Questions concerning Atlas/Kato GP30

[Power Stroke]

I picked up one these on ebay recently at a resonable price. The unit had never been used, and the chassis is dated 1992. It took some time and effort to get
this thing to move but after several applications of Deoxit, and lubing with WS extra light oil, it has come to life.
It initially was very noisy, and one of the things I noticed was there were no shims for the worms and there was tons of free play. Although it has not
always worked for me (possible frame issues, and not Ron's methods), I applied Ron's logic to quieting this down. It has worked to a point, however, I noted that the driveshafts are very short, and if you remove the inner bearing block and try to adjust the hex, the shaft is short enough for the hex to come off before freeplay is removed.
Is this normal, and is there an update?
What I ended up doing was leaving both bearing blocks, and installed a shim between the worm and outer block to try and achieve Ron's minimal freeplay result.
The front is perfect, the rear seems a little tight but there is play(no bind). I now hear more motor whine than gear noise. The unit now has approx. 2 hrs run time loaded w/ 10 cars, and at various speeds, noise is acceptable but I wonder if it can't be made to run as quietly as a Chinese Atlas.
I was also wondering about the Atlas scale speed motor. Did this actually exist or was it vaporware? There was a topic on the Atlas Forum with a part number but the motor does not seem to exist. The part number was 470000.
Is it even worth the change?
Thanks for any help.

[Power Stroke]

Really? 125 views and no one has any input? I know I don't actively particapate, because my modeling skills are average at best but since Atlas shut down I've been coming here to learn and improve my skills, and that includes improving locomotive running mechanics, or am I in the wrong place?
I know that there are a large number of former Atlas members here including Ron Bearden.
Here is a link to Ron's article if you don't have it.http://trainweb.org/passengercars/Bearingblock.pdf
The problem I am having is that the shaft seems too short and moving the hex nut to take up slack causes the nut to come off
before any slack is taken up. Has anyone else had this issue, and can a longer shaft be employed?
Thanks for any advice.
Stephen.

[Catt]

My GP30s ,GP35s and U25-Bs are from about 1993 and were bought new and still run like new.Just like any other electrical product sitting and doing nothing can make them quite contrary.I find that about 15 minutes of run in time and they smooth right out.I have never had to do any under the hood maintainance except a lube job every now and then.

As for the low speed motor yes it is very real,but not all ATLAS units got the motor at the same time.It can be quite aggravating trying to match up a older and a newer loco because of the speed ranges (unless you have DCC and it can still be a pain in the caboose)of the different motors.

[u18b]

Hi Stephen,

There have been a couple of variations of the GP30/35.

If it was made by Kato, it will say Japan on the fuel tank.

If it says China, then it was made later after Atlas and Kato parted ways.

I'm glad you have read my article.  I can honestly say that after dealing with WELL over 100 conversions, I have NEVER seen an appropriate  loco (meaning no universal joint) not be improved by removing the inner bearing blocks.  Occasionally through the years, someone would come on Railwire, the old Atlas board or Trainboard and say that they tried the procedure and id does not work.  Every single time I Private Messaged that person and told them to send it to me, I got it running correctly in about 15 minutes (every single time).  They just weren't doing it correctly.

So you are correct on two points.

1.  The LATERAL movement of the worm shaft is the key delicate touch to getting this to work properly.  It needs only the SLIGHTEST amount of movement in it (enough to not be in a bind).

2.  AND while I have never had this NOT work, that does not mean that some locos are harder than others.  And it just so happens that the GP30/35 is one of the tougher ones.  The drive shaft, as you discovered, is just a little too short.

Now, the goal is to get the hex nut to almost "bottom out" inside the flywheel.  And this is where the versions are different.  I'm going by memory, but I'm thinking that the Kato version is just a little easier than the China version.

The China version uses a plain hex nut on the worm shaft.  You don't have enough shaft to pull that nut out properly so that it bottoms out inside the flywheel.

The Kato hex nut is different.  It has a rim and sort of looks like a hat.  That is a little easier to deal with because only the RIM needs to be flush with the flywheel.  If the hat is a little loose on the shaft, you can place a micro drop of super glue to help hold it.

