Atlas Scale Motors

TMC Aug 4, 2022

  1. TMC

    TMC TrainBoard Member

    32
    22
    2
    Hello,

    I recently came into possession of 3 Atlas SD24 locomotives from their 2003 run. They are all DC so far. One of the locos runs average the second runs considerably slower with a louder buzz and the third would probably lose a race to an inchworm it goes so slow. Are the motors cooked? What motors on the market could I replace them with? Kato maybe?
     
  2. jwaldo

    jwaldo TrainBoard Member

    442
    950
    29
    If they haven't been run in a while I'd start by checking the lubrication on the gears and bearings. When I recently pulled my locomotives out of storage, I found that several whose lubricant had gooped up and become sticky enough to slow them down (and in one case prevented it from moving at all). I was worried they were goners, but a wipe-down with rubbing alcohol and reapplication of new grease got them running again, no replacement parts needed.

    That said, if it IS the motor, the Spookshow review has pictures of what both generations look like under the hood. That'd be a good starting point for figuring out whose replacement motor you'd need.
     
  3. bman

    bman TrainBoard Member

    477
    148
    21
    As mentioned above good cleaning might help. I also wonder if one or more of the universals are slipping on the shaft that spins the worm gear that engages the truck gears. The loco will then be pushing that truck with the remaining operational truck. That could explain the slow speed. The buzz could be one of several things. Hard to say without hearing it. There should be a parts diagram in the boxes showing the components of the drive train. If not go to the Atlas website and unddr then formation tab choose parts diagrams and the pdf's are listed there.
     
    TMC, Martin Station and Allen H like this.
  4. jwaldo

    jwaldo TrainBoard Member

    442
    950
    29
    Now that you mention it, this is exactly what happened to one of the two actually-broken locos I HAVE encountered. A first-run Intermountain SD40T-2, with a really tiny flimsy universal joint that cracked. It got power to the front truck, but not the rear. So it's definitely worth a look to make sure all six axles are actually turning when the locomotive moves.
     
    TMC likes this.
  5. TMC

    TMC TrainBoard Member

    32
    22
    2
    I’m hoping it’s just a cleaning because this sounds like major surgery… but this sounds like it could be the problem. I ran them without the shells and it looks like the motors are running fine just little or no power transfer to the wheels. If this is the case are these parts still for sale from atlas? Why can’t everything just run like a kato.
     
    DeaconKC likes this.
  6. Allen H

    Allen H TrainBoard Supporter

    1,366
    1,606
    41
    This is very common with the SD24's, there were a few other models that suffered from the split universals.
    I was able fix a couple for a friend using a 2 part 5 min epoxy after roughing up the shaft. They're still running.
     
    TMC and Martin Station like this.
  7. MRLdave

    MRLdave TrainBoard Member

    1,024
    428
    32
    Before you tear everything apart, start with the trucks......sounds like you got these used and no telling where they were run before you got them. You can pop the side frames off the trucks without removing them from the chassis. The little brass/copper cups that the wheels ride in (and that transfer power to the motor) frequently fill up with assorted gunk and prevent the motor from getting power.

    It could also be a universal.....to check that, use a 9 volt battery. You can touch the battery terminals across an axle and everything should spin. Since it's in your hand, it's easy to put a finger against each wheel and see if you can stop them from spinning.
     
    TMC and mtntrainman like this.
  8. Hardcoaler

    Hardcoaler TrainBoard Member

    8,851
    31,889
    125
    I have some older SD-35s that ran at different speeds and it's because they had different motors. Atlas has produced some with Scale Speed motors (these are the slowest, black surround with a green armature I think), a Slow Speed motor (between the Scale Speed and regular speed) and the regular speed. I bought a new motor or two from Atlas and have the same motors in them now. I'm not saying this is the source of your situation, just suggesting that you take a look under the hood to see what you have.
     
    TMC, BNSF FAN, MK and 1 other person like this.
  9. Martin Station

    Martin Station TrainBoard Member

    214
    315
    13
    I had purchased some older Atlas GP38 locomotives and one of mine had the "buzz". After removing the old grease which just brakes down, thickens over time and picks up dust somehow, and taking the trucks apart and cleaning the gears and goop out of the wheel contacts, I then relubed the bearings with Labelle 108 oil. The ones closest to the motor I put just a small amount on a thin piece of wire and added a little over time as not to pull it into the motor.
    As for the trucks I put a small amount of Labelle 106 lubricating grease with teflon to the worm gears. After that I just let it run for a while at varying speeds.
    Sometimes it just takes a while for the oil to reach everywhere, but you can always add more if needed. Also there one more thing I do before removing any parts after separating the chassis, I take a photo of it with my iphone so there in no question as to which way the bearing seat or parts go back together. I also clean all the electrical contacts with alcohol.
    As far as broken or split parts, I didn't have that issue, but over time I can see where plastic can dry out and crack and I also believe Atlas had this issue with some of it's unversals. You can still go to the Atlas website and order parts and if there not listed, call their customer service and ask, I have heard of them being able to help.
    Good luck, there is a lot of great and experienced people on this fourm to help you through this.
    Ralph
     
