I've always had a love-hate relationship with gearboxes in model locomotives. On one hand I can't mesh gears for toffee, on the other, making the gearbox work can be a real pain in the backside if the etcher hasn't done their job properly.
Branchlines boxes are usually better than most and it's rare the motor mounting holes have to opened out to increase the separation between the gears unlike some I've built !
This one is designed to take (supplied) Romford 40:1 gears and an open frame Mashima motor. Construction is simply a case of bending up the sides and fitting the super-slim axle bearings. As you can see I popped a jig-axle through these to keep them square. A touch from the reamer was needed to accept these
Once the metal was cleaned and dry, the motor was screwed into place, work gear fitted and finally the axles and final gear inserted. With a bit of power, the whole lot revolved beautifully first time. Very satisfying.