A couple of years ago I bought my first original AF diesel. This unit is a satin Rocket 474.
The reverse unit has always been a little ornery in this diesel. I have a few LTI diesels and several steam original AF engines. Anyway this was my first experience with an original AF twin motor diesel. On with the Story... I decided to do a rebuild on this unit. I have always prided myself in how smooth my reverse units work in all my steamers and how well they all run, but this diesel is eating my lunch. I turned the armatures and put new brushes in the motors and then lubed everything up. I have a little chassis wear in the axle bushings, but not bad so elected not to do this rebuild. The reverse unit looked reasonably good so I polished the drum, made sure everything was free in the ratchet mechanism and set the fingers so they had minimal drag on the drum, but still provided good contact. There were a couple of dings in the drum between contacts, but the didn't look bad and I deburred the craters so they wouldn't be as apt to catch the fingers. Well the unit didn't improve much. It pulls better, runs cooler and draws less amps, but the reverse unit is not as silky smooth as my steamers. (What I mean by this is low voltage to drive the ratchet solenoid for the drum and no movement of the engine to create the shift.) Well, I pulled the unit back apart and put in a new drum, and new original fingers (I think the originals are a little less stiff than the repros I have). Ok so I now have done everything I know. New drum, check coil resistance and compare force to a good working reverse unit from a steamer, smooth everything on mechanism. Test operation with the unit suspended where the wheels don't touch the ground would still require more of a hit with transformer voltage to shift than I think is proper. The reverse unit shifts nicely when the wires are unsoldered to the two drive motors/fields. My conclusion after messing with this all this time is that there is sufficient voltage drop/current draw to the motors that this is just the way an old dual motor chassis works. This shows up in a more positive shift with from neutral to power than from either powered position to neutral. So what am I missing here? I thought about running a wires up to the coil on the reverse units from the contact shoes thinking that this would to some extent reduce the voltage drop through the normal path, and provide track voltage direct to the coil, but haven't tried it yet. Does anyone have one of these dual motor diesel chassis that shifts like a steamer? S-Trains list sponsor: http://www.americanflyertrains.com All the Flyer you desire...books and accessories too! To UNSUBSCRIBE from this list send a note to [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
