About rotating axle holders

LS Models has designed rotating axle holders, as does Roco for large-wheelbase wagons, for a better running in curves. And I wonder whether the connection wires I have planned, quite rigid (diameter 0.3 mm), could hinder the rotation?

While the wagon is in its cradle, legs up, I take the opportunity to do a little experiment. I place an R 356 Fleischmann Profi curved track coupon on the wagon wheels to observe the behaviour of the axle holders. Result: they don’t move a jot and remain desperately aligned. I still increase the angle between the rails and the wheels: nothing happens.

I do the same test with another TA60 devoid of electrical connections: same observation.

May it be because of the little too rigid return springs moulded with the axle holder? I inhibit them with small clamps: no more results! And if I rotate the axle holder by hand, it remains as it is even on a straight track!

Conclusion: this system of so-called radiant axles is totally inefficient and therefore unnecessary. But it exists; let it be as it is.

But why this doesn’t work?

I can hardly accept the above observation without a justification. It may be a matter of mechanical clearance between the axle and the track. So, let’s look at the NEM standards and let’s do some small calculations.

The NEM 110 standard gives the distance Gmin = 16.5 to Gmax = 16.8 as track gauge, in HO scale of course. According to NEM 310, for the axle, this rating is not given directly; it depends on the dimensions B (back-to-back distance between the wheels) and K (distance between a wheel back and the rolling point of the opposite wheel). These dimensions are: B = 14.5 ± 0.1 and K = 15.2 ± 0.1.

The distance between the wheels at the rolling points, which I note Z, can be deduced by the formula Z = 2K - B, with three times the tolerance, i.e. ± 0.3, because the tolerances must be added. This gives Z = 30.4 - 14.5 = 15.9 ± 0.3, i.e. Zmin = 15.6 and Zmax = 16.2. The clearance between the track and the axle is thus:

NEM axle dimensions

Extract from the NEM 310. © Morop.

Min. clearance = Gmin − Zmax = 16.5 − 16.2 = 0.3

Max. clearance = Gmax − Zmin = 16.8 − 15.6 = 1.2!

With relatively thin flanges and such a tolerance, it is not surprising that the axle position is not influenced by the curvature of the track! But, as long as there is no derailment, eh. By the way, I’ve been told that the actual TA60 wagons were rather prone to derailments…

Detail improvements

These are details that LS Models did not think fit to represent, but which are nevertheless clearly visible on the actual wagons.

Security chains

These chains, which block the upper deck ends, are wrapped into a sheath, the probable function of which is to protect the car bodies.

I have imitated them with a ø 0.1 copper wire wrapped into a ø 0.5 wrapping wire sheath. I fix this wire by wrapping it around the railings in a rather loose way. When in the correct position, I place a micro droplet of superglue just where the wire comes in contact with the railing.

Security chains

From the Het Utrechts Archief website

Once the glue dries, I unwind the excess wire and cut it with a scalpel blade. The ends that protrude from the sheath are painted grey.

It would perhaps have been more elegant to drill a ø 0.3 hole into the railing itself to pass the wire, because, in reality, and as can be seen in the picture, the chain is attached to a lug welded on this railing… And why not make these lugs, while we are at it!

Lower gateway locking bars

These bars are actually articulated near the body pillar to lift and release the lower deck lifting-bridge.

I used a simple ø 0.3 nickel silver wire, folded and burnished. Its vertical part is intentionally too long so that it can rest on the wagon floor and not remain in the air in cantilever. The body pillar is drilled at ø 0.4. The drilling is done at the point where there is a right angle moulding mark, which helps to centre the drill bit.

Locking bars

From the Het Utrechts Archief website

I drill with the mini-drill set at very low speed, with a carbide drill bit. A test with a drill bit holder was immediately punished by the breakage of the drill bit, while with the mini drill I made sixteen holes without a problem…

Tip: to burnish brass or nickel silver, parts must be completely degreased after handling, otherwise the result is not regular and does not hold. The best way to do this is to use not an organic solvent such as alcohol, for example, but caustic soda (sink unblocking type). It is a very aggressive but very effective product, to be handled with suitable gloves (the latex examination gloves are destroyed rather quickly). It is necessary to wash the parts thoroughly before going to burnishing. This is the degreasing method used in industry, before chemical or electrolytic surface treatment.


Click the list items to see the details.

  1. Security chain attachment.
  2. Passage of the tail lamp wires
  3. Locking bar.
Security chain Passage of the lamp wires Locking bar
  1. Security chain attachment
  2. Passage of the lamp wires
  3. Locking bar

For information, and because I still have a little space, here are the references of the cars loaded on this wagon:

Three quarters view

TA60 wagon equipped with lamps