Improving the Hornby-Jouef
Mistral 69 coaches (3)

Original page created on 19/03/2023.

Mechanical improvements

Change of axles

The coaches as delivered are leaning on the vertical axis, and are askew on the longitudinal axis, which is not very dignified for a luxury train! This is partly due to the fact that the axles float in the bearings. Curiously, the clearance is not the same on the front and rear axle of the same bogie, whatever the type (Y26 or Y28)… This clearance is at least 0.7 mm. The axles have a length between tips of 23.6 mm, whereas ideally they should be 24.4.

So, the first improvement is to change the axles, or the wheel sets themselves, for example to micro-modele standard or RP25 wheel sets.

I photographed the coaches at the end, next to a square, to get a vertical reference. I took into account the clearance of the axles on the track by pushing the coach as far left as possible.

A⁸u coach in its original condition:

You can clearly see that it is tilted, the angle varying from 88.8° to 89.1° precisely, depending on whether it is pushed to the left or right rail — I was expecting more difference due to the taper of the axle tips.

After replacing the axles, here’s what it looks like (it’s the same coach and the same end):

Surprising, isn’t it?

Three-point span

But it’s not perfect yet. I will therefore create a three-point span. It should be noted that HJ is one of the few manufacturers not to apply this principle systematically to its rolling stock.

After testing, it turns out that the height of the spans must be 4 or 6 mm, depending on the case. Here, on an A³rtu with Y28 bogies, the spans are made with 4 mm Plexiglas. To avoid shortening one of them by rounding off the profile, I tinted the surface with a red marker. You can see that there is some red tint left in the middle. Of course, the central pivot is shortened.

In another example, on the A⁴Dtux, the spans are made with a stack of 2 mm PS plates. The final adjustment is made with Evergreen spacers glued to the bogie.

On the single-span side, I round the pivot so that it looks (a bit!) like a ball joint.

Here is the combined result of the axle change and the three-point span:

Small comparative summary.