Original page created on 15/09/2020.
Lowering the body
Assessment of the accident
As already mentioned, the breakage was limited, but real. The most serious is that of a bogie pivot, the one with two supports (the short dog points visible on either side of the pivot).
On the corresponding bogie, the U-shaped part which covers the worm has a broken arm. These arms hold the bogie in the body when lifting the machine. On the right, the aluminium part that will replace this arm.
Other damage: a handrail is bent. Two pantos taken off, but intact. A buffer bushel, ditto. Bogie sides dislocated, wires torn off. The SNCF and CC 40105 sidewall markings are quite damaged, and the sidewall itself has some marks, as if it had received a hail of pebbles. Parts not found: a jack supply pipe, a sandpit inlet.
Repairs
The most important thing is to repair the pivot. Slow-setting epoxy resin bonding (bonding will be better than with fast epoxy). Note that this pivot only serves to transmit the traction of the bogie to the chassis — which is no small feat. Support is provided by the two-point dog points. During curing, the parts are held together simply by a piece of tape.
Then, attempt to glue the screed arm with epoxy, which fails. The glue does not adhere to the plastic, which I had however scratched to improve the adhesion. Glueing redone with CA, retaining the epoxy layer which adheres well to the aluminium.
At this time, I decided to lower the body. Indeed, it is too high by 0.5 to 1 mm. Since the machine is dismantled, why not take advantage of it? The idea is to dig the bogie cups that receive the pivots. As these have their ends rounded, I will use a spherical mill bit, diameter 2.5 mm (ideal would have been ⌀ 3, but I don’t have). Of course, we have to proceed with caution and often check the progress of the machining.
Machining of bogie cups
First, almost completely dismantle the bogie. Note that the wheel set with tyres is the one located towards the end of the locomotive. In this photo, the pivot is not yet bonded, and the yoke, intact, is the other bogie’s…
Next, protect the very greasy interior of the worm cage to prevent swarf penetration.
Finally, machining of the cup. Carefully, I only remove 0.5 mm of material to begin with. The most difficult thing is to properly centre the mill bit.
Machining control
First, here is the control device: a simple countersunk screw that goes to the bottom of the cup.
Here is an example of a control measurement. Naturally, a measurement was taken before machining.
Another check, more important than the previous one, consists in looking at the height of the chassis placed successively on each bogie.
A priori, the two bogies are practically at the same height. But beware: the tests were made on the same pivot, the one that is intact. On the other end, there are the two dog point to adjust. I mill them about 0.5 mm. Checking with a caliper, rectification then rounding off the ends with a file.
