Below floor drivetrain for Multiple unit

[outcastjack]

Hello all, I am building some tube stock at the moment and would ideally like to tuck all of the drivetrain below floor level, so with this in mind, are there any very low profile motor bogie set ups around available off the shelf? If not does anyone have a recomendation for very compact motor, which may fit below the floor? if they are small enough to be mounted within the bogie then they do not have to be powerful as the stock can be made very light and i could if necessary power all of the bogies.

[Miss Prism]

Assuming 4mm scale, and it may or may not accord with what you regard as 'off the shelf', but:

http://clag.org.uk/tube-bogie.html

http://clag.org.uk/lpmu.html

 

The very small motors do need to be geared up sufficiently, otherwise they will not develop sufficient torque at low revs (and keep from getting too hot).

[Andy Reichert]

My struggling with power bogie designs over the past few years has led me to conclude is that EFE tube models are just about the most difficult cars to motorize without breaking at least part way into the interior. Most RTR self contained power bogies, such a the Tenshodo, Blackbeetle, Stanton, etc., are too high to fit into the space left by just removing the existing bogie. It's not so much a "space" as it is 4 separate wheel arches. So some cutting into (through) the floor would seem to be necessary

 

The alternative to self contained bogies is using one with very low height gearboxes, driven through end shafts from a separate very flat motor mounted under the floor centrally. That's something I'm looking into personally, but with so much else going on, progress is slow.  I'll post any other information that I may have stored away, later.

 

Andy

[outcastjack]

Those ideas are suitably off the shelf 

 

Thanks for the links I will be having a good look through them, I have ordered some micro motors to have a play with, so I am looking forward to that.

 

Andy, do you have a thread showing your approaches for the centre mount? I am tempted to give that a go too, the A stock i am making at the moment have a tonne of boxes (I assume for power electronics) under the centre of the coach where I could hang the motor and gearboxes.

[Andy Reichert]

Those ideas are suitably off the shelf 

 

Thanks for the links I will be having a good look through them, I have ordered some micro motors to have a play with, so I am looking forward to that.

 

Andy, do you have a thread showing your approaches for the centre mount? I am tempted to give that a go too, the A stock i am making at the moment have a tonne of boxes (I assume for power electronics) under the centre of the coach where I could hang the motor and gearboxes.

 

 

Here's a picture of a sub-floor unit I made up for a pair of 3v pager motors. Out put shaft is 1.5 mm and the first stage motor gear reduction is 1:3. A tiny axle worm drive gearbox will typically give another 14:1, for 42:1 total.  As Miss Prism points out, that may still be insufficient torque and low speed).

 

It's very similar looking to a CLAG project, although I came up with mine independently. The problem is getting hold of sufficient motor spur gears economically. (for less than the motors cost). I've since thought that adding a second unit on the same drive shaft (4 motors total, will allow for direct 12 v drive, which helps prevents motor burn out if one motor stalls.

 

The tiniest (lowest possible)  gearboxes are expensive but can be homemade using 2mm shop parts I think.

 

Andy

[DCB]

I have a small motor 1"  X 5/8" X 1/2" from a computer on my desk at present, it drove a spur gear train which drove a long lead screw which pulled the traversing head across a CD drive, 

I think the trick is to only power one axle per motor and no traction tyres to avoid overloading and overheating the motor.  N gauge gears are good for squeezing drive systems into small spaces.

[Mike Storey]

Have you looked at the Replica Railways (www.replicarailways.co.uk) powered, low floor 00 EMU chassis? These are currently just for 64 foot vehicles, but they are bringing out a 57 foot version soon. I am no expert on tube stock - would that be too long for your purposes? They do 14mm and 12mm wheel sets. You can easily change the bogie sides to suit the necessary appearance. I have used them on several BR EMU kits and they run superbly, with little adaption needed for the kit or the chassis.

[SRman]

Much of the underground stock was in the 51' - 52' range for length, although later stocks were longer.

 

The Replica chassis would still not be low enough for proper tube stock. They come up to a couple of millimetres below the window line of class 319 and 455 stock (Bratchell kits).

