Original Con-Cor PA-1 Motor

[trainutz]

I looked at the PAs that I referred to: all employ the plastic fuel tank to retain the body shell. Sorry...

[Doug G.]

No apology necessary. Thanks for checking.

Doug

[Doug G.]

BTW, reducing the worm shaft end play by placing washers between the end bearing and worm quieted down my one PA chassis quite a bit.

For some reason, tightening the four top cover screws even just snug causes the loco to run noisier and slower (indicating binding) than if they are just barely loosened. All I can think of is the worm bearings get pushed down by the cover just enough more to push the cup gears into the motor pinions, creating a tight mesh. The weird thing is, though, is putting shims under the cover to hold it up a few thousanths and tightening the screws doesn't work to duplicate leaving the screws loose.

Doug

[jdcolombo]

@Doug G.

I just got back from vacation and saw this thread.  I have one of those motors (actually, I have two; I just tested them and one doesn't work, but one does).  Many, many years ago I bought a couple of old PA1's for truck parts for my own set of PA's, which were then displaced by the LifeLike PA's, which were then displaced by the BLI PA's.  So I will NEVER EVER use this motor.  I have a couple of these old chassis (sans trucks, which I used the parts from for my own set of PA's) sitting in my parts bin.

If you still want the motor, it's yours for just the postage to send it to you.  PM me or email me directly at jdcolombo at gmail.

John C.

[mmagliaro]

BTW, reducing the worm shaft end play by placing washers between the end bearing and worm quieted down my one PA chassis quite a bit.

For some reason, tightening the four top cover screws even just snug causes the loco to run noisier and slower (indicating binding) than if they are just barely loosened. All I can think of is the worm bearings get pushed down by the cover just enough more to push the cup gears into the motor pinions, creating a tight mesh. The weird thing is, though, is putting shims under the cover to hold it up a few thousanths and tightening the screws doesn't work to duplicate leaving the screws loose.

Doug

Having fiddled with the cup gear meshes in the Arnold GP9 (not your engine, I know, but...), I think the problem isn't the downward pressure or tightening of the mesh that is causing the problem.  The alignment of the motor pinions and cup gears just isn't that precise in these things, and you need some play in the gears to allow it to work.   If you are ever able to watch one of those cup gears on its axle going 'round and 'round, you'll see that it isn't perfectly concentric.  It's "pretty good", but there is definitely a little wobble to that cup gear.  So everything needs to be a little loose to let the pinion and cup teeth run over each other without binding.

[Doug G.]

I think you're right, Max. There are a lot of "if's" IF the cup gear was perfectly (or nearly so) concentric and IF the worm bearings were closer to the cup gear and IF the motor was more precisely located relative to the cup gear, I think the mechanism would be quieter and still run smoothly. The very things that quiet the mechanism also cause binding between the motor pinions and cup gear teeth.

In fact, I think Kato accomplished that, at least partially, with the second version of the PA. As I have written elsewhere, mine just had a low level hum when I first got it. None of the typical hashy gear noise prevalent in this first version.

And thank you for the motor, John.

Doug

[Doug G.]

There is a fairly large thread, from 2008, in the archives of the old Atlas forum concerning these locos and contains much of the information Mark Peterson used to create his page on his spookshow site (he was involved in the thread as was I and others on this forum).

http://forum.atlasrr.com/forum/topic.asp?ARCHIVE=true&TOPIC_ID=46235&whichpage=1

At first, there was much confusion as to what version appeared when and who made them but it finally got straigtened out and Mark's page has everything correct now.

Another couple of notes: The early shells had "SEKISUI MADE IN JAPAN" in the circular area toward the inside rear at the top. Later, the "SEKISUI" was blanked out and the "MADE IN JAPAN" left.

You can get a rough idea when your 2nd version was made. If there is no semi-circle opening in the upper chassis piece at the rear, it was made before 1982 when the DL-109 was released. If the opening is there, it was made during the manufacturing time period of the DL-109 since Con-Cor used that same upper chassis piece for both locos and the DL-109 required the opening for the shaft/worm to reach the rear truck.

