There are gears and there are gears! Updated

The splitting of the muff gears on the Trainorama 44 class is a well known fault and my locomotive 4473 was no different. A few years ago, at a model railway exhibition, I purchased a pack on replacement gears which were put away until I could find time to get around to it. 

A few months ago, I joined the NMRA and at a recent meeting, there was a short demonstration on how to replace the cracked gears on a 44 class. The first part of the demonstration focused on the technique to remove the cover plate on the bogies and second part showed how to replace the gears. The replacement gears were the same type as those which I had purchased earlier.

Armed with this knowledge, I decided that it was high time, I tackled this job. The removal of the bogie cover plate was achieved without difficulty as was the change over of each gear. The problems began when I started to reinstall the gears. The axles did not drop easily into place and required a lot of fiddling to settle in the bogie frame. When tested, the reassembled front bogie ran roughly and the rear bogie seized completely.

After several more unsuccessful attempts, it seemed that the gears were not meshing properly, certainly not as well as the set used in the demonstration. As a final throw of the dice, I purchased another pack of gears. These fitted dropped into the bogies without difficulty and 4473 was mobile again.

It seems there are gears and gears. Comparing the two packs, the teeth on the older pack seemed a bit smaller and the spacing may have been slightly different. I don't know if the older pack was faulty or if there had been some refinement in the design.

However, although 4473 is again mobile, the issue is still not fully resolved.  I have noticed that the axles on the front bogie are moving laterally, enough to displace the bushes which provide the electrical connection between the wheels and the frame. I'll check the gauging again but I suspect that the gears might be slightly shorter allowing the bushes to move more than they should. If all else fails it's off to Trainorama to purchase three new axles.

Update: I did check the gauging again and it seems I may have erred slightly in my earlier work. To date, the bushes appear to remain in position but I'll need to keep an eye on it.

 Further Update: It has still not run properly, so I gave up and purchased a complete set of wheels. That seems to have fixed it and 4473 has returned to service minus the original clicking sound.