another CAN m37 resto

[Edwin Wand]

Recently our M43 ambulance broke a rear axle, the short one. It was under no particular strain, had just been started and put in gear when there was a loud clunk and that was the end of the axle.

We replaced both axles albeit we had considerable difficulty in extracting one half of the broken axle that had become wedged. We removed and cleaned the differential and there was no further damage.

The interesting point is that in our opinion the steel was defective. Sheared in the middle, each piece ended in a sharp dagger much like a wet piece of wood might have split.

That it lasted 60 years is remarkable given this defect at the time of installation.

The metal was crystalled and discolured. It seems likely the cause was improper heat treating combined with too rapid quencing.

It would be interesting to know if others have experienced a similar short rear axle fracture as the result of defective steel.