I'm curious, as I have one locomotive that might need similar work. But I also have old MRs to refer to if your time is tight.

Tank drive is a new term for me.

K9,

While this may be a new term to you. Tank drive is an old basic design a lot of engines early on were made with this design.

Andddddd then they designed the tower drives.

Now the innovation is pushing the powered truck design.

A Tank drive is where the motor (above frame) drops power into the fuel tank (via a gearbox) then both trucks are powered via drive shafts which come out of the fuel tank ends.

One of the main reasons they failed as a usable model was because the early gearbox housings were made of poor cast metal (called by all kinds of names) (I just called them crap).

If the gearboxes held up over the years I think the models would have had a different history.

However, probably the main draw back of the tank drive for the discerning modeler was the drive shaft sticking out of both ends of the tank.

And if that wasn't enough the manufacturers tried to solve this unsightly problem by bringing the center of the trucks a little closer to close the gap between the tank and the truck so one couldn't see the drive line as easy.

This opened some other problems which I didn't tackle with great interest on my build so I won't get into those things.

However with anything in life that one spends way too much time on, one can usually find solutions to man made design problems.

And I managed to finish up this dissertation answer in just under a 100000 words.

I'm sure there are more here on the forum who are better and more to the point wordsmither's than I in explaining all that I missed.

Thanx Thom...

Hi Thom,

Having built a couple of things in brass, which are posted here on the forum someplace I'd be very much interested in your ideas of a tank drive. I have several brass diesel engines that I'd like to get rid of the noisy tower drives. One thing some modelers don't realize is that using a tank drive gives more room in the shell. I think one other thing that didn't help was the use of large square drive shafts. I think those could be made much smaller to the point of not even noticing them.

Count me in a participant in this project. Have many ideas I'd like to share. Perhaps we can come up with a better tank drive.

Bernd

Hey guys,

Here is a couple bad pics of the drive shaft improvements the manufacturer of my model offered back in the day. (while during my build of my c-430 I didn't use these and stuck with the bigger original ones) the model was completed to a fair point.






Ok I see there's a few interested (or at least super supporting) here. Besides if I can help someone else with their build or receive some knowledge from others to help me become a better modeler than it's all good right?

I'll write up a pictorial this week and post as I'm able on time. Besides judging by the drove of others who viewed but don't have interest, maybe I might be able to inspire the model is still redeemable?[:-bigeyes2]

Thanx Thom...

I have four subjects that I'd like to put tank drives in.

I've had these two LV C-628's for years. The first picture is one with the original drive, a KTM motor. Very noisy, plus draws alot of current. The second C-628 I removed the motor and installed a Neodymium magnet. I had to mill some of the motor out to fit the magnet. Never put the motor back in the engine.





The second set of C-628's I picked up at a show for $40.00 apiece. I believe the previous owner had removed the KTM motor and use a Sagami motor in both and replaced the drive shafts. The units didn't run well because to the heavy lube used in the gears. Again I started on cleaning one and never got around to the other.





These would be my project engines for the tank drive conversion. Note how much room you'd have with just a motor and drop down gearbox. I was also contemplating installing ball bearings for all the shafts to run in. One thing I wish is that you could get Hobbytown helical gears for the axles. The guy that runs Hobbytown now has them but they are plastic. I'd much prefer brass. I did at one time send a message to Northwest Shortline to see if they'd make those gears. They didn't seem to enthused about the project. I wonder if they are still trying to catch up on orders. Haven't heard any news from them for quite a while.

I have lots more ideas to expand on if interested.

Bernd

I hadn't realized those C-628s were actually A-1-A, Bummer. A few years back I dug around in Boston Gear Works' on-line catalog. They no longer listed helical gears of the sizes Hobbytown used but they expressed interest in custom orders.

Sorry I was such a dunce, thom.. it’s so much easier to understand after seeing yours wrapped up in the box.

