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Model Railroader 1937 June
CONTENTS
THE ALLEGHANY ROUTE O gauge ba&p, started in 1928 now handles heavy interchange traffic
A LAYOUT PROTOTYPE build a belt line and copy the original in trackage as well as equipment
1937 PROTOTYPE FAVORITES pacific type locomotive, box car, coach are winners OO gauge gains
BUILDING A LOCOMOTIVE part 6 how to make up a cab and form a firebox out of sheet brass
AN O GAUGE ARTICULATED LOCO
RAIL SANDING DEVICES
CAPACITYAND LOAD LIMIT
SIGNALING FOR TWO-RAIL a review of methods and a brand new, simple, workable track circuit
A TINPLATE CONVERSION
Smooth Locomotive Operation.
SMOOTH locomotive operation on a model railroad is not an accident. It comes only after careful mechanical planning and accurate workmanship. And this applies not only to the locomotive but to the track on which it runs.
The ease and speed with which tinplate locomotives tear down the right of way gives an impression that most anything will run. We must remember, however, that the tinplate locomotives, despite their unrealistic appearance, are the product of long experience in mass production of operating miniature railroads. They run, because they're made to run. Many scale model locomotives are built with so much attention to detail that the primary object of having them operate is lost sight of.
The tinplate drive unit uses all spur gears and no thrust bearings are needed. To get greater reduction, most scale locomotives use worm drives, and the thrust bearing becomes a matter of prime importance. Did you ever stop to realize that the thrust exerted at the worm is greater than the entire tractive effort exerted at the rims of the driving wheels? If your locomotive is pulling a good string of cars, perhaps on an up grade, there's plenty of push backwards against the motor, and if bearings are not provided to properly absorb this push your motor will quickly go to pieces.
Good practice demands thrust bearings on both sides of the worm itself to take up the thrust produced by both forward and backward running. Ball thrust bearings are preferable, although plain friction type is much better than none. You can buy small ball thrust bearings from various commercial sources.
The thrust against the worm also means wear on the gears unless special care is taken in lining them up just right. The worm and gear should not mesh too closely or there will be
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