Lionel Legacy K-4 Gear Issue

Have you looked at the bushings in the chassis behind the center wheels and checked the wear?

I think it's the bushing that failed and caused the gear to slip.

I parted with my prewar version of this Loco because I could see excess play between the idler shaft and this bushing , due to excessive wear on the bushing on  "fireman's side" of the frame. 

So much wear , the bushing was visibly oblong and there was even a few bronze shavings. I presume this side of the shaft bears most of the load. That bushing is pressed into the frame.

My Loco was well lubed with red n tacky and had only a few hours of run time at most.

While this gearbox setup is key to great low speed performance due to the reduction by the extra gears. I feel it is a vulnerable weak spot on new legacy locos.

Other locos that use this stye gearbox are the heavy and light mikes, 1st run legacy class j( not sure about the latest run j ) legacy mohawk (possibly the legacy m1a) , and the new h10. There may be others.

One can check their Loco by looking above the shaft through the spokes of the driven axle to see if it has the bushing with the shaft in it for this secondary gearset.

I'm considering grabbing an old tmcc k4 with a simpler bullet proof gear box ( and large Pittman motor) in spite of the loonnng firebox.

I suspect we will see more of these gearboxes failing in the future.

I have two proposed solutions:

1. Check to see if NWSL has a replacement. They are back in business! They just might have your gear as a "stock item," and if not they are ramping back up for custom gears. If it's custom, it's going to cost you for set-up.

2. Contact James Norris at https://jamestrainparts.com to see if he can design replacement gear for you and have it produced at shapeways.com using 3-D printing. I did this for a 10-tooth mod 75 left-hand(!) gear for a Sunset 3rd Rail Cab Forward (everything's backward!). Talk about impossible to find! The cost was very reasonable (I'm almost ashamed how inexpensive the entire process was). One gear will cost you less than $20 once Norris posts the design on shapeways.com for your review and production. Multiple gears can be made in one design, again for less than $20. It looks like your gear is metallic (I'm probably wrong because it's hard to tell from the photo), and if the other gears or worm are also metal, you are guaranteeing excessive wear. Consider having the gear made of PA12 on shapeways.com. It's a very tough, structural material. Shapeways can do brass and stainless steel, but I'm not sure that's the way to go. Anyway, talk to James...

Well, Lionel has the drive block in stock, so anything that costs more than just buying the whole drive block is a non-starter.  If I could find the exact gear, I might consider ripping this apart and keeping it as a spare for the next time.

It's hard to see the bushings as they're behind the wheels, but I can't detect any wobble in the shaft.  The original issue is the gear was wandering on the shaft and moved over (to the bottom in the picture), and chewed up the edge of the gear.

I added shims to keep it centered, but apparently the damage was done, and after a little running, the gear jumping was back.

I'm afraid the analysis about them wearing out may be correct.  This may be one thing they shouldn't have copied from K-Line!

I would replace both worm gear and this gear to ensure proper mating. Not only pitch but addendum and dedendum must match.

Steel worm gear vs Bronze gear the steel will win. This is a designed failure. 

I don’t believe in “Run in” The gearbox design is flawed. Running in? well that bronze material is only going to stay in the gearbox causing additional wear unless you remove and clean and  re grease after a “run in”. I doubt the Lionel replacement is re engineered. Sorry I can’t help suggesting a source. I will eventually be in this situation i am sure. In the past My father would have machined a new set being master machinist.  

Im in the almost same boat . I have a 1872 General that keeps wiping out that brass gear after a few hours of operation. Just got an ebay chassis for it and the **** thing wiped out another gear. Seems like the brass wears down just enough that the armature shaft doesnt make complete contact. Runs great in reverse but slips in forward. Even changed motors to no avail.

Well, I'm going to go with the new drive block, I don't see any easy way to replace this gear, even if I could find it, which is a long shot.

Very instructive John, thanks for sharing.  A perfect example of why I've been saying  our locos should have:

• worm gear connected to the motor via universal joint (not pressed onto the motor shaft)
• a separate gearbox that clamps around the worm wheel
• a two-piece chassis with "bottom plate"
• removable wheel-axle-bearing assemblies
• segmented drive rods (if necessary to accommodate slight play in the bearings and chassis)

If the above were true, this would have been an easy job.  More likely, it wouldn't have failed in the first place.  This recommended approach isn't new, and doesn't require any major engineering breakthroughs.  Lionel should have copied 1960s US Hobbies, or even early '90s Williams and Weaver brass, not K-Line! 