I’m very familiar with, made 3 back in ‘the day’, Hobbytown of Boston and their drive train method. I still have an FA/FB set of Alco diesels. They were stump pullers in their day but have not been on a layout in close to 40 or more years. They’d pull every car on the layout of the long time departed Bob Jarkow of Lansing, MI. He ran one of the old time Mom and Pop hobby shops in his garage on the West side of Lansing, MI. What a task it was building the loco set with Lindsay Cast metal bodies and a thick stack of Linotype slugs in the unpowered unit for a might more traction. Drilling holes for the grab irons up the side of the nose was exciting with a pin vise.

https://en.wikipedia.org/wiki/Linotype_machine[:-jester]

Oh wow Bern-I forgot about those KTM's. Yeah I did one like you did back in the day.

Oh boy, that brings back memories. I must be really old?

Ha-ha,[:-headphones] Thanks K9, just for the record that's the before shot of the loco when I first received it.[}]

and yeah, speaking of hobbytown, I also started a couple old heavy cast engines and never finished them- now you flung a craven on me...Karl I have to go dig them up again?

I got my pictures all sized and ready to go here, I just have to write up what each one is.

I hope others here post some of their tank drive worx. That was cool to see one.

Thanx Thom...

I have one of these old Alco models C628's and a fellow club member installed one of the Stewart (Bowser) C628 frames and motors into the brass shell and came up great running locomotive, and I will do the same with the brass C628 in the future.

I am also going to install an Atlas S-4 drive into a crap running Alco Models T-6.

Rick Jesionowski

A few more things to add.

I found my pictures of the motor rebuild and think I know why I didn't finish the job. I'll explain in the last picture.

Here's the motor disassembled showing the original magnets in the motor housing.



This is what was needed to fit the new magnets in, or so I thought.



Two of these magnets were of close size in one direction only.



It was a little to thick.



A bit more milling on the motor frame and I was able to get the screws back in. Except the magnets stuck out to far above and below the motor. There was no way of fastening it back into the loco frame. So that ended that project.



Then on another forum (MR) there is a guy who calls himself "DarthSantaFe". I've seen several of his loco mods and was impressed when he did a Hobbytown conversion of a very old style kit Hobbytown offered. I have one of those.



He replaced the old Pitmann 70DC motor with a better motor from E-bay. So I purchased that same motor. I need to check to see what it was. I believe it was either a 7 pole ot 9 pole coreless. It's powerful, runs slow at 12 volts and has a low amperage draw under load. This got me to thinking about a tank drive system.



Now if we could only find a planetary gearbox to add to the motors available to us on E-bay.



The rest of the drive from the planetary gearbox down through the drop box to the helical gear sets in the trucks could all be 1:1 ratio for a smooth and quite drive.

Another idea I've got is to use one motor in an A-B-A F7 permanently coupled engine set with all wheels powered using drive shafts from the middle powered unit (B unit) to the A units. Hobbytown offered that system at one time for powering an A-B-A combination.

I'm just throwing ideas out here for your thoughts. Comments welcomed.

Sorry if I hi-jacked your thread Thom.

Bernd

Bernd,

Wow! I'm impressed, I've never thought of doing anything with magnets. I do have a few cast hobbytown units I need to dig up to take pictures of and get busy updating to today's standards, but that will take me a couple months for sure.

Here's one quick pic I had of a unfinished RS-3 Hobbytown tank drive with missing rear railings some 15+ years ago.

Thanx Thom...

Once you start you really stick to,it....[:-angel]
Berne, can you mill material from a magnet successfully?

Karl,

One word - NO

Here's why. Quote from K&J Magnetic's.

"Machining

Neodymium material is brittle and prone to chipping and cracking, so it does not machine well by conventional methods. Machining the magnets will generate heat, which if not carefully controlled, can demagnetize the magnet or even ignite the material which is toxic when burned. It is recommended that magnets not be machined."

More information can be found here: https://www.kjmagnetics.com/neomaginfo.asp

This the place I go for my magnets. They have a very large variety of magnets plus some useful info on them.

Bernd