    TMC and mtntrainman like this.
  10. Martin Station

    Martin Station TrainBoard Member

    214
    315
    13
    As far as the different motor speeds, I just aquired an older Atlas B23-7 with the higher speed motor. I don't run DCC so I'm going to see how well it speed matches with my Kato locomotives, if so this will give me more locomotive power options putting together trains. My point is if they do have different speed motors and if you only run DC, then maybe you can run them together with Kato locomotives that still use higher speed motors. Hope this helps.
    Ralph
     
    TMC and Hardcoaler like this.
  11. TMC

    TMC TrainBoard Member

    32
    22
    2
    A quick update. I took the two slow runners apart and did a complete clean with alcohol and soap and water on plastic parts. There was lots of old grease and gunk. I added Labelle 108 on the near the worm gear and by the shaft coming out of the motor being careful not to get any in. Cleaned the wheel assembly and the washers and they are still crawling along. There doesn’t seem to be any cracked joints or parts. Very frustrating. I might buy new contact strips and wheel assembly’s. They don’t seem to be getting enough power.
     
  12. Carl Sowell

    Carl Sowell TrainBoard Supporter

    2,840
    6,437
    76
    TMC,

    I know you just stated that you have " cleaned the wheel assembly ". Not real sure what you mean by that statement.

    As MRLDave suggested above the brass pickkup strips and the cups in them need to be cleaned. I post 2 pictures to show what I am talking about. These were out of one of my Atlas SD-60's that I bought new.

    1st one shows the dirty cups, a lot of crap that insulates the points on the axles as well as the cups:
    [​IMG]

    Cleaned with alky, Q tips, and #11 Exacto blade (carefully). Loco runs like new now :
    [​IMG]

    Just trying to assist, dontcha know.
     
    TMC, mtntrainman, Hardcoaler and 4 others like this.
  13. TMC

    TMC TrainBoard Member

    32
    22
    2
    I appreciate the help from everyone in this thread. I cleaned the brass pickup strips with a toothbrush and microbrush but I will get right in there with the exacto knife. I’m just giving it a day I thought the cleaning and lubrication would fix things so just giving them a rest for a few days before I start again.
     
    Hardcoaler and DeaconKC like this.
  14. TMC

    TMC TrainBoard Member

    32
    22
    2
    I just purchased some new ones I will let you know.
     
  15. ns737

    ns737 TrainBoard Supporter

    723
    131
    25
    the two motors could have a bad winding. you may need two new motors
     
    TMC likes this.
  16. Doug Gosha

    Doug Gosha TrainBoard Member

    2,875
    4,864
    69
    The thing with five pole motors is, if one does have an open winding in one of the coils, the motor won't stall at low speeds, like a three pole motor, but the motor will run slower than others of the same type that are not damaged.

    Doug
     
    Hardcoaler and TMC like this.
  17. TMC

    TMC TrainBoard Member

    32
    22
    2
    Both motors seem to run really smooth just something is getting lost in power transfer to the wheels. I’ve looked into a bit more and I’m convinced it’s the universal joints. I’m still going to replace old contact strips and those brass cups the wheels go into as well as some contact cleaner in the motor. After that if they still run slow I’ll start a new thread to see if it’s possible to transplant a Kato motor to replace the atlas ones.
     
    MK and mtntrainman like this.
  18. ns737

    ns737 TrainBoard Supporter

    723
    131
    25
    do the motors run fast out of the frame?
     
  19. NtheBasement

    NtheBasement TrainBoard Member

    376
    446
    19
    If I may suggest... watch closely and see if you can narrow it down. Remove the shell and the trucks. Put marks on a flywheel with a felt tip so you can see it turn.

    Put the frame on the track so that each side of the frame touches a rail. Then run at the slowest speed you can and watch what happens. If the motor spins smoothly, the problem is not the motor, next step. If it hesitates at the same point in each rotation, its the motor or the windings or interference between armature and motor housing.

    Add a truck and test, slow speed again. The motor will spin many times per driver wheel rotation. If its smooth, check the other truck. If it hesitates, there is a tiny piece of junk in the trunk gears.

    Run the loco with trucks on and no shell. If its smooth, you might have interference between the frame and the drive train.
     
    BNSF FAN likes this.
  20. ogre427

    ogre427 TrainBoard Member

    251
    180
    15
    I'm pretty sure the SD24s have the ball-style universals on the motor shafts. These have somewhat of a reputation for cracking. They aren't too bad to replace, I've done quite a few of my locos. I order them 20 at a time from Atlas. A couple of tests you can try are powering up the unit and lifting the trucks just off the rail one end at a time and see if you can feel one truck pulling and the other one not. Second, on the super slow one power it up to 3/4 throttle or so and GENTLY put pressure down on the unit. If the wheels stop turning and the motor keeps running that is your problem.
     
    Martin Station and MK like this.

Share This Page