I wonder if the first version was originally much quieter and got noisy through use because, in the March, 1968 MR review, no mention is made about the loco being noisy and MR usually always mentioned that if it was true. They just mention it ran smoothly and were impressed by the really good slow speed performance (.85 SMPH minimum on filtered DC) in the early days when 15-20 SMPH minimum was common.

Doug

[jdcolombo]

I have the second run of the ConCor PA's, and but for the pilot arrangement (pilot part of the front truck), I'd still be running them today.  In fact, I DO still run them at Ntrak shows.  I don't know exactly why, but the PA seems to have been a bellweather for N scale - the ConCor units demonstrated that N scale could be more than just toys; the LL PA's were simply superb runners in every way, as are the Kato units.  My BLI's are excellent, too, but in terms of pure performance, I'd rank them slightly behind the LL and Kato units (but BLI made a proper NKP Bluebird, so it was sort of a no brainer for me).

John C.

[Doug G.]

I have one second version of the PA and a DL-109, too and they both use the same basic mechanism and are still impressive to this day. I remember how surprisingly heavy they were when I first picked one up. I bet they are still heavier than the newer versions which I have never had but will get if the opportunity arises.

Doug

[Doug G.]

I have determined that the first Con-Cor version was not a "grinder" when new. What happens over time is that, because the worm bearings are round, even though they are held down by the upper chassis plate, they eventually start to turn slowly, from torque, and get worn. These originally are a friction fit in the chassis cavities and don't rattle around and hold the worm the correct distance from the worm gear.

Once the diameter is reduced by wear, they are free to both move around in the chassis and the worm drops so the mesh between the worm and worm gear is reduced, creating the typical gear grinding noise produced by a too close mesh between the two gears.

I have one early chassis with practically unworn parts and it is very close in noise level to the second version. I shimmed the parts in another one to raise the worm bearing/worm and it is now a lot quieter too. Of course, another consequence of the worm being too low is increased load on the motor which can overheat it and lead to burn-out.

Kato/Sekisui addressed this in the second version with square bearing blocks and metal bearings within the plastic blocks. A configuration used to this day.

And I want to publicly thank John Colombo for the motor to fix one of my PA's.

Doug

[nkalanaga]

John:  If they're still in use, I wouldn't start cutting on them now, but the pilots can be body mounted.  The truck frame/gearbox pieces will still work with the pilot extensions cut off, and I did it on one of mine, in the 70s, just to see if it would work.

[peteski]

Kato/Sekisui addressed this in the second version with square bearing blocks and metal bearings within the plastic blocks. A configuration used to this day.

Wile that was true (they used spherical-shaped brass bearings and molded a rectangular plastic bearing block around them), that configuration has not been used for many years now.  All the Kato (and similarly designed Atlas) locos no longer have the brass bearing inserts. It is just a rectangular plastic bearing block with a hole in it for the worm shaft. They cheapened the design.

[Doug G.]

it's not fair to pick on an older person who's memory could be failing.



Doug

[strummer]

I think you're right, Max. There are a lot of "if's" IF the cup gear was perfectly (or nearly so) concentric and IF the worm bearings were closer to the cup gear and IF the motor was more precisely located relative to the cup gear, I think the mechanism would be quieter and still run smoothly. The very things that quiet the mechanism also cause binding between the motor pinions and cup gear teeth.
Doug

This "cup gear" (bell gear) system is utilized in the equally venerable Z scale MTL F7, which might explain why, although it's highly regarded as a reliable and sound puller, it also is often referred to as a "coffee grinder"...

Also, isn't it interesting that this thread has grown to 3 pages; that must say something, though I'm not sure what. 

Mark in Oregon

[peteski]

it's not fair to pick on an older person who's memory could be failing.

Doug

Not picking - just setting the record straight. 
I wish they still made those bearing blocks with brass inserts. The brass bearing tolerance was tighter than the plastic one, and the spherical shape of the brass insert allowed the bearing to self-align in the chassis.