Lionel Command GP7

[luther_stanton]

Hello Again!

I have a question regarding my Lionel ACL GP-7 (it is the command version). I just finished installing Atlas nickel track, so the Magne-Traction is pretty much rendered useless. It seems the first wheel set of the rear truck is just dragging – not rolling. The center of the axle has a clear football shaped plastic piece which contacts a small tab thereby activating a small switch – twice per wheel revolution. What is this? I believe it is causing enough mechanical resistance to keep the wheel from spinning.

Since I went with the nickel track, any ideas on how to stop the wheel set from dragging?

Thanks,
Luther

[Big_Boy_4005]

That cam is part of the sound system. It is measuring wheel revolutions. I'm not sure if that's the source of your trouble or not. It shouldn't be.

[dougdagrump]

Is this a powered or non-powered truck ?
If non-powered have you tried turning it with your fingers ?

[Roger Bielen]

If a powered truck, or sometimes a non-powered truck with gears and no motor, check the gears for something jambed in, i.e. ballast, lint, etc.. Try not to force the gears to turn you might strip one. Been there, done that. Use a pair of tweezers and a long pin the clean the teeth out if dirt is visible.

[Big_Boy_4005]

Nah guys, the cam is on the non powered truck. I have 2 of these engines (different paint) and the axel spins freely.

The cam isn't hitting the metal plate that holds the roller, is it? There is a notch in the plate, and the fit is fairly close. If the cam isn't centered on the axel, it could be rubbing.

[luther_stanton]

It is on the non-powered truck. I was able to spin the wheels by hand so they were not bound up, etc.

I started tinkering around and looking at the brass bushings, axles and such. I put a drop or two of oil at each contact point between the axles and the bushings (this is a relative new engine – had maybe 10 hours on some FasTrack and I had just finished a more permanent set up with Atlas track when I noticed this problem). I started to see everything free up with the oiling but there was still a good bit of resistance when the contact between the cam and the switch was at its greatest. I put one drop of oil on the cam and spun the wheels through a couple of revolutions which really freed things up.

I put it back on the track and there is no more dragging – all the wheels spin freely. Also, the slow speed performance of the engine is noticeably better AND I now get the brake squeal each time I press the brake button on the Cab 1 – previously it was intermittent.

Thanks for the posts!

[wrmcclellan]

The cam contacts a micro-switch which lets the sound system know the loco is rolling and how fast.

Use some heavier lubricant on the cam like the Lionel grease (in the tube) or white lithium grease when you get a chance. Not much is needed.

Glad you got it working again!
Roy

[pbjwilson]

Luther,
Had the same problem on mine. The little cam prevented the wheels from turning. I actually wore a groove in the wheels before I noticed what was happening. This was about 10 years ago, and my first TMCC engine. I fixed it by gently prying the cam away from the axle. Talked to someone at Lionel and they said they would send me a new truck but I didnt feel like replacing it and it's been running fine for ten years now. These are great engines with basic railsounds and TMCC. Noticed one on e-bay the other day that sold for about $100. Thats a deal for command control and nice sounds.