The J3a Hudson guys are grousing about mix-and-match driving wheels, or the lack thereof.  If the wheels and axles dropped out of the chassis (and assuming extra parts were available for sale), they could use any combo they want.  But that would constitute modelling, not collecting.  Oops, sorry!  

I was chatting with John about my Legacy Polar Railroad K4 earlier today...I had purchased it new and it was fraught with problems out of the box which he was able to fix (smoke unit and Railsounds board), in addition to loose motor mounts and screws inside the locomotive. Buying stuff out of Lionel's 3-year warranty is a crap-shoot.

Anyway, my Polar RR K4 model is in the same category (former K-Line design) as the PRR K4 with gear box issue, above. I had speculated whether the undersized motor (and possibly being run under heavy-load) and the way the motor is mounted (towards front of model) could've caused the gears falling out. I guess I won't know until I get some hours of runtime on my model. But, maybe doubleheading it with another Legacy engine would help? I typically pull 7-8 heavyweights.

Anyone , reach out to Dave or someone at Lionel. Maybe, they can address the issue. 

Paul Kallus posted:

 

Anyway, my Polar RR K4 model is in the same category (former K-Line design) as the PRR K4 with gear box issue, above. I had speculated whether the undersized motor (and possibly being run under heavy-load) and the way the motor is mounted (towards front of model) could've caused the gears falling out. 

 

The motor is not the problem. The gearbox is, too delicate. There's 4 gears not including the worm. Great for fine slow speed control but terrible for reliability where the typical worm gear turning the axle gear is bullet proof.

The weak spot is the shaft for the intermediate gear as I mentioned above.  Once the bushing on the load side of the shaft wears, the gears will slip. Mine had substantial wear but hadn't reach the point that the gears started chattering. The Loco had light run time for being 7 years old.

Most folks don't even know this extra shaft exists and it needs a drop of lube just like the axles. It's hidden behind the spokes of the powered axle. This gearbox design is used in many legacy locos and the reason I'm reconsidering some tmcc versions of  legacy models I have....before it's too late.

You can see this shaft spinning in the bushing behind the 3rd pair of drive wheels starting at about the :20 on this legacy Mohawk video ( not mine):

https://m.youtube.com/watch?v=0y60BIICyng#

Anyone who owns the new legacy h10 can easily remove the bottom plate and view this complex and somewhat fragile gearset.

RickO posted:

Paul Kallus posted:

 

Anyway, my Polar RR K4 model is in the same category (former K-Line design) as the PRR K4 with gear box issue, above. I had speculated whether the undersized motor (and possibly being run under heavy-load) and the way the motor is mounted (towards front of model) could've caused the gears falling out. 

 

The motor is not the problem. The gearbox is, too delicate. There's 4 gears not including the worm. Great for fine slow speed control but terrible for reliability where the typical worm gear turning the axle gear is bullet proof.

The weak spot is the shaft for the intermediate gear as I mentioned above.  Once the bushing on the load side of the shaft wears, the gears will slip. Mine had substantial wear but hadn't reach the point that the gears started chattering. The Loco had light run time for being 7 years old.

Most folks don't even know this extra shaft exists and it needs a drop of lube just like the axles. It's hidden behind the spokes of the powered axle. This gearbox design is used in many legacy locos and the reason I'm reconsidering some tmcc versions of  legacy models I have....before it's too late.

You can see this shaft spinning in the bushing behind the 3rd pair of drive wheels starting at about the :20 on this legacy Mohawk video ( not mine):

https://m.youtube.com/watch?v=0y60BIICyng#

Anyone who owns the new legacy h10 can easily remove the bottom plate and view this complex and somewhat fragile gearset.

Rick, is the shaft for that gear the root of all evil? Do you know what that shaft material is? Do you think the shaft is just too small or something causing it to tilt and move away from it’s mesh? ...... Pat 

Ted S posted:

Very instructive John, thanks for sharing.  A perfect example of why I've been saying  our locos should have:

• a separate gearbox that clamps around the worm wheel, 
• a two-piece chassis with "bottom plate"
• removable wheel-axle-bearing assemblies
• segmented drive rods (if necessary to accommodate slight play in the bearings and chassis)

If the above were true, this would have been an easy job.  More likely, it wouldn't have failed in the first place.  This recommended approach isn't new, and doesn't require any major engineering breakthroughs.  Lionel should have copied 1960s US Hobbies, or even early '90s Williams and Weaver brass, not K-Line! 

