Tuesday, February 17, 2015

Round holes

Wheels and steam

Anonymous asks in response to last weeks wheels question: Why aren't Gibsons on square axles? Surely there aren't many uses for unquartered drivers. Ease of production possibly?

Ease of production for one certainly. As one society new products officer found out, accurate and consistent square holes in the middle of plastic wheels are harder to make than you would think.

There are other reasons though - first, if you look at the ends of real loco axles, you see a circle of metal. Getting this wrong doesn't bother me but it does others. Markits make etched covers for their axles which are held in place by the screwed in crank pins but at the cost of making access to the wheel retaining nuts much harder.

More importantly, real locos aren't always quartered. 3-cylinder versions can have wheels at 120 degrees to each other. While you can't see both sides of a loco, replicating this accurately matters to a lot of people and the Gibson wheels allow this.

1 comment:

Ken555 said...

Lets not even mention Gresley Pacifics. Which had 120°, 114° and 126° depending on the angle of the cylinder.