Thomas Tank Engine Mechanical Issue

It sounds like the front driver is 1 or 2 gear teeth off. Take off the bottom plate and move the front driver 1 tooth forward or back. The engine can easily slip a gear tooth if a junior engineer tries to push Thomas by hand.

John,

Sounds like excessive sideplay in the axles(front or rear). Remove the

side rods and check for that. Thats my best guess.

Joe

Since the front two sets of wheels are free-wheeling, how can that affect the timing?  I guess I don't understand.

 

Nothing has changed in that area, the wheels seem firmly on the axles.  They can move a bit, but I don't see any way to stop that.  Do you think shims between the wheel and case would help?

The front axle drives the shifting eyes, that gear box might be your problem.

 

Bill

I don't feel any binding when I turn the front wheels by hand.  Also, when I run it without the rods. the eyes move continuously, no hint of any binding.

 

I suppose I could take the front gearbox off and see if that changes things.

I have an earlier version without moving eyes or whistle. Out of the box when new, it had slightly elongated holes in the side rods to compensate for the sloppy wheel quartering. It took a couple hours of running to get the jerky motion to smooth out.

You are right John, I was thinking about the other Thomas (G scale). The front driver must have slipped a little on the axle. I have new if needed.

The axles are hex shapped on the end. I don't think they can slip just a little.

The center wheel rods do have the elongated holes.  However, if I remove the screws from the center wheels and let them run free, the problem still occurs.

 

The only thing I could think of was one of the wheel sets are not right.  When it was under the tree last year (only other time it ran), it probably was making all right turns, so I never noticed this.  It seems that the traction tire causes it to not have all wheels on the rails.  However, I took the tire off, and that didn't fix it, though it did run a bit better through the corners.

 

I was thinking of putting some polishing compound on the front and back screws and running the crap out of it, maybe that's the solution.

 

bigo is right, it looks like the wheels are on with hex axles, I can't see how they'd slip.

 

It appears that the rods on each side should be offset by exactly 90 degrees, maybe I should try to measure the angles and see if one is off?  I'm not sure how I'd know if I was getting a replacement with the same problem if that's the case, that's the only rub.

Hi John, did your Thomas do this from the first day out of the box? If so check the screw holes in the side rods where they mount into the drive wheel, make sure that they are both positioned the same.

I'm thinking that maybe one of the holes are off center or something like that. Other then the slipped gear issue mentioned above I can't picture what could cause this.

 

Is it possible for you to take some pictures and post them here so we can look at it. You never know with ten or twenty of us comparing yours with the ones we have at home hopefully one of us might see something.

I had EXACTLY the same issue with my Thomas when I got it about a year ago... Lionel sent some replacement parts which did not solve the problem. I took the side rods off and it runs great, side rods on and it's like the wheels are jammed... I now run it with the side rods off - not a single kid has notice they weren't there! ( nor any of the adult visitors to the layout ) Ed

Ed, we need to check the one at the club. I do not recall this problem but there may not be a problem due to the wider curves.

Sounds like a classic quartering problem.  

 

Hex shafts would seem to indicate a bad batch. 

 

Gots ta be bunches of similar locos.  At this unit's typical level of toy use the problem may not be noticed by the casual observer.

 

 

I don't know if this happened right out of the box, it's only other run was around the tree last Christmas.  I'm thinking back, and I think it was running so it made right turns, so this issue wouldn't have shown up.

 

Nothing has changed, and it wasn't dropped or anything, so I can't imagine the mechanics have changed.  The axles are not bent, I opened it up and checked.

 

I'll take a video of it going each way and you can see the issue.  Runs great if you only make right turns.

 

 

That is the fallback position, but I'd like it to have the rods if possible.

 

 

That's what I was afraid of after examining the wheels and shafts.  The problem is, if I order another set, I may just get another bad set!

Depends on how much side play there is and how centered the axles are with the

frame. A few thousands of an inch is all the side play you need. Compare the the

axles side play and make sure they are equal. I don't have a Thomas engine so

I have a question. Is there only one drive tire? If so, try moving that wheel to the

opposit side and see if the trouble follows. (right hand turns become a problem)

This is an interesting problem wiht a lot of good suggestions in the thread.

I don't know that I can turn the powered axle around and still have the gears engage properly, but that's an interesting idea. However, it appears that turning the axle around will put the other side's rod connection 180 out from where it needs to be, they are 90 degrees offset now.

 

Yes, only one traction tire.  However, removing the traction tire didn't eliminate the issue, though it made it better.  The axles are centered, but there is some sideplay.  FWIW, I have as much or more in most of my locomotives, and I've never seen this issue with any of them.

We choo-choo types are so versitile and so well connected with others of like mind and skill we frequently fix things that may best be returned.

 

I am the king of returning problem stuff.  Life is too short to straighten others problems.  Is this option still open to you?   Was this a credit card transaction?  Is it still under warranty? 

 

Fixing other's problems enables them to continue on.  tt

If you look at my thread in the TMCC forum, you'll see after the modifications to Thomas in the electronics area that I doubt I can return it.   I didn't change any of the drive stuff, so I didn't expect any issue here.

John,

   You say the loco operates properly with the siderods disconnected or off, so therein lies the problem. The siderods may be binding slightly on turns because either the wheels are shifting slightly binding the rods, or the possibility that the holes drilled/punched in the rods do not line up exactly with the screw holes in the wheels.