The J3a Hudson guys are grousing about mix-and-match driving wheels, or the lack thereof.  If the wheels and axles dropped out of the chassis (and assuming extra parts were available for sale), they could use any combo they want.  But that would constitute modelling, not collecting.  Oops, sorry!  

You mean like "old school" HO scale steamers? Penn Line, MDC, Mantua, etc...

Mark in Oregon

Or like new school Broadway Limited and... <drum roll> MTH!!  They practiced making toy trains in O gauge and made a lot of money doing it.  But they saved their top-shelf design for their H.O.  They even put an extra rubber-tired axle in the box, for those who want it!

I think if they sold an H.O. loco with pressed-on wheels and captive axles, no one would buy it.  Their H.O. locos earn rave reviews from a demanding audience.  But do you think they would come back home to where they started and spend a little money to retool their Premier steam chassis along those lines?  Nope.

Too many uninformed buyers in 3RO, and too easy to keep milking that cash cow.  I understand the nature of die-cast is mass production.  All the more reason to get it right in the first place!  30:1 or bust!!

"Most folks don't even know this extra shaft exists and it needs a drop of lube just like the axles. It's hidden behind the spokes of the powered axle. This gearbox design is used in many legacy locos and the reason I'm reconsidering some tmcc versions of  legacy models I have....before it's too late."

Anyone know if the gear box needs to be disassembled on the K4 in order to lube the extra-shaft, or how to lube it?

Its interesting how this all developed. K-Line's scale K4 was a marked improvement in a scale K4...at least visually speaking. I recall vaguely back in those days we were at the cusp of the "Slow Speed Wars" - and while MTH developed PS2.0 and Lionel developed Odyssey, K-Line and 3rd Rail were left developing their own system...TAS came out with EOB and K-Line started with reduction gearing and I think then developed their own electronic speed control system...although I am not sure about that. I remember buying one of those early K-Line K4s with elephant ears...a real nice model but the sound system was a bit off. Then, they came out with a real nice scale Hudson.

K-Line did have their own speed control, although it enjoys a somewhat checkered reputation.  It has the propensity to crap out for no apparent reason.  The encoder appears to be the model for the Legacy encoder, so they were headed in the right direction.

gunrunnerjohn posted:

K-Line did have their own speed control, although it enjoys a somewhat checkered reputation.  It has the propensity to crap out for no apparent reason.  The encoder appears to be the model for the Legacy encoder, so they were headed in the right direction.

The encoder is actually a copy of an early Legacy prototype, which is what led to the lawsuit that in turn led to K-Line's demise.

Must be why it looks so close to the Legacy model.

Paul Kallus posted:

"Most folks don't even know this extra shaft exists and it needs a drop of lube just like the axles. It's hidden behind the spokes of the powered axle. This gearbox design is used in many legacy locos and the reason I'm reconsidering some tmcc versions of  legacy models I have....before it's too late."

Anyone know if the gear box needs to be disassembled on the K4 in order to lube the extra-shaft, or how to lube it?

@Paul Kallus I don't believe the use of an idler gear is an inherently bad design.  If the bearings of the intermediate shaft are Oilite bronze, they should last as long as the bearings for the worm shaft and the main driving axle.  I certainly wouldn't trade a good-running Legacy loco with the intermediate shaft for a TMCC direct-drive version, just for the promise of greater longevity.  The gear ratios of locos with idler gears are a little lower (smoother) than their direct-drive counterparts, but the difference isn't huge.  I think the idler gear setup really helps achieve realistic gearing in locos with smaller driving wheels.

The ends of the intermediate shaft ARE accessible without special tools.  You can usually see them through the spokes of the driving wheel.  (I guess if you have Scullin discs you're out of luck!)  Putting a drop of Labelle 107 on either end when you do the driving wheel bearings will hopefully keep the loco in service until you're bored with it.

My beef is that these gearboxes are cast into the chassis.  All of the gears and axles are "captive," i.e., they can't be removed without special tools, and reassembly to factory spec is extremely difficult.  This frustrates both maintenance and customization.  It's very difficult to adjust the gear mesh, and as GRJ concluded it's basically impossible to replace just one gear.  You have to get a whole new chassis. 

If a wheelset is out of quarter from the factory;  if the loco leaves the table and chips a wheel or bends an axle;  if you strip the threads reinstalling a side rod after you replace those $^*@#!% tires -- again, you'll need a whole new chassis.  This is true of BOTH the idler and direct-drive TMCC versions.  A very few Vision and JLC locos have been made with a two-piece chassis and removable gearbox.  The Niagara is one that comes to mind.  But nothing affordable that will run on traditional O curves.    A two-piece chassis with removable gearbox is accepted practice in HO, S, and two-rail O scale.  Why not here?

