MTL F-7 question

I thought this was discussed before, but I'm not finding the thread. Then, again... it could be posted on one of those other forums.

I have a new MTL F-7 A-unit. It runs fine in reverse. The usual coffee grinder. Switch to forward... it runs... it starts to slow down... it sputters... it stops. Put it in reverse... no troubles.

Anyone have any ideas or tips?

ThankZ!

run it backwards as a cab-backward?? :0)

Don't know if this is the "right" answer or what you'd want to read, but when I've changed the brushes on the motor I've experienced similiar one way issues when I didn't get them in right.

Mark

I don't know, Mark. I wasn't aware that the MTL F-7's had brushes. I've never seen a F-7 run like this.

Before I open it up... Is there anything I need to be aware of? Just loosen the four screws and ?

Yeah they have brushes. Check out the instruction sheet in the bottom of the jewel box. Spread the shell with a toothpick in the center at the chasis to get it off. Fig 1 in the instructions shows the rest. Of course if its new, I'd consider it a factory issue. If they installed the brushes wrong, what other issues might you find?

Mark

Mr. JA, Do you think it might be your controller. since forward is used more then reverse maybe the controller may be worn down bad try a different controller. Just a thought!

Walt, I blame it on the controller of the controls.

So! What was the problem? It couldn't have been the controller of the control, you were in control! Right? meaning the hand held controller or transformer forward of reverse.

There are always a lot of possibilities and the twisted motor brushes is the only one that meets the description that I've seen. The missing piece of info is whether the headlight stays on when the loco grinds to a halt. If so that pretty much eliminates the electrical issues (including operator error).

southernnscale wrote: Mr. JA, Do you think it might be your controller. since forward is used more then reverse maybe the controller may be worn down bad try a different controller. Just a thought!

It's not a controller issue. Other locos run fine... including other MTL F-7 units.

markm wrote: The missing piece of info is whether the headlight stays on when the loco grinds to a halt. If so that pretty much eliminates the electrical issues (including operator error).

As the loco runs from normal to sputtering to dead stop... the headlight goes from steady to flickering to dead.

The track is clean... the controller is fine. Other locos of all types are running fine and normally on the same loop of track with the same controller. As I wrote in my original post... this is a NEW MTL F-7 A-unit.

stonysmith wrote: Unless I'm totally off my rocker, there are also a set of (brushes) also known as wheelwipers that pickup power off of the wheels. They are in the shape of an upside-down V. Plus, it could be actual 'dirt' or it could be simple oxidation. Might have to clean the wipers, or possibly even clean the wheels.

Unless I'm off my rocker... wheelwipers on the MTL F-7's are an after-market add-on. Everything is clean... track and wheels.

With everything else checked there is only one tiem left that I can see. The trucks on the F7 have some play front to back due to teeth and worm clearances at top of truck.If you try starting the F7 slowly, you can see the body move before the engine moves, when going forward the body moves forward a bit on the trucks as slack in worm drive is taken up and when going in reverse the same thing happens only body starts to move in reverse before the trucks do. so if one of the cats whisker bronze strips is out of tension,or position then in one direction you could have an open connection and the engine would run in one direction and not in the other. Usually if these strips are damaged the engine flops over on one side. These cats whiskers are phosphor bronze are easily damaged if the engine has been taken apart and on reassembly they were not in proper alignment when the second half of the body was put back on.The tip of the whisker contacts a very small area at the top of the truck, above the gimble so minor misalignment can lead to loss of contact. unfortunately the Glenn Chenier wipers do not solve this problem but they do improve overall operation when they are used, but the cats whisker sticks out from holes in body casting and have to positioned correctly and tensioned correctly to make contact and keep engine upright on its trucks.The trick to installing the Glenn Chenier contact strips is to do it by removing the truck side frames only and not opening the engine up. When you take the shell off make sure the end of the bronze strip is at least flush with side of body metal casting. they are just a friction fit in the holes. if they protrude from the outside of the body casting they are too short to make contact reliably. over 70% of the time whenI am repairing an F7 the i find the cats whisker is not correctly positioned or tensioned and is usually the first thing I have to fix to get it running again.

ThankZ, Garth, for the details. I took off the shell, but did not open the chassis. My solution, since this is a new locomotive is to return it to MTL.

I'm sorry you have to retire your F-7 Engine to the bone yard! I've never had that problem with any of my Engines except for dirty track or a truck not setting right. One time I had two Engines on the same track and would run and the other not, I took one off and the other would run fine. So it stays a Mystery !!!!!!