One thing I have discovered that helps the China GP30/35 (and a few other tough locos) is to place a tiny wad of tissue paper in the flywheel hole.  That helps fill the gap so the hex nut has something to come up against.

Problem is... it takes a lot of trial and error testing to get it all correct.

Hope some of this helps.  You're on the right track.

[johnh35]

I have never needed/used Ron's technique to get a locomotive to run properly. This is not to say that it is without merit, but if the motor flywheel is not in alignment with the worm to begin with you have a problem that really needs to be solved. It is normal (and necessary) for the worm to have some slack between the bearings. If you do not have the slack, when the truck pivots while going around tight curves it can cause binding of the worm.

With all bearing blocks in place, you should be able to rotate the motor in 90 degree increments and move the worm back and forth freely with a small probe or such. If not, you either have a bad motor saddle, bent worm'shaft, offset hole in the hex/universal, or a flywheel issue. If I were facing a problem that I could not fix by checking/replacing these items, I would not remove the inner bearing block. I would ream the hole slightly larger to allow the block to remain in place to limit worm travel, yet compensate for run-out.

[Power Stroke]

Thanks for the replies.

Ron.
Unfortuately, I am one of "those" guys that got an e-mail from you.  Removing the bearing block on some has worked, on others no.
For whatever reason, some, with alot of tweaking have returned to factory quietness with all bearing blocks. I have some GPs that, no matter what
growl like no one's business, and I think the frames are tweaked, as the gap is tighter on one end versus the other. Have you seen this?

As far as this GP30 goes, it is the Japanese Kato. This is the first Atlas/Kato I have purchased, and I noticed that the hex nut has a taper on the worm end, and the machined hex in the flywheels does not bottom, unlike the Chinese Atlas.

Should I place something inside these wheels for support of the hex? This was a brand new, unused, virgin locomotive, that had a siezed motor. I kept at it with the Deoxit and spinning by hand until it loosened. I then oiled it and started running it w/o the body, then after 20 minutes of foward and reverse, installed the body, and started running it loaded. With the body on, you really heard the gear noise. I then started to make adjustments to try and quiet it down.
The odd thing I noticed was that unlike the Chinese Atlas locos, there were no freeplay shims (thrust washers), and the freeplay of the worms was near .030".
Another question I have concerns the trucks. What should their orentation be? On the Chinese Atlas, the truck gearing is offset front to rear, should the Kato be the same way, or does it even matter?

Thanks again for the help!

[Power Stroke]

I have never needed/used Ron's technique to get a locomotive to run properly. This is not to say that it is without merit, but if the motor flywheel is not in alignment with the worm to begin with you have a problem that really needs to be solved. It is normal (and necessary) for the worm to have some slack between the bearings. If you do not have the slack, when the truck pivots while going around tight curves it can cause binding of the worm.

With all bearing blocks in place, you should be able to rotate the motor in 90 degree increments and move the worm back and forth freely with a small probe or such. If not, you either have a bad motor saddle, bent worm'shaft, offset hole in the hex/universal, or a flywheel issue. If I were facing a problem that I could not fix by checking/replacing these items, I would not remove the inner bearing block. I would ream the hole slightly larger to allow the block to remain in place to limit worm travel, yet compensate for run-out.

I understand and agree with your analysis, however, this goes around my Atlas GS&SV with no problems or binding in curves of which I have many. Even on straight track it is somewhat noisy, not like I can't run it noisy, just not quite right noisy. In fact, if I have another consist running, you don't even notice it.

[u18b]

John is correct.  Sometimes the problem is ultimately not the bearing blocks.  I also have dealt with a couple of locos (about 2 from Atlas and one from Fox Valley) where the drive shaft was actually slightly bent.  The way I confirmed it was to swap motors with another loco.

Truck orientation does not matter.

One thing you can do is swap out the hex.  The Atlas hex has no lip and they are pretty cheap.  Unfortunately, as much as I really love Atlas locos, I and a few others have noted that sometimes there is not perfect uniformity (read quality control) with the Chinese hex nuts.  They themselves can be unbalance and not shaped perfectly.