Agreed Ted. Almost makes me want to unbox my HO and return to that scale. 

Reduction gears = slower starts, greater torque for pulling, less current draw, cooler running. I really am at a loss why we don’t see more often. I actually love the initial belt drive in the 3rd rail steamers. 35 cars the locomotive is yawning like “that’s all you got?”

Well, you don't need belt drive for that.  My VL-BB pulled 70 cars and seemed it could handle a lot more if I was so inclined.  The is a point of diminishing returns with the gear ratio.  Something around 26-28 to 1 would be about right.  If the gear ratio gets much higher than that, you start having a whole new set of issues.

I did a couple of Williams brass steamers with 44:1 gearing.  Once you got past around 30 scale MPH, the motor was starting to really create some noise.  The scale speed topped out around 44-45 scale MPH at 8,000 RPM of the motor, and you could REALLY hear the motor.  I will allow for most running, the 30 scale MPH would probably be fine for me, but it's just the idea of being "limited".

Thanks for this VITAL LUBRICATING information RICKO and TED S, in all these years I have NEVER known about the existence of this intermediate gear shaft, and that it needs lubrication. Lucky I guess that I have had no reason to open up those gearboxes. My Legacy M1a does indeed have it also, and the recently made light 4-8-2, and the Legacy 2-8-0s built before the H-10s, and my Legacy 2-6-6-2 on the rear driver set only. My owner's manuals do not itemize this shaft and bearings as lubrication points, and it's hard to find even when knowing what to look for, sometimes completely hidden behind the drive wheel's counterweight. The H-10 manual does show a second point on the main driver rods though, to lubricate.  But these bearings all have a drop of LaBelle on them now and hopefully have not sustained damage in the years till now.  

Rick

Downers Grove Illinois

gunrunnerjohn posted:

Well, you don't need belt drive for that.  My VL-BB pulled 70 cars and seemed it could handle a lot more if I was so inclined.  The is a point of diminishing returns with the gear ratio.  Something around 26-28 to 1 would be about right.  If the gear ratio gets much higher than that, you start having a whole new set of issues.

I did a couple of Williams brass steamers with 44:1 gearing.  Once you got past around 30 scale MPH, the motor was starting to really create some noise.  The scale speed topped out around 44-45 scale MPH at 8,000 RPM of the motor, and you could REALLY hear the motor.  I will allow for most running, the 30 scale MPH would probably be fine for me, but it's just the idea of being "limited".

Yeah i understand. I just like the concept of the belt drive. and there is some reduction. Not sure the ratio. There are always extremes one way or the other with gear reduction. just need the right balance. Why hasn’t  this industry embraced brushless motors? they produce higher torque, smaller in size, higher rpm and quiet. 

Thanks, everyone.

I have to admit I tend to not lubricate my steamers very often...and some of my oldest models (15-20 years old now) have only received light machine oil...and I've rarely added grease to the drive chains via the ports. I've always been of the school "if it doesn't squeak or grind - don't oil or grease", but that maybe a recipe for trouble.

I'd love to see brushless motors come into use in the model trains.  I suspect the need to redesign the electronics for the motor has stopped many in their tracks.

I have an H10.  Are there any pictures of the 'intermediate drive shaft' that needs lubircated?

RickM46 posted:

I have an H10.  Are there any pictures of the 'intermediate drive shaft' that needs lubircated?

As RICKO posted above:
"  You can see this shaft spinning in the bushing behind the 3rd pair of drive wheels starting at about the :20 on this legacy Mohawk video ( not mine):

https://m.youtube.com/watch?v=0y60BIICyng#  "

On the new H10, you can split the frame and work on individual gears, so they did learn something.

Yeah John  Same exact setup in many HO locomotives. Down to the square bushings. The drivers should be pressed on to a spleen. Makes even replacing the axle bushing easy. 

gunrunnerjohn posted:

I'd love to see brushless motors come into use in the model trains.  I suspect the need to redesign the electronics for the motor has stopped many in their tracks.

You are spot on.   We have moved to brushless in the r/c car racing world.    They need a special ESC (electronic speed control) and you have to watch the gearing.

From what I understand, DCC can't currently handle Brushless motors.  Also the current brushless in the size that might fit in our trains spin at 25K rpm at around 12V.

We love these in R/C racing as they also draw less amps, and we longer battery life.  They also get very warm/hot, so most of us have heatsinks installed as well when we make the conversions.

