For several years, train builders had been using the standard train wheels in those chunky, unrealistic encasings. Then some people came along and changed things for the better.
Enter the infamous “3mm tube method.” The idea here is to use a 3mm tube and insert it in clips or the equivalent:
The metal axles from Lego which clip into the wheels are inserted into the tube, and then lubricated to reduce resistance as much as possible. This design has been the mainstay for many years. But now train builders have been looking for the next best thing.
The answer? Ball bearings! Tiny ones, at that. Andrew Mollmann has discovered a bearing which is able to be press-fitted into a technic pin hole. It turns out, an MR52zz bearing fits right into a technic brick, albeit snugly. The Lego axle then fits through the center of the bearing.
Bearings have begun to slowly creep their way into train MOCs. Andy Mollmann and Cale Leiphart have been doing some testing on their own. Both have incorporated them into common freight truck designs:
Testing resistance compared to lubricated 3mm tubes:
And testing pulling power:
It’s always cool to see people think of new ways to do things. With less rolling resistance, cars can now be a little heavier and trains can be longer, but a locomotive doesn’t have to be any more powerful than it was.
Though, I’m sure we’ll come up with a new method for that too, sometime.