop the axles, even if Lionel sold flanged wheel axles you would need to be able to pull the wheels off the axle and then press the wheels back on after installing them into the frame.

Try cleaning the wheels,pu roller  and track with lacquer thinner and a Q tip/ if that doesn't work,put a voltmeter between the wheels and transformer ground. If you get a voltage you have a ground problem. Hope this helps

You could put a lighted caboose next to the loco and run a wire from the caboose power to the loco P.U. While you are there run a ground wire from the caboose frame the loco frame