A Replacement Drive Shaft for an N Scale Bachmann 4-4-0

Since releasing my N Scale MDC/Roundhouse/Athearn 2-8-0 & 2-6-0 drive shaft repair kits back in 2014, which can be found here, I have been asked to produce replacement drive shafts for several other N Scale locos.  One of these is the Bachmann 4-4-0.  So in this post I will share with you the results.

The Bachmann 4-4-0 or ‘American’ has been around since 1979 and for years was the only choice for a ready-to-run model of this locomotive.  The first generation, as pictured below, housed the motor in the tender.  This was then connected via a thick drive shaft to the driving wheels through to the back of the cab.

Bachmann 4-4-0 Old Style

The model had several improvements over the years but the one that I’m interested in  was made in 1998 when the drive shaft was changed, leaving the locomotive looking like the one below.

Bachmann 4-4-0 New Style

Together you can see the locomotives are basically the same, the newer one just has finer paint and details.

Bachmann 4-4-0 New & Old Style

The original locomotive’s drive shaft was a Hex-Cup style, pictured on the left in the image below.  This drive shaft was fairly bulky and dominated a lot of the space between the cab and tender.  On the end of the motor and worm gear inside the locomotive is a hexagonal nut that the ends of the drive shafts fit over.  This arrangement allows the linkage to flex as it goes round curves in the track.  The improvement in 1998 was to replace the bulky Hex-Cup with a Ball-Cup and peg design, as shown on the right.  The ball fits into a cup with slots on ether side.  The ball can rotate in all directions within the cup and the pegs rotate the shaft via the slots.

Bachmann 4-4-0 Drive Shafts

The Ball-Cup and peg design, apart from being much smaller, makes for a smoother motion which improves the performance of the loco.

However, as with all small parts it’s possible to lose these bits when servicing the loco or possibly they could break, particularly with those tiny pegs on the ball and cup connection.

Bachmann do sell replacements parts for the newer style drive shafts but they have been out of stock for a long time. As for the older Hex-Cup shaft it is likely that these are no longer available.

So I have drawn up both drive shafts and made them available on Shapeways.

Bachmann 4-4-0 Drive Shafts Rendering

The larger and earlier Hex-Cup type is available here and can be printed in either Shapeways’ Frosted Ultra Detail or their Frosted Extreme Detail materials.  As usual with these materials they can be used directly out of the bag but they are a white or translucent color.  They can be painted but they will need of be cleaned with a product such as Goo Gone in order to remove any wax residue left over from the print process.  The wax will prevent the paint from drying or adhering to the part.

The smaller Ball-Cup style drive shaft is available here and comes in a pair.  This is because, unlike its predecessor, the Ball-Cup drive shaft is a bit more delicate, particularly around the pegs so just in case the first one gets broken I have supplied a spare.  Again the second generation drive shaft is printable in both FUD and FXD materials from Shapeways.

This Ball-Cup and peg system has become a commonly used drive shaft across a lot of model manufactures but sadly the actual drive shafts are all a bit different; whether it is length or peg diameter the chances of one manufactures drive shaft fitting into an others locomotive is slim.  However if you are in need of a drive shaft for a particular model please let me know through the contacts page and I can draw up the parts and make them available on Shapeways.