Here is the deal, I purchased 2 SD24’s off Ebay and got them the other day and am very happy with them. They are in near perfect condition with nothing broken or missing, I took them to the track and put the power to them. found out they both needed a good cleaning and some oil, so I took them apart to do this and discovered something. One is a older dual flywheel drive, and the other is I beleive the newer Kato drive, it only has on flywheel. This one for some reason or another will not acheive the slow speed response I was looking for, the older Concor drive will crawl along at about 3mph with no problem. Both the truck assemblies are the same on each unit, I cleaned them, oiled them, and made sure they are free turning on the gears with no binds. The Kato drive unit seems to lurch when applying power and then shoots up to about 40mph, and I cannot get the slower speeds I was looking for. Something I noticed is that the older Concor can motor is all inclosed, the Kato unit has open holes on both sides.
Is it me or is the Concor motor the better motor and the Kato pretty much junk, ot do I have a problem I did not see somewhere else??
I am a little confused which engines your talking about. Atlas back in the mid 70s purchased SD-24s from Roco. The first run came with 2 flywheels. A second run was identical except they had a circuit board and only 1 flywheel. Sold in yellow Atlas boxes. Later Con-Cor sold these. The motor in the Con-Cor version was still Roco but was open on the sides with one flywheel and the circuit board. You can pretty much mix and match all three versions. Later Atlas came up with a completely new SD-24, which had nothing in common with the earlier ones. All of the 3 older versions have 2 screw holes in the bottom of the frame. White motor mounts hold the motor in place. You said that both units have the same trucks so it sounds like you have 2 of the older versions. If you have 2 of these versions it should be easy to determine what is wrong. I would try swapping the good motor with the bad. If the problem goes away then it is obviously the motor, if not then something in one of the trucks is binding or has poor electrical pickup. Again, divide and conquer. Swap one of the trucks from the good engine and see if it is fixed. Let us know.
Ok Jim, thanks for the help. The one I am having problems with is the one with only one flywheel. I have the older style motor on hand in my parts box, so am going to swap it out and see if it is the motor. Thanks for the help, hate ripping things apart before doing some trouble shooting first.
Please note that Kato has had no involvement with any HO scale Atlas SD24. As Jim explains above, the earlier ones were made by Roco, and the latest runs are completely different, and produced in China.