Re-wiring a DC locomotive for 2-truck pickup

[the_fly_boy]

Hey,

I recently discovered something with one of my locomotives (an Athern SW-7). It appears to pick up electrical current with the front truck only. This causes it to hickup every time it hits a switch frog, and because it's a switcher operating at low speed, it very occaisonal just stops. I tested another locomotive (GP-35) with two-truck electrical pickup and it goes over the switches without issue. My question is, can the locomotive be re-wired so it picks up current from both trucks? I know how to do this in theory, but I'm not familiar with the way these locos are grounded or anything and the last thing I want to do is torch my switcher.

Thanks 

[Mark R.]

If it is in fact an Athearn switcher, Athearn's have had all wheel pick-up for generations ! The wheels on one side of the truck are grounded through the frame while the other side connects through the flat metal "spring" attached to the top of the motor on older units.

At this point, not sure what your problem would be .... you're certain it IS an Athearn ?

Mark.

[the_fly_boy]

If it is in fact an Athearn switcher, Athearn's have had all wheel pick-up for generations ! The wheels on one side of the truck are grounded through the frame while the other side connects through the flat metal "spring" attached to the top of the motor on older units.

At this point, not sure what your problem would be .... you're certain it IS an Athearn ?

Mark.

 It is definetly an Athearn. I bought it new in box, though I should mention that this was at least 8 years ago -I never ran it on the layout until now. The rear truck definetly has no power pickup. I held it on the end of a track with the forward truck off the end and the power at full and nothing happens. Vise-versa with the forward truck on the track the wheels spin away happily.

I'll remove the body and take a look at the inside to see if anything has disconnected or something in the years of sitting in a box. 

[Mark R.]

Hearing as how you haven't even removed the body for inspection yet, I'm willing to bet the rear contact spring has become dis-connected .... not an unusual thing to happen if the trucks have been free-floating in the box.

Mark.

[the_fly_boy]

Hearing as how you haven't even removed the body for inspection yet, I'm willing to bet the rear contact spring has become dis-connected .... not an unusual thing to happen if the trucks have been free-floating in the box.

Mark.

Wow, this was an interesting little learning experiance.

The first thing I noticed when I took the body off was that the connector clip, under the contact for the rear truck, had some rust on it. After scraping that off and testing the chassi the problem appeared to be solved.

Put the body back on, problem persisted. After examining the back of the interior of the body, I noticed a little piece where the hood connects to the cab that appeared to be broken and hanging down. It was ridged enough to push the connector clip clear of the rear truck pickup. After removing it and testing again with the body back on, I now have power pickup with both trucks.

Interesting little problem. Thanks for the input Mark. 

[jeffrey-wimberly]

If you want to eliminate any possibility of losing contact between the trucks and the motor simply remove the contact strip and solder a piece of flexible wire from the contact arm of each truck to the motor.

[jasperofzeal]

I'll echo what Jeffrey suggested in regards to soldering a flexible wire to the truck metal contacts.  You can also get a kit from A-line to do just that, here is a link to the item I recommend to you: Electrical Hook-Up Kit.  This kit is enough for wiring two locomotives.

[the_fly_boy]

I might just do some soldering. Seems like an easy way to ensure good operation.

[loathar]

Definitely loose that top brass strip and hard wire the truck towers to the top of the motor. Hard wiring the bonfire bulb will help stop any flicker too.
In case you don't have the diagram, here's the one for the SW 1500. The mechanism should be the same.
http://www.hoseeker.org/assemblyexplosionAthearn/Assembly%20Explosion%20Athearn%20SW1000%201500.jpg

 

 

[the_fly_boy]

Definitely loose that top brass strip and hard wire the truck towers to the top of the motor. Hard wiring the bonfire bulb will help stop any flicker too.
In case you don't have the diagram, here's the one for the SW 1500. The mechanism should be the same.
http://www.hoseeker.org/assemblyexplosionAthearn/Assembly%20Explosion%20Athearn%20SW1000%201500.jpg

 

 

Thanks for the link, though i do have the diagram. After opening it up though and looking at the device it's a lot easier to understand how exactly it works.