[Andy Reichert]

 

One possibly useful item that I missed mentioning, Alan Kirkman's tram chassis units, using Halling of Germany tram bogies, or the bogies directly themselves. The picture is Alan Kirkman's, which I lifted from the facebook tramway group. Hopefully Alan is OK with that.

 

Andy

[SRman]

That might just work! If it needs lengthening, one could cut through ahead of (or behind) the motor and lengthen the drive shaft to suit with a bit of brass tube. As for width, it may be optical illusion but it looks a little too wide for tube stock but if it does need narrowing, there looks to be a bit of material that could be shaved off without compromising strength too much.

[Andy Reichert]

That might just work! If it needs lengthening, one could cut through ahead of (or behind) the motor and lengthen the drive shaft to suit with a bit of brass tube. As for width, it may be optical illusion but it looks a little too wide for tube stock but if it does need narrowing, there looks to be a bit of material that could be shaved off without compromising strength too much.

 

I was thinking more of using the bogies and motor as mounted components rather than replacing the floor completely. However that's also a possibility.

 

 

The difficult aspect of completely preserving the interior is the way it drops down below the top of the wheels height, between the wheels.  As you can in the picture above. There is no gearbox I know of, that sits that low.

 

 

 

Just re-wheeling the trailing bogies is no problem.

 

Andy

[SRman]

I rewheeled mine with Steam Era wheels which are nice and heavy as well as running true, but there is still a lot of friction, just from the overall bogie design (I did remove the metal springing bits as they were acting as handbrakes).

I am about to replace the trailing bogies with Metro Models pin-point axle versions - with more Steam Era wheel sets.

[Joseph_Pestell]

I was thinking more of using the bogies and motor as mounted components rather than replacing the floor completely. However that's also a possibility.

 

 

The difficult aspect of completely preserving the interior is the way it drops down below the top of the wheels height, between the wheels.  As you can in the picture above. There is no gearbox I know of, that sits that low.

 

 

 

Just re-wheeling the trailing bogies is no problem.

 

Andy

 

Surely, your issue here is (as so often on our models) that you need the model to get round corners that are sharper than in real life. On the real thing, LUL get around the problem of low floors on tube stock by having a lot of kit above floor level but hidden by the seats.

 

I note the OP is currently working on A stock (sub-surface). That should be easy enough with powered bogies.

[Andy Reichert]

I rewheeled mine with Steam Era wheels which are nice and heavy as well as running true, but there is still a lot of friction, just from the overall bogie design (I did remove the metal springing bits as they were acting as handbrakes).

 

I am about to replace the trailing bogies with Metro Models pin-point axle versions - with more Steam Era wheel sets.

 

The "lot of friction" may be because the deep wheel flanges are touching the tops of the wheel arches. They actually were on my models, once the springy plates were removed. Fitting slightly smaller wheels or using P4 flanges fixed that aspect for me.

 

Andy

[Andy Reichert]

Surely, your issue here is (as so often on our models) that you need the model to get round corners that are sharper than in real life. On the real thing, LUL get around the problem of low floors on tube stock by having a lot of kit above floor level but hidden by the seats.

 

I note the OP is currently working on A stock (sub-surface). That should be easy enough with powered bogies.

 

The LT tube stock is a special case. The floor actually dips between the wheels and well below, into the traditional worm gearbox space, even if the bogies are running dead straight.

 

Andy

[Red Devil]

The Halling bogies shown above are 21.5mm wheelbase, so I think that may be a bit on the short side for tube stock, not certain, not my field....

 

But I think that Halling do a number of bogies similar for various things including Vienna Underground cars....

 

Pics and details of these can be found on this site http://www.skiptram.nl/

 

click modelbouw

click draaistellan

click systeem Halling

 

That'll give pics and dimensions.

 

An email to Halling should give details and prices, always very helpful and better English than I can muster!

 

I use quite a few various Halling bogies and a pair delivered to the UK is in my experience sub £30, bogie mounts are easily fashioned using Evergreen 40 thou x 250 thou strip and a file....

 

Hope that may help and give a few more ideas.

[6892 Oakhill Grange]

Have you considered the Hollywood foundry gozunder

 

www.hollywoodfoundry.com (never worked out how to do a link on an iPad)

 

This gives a floor height of approx 10mm above axle centre. I have never used them and cannot comment on performance.

 

Oakhill