I can see that the H10 is better than the K4 in terms of serviceability.  But I believe that intermediate shaft is still captive in the chassis.  And the worm gear is still pressed onto the motor shaft.  So when the motor fails, you'll have to find an exact replacement  (or transfer the worm to another motor, which is very difficult to do.)

Also, there's nothing there to establish a precise mesh between the worm and worm wheel.  Hopefully thrust bearings are incorporated in the gear end of the motor, but i doubt it.  If the worm was pressed too far onto the motor shaft (or not far enough), there will be problems with the mesh.  Adding shims would be tricky.  Doing the opposite means removing material from the chassis with a file.  Take a little too much out and you've ruined it!

In all fairness some lower-priced HO locos are made like the H10.  But the best setup is a self-contained gearbox clamped around the worm wheel.  A separate gearbox also facilitates changing gear ratios, as does the 3rd Rail setup with pulleys.  So those of us who are willing to accept some motor noise in exchange for smoother performance can make that trade-off.

Regarding brushless motors... Marklin tried them in their HO product line about ten years ago.  Google 'Softdrive Sinus' or something like that.  They met with mixed reviews.  I think Marklin ended up dropping them and going back to brush (servomotors) with feedback speed control.  As an aside, Marklin cataloged locos with back-EMF speed control in 1995, well before Lionel or MTH.  So maybe their pioneering use of brushless motors is a harbinger of things to come.

I'm not really sure what the issues with brushless motors were, or why they weren't better accepted by the Marklin crowd.  I know brushless and battery power are now competing with small gasoline engines for use in R/C airplanes!

Soft drive Sinus?? .........sounds like a soothing way to clear up head congestion!...😂😂😂😂😂.........Pat

gunrunnerjohn posted:

On the new H10, you can split the frame and work on individual gears, so they did learn something.

Actually that's the same setup as the original 28086 h10/9 from 2001.

The only difference being the extra gears and shaft on the legacy version.

On the tmcc version, if the worm wears out you change it. If the axle gear wears out you change out the whole axle with the gear on it, fairly easy.

It's the gears in between pressed on the intermediate shaft that ride in bushings pressed into the frame that cannot be replaced, or at least....not easily. Which brings us back to the k4 situation.

I have a way to go yet to reach retirement when I can really enjoy my trains.i.e. kids will all be grown, etc.

I'm confident my nearly 15 year old tmcc Mohawk will still be running at that time. It's gearbox is as tight as the day I bought it ,as is my first run legacy M1b and pm berk.

The new legacy with the extra gears, I dunno. 

Ted S posted:

@Paul Kallus I don't believe the use of an idler gear is an inherently bad design.  If the bearings of the intermediate shaft are Oilite bronze, they should last as long as the bearings for the worm shaft and the main driving axle.  

Mine was lubed and it didn't matter. There was  a few visible shavings and the bushing itself was oblong. Gently pushing the Loco back and forth while powered down would rock the shaft end side to side 2 or 3 mm within the bushing.

Again, it was the "load" side of the shaft as one side of the shaft takes more of the load as the axle gear is offset so everything will fit. The opposite side showed no excessive wear.

This intermediate shaft  and bushing setup appears a bit smaller than the typical driven axle of a steamer where the gear is centered on the shaft distributing the load to both sides.

https://www.youtube.com/watch?v=667XSSxieXM

What happens when these locomotives get 5 to 10 years on them? My guess is that parts for it won't be available. Something has to change.

As Rick mentioned, lubing the intermediate shaft may not hurt but will it really help? The picture John showed in the initial post shows plenty of grease on the gears, yet the gears are still chewed down.

At the risk of beating this horse to death, does anyone agree that it'd be a good practice to either assuming one wants their locomotive to run a hundred hours or more: (1) not load these engines with too many cars, or (2) create lashups to thus distribute the pulling load. To me, this is logical as it means less load on gears = less wear, but what do I know.

Paul Kallus posted:

As Rick mentioned, lubing the intermediate shaft may not hurt but will it really help? The picture John showed in the initial post shows plenty of grease on the gears, yet the gears are still chewed down.

At the risk of beating this horse to death, does anyone agree that it'd be a good practice to either assuming one wants their locomotive to run a hundred hours or more: (1) not load these engines with too many cars, or (2) create lashups to thus distribute the pulling load. To me, this is logical as it means less load on gears = less wear, but what do I know.

If the gear box was engineered correctly in the design process there would be proper meshing. All this “running in” is doing exactly what you described.

There was tons of lube in the gearbox, that picture was after I scooped loads of grease out and cleaned the gears off good enough for a picture.