But I keep about 20 or 30 at all times as part of my standard parts box.

[johnh35]

Concerning truck orientation, the worm gear (engages the worm) on the older Kato built models is not a straight cut gear like the Chinese models. While orientation may not be critical, if you have the truck oriented wrong the angle of the worm gear will not match the worm and will be noisier.

[Philip H]

Interesting thread. My Atlas/Kato GP30 made more noise initially then my old Arnold, but with DCC on both I' e managed to get them about even.

[Power Stroke]

I just opened this up again to take a look, and I incorrectly stated the taper on the hex nut. The taper faces the motor, not the worm.
I am going to attempt to tighten up the freeplay some more, and will repost my results.

[u18b]

Concerning truck orientation, the worm gear (engages the worm) on the older Kato built models is not a straight cut gear like the Chinese models. While orientation may not be critical, if you have the truck oriented wrong the angle of the worm gear will not match the worm and will be noisier.

Interesting John.

Do you have a suggested orientation?

I'm looking at my old Atlas CSX GP30 (from the first run, I think).  I has assembled and reassembled it many times over the years.

At this moment, the off-set slots for the exposed gear are both on the same side.  So if what you are saying is true, then I assume that one of the trucks is correct and one reversed.

But which would you say is the "correct" orientation?

[johnh35]

Interesting John.

Do you have a suggested orientation?

I'm looking at my old Atlas CSX GP30 (from the first run, I think).  I has assembled and reassembled it many times over the years.

At this moment, the off-set slots for the exposed gear are both on the same side.  So if what you are saying is true, then I assume that one of the trucks is correct and one reversed.

But which would you say is the "correct" orientation?

When oriented correctly (or at least by my observations), the bottom gear exposures will be on opposite sides. On the front truck, the openings should be on the engineer's side, and on the rear the openings should be towards the fireman's side. IIRC, the classic has straight cut gears so orientation is of no importance. Even on the Kato trucks, the teeth angle is so very slight.

[u18b]

Hi John.

I have two GP30s in front of me.  On Japan, one China.

You are correct in that the double drive gears are not identical.  So Atlas did not use Kato's mold when it comes to gears.  The gear teeth number may be the same, but the contour of the teeth is a bit different.

Two observations.

1.  Clearly, it is easy to see that the Kato gears are cut at an angle.  But when I study the Atlas truck, they are not straight as you say.  They are cut at an angle as well.  It is admittedly a bit harder to see because of the difference in gear contour, but they are clearly angled.  The Kato gear is wider and the Atlas gear is narrower, so that adds to the visual difference.

2.  Orientation does not matter.  As I am holding the Kato truck in my hand looking down on the double drive gear..... the gear teeth slant front high left to down right.

But if you reverse the truck, the angle stays the same.

If needed.  Draw a rectangle on a piece of paper.  Make slanted lines.  Note that the angle of the slant does not change no matter which side is "up".

So I think you might be mistaken.

[johnh35]

Hi John.

I have two GP30s in front of me.  On Japan, one China.

You are correct in that the double drive gears are not identical.  So Atlas did not use Kato's mold when it comes to gears.  The gear teeth number may be the same, but the contour of the teeth is a bit different.

Two observations.

1.  Clearly, it is easy to see that the Kato gears are cut at an angle.  But when I study the Atlas truck, they are not straight as you say.  They are cut at an angle as well.  It is admittedly a bit harder to see because of the difference in gear contour, but they are clearly angled.  The Kato gear is wider and the Atlas gear is narrower, so that adds to the visual difference.

2.  Orientation does not matter.  As I am holding the Kato truck in my hand looking down on the double drive gear..... the gear teeth slant front high left to down right.

But if you reverse the truck, the angle stays the same.

If needed.  Draw a rectangle on a piece of paper.  Make slanted lines.  Note that the angle of the slant does not change no matter which side is "up".

So I think you might be mistaken.

Hi Ron,

You are correct in that the gear orients the same. And to think I just got new glasses....

I will have to look again at my classic GP30. I could have sworn they were straight, but that is just from memory (and that is failing along with my eyesight).