Wednesday, February 25, 2009

Moded gearbox

Moded gearbox
Originally uploaded by Phil_Parker
Yesterday I blithely said "and motor/gearbox combo installed " which glossed over the fun involved in this process so today a little more details.

First, a history lesson. In the old days there was no such thing as a model railway gearbox outside the realms of the highest quality model makers with a fully equipped machine shop at their disposal. Normal souls would fit the crown gear to the axle and then fudge some sort of plate to hold the motor and its worm gear in something like the right place. Various suggestions were advanced to achieve a perfect mesh such as wrapping thread around the worm or using a piece of Bronco toilet paper between the two. Most people fiddled and adjusted finally settling on a less than perfect mesh as a better option than flinging the model across the room in frustration.

Sometime in the late 80's along with neon coloured clothing and Kajagoogoo the etched kit business got serious and people started to manufacture gearboxes to help the mesh challenged. Iain Rice's book of the time explains how to deal with both types of motorising as older kits still required you to put a DS10 or even X04 into your cast whitemetal chassis .

Anyway as far as I am concerned a gearbox is A Good Thing. My meshing is always terrible without one. I also like the opportunity to sort it out off the model. When asked how to do the mechanical bits my stock answer usually involves a Branchlines gearbox or for the really keen, something from High Level Models.

In the S&D tank a 'box is supplied on the etch. Sadly it's designed to use Ultrascale gears which are frequently difficult to obtain. Anyway I'd been supplied with a Romford set. This is fine except that the motor is offset to one side and the worm gear has a boss with the grub screw in it which wants to occupy the same space as the gearbox side.

To fix this I loped the offending metal off with a piercing saw. Hopefully this won't affect the structural strength detrimentally. So far I've got away with it.

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