I have three track cleaning cars ... one home made and two commercial. My home made car works! Both commercial cars, one with a motorized rotating pad (requires a consist to run) and one with a "Brite Boy" type rotor: Both of the commercial cars hang up on my uncoupling magnets ... I have shimmed the wheel sets to try to relieve the pressure, which helped but I now think that I need more pulling power. Any suggestions for the strongest diesel? A minor annoyance but it's on my todo list. Thanks.
Most F units, whether EMD Fs or Alco FA/FB pull reall well. Kato, Life Like, Intermountain, whatever you can find.
It's not pretty, but an old Arnold FA with cast metal body will pull like crazy. Here's Spookshow's page on it: http://www.spookshow.net/loco/arnoldfa2.html
I use homemade Masonite slider cars to clean my track. One in each train. They do create some drag but one GP-38 or B23-7 or RS-3 will push or pull it around by itself. But when included in a train, depending on its length I use a pair of locos or even three mu-ed to do the trick. I also sometimes use two slider cars in a train.
I have a CMX cleaning car and I always use at least two locomotives because the pad hangs on some turnouts. The F units work well and so does a Kato SD70MAC paired with a Fox Valley ES44AC. Those 6 axle AC locomotive pull almost as well as the old F units.
Some of the later Life-Like pre-Walthers units, like the last run of FAs and the C-Liners, will pull the paint off a wall. (The earlier releases, not so much... so be careful.)
Pre Walthers Life Like E8 or E9 pull real strong. These have a plastic frame. Would not pay much for one. Can not find any engine that will out pull the Cotton Brute. Dan
Gotta go with George on this one. Of all my fleet, the Atlas Trainmaster is the true beast. Pulls like a mule team. Kato E-8's are a close second.
Life-Like plastic frame FA-2s are the best pullers out there. They are long out of production, but you can find them at shows. More than a few vendors will price them far beyond their value, but that is not atypical of vendors at shows. If you look enough, you will find a vendor who actually wants to sell his wares, rather than schlepping the same stuff to show-after-show, year-after-year,so ,he will price them appropriately. These things are worth twenty to twenty five dollars. They came in an A-B set, with a dummy B, but if I needed one and found only the A with a price tag of twenty five dollars, I might pay that, but I would have to think about how badly did I really need it. The split metal frame FAs that LL subsequently sold, and WKW issues from time-to-time are also good pullers, but not quite as good as the plastic frame. If you can not find one and want one, send me a PM, I have some around here somewhere and will see if I can find one.
Based on my experience, I would have to say a Kato SD80MAC or the Kato SD90/43MAC as a single locomotive solution. The are a combination of weight and really strong motors. It is not about the weight by itself, it is the combination of weight and motor torque.
The split-frame LifeLike FA1/FB1 or the FA2/FB2 sets are 'stump pullers'. The old ConCor/Kato PA1/PB1 are likewise great pullers. For a while, the LifeLike FA's were selling in dual powered sets for $40.00... one of the best deals I ever found for fantastic running DC locomotives in N scale. IF... the D&RGW had actually purchased FA/FB sets... I would have bought enough to roster the whole D&RGW fleet. I only got the Great Northern, MoPac and Rock Island versions. They were greatly overproduced a the turn of the millennium... and were being sold at virtually wholesale prices. You probably won't find them NOW for less than $100 for the FA/FB pair.
Try two Atlas Trainmasters or Kato E-8's These diesels easily pull my CMX+ track cleaning car. Shades