Thursday, January 06, 2011
High Level Models Hump shunter gearbox
The 165DS needs a motor and gearbox if it's be something other than a static model. As a shunter it's top speed needs to be low, instead an ability to traverse the goods yard at walking place. Once upon a time we'd have struggled to mesh some Romford gears, nowadays it's a whole lot easier to buy a simple to assemble double reduction gearbox from High Level Models.
For your money you get a slim package with an etched cradle, some plastic gears, bearings and steel rod. A motor is also required, I've used a Mashima 1220. This combination has proved reliable in other models I've built so I can't see any point in getting experimental.
Construction starts with the fitting of the axle bearings. The holes have to be reamed out very slightly to accept these. I'd recommend a tapered reamer for this. In fact I wouldn't try and put one of these 'boxes together without one or a decent set of cutting broaches. Round files are OK for some jobs but the accuracy available to the user of the proper tools does make the job a lot easier.
Next, the etch is folded up and checked for squareness. Tweak with fingers to get this right.
Then the steel rod has to be cut to length for the intermediate gears. The instructions say to use a cutting disk but I find a big pair of wire cutters works fine. Finish off with the file (hint, hold the rod in a pin vice) and keep it no longer than required.
Then fit the worm gear to the motor and pop the rest in. I retain the intermediate shafts with a smear of superglue on the outside of the cradle. Engineers will solder a little plate over the ends but I wasn't sure if this would make the gearbox too wide for the chassis. Anyway, I'd probably have melted the gears.
I can honestly say that no adjustment was required to get the mechanism running perfectly smoothly. Now will it fit in the loco ?
High Level Models website