If you remove the motor and push the loco by hand, maybe you can isolate the problem. Watch and feel the rods for any binding at any wheel as the loco goes around the curves.

 

Larry

Here's a couple of videos of Thomas in action on the left turn, and one on the right to show the difference.

 

 

 

If the wheels are quartered properly and  one main drive rod had a slight miss drilled hole the dimensional misfit will be the same anywhere in the rotation sweep of the axel.

 

Part of the issue in quartering is if one fastening point of one driver on one side is exactly at the 12 o'clock position then all the other drivers on that side need to be also exactly at 12 oclock.  You can use a dial indicator and an height gauge to find TDC (or BDC) of each wheel.   Coming from my racing background the process is much like degreeing in a cam shaft.  A model engine service tech could give you another technique.

 

The hex shaft end design can be a show stopper.  If the wheel is solid and the hex is broached or if the axels are solid and no adjustment is possible and the issue is quartering you may very well have a doorstop.

 

IMO, some of these loco manfactures should be limited to neoprene side rods.

 

Can you return the electronics to  an "as delivered" condition and get out of this unnecessary project?

 

I have watched some real wobblie engines run on the mfg's table at York and not a word was said by any obseever.  Mediocrity is taking over this society.

Newbie to the forum and Model Railroading.  Reading this with interest since I just bought a Thomas RTR. Won't have it setup until November though.  Can't offer much to the solution.  But mechanically speaking I can survice in the world.  Does the problem occur when running the train in reverse direction?  Just a thought that might provide some insight.

 

  A slight wearing of axle bearings, or a wheel set that is not turning 100% concentric to the axle hole can cause perfectly quartered wheels to bind the side rods. Taking the motor out and pushing the loco by hand slowly around the curves should show if this is the problem or not. The fact that removing the side rods cures the problem indicates that there is a wheel/side rod relationship problem.

 

Larry

Good question, and the answer is not nearly as bad, however for it does have some binding in reverse.  Running in the opposite direction, no apparent binding either forward or reverse.

 

There is no possibility of returning the locomotive, that's a non-starter.  The rods on all of these are offset 90 degrees, so if the rods are all at 12 o'clock on one side, they're at 3 o'clock on the other side.

 

The locomotive hasn't run for more than two-three hours in it's life, hard to believe a lot of wear is present.  Of course, the "bearings" on these are just the plastic motor case!

John,

I was thinking of just reversing the wheels not the axle. Pull the two wheels

off and swap sides. Is that possible?

Pulling the wheels off will be somewhat of a PITA, and getting them properly aligned will probably be fun as well.  Don't think I want to start yanking wheels just yet.

 

John,

After watching this I also think that an axle set (power)might be moving and causing

a wheel to rub against the frame. I saw this happen a long time ago and a

thin shim on the affected side eliminated it. If I remember correctly it was a

671 type with worm drive. The worm drive was pusing the axle over(thrust)

to one side and causing the inside of the wheel to rub on the frame The engine

ran fine in reverse because the axle slid back to the opposite side and there

was enough clearance between the wheel and frame that the other wheel

didn't rub on the frame. To check this your gonna have to pull the wheels and

look for a "shiner" on the wheel or frame.

Boy this is really a strange case of trouble, would like to know what finally

resolves this.

On other locomotives for sloppy wheel fit, I've used some plastic shims slipped between the wheels and the frame to minimize the side play.  Maybe I'll try that.

B4 you do. Use a "feeler gauge" and see if and how much clearance there is
when pushing the wheel against the frame. That will give you an idea how
much "shim" you'll need.
ps: Its best that the shim is between the axle bearing and wheel. Any place else

on the frame or wheel will just add to the problem.

Well, there is no "bearing" as I said, the axles just come through the plastic case.

 

Then just go with the shim. But I would check clearance first to make sure

you really need them.

Joe

One other thing I was thinking of. Turn the engine over, connect power

and see if you have "wheel wobble" as its running.

Actually, the clearance is pretty close, I don't see a shim fitting.  I put shims on the center floating axle, it was pretty sloppy, but it didn't help.  The front and back are actually pretty tight.  I did notice that there's a bit of fore-n-aft play in the front axle, that's probably an issue.  Don't know how I'd fix it however...

 

I did run it on a set of test blocks, no wheel wobble that I see.

Well John,

Its sounds like you are about to: "Go Where No Man Has Gone Before"

Keep us updated.

Joe

John,

 

Quartering is not an eyeball procedure.  It is a process guided by exact measurement.

 

In rereading your opening statement you say it runs evenly if you disconnected the linkage from the front axel. 

 

 IMO, that isolated the problem.  The front wheel set.

 

Try swapping a front wheel set from another Thomas.  Preferably not one made around the same time yours was made. 

Good point,

He does say there is "a bit of fore-n-aft play in the front axle" Didn't

say if on both sides or just one. My guess its only on one side (right side)

That would throw the relationship of axle to the side rod outta quarter.

However, since there is no bearing to replace, fixing it could be a problem for

him.

I still think one wheel one the front axle is the problem. The wheel center is hex, but the axle is still round with knurls. They do slip. Have you tried to slightly turn the wheel on the axle by hand?

Well, having another Thomas to swap wheels with would be a plus here, but I don't have that.

 

Since there's no adjustment of any kind afforded by this design, and the wheelsets are fixed, I'm not sure what options exist.

 

The fore-n-aft wheel play appears to be similar on either side.  When looking at the plastic case, there doesn't seem to be any significant wear on either side, I think this